ISOACTEOSIDE DERIVATIVE AND USE THEREOF

Abstract

An isoacteoside derivative and forming method and uses thereof are provided. The isoacteoside derivative has the structure of formula (I):

Description

BACKGROUND

1. Field of Invention

The present invention relates to an isoacteoside derivative and forming method and use thereof. More particularly, the present invention relates to an isoacteoside derivative, forming method thereof and use of medicine including the isoacteoside derivative.

2. Description of Related Art

Isoacteoside belongs to a kind of phenylpropanoid glycosides, and presents in many plants. For example, Cistanche also contains this ingredient. The structure of the isoacteoside includes dihydroxy-phenethyl-D-glucoside, cinnamic acid ester, and a monosaccharide.

Based on current research, the isoacteoside has efficacy of neuroprotection, liver protection, antioxidant, and reducing biological activity of amyloid peptide aggregation. According to the test results for researching activity of WO 2011/157059 A1, when caffeoyl group was at the sixth position (such as isoacteoside), the activity of inhibiting β-amyloid peptides (Aβ) accumulation was better, and when the caffeoyl group was at the fourth position (such as acteoside), the activity decreased. These results show that the position of the caffeoyl group has a great effect on the activity of the isoacteoside.

Further, in pharmacological mechanism of isoacteoside for reducing Aβ aggregation, one possibility is that the bisphenol group of catechol and transition metals (such as copper, iron, zinc, etc) have a metal chelation reaction. A phenylethanoid group at the first position also includes a catechol group. Therefore, the phenylethanoid group should have a similar effect of metal chelation, and may be a necessary active group.

Accordingly, the present invention synthesizes a series of isoacteoside derivatives, which have efficacy of treating of preventing amyloid-related diseases (such as neuroprotection, reducing amyloid peptide aggregation, neurodegenerative disease, and eye disease).

SUMMARY

An aspect of the present invention provides an isoacteoside derivative, having a structure of formula (I):

in formula (I), R₁ and R₂ being independently selected from hydrogen, halogen, a hydroxy group, or a hydrocarboxyl group, R₃ and R₄ being independently selected from a hydroxy group, a hydrocarboxyl group, or an acyloxy group, and R₅ being independently selected from a hydroxy group or an acyloxy group.

According to one embodiment of the present invention, when at least one of R₁ and R₂ is the hydrocarboxyl group, the at least one of R₁ and R₂ is independently selected from an alkoxy group, an alkenyloxy group, or an aryloxy group.

According to one embodiment of the present invention, when at least one of R₁ and R₂ is the alkoxy group, the at least one of R₁ and R₂ is a methoxy group.

According to one embodiment of the present invention, when at least one of R₁ and R₂ is the alkenyloxy group, the at least one of R₁ and R₂ is an allyloxy group.

According to one embodiment of the present invention, when at least one of R₁ and R₂ is the aryloxy group, the at least one of R₁ and R₂ is a benzyloxy group.

According to one embodiment of the present invention, when at least one of R₃ and R₄ is the hydrocarboxyl group, the at least one of R₃ and R₄ is independently selected from an alkenyloxy group or an aryloxy group.

According to one embodiment of the present invention, when at least one of R₃ and R₄ is the alkenyloxy group, the at least one of R₃ and R₄ is an allyloxy group.

According to one embodiment of the present invention, when at least one of R₃ and R₄ is the aryloxy group, the at least one of R₃ and R₄ is a benzyloxy group.

According to one embodiment of the present invention, when at least one of R₃ and R₄ is the acyloxy group, the at least one of R₃ and R₄ is an acetoxy group.

According to one embodiment of the present invention, R₃ and R₄ are the same substituent.

According to one embodiment of the present invention, when R₅ is the acyloxy group, R₅ is an acetoxy group.

According to one embodiment of the present invention, R₅ are the same substituent.

According to one embodiment of the present invention, the isoacteoside derivative is selected from following structures:

Another aspect of the present invention provides a use of a medicine for preventing or treating an amyloid-related disease, which the medicine includes the aforementioned isoacteoside derivative.

Preferably, the amyloid-related disease is a neurodegenerative disease.

Preferably, the amyloid-related disease is Alzheimer's disease, mild cognitive impairment, Lewy body dementia, Down's syndrome, hereditary cerebral hemorrhage with amyloidosis-Dutch type, the Guam Parkinson-Dementia complex, progressive supranuclear palsy, multiple sclerosis, Creutzfeld Jacob disease, Parkinson's disease, frontotemporal dementia, Pick's disease, amyotrophic lateral sclerosis, inclusion-body myositis, adult-onset diabetes, senile cardiac amyloidosis, or endocrine tumor.

According to one embodiment of the present invention, the amyloid is β-amyloid peptide.

Yet another aspect of the present invention provides a use of a medicine for preventing an eye disease, which the medicine includes the aforementioned isoacteoside derivative.

Preferably, the eye disease is neuronal degeneration, visual cortical defect, glaucoma, cataract, ocular amyloidosis, macular degeneration, optic nerve drusen, optic neuropathy, optic neuritis, or lattice corneal dystrophy.

Yet another aspect of the present invention provides a method for forming an isoacteoside derivative, including reacting a compound having a structure of formula (II) with β-D-glucose pentaacetate to form a compound having a structure of formula (III), which formula (II) is:

• •  and formula (II) is:

In formula (II) and formula (III), R₁ and R₂ being independently selected from hydrogen, chloride, or a methoxy group. Next, (1) the compound having the structure of formula (III) is reacted with a mixture of palladium on carbon and methanol, after removing the palladium on carbon and purifying, is mixed with potassium carbonate, allyl bromide, and acetone, and after refluxing, is stirred in a potassium hydroxide-methanol solution to form a compound having a structure of formula (IV-1), which formula (IV-1) is:

in formula (IV-1), R₃ and R₄ being independently selected from hydrogen or an allyloxy group, (2) the compound having the structure of formula (III) is dissolved in methanol and mixed with sodium methoxide to form the compound having the structure of formula (IV-1), which R₃ and R₄ are independently selected from hydrogen, chloride, a methoxy group, or a benzyloxy group, or (3) the compound having the structure of formula (III) is reacted with acetyl chloride and methanol-dichloromethane to form a compound having a structure of formula (IV-2), which formula (IV-2) is:

in formula (IV-2), R₅ and R₆ being independently selected from hydrogen or chloride. Then, the compound having the structure of formula (IV-1) or the compound having the structure of formula (IV-2) is reacted with di-O-acetylferulic acid chloride, di-O-allylferulic acid chloride, or di-O-benzylferulic acid chloride in a solution of dichloromethane and pyridine to form a compound having a structure of any one of formulas (V-1)˜(V-4), which formula (V-1) is:

in formula (V-1), R₇ and R₈ being independently selected from hydrogen or an allyloxy group, formula (V-2) is:

in formula (V-2), R₉ and R₁₀ being independently selected from hydrogen, a methoxy group, or a benzyloxy group, formula (V-3) is:

in formula (V-3), R₁₁ and R₁₂ being independently selected from hydrogen, a methoxy group, or a benzyloxy group, and formula (V-4) is:

in formula (V-4), R₁₃ and R₁₄ being independently selected from hydrogen or chloride.

According to one embodiment of the present invention, the forming method further includes reacting the compound having the structure of formula (V-1) with copper(I) chloride and palladium dichloride in a mixture of methanol and water to form a compound having a structure of formula (VI-1), which formula (VI-1) is:

in formula (VI-1), R₁₅ and R₁₆ being independently selected from hydrogen or a hydroxyl group.

According to one embodiment of the present invention, the forming method further includes reacting the compound having the structure of formula (V-2) with methylamine in methanol to form a compound having a structure of formula (VI-1), wherein formula (VI-1) is:

in formula (VI-1), R₁₅ and R₁₆ being independently selected from hydrogen, chloride, a methoxy group, or a benzyloxy group.

According to one embodiment of the present invention, the forming method further includes reacting the compound having the structure of formula (V-4) with methylamine in methanol to form a compound having a structure of formula (VI-2), wherein formula (VI-2) is:

in formula (VI-2), R₁₇ and R₁₈ being independently selected from hydrogen or chloride.

The isoacteoside derivative of the present invention modifying the chemical structure of isoacteoside equips the drug including the isoacteoside derivative of the present invention with uses of treating or preventing the amyloid-related disease and preventing the eye disease.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:

FIGS. 1A-1D are result diagrams of the isoacteoside derivative of the embodiments of the present invention in inhibiting amyloid accumulation and cell viability;

FIGS. 2A-2B are result diagrams of the isoacteoside derivative of the embodiments of the present invention in inhibiting amyloid accumulation and cell viability, respectively;

FIGS. 3A-3B are result diagrams of the isoacteoside derivative of the embodiments of the present invention in inhibiting amyloid accumulation;

FIGS. 4A-4B are result diagrams of the isoacteoside derivative of the embodiments of the present invention in inhibiting amyloid accumulation;

FIG. 5 is a degradation result diagram of the isoacteoside derivative of the embodiments of the present invention; and

FIGS. 6A-6B are result diagrams of the isoacteoside derivative of the embodiments of the present invention in preventing eye disease.

DETAILED DESCRIPTION

The detailed description provided below is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples.

An aspect of the present invention provides an isoacteoside derivative, having a structure of formula (I):

in formula (I), R₁ and R₂ being independently selected from hydrogen, halogen, a hydroxy group, or a hydrocarboxyl group, R₃ and R₄ being independently selected from a hydroxy group, a hydrocarboxyl group, or an acyloxy group, and R₅ being independently selected from a hydroxy group or an acyloxy group.

It is noteworthy that the “hydrocarboxyl group” described herein represents a group generated by bonding a carboxyl group and oxygen ions, which the carboxyl group is an organic compound composed by carbon and hydrogen, including alkanes, alkenes, alkynes, cyclic hydrocarbons, and aromatic hydrocarbons. “Acyloxy group” represents a group generated by bonding an acyl group and oxygen ions, which the acyl group represents a functional group derived by the removal of one or more hydroxyl groups from an oxoacid.

Further, the “amyloid-related disease” described herein represents neurodegeneration, Alzheimer's disease, mild Cognitive Impairment, Lewy body dementia, Down's syndrome, hereditary cerebral hemorrhage with amyloidosis (Dutch type), the Guam Parkinson-Dementia complex, progressive supranuclear palsy, multiple sclerosis, Creutzfeld Jacob disease, Parkinson's disease, frontotemporal dementia, Pick's disease, amyotrophic lateral sclerosis, inclusion-body myositis, adult-onset diabetes, senile cardiac amyloidosis, or endocrine tumor.

Moreover, the “eye disease” described herein represents neuronal degeneration, visual cortical defect, glaucoma, cataract, ocular amyloidosis, macular degeneration, optic nerve drusen, optic neuropathy, optic neuritis, or lattice corneal dystrophy.

In an embodiment of the present invention, when at least one of R₁ and R₂ is the halogen, the at least one of R₁ and R₂ is chloride.

In an embodiment of the present invention, when at least one of R₁ and R₂ is the hydrocarboxyl group, the at least one of R₁ and R₂ is independently selected from an alkoxy group, an alkenyloxy group, or an aryloxy group.

It is noteworthy that the “alkoxy group” described herein represents a group generated by bonding an alkyl group and oxygen ions. The “alkenyloxy group” described herein represents a group generated by bonding an alkenyl group and oxygen ions. The “aryloxy group” described herein represents a group generated by bonding an aryl group and oxygen ions, which the aryl group represents a functional group derived from any aromatic rings.

In an embodiment of the present invention, when at least one of R₁ and R₂ is the alkoxy group, the at least one of R₁ and R₂ is a methoxy group. The methoxy group has a structure of —O—CH₃, and is indicated as “OMe” in the following formulas.

In an embodiment of the present invention, when at least one of R₁ and R₂ is the alkenyloxy group, the at least one of R₁ and R₂ is an allyloxy group. The allyloxy group has a structure of

• •  and is indicated as “OAII” in the following formulas.

In an embodiment of the present invention, when at least one of R₁ and R₂ is the aryloxy group, the at least one of R₁ and R₂ is a benzyloxy group. The benzyloxy group has a structure of

• •  and is indicated as “OBn” in the following formulas.

In an embodiment of the present invention, when at least one of R₃ and R₄ is the hydrocarboxyl group, the at least one of R₃ and R₄ is independently selected from an alkenyloxy group or an aryloxy group.

In an embodiment of the present invention, when at least one of R₃ and R₄ is the alkenyloxy group, the at least one of R₃ and R₄ is an allyloxy group.

In an embodiment of the present invention, when at least one of R₃ and R₄ is the aryloxy group, the at least one of R₃ and R₄ is a benzyloxy group.

In an embodiment of the present invention, when at least one of R₃ and R₄ is the acyloxy group, the at least one of R₃ and R₄ is an acetoxy group. The acetoxy group has a structure of

• •  and is indicated as “OAc” in the following formulas.

In an embodiment of the present invention, R₃ and R₄ are the same substituent.

In an embodiment of the present invention, when R₅ is the acyloxy group, R₅ is an acetoxy group.

In an embodiment of the present invention, R₅ are the same substituent.

In an embodiment of the present invention, the isoacteoside derivative is selected from following structures:

Another aspect of the present invention provides a use of a medicine for preventing or treating an amyloid-related disease, which the medicine is prepared from the aforementioned isoacteoside derivative.

According to one embodiment of the present invention, the amyloid is β-amyloid peptide (Aβ).

β-amyloid peptide is an amyloid precursor protein (APP), and by reactions of different secretases, the β-amyloid peptide with about 37-49 amino acids is formed from a protein originally with 770 amino acids. Aβ₄₀ and Aβ₄₂ are commonly seen β-amyloid peptide, which β-amyloid plaque is more easily formed for Aβ₄₂ comparing to Aβ₄₀ due to its higher hydrophobicity. The accumulated Aβ has cytotoxicity, which may induce a series of complex reaction, such as synaptic change, Tau protein phosphorylation, neurotransmitter reduction, glial cell proliferation, and inflammatory reactions. These reactions may cause a series of pathological damage, such as plaque formation and neurofibrillary tangle, resulting in neuronal degeneration and dysfunction, or even death, and eventually leading to neurodegenerative diseases. β-amyloid plaque accumulation is considered to be one of the causes of Alzheimer's disease, and therefore most development of related medicine for treating or preventing the occurrence of Alzheimer's disease and worsening of symptoms currently is mainly to interfere the production pathway of the β-amyloid peptide. By reducing the generation of β-amyloid peptide, inhibiting the accumulation of β-amyloid peptide extracellularly, and inhibiting the aggregation of β-amyloid peptide, the formation of β-amyloid plaques can be prevented. The isoacteoside derivative of the present invention can inhibit the aggregation, and thereby having effects of neuroprotection, treating neurodegenerative diseases, etc.

Yet another aspect of the present invention provides a use of a medicine for preventing an eye disease, which the medicine is prepared from the aforementioned isoacteoside derivative.

As individual ages, the accumulation of oxidative damage caused by free radicals to cell DNA, proteins, lipids, and other cellular macromolecules can cause aging, which the degeneration of the retina and the central nervous system are believed to be highly correlated to oxidative stress damage. Retinal pigment epidermis (RPE) cell is located between neuroepithelial layer of retina and choroid, and has a variety of physiological functions, such as retinal barrier, phagocytosis, involving in metabolism of visual cycle, antioxidant, and secretion of growth factors. Like other tissues, retinal pigment epidermis cell is susceptible to oxidative stress damage, which causes cell death and leads to retinopathy, visual dysfunction, or loss of visual function in severe cases. Therefore, retinal pigment epidermis cell is often used as cell model for retinopathy diseases, such as diabetic retinopathy and age-related macular degeneration. The isoacteoside derivative of the present invention can reduce the free radicals, and prevent oxidative stress damage, and thereby having effects of antioxidant, protecting the retinal cells, preventing the eye disease, etc.

The isoacteoside derivative of the present invention modifies the chemical structure of isoacteoside to have the effects of treating or preventing the amyloid-related disease, neuroprotection, treating neurodegenerative disease, preventing the eye disease, etc.

The following provides several examples to describe the method of the present invention in greater detail, however, it is intended as a exemplary description, and is not intended to limit the present invention. The protection scope of the present invention depends on the appended claim.

Synthesis of Isoacteoside Derivative

Procedures A-G were used to synthesis the isoacteoside derivative of the embodiments.

Procedure A included the following steps:

• • 1. At room temperature (r.t), 5 mmol of boron trifluoride-diethyl etherate (BF₃Et₂O) solution was added to 25 mL of dichloromethane (DCM) solution, which included 5 mmol of β-D-glucose pentaacetate, and respectively included 10 mmol of compounds 1a-1f having structures of formula (II). Formula (II) was:

• •  which the compound 1a's R₁ was hydrogen, and R₂ was hydrogen; the compound 1b's R₁ was hydrogen, and R₂ was chloride; the compound 1c's R₁ was a methoxy group (OMe), and R₂ was a methoxy group; the compound 1d's R₁ was hydrogen, and R₂ was a benzyloxy group (OBn); the compound 1e's R₁ was a benzyloxy group, and R₂ was a benzyloxy group; and the compound 1f's R₁ was a benzyloxy group, and R₂ was hydrogen.
  • 2. The mixture of step 1 was stirred for 6 hours, and then was vigorously stirred with saturated aqueous sodium bicarbonate solution for 30 min.
  • 3. The combined extracts of step 2 were dried, filtered and evaporated. Then, the residue was purified by silica gel using a solvent mixture of ethyl acetate/n-hexane (EA:n-hexane=1:4, v/v) to give compounds 2a-2f having structures of formula (III), which the yield for compound 2a was 45%. Formula (III) was:

• •  which the compound 2a's R₁ was hydrogen, and R₂ was hydrogen; the compound 2b's R₁ was hydrogen, and R₂ was chloride; the compound 2c's R₁ was a methoxy group, and R₂ was a methoxy group; the compound 2d's R₁ was hydrogen, and R₂ was a benzyloxy group; the compound 2e's R₁ was a benzyloxy group, and R₂ was a benzyloxy group; and the compound 2f's R₁ was a benzyloxy group, and R₂ was hydrogen.

The reaction process of Procedure A was as follows:

Procedure B included the following steps:

• • 1. 2 mmol of the compounds 2d-2f were respectively mixed with 10% of palladium on carbon (Pd/C) in methanol (MeOH), which was stirred at room temperature under hydrogen (H₂) for 6 hours. Then, the catalyst was filtered off, and the filtrate was concentrated in vacuo to give a yellow residue. The residue was purified by silica gel using a solvent mixture of ethyl acetate/n-hexane (EA:n-hexane=1:1, v/v) to give an intermediate product.
  • 2. The intermediate product of step 1 was mixed with potassium carbonate, allyl bromide, and acetone. The mixture was refluxed under a CaCl₂ drying tube in a silicone oil bath for 10 hours and then cooled to room temperature.
  • 3. The insoluble salts of step 2 were filtered, and washed with DCM. Then, the filtrate and DCM were evaporated.
  • 4. The crude product of step 3 was stirred in 10% of potassium hydroxide-methanol (KOH-MeOH) solution for 30 minutes. Then, the mixture was evaporated under reduced pressure. The residue was purified by silica gel using a solvent mixture of ethyl acetate/n-hexane (EA:n-hexane=1:2, v/v) to give compounds 3d-3f having structures of formula (IV-1). Formula (IV-1) was:

• •  which the compound 3d's R₁ was hydrogen, and R₂ was an allyloxy group (OAII); the compound 3e's R₁ was an allyloxy group, and R₂ was an allyloxy group; and the compound 3f's R₁ was an allyloxy group, and R₂ was hydrogen.

The reaction process of Procedure B was as follows:

Procedure C included the following steps:

• • 1. 1.5 mmol of sodium methoxide (NaOMe) was respectively added to 3 mmol of compounds 2a-2f in 15 mL of methanol solution. The mixture was stirred at room temperature for 30 minutes.
  • 2. The mixture of step 1 was evaporated under reduced pressure. The residue was purified by silica gel using a solvent mixture of ethyl acetate/n-hexane (EA:n-hexane=1:4, v/v) to give compounds 3a-3c and 3g-3i having the structures of formula (IV-1), which the yield for compound 3a was 85%. The compound 3a's R₁ was hydrogen, and R₂ was hydrogen; the compound 3b's R₁ was hydrogen, and R₂ was chloride; the compound 3c's R₁ was a methoxy group, and R₂ was a methoxy group; the compound 3g's R₁ was hydrogen, and R₂ was a benzyloxy group; the compound 3h's R₁ was a benzyloxy group, and R₂ was a benzyloxy group; and the compound 3i's R₁ was a benzyloxy group, and R₂ was hydrogen.

The reaction process of Procedure C was as follows:

Procedure D included the following steps:

• • 1. 0.01 mmol of acetyl chloride was respectively added to a solution with 2 mmol of compound 2a or 2b in 10 mL of 1:1 methanol-dichloromethane (MeOH/DCM). The mixture was stirred at room temperature for 48 hours, and at the end of which time, thin layer chromatography (TLC) was used to indicate the reaction was complete.
  • 2. The mixture of step 1 was neutralized with triethanolamine (TEA). Then, the reaction mixture was concentrated, and the residue was passed through a silica gel column with ethyl acetate (EA) as the eluent to give compounds 3j and 3k having the structures of formula (IV-2). Formula (IV-2) was:

• •  which the compound 3j's R₁ was hydrogen, and R₂ was hydrogen; and the compound 3k's R₁ was hydrogen, and R₂ was chloride.

The reaction process of Procedure D was as follows:

Procedure E included the following steps:

• • 1. Based on different compounds, step 1 of Procedure included the following three conditions:
    • a. 2 mmol of compounds 3a-3c, 3g, 3h, 3j, and 3k were respectively added at 0° C. to a solution with 2.2 mmol of di-O-acetylferulic acid chloride, dichloromethane, and 1.5 mL of pyridine.
    • b. 2 mmol of compounds 3d-3f were respectively added at 0° C. to a solution with 2.2 mmol of di-O-allylferulic acid chloride, dichloromethane, and 1.5 mL of pyridine.
    • c. 2 mmol of compounds 3a, 3c, 3g, and 3i were respectively added at 0° C. to a solution with 2.2 mmol of di-O-benzylferulic acid chloride, dichloromethane, and 1.5 mL of pyridine. The mixture was stirred at 10° C. for 10 hours. The solvent was evaporated and the residue was dissolved in ethyl acetate.
  • 2. The organic layer of the intermediate product of step 1 was washed successively with water and brine, and dried with MgSO₄ and evaporated. The residue was purified by silica gel using a solvent mixture of ethyl acetate/n-hexane (EA:n-hexane=1:1, v/v) to give compounds 4d-4f having the structures of formula (V-1), compounds 4a-4c, 4g, and 4h having the structures of formula (V-2), compounds 4i and 4m-4o having the structures of formula (V-3), and compounds 4j and 4k having the structures of formula (V-4), which the yield for compound 4a was 43%.
    • Formula (V-1) was:

• •  which the compound 4d's R₁ was hydrogen, and R₂ was an allyloxy group; the compound 4e's R₁ was an allyloxy group, and R₂ was an allyloxy group; and the compound 4f's R₁ was an allyloxy group, and R₂ was hydrogen.
    • Formula (V-2) was:

• •  which the compound 4a's R₁ was hydrogen, and R₂ was an hydrogen; the compound 4b's R₁ was hydrogen, and R₂ was chloride; the compound 4c's R₁ was a methoxy group, and R₂ was a methoxy group; the compound 4g's R₁ was hydrogen, and R₂ was a benzyloxy group; and the compound 4h's R₁ was a benzyloxy group, and R₂ was a benzyloxy group.
    • Formula (V-3) was:

• •  which the compound 4i's R₁ was a benzyloxy group, and R₂ was hydrogen; the compound 4m's R₁ was hydrogen, and R₂ was a benzyloxy group; the compound 4n's R₁ was hydrogen, and R₂ was hydrogen; and the compound 4o's R₁ was a methoxy group, and R₂ was a methoxy group.
    • Formula (V-4) was:

• •  which the compound 4j's R₁ was hydrogen, and R₂ was hydrogen; and the compound 4k's R₁ was hydrogen, and R₂ was chloride.

The reaction process of Procedure E for forming the compounds 4d-4f was as follows:

• •  the reaction process for forming the compounds 4a-4c, 4g, and 4h was as follows:

• •  the reaction process for forming the compounds 4i and 4m-4o was as follows:

• •  and the reaction process for forming the compounds 4j and 4k was as follows:

Procedure F included the following steps:

• • 1. The compounds 4d-4e were respectively mixed with copper(I) chloride (CuCl) and palladium(II) chloride (PdCl₂) in methanol and water, and was stirred strongly at room temperature to give compounds 5d-5f having the structures of formula (VI-1).
    • Formula (VI-1) was:

• •  which the compound 5d's R₁ was hydrogen, and R₂ was a hydroxyl group; the compound 5e's R₁ was a hydroxyl group, and R₂ was a hydroxyl group; and the compound 5f's R₁ was a hydroxyl group, and R₂ was hydrogen.

The reaction process of Procedure F for forming the compounds 5d-5f was as follows:

Procedure G included the following steps:

• • 1. 1 mL of 40% methylamine in methanol was added to a solution respectively with 2 mmol of the compounds 4a-4c, 4g, 4h, 4j, and 4k in dichloromethane at 10° C.
  • 2. The reaction mixture of step 1 was stirred for 20 minutes and then concentrated in vacuo. The residue was purified by silica gel using a solvent mixture of methanol/dichloromethane (1:20, v/v) to give compounds 5a-5c, 5g, and 5h having the structures of formula (VI-1) and compounds 5j and 5k having the structures of formula (VI-2), which the yield for the compound 5a was 90%. The compound 5a's R₁ was hydrogen, and R₂ was an hydrogen; the compound 5b's R₁ was hydrogen, and R₂ was chloride; the compound 5c's R₁ was a methoxy group, and R₂ was a methoxy group; the compound 5g's R₁ was hydrogen, and R₂ was a benzyloxy group; and the compound 5h's R₁ was a benzyloxy group, and R₂ was a benzyloxy group. Formula (VI-2) was:

• •  which the compound 5j's R₁ was hydrogen, and R₂ was hydrogen; and the compound 5k's R₁ was hydrogen, and R₂ was chloride.

The reaction process of Procedure G for forming the compounds 5a-5c, 5g, and 5h was as follows:

• •  and the reaction process for forming the compounds 5j and 5k was as follows:

The following experimental examples used samples 1-9 listed in the following Table 1 to prepare solutions with different concentrations to conduct various experiments.

TABLE 1
Sample 1 (Compound 4j)
Sample 2 (Compound 4k)
Sample 3 (Compound 4n)
Sample 4 (Compound 5a)
Sample 5 (Compound 4m)
Sample 6 (Compound 4i)
Sample 7 (Compound 4o)
Sample 8 (Compound 5g)
Sample 9 (Compound 5e)

4o¹HNMR (CDCl₃) δ7.60 (d, 1H, J=18), δ7.43-7.21 (m, 15H), δ7.31-7.25 (m, 3H) δ6.77 (d, 1H, J=9), δ6.29 (d, 1H, J=18), δ5.16 (d, 4H, J=9), δ4.64-4.40 (m, 1H), δ4.36-4.11 (m, 2H), δ3.76-3.35 (m, 6H), δ2.94 (t, 2H, J=6).

4i¹HNMR (CDCl₃) δ7.67 (d, 1H, J=16), δ7.45-7.29 (m, 3H), δ7.24 (d, 1H, J=12), δ6.8 (s, 1H), δ7.76 (s, 2H), δ6.53 (d, 1H, J=16), δ4.45-3.90 (m, 3H), δ3.90-3.81 (m, 1H), δ3.78-3.74 (m, 8H), δ3.73-3.70 (m, 1H), δ3.60-2.86 (m, 5H).

4m¹HNMR (CDCl₃) δ7.60 (d, 1H, J=18), δ7.43-6.84 (m, 22H), δ6.29 (d, 1H, J=18), δ5.13 (s, 4H), δ4.97 (s, 2H), δ4.68-4.63 (m, 1H), δ4.37-4.06 (m, 2H), δ3.73-3.36 (m, 6H), δ2.94 (t, 2H, J=6).

4n¹HNMR (CDCl₃) δ7.60 (d, 1H, J=18), δ7.43-7.01 (m, 15H), δ7.41-7.45 (m, 3H) δ6.87 (d, 1H, J=9), δ6.29 (d, 1H, J=18), δ5.16 (d, 4H, J=9), δ4.64-4.40 (m, 1H), δ4.36-4.11 (m, 2H), δ3.76-3.35 (m, 6H), δ2.94 (t, 2H, J=6).

5a¹HNMR (CDCl₃) δ7.34-7.21 (m, 7H), δ6.80-6.53 (m, 3H), δ5.02 (s, 2H), δ4.38-4.05 (m, 3H), δ3.73-4.3.70 (m, 1H), δ3.22-2.92 (m, 3H), δ2.91-2.62 (m, 7H), δ2.62 (t, 2H, J=6).

First, samples 1-9 listed in Table 1 were accurately weighed respectively, and dimethyl sulfoxide (DMSO) was used as a solvent to prepare stocks with a concentration of 10 mM. The molecular weight and weight of the samples and the volume of the solvent included in the stocks are listed in the following Table 2.

	TABLE 2
	Sample molecular	Sample
	weight	weight (mg)	Solvent volume (mL)
Sample 1	656.6	10.1	1.53
Sample 2	691.6	11.2	1.62
Sample 3	626.4	10.8	1.72
Sample 4	446.5	11.2	2.50
Sample 5	732.4	11.8	1.61
Sample 6	732.4	10.5	1.43
Sample 7	686.7	11	1.60
Sample 8	552.5	10.2	1.85
Sample 9	478.45	20	4.18

Then, the stocks with the concentration of 10 mM were used to prepare solutions with different sample concentrations. The stocks were used to prepare a concentration of 5 μM, which 0.5 μL of the stocks were diluted to 1 mL; to prepare a concentration of 10 μM, which 1 μL of the stocks were diluted to 1 mL; to prepare a concentration of 20 μM, which 2 μL of the stocks were diluted to 1 mL; to prepare a concentration of 50 μM, which 5 μL of the stocks were diluted to 1 mL; to prepare a concentration of 100 μM, which 1 μL of the stocks were diluted to 0.1 mL; and to prepare a concentration of 200 μM, which 2 μL of the stocks were diluted to 0.1 mL.

Experimental example 1 to Experimental example 4 used the following three aspects to evaluate the efficacy of the isoacteoside derivative of the present invention, including: 1) whether the formation of β-amyloid peptide (Aβ) in cell can be decreased; 2) whether by promoting the activity of the enzyme that is responsible for eliminating β-amyloid peptide, the efficiency of eliminating β-amyloid peptide can be thereby increased; and 3) whether the aggregation of Aβ₄₀ and Aβ₄₂ can be inhibited.

Experimental Example 1

Experiment on Inhibiting Aβ₄₀ Accumulation (I)

This experiment was divided into two stages: The first stage used a lower sample concentration for preliminary screening; the second stage was based on the result of the first stage to choose effective samples and increased the testing concentration of the samples in order to obtain the best concentration and the best result of sample for inhibiting Aβ₄₀ accumulation without affecting the cytotoxicity.

Experimental method: Human neuroblastoma cell (SH-SY5Y-APP695), which expresses Swedish APP695 mutation, was incubated in a 3.5-cm culture dish until the cell concentration reached 90% full. When passage, each well of a 24-well plate was seeded with 4×10⁵ cells. The culture medium was replaced with 300 μL of chemical-defined medium, which is a DMEM/F12 medium including 5 mM of Hepes buffer, 0.6% of glucose, 3 mM of NaHCO₃, 2.5 μM of glutamine, 100 μg/mL of transferrin, 20 nM of progesterone, 60 μM putrescine, 30 nM of sodium selenite, and 2 μg/mL of heparin, the next day. 3 μL of the testing sample was added into each well, and each concentration of each sample included 4 groups. After the cells were placed in an incubator (37° C., 5% CO₂) and treated with the samples for 24 hours, the culture medium was collected and analyzed the amount of Aβ₄₀ in the culture medium after treated by the samples through Human Aβ_1-40 Immunoassay kits (Cat.KHB3482, Life Technologies). The cells treated by the samples were analyzed by MTT assay to evaluate the toxicity to the cells caused by sample treatment.

The testing concentrations of Sample 1 were 5 μM and 10 μM, and the testing concentrations of Samples 2-8 were 10 μM and 20 μM. The amount of Aβ₄₀ in a SH-SY5Y-APP695 cell medium that there was no sample added as a control and set to 100%, and the amounts of Aβ₄₀ in the medium after respectively treated by the testing samples were compared to the control and expressed in percentage. β-secretase inhibitor (β-SI) was used as a positive control. The experiment results are shown in FIGS. 1A-1D, which FIGS. 1A and 1C are result diagrams of the samples in inhibiting Aβ₄₀ accumulation, and FIGS. 1B and 1D are result diagrams of the cell viability after treated by the samples. The results shown in FIGS. 1A-1D are mean±standard error of four experimental groups (n=4), and the statistical differences between the control and the testing samples were analyzed by Dunnett's multiple comparison test, which “*” represented p<0.05; “**” represented p<0.01; “***” represented p<0.001; and “****” represented p<0.0001.

Experimental example 1 used a lower sample concentration for preliminary screening, and the results showed in FIGS. 1A-1D suggested that Sample 3, 4, and 6 had effects of inhibiting Aβ₄₀ accumulation, which Sample 3 had the best result of inhibiting Aβ₄₀ accumulation, and the efficacy of inhibiting Aβ₄₀ accumulation of Sample 3 increased as the sample concentration increased.

Experimental Example 2

Experiment on Inhibiting Aβ₄₀ Accumulation (II)

Based on the experiment results of Experimental example 1, Sample 3, 4, and 6 having efficacy of inhibiting Aβ₄₀ accumulation were selected. The testing concentrations of the samples were increased to 20, 50, and 100 μM, and were experimented using the method of Experimental example 1. Each concentration of each sample included 4 groups, and the experiment results are shown in FIGS. 2A-2B. FIG. 2A is a result diagram of the samples in inhibiting Aβ₄₀ accumulation, and FIG. 2B is a result diagram of the cell viability after treated by the samples. The results shown in FIGS. 2A-2B are mean±standard error of four experimental groups (n=4), and the statistical differences between the control and the testing samples were analyzed by Dunnett's multiple comparison test, which “*” represented p<0.05; “**” represented p<0.01; “***” represented p<0.001; and “****” represented p<0.0001.

In Experimental example 2, the concentrations of Samples 3, 4, and 6 were increased in order to obtain the best concentration and the best result of the samples for inhibiting Aβ₄₀ accumulation in a condition of not affecting the cytotoxicity. The results showed in FIGS. 2A-2B suggested that in the condition of not affecting the cytotoxicity, Sample 3 could inhibit about 20% of accumulation in the concentration of 20 μM, and Sample 6 could inhibit about 40% of accumulation in the concentration of 50 μM, while increasing the sample concentration could not further enhance the efficacy of inhibiting Aβ accumulation for Sample 4.

Therefore, based on the results of Experimental example 1 and Experimental example 2, the isoacteoside derivative of the embodiments of the present invention does have the efficacy of inhibiting Aβ₄₀ accumulation.

Experimental Example 3

Experiment on Inhibiting Aβ Aggregation (I)

Experimental example 3 was to confirm the efficacy of the samples on inhibiting Aβ₄₀ and Aβ₄₂ aggregation.

Aβ₄₀ aggregation: The Aβ₄₀ stock was redissloved in DMSO to 10 mg/mL. Each group included 0.5 μL of 10 mg/mL Aβ₄₀ and 4.5 μL of the testing sample diluted with Dulbecco's Phosphate-Buffered Saline (D-PBS). The concentrations of Sample 1 were 10 μM and 100 μM, and the concentrations of Sample 2-8 were 20 μM and 200 μM. The total reaction volume was 5 μL, and each concentration of each sample included 6 groups. After incubating in a 37° C. incubator for 4 hours, 200 μL of thioflavin T working solution (ThT working solution) was added and mixed thoroughly, which the thioflavin T working solution was 10 μM of thioflavin T dissolving in potassium phosphate buffer (PB buffer, pH 6.0). 200 μL of the mixture was placed into a black, clear bottom 96-well plate, and the ThT fluorescence intensity (Ex: 440 nm, Em: 482 nm) was measured to determine the level of Aβ₄₀ aggregation. This experimental example used thioflavin T assay (ThT assay) to evaluate the level of Aβ₄₀ aggregation. Since ThT and Congo red derivatives can form bonds with aggregated form of Aβ protein, the level of Aβ aggregation is higher when the amount of bonded ThT is more. By detecting the variation in the amount of ThT, the change in the level of Aβ aggregation can be estimated. The value of not reacting with any sample (i.e. only containing 0.5 μL of Aβ₄₀ and 4.5 μL of D-PBS, which the final concentration of Aβ₄₀ was 1 mg/mL) was a control and set to 100%, and isoacteoside (IsoA) was used as a positive control. The values of the testing samples were compared to the control and expressed in percentage, and the experiment results are shown in FIGS. 3A-3B. The results shown in FIGS. 3A-3B were mean±standard error of six experimental groups (n=6), and the statistical differences between the control and the testing samples were analyzed by Dunnett's multiple comparison test, which “*” represented p<0.05; “**” represented p<0.01; “***” represented p<0.001; and “****” represented p<0.0001.

FIG. 3A shows the experiment results of Samples 1-9 with a lower concentration in inhibiting Aβ₄₀ accumulation. The concentration of Sample 1 was 10 μM, the concentration of Samples 2-9 was 20 μM, and the concentration of IsoA was 10 μg/mL. The measured value of the control without adding any sample was set to 100%, and other values were adjusted accordingly. FIG. 3B shows the experiment results of Samples 1-9 with a higher concentration in inhibiting Aβ₄₀ accumulation. The concentration of Sample 1 was 100 μM, the concentration of Samples 2-9 was 200 μM, and the concentration of IsoA was 100 μg/mL. The measured value of the control without adding any sample was set to 100%, and other values were adjusted accordingly. The experiment results shown in FIG. 3A suggested that in the lower concentration, Sample 2 could inhibit about 20% of Aβ₄₀ aggregation in the concentration of 20 μM, and in the same concentration, Samples 4 and 8 could inhibit about 30% of Aβ₄₀ aggregation. The experiment results shown in FIG. 3B, which increased the concentrations of the samples and repeated the experiment, suggested that in the concentration of 200 μM, Samples 2 and 4 could inhibit about 20% of Aβ₄₀ aggregation, and Sample 8 could inhibit up to 70% of Aβ₄₀ aggregation.

Experimental Example 4

Experiment on Inhibiting Aβ Aggregation (II)

Experimental example 4 increased the testing concentrations of the samples to confirm the efficacy of the samples on inhibiting Aβ₄₂ aggregation.

Experimental method: Aβ₄₂ was redissloved in DMSO to 2.5 mg/mL, and Samples 1-9 were diluted with D-PBS to appropriate concentrations. The concentrations of Sample 1 were 10 μM and 100 μM, the concentrations of Sample 2-9 were 20 μM and 200 μM, and the concentrations of IsoA were 10 μg/mL and 100 μg/mL. Each reaction included 1 μL of Aβ₄₂ (final concentration was 0.25 mg/mL) and 9 μL of the testing sample, which each concentration of each sample included 8 groups, and was placed at 37° C. reacting for 30 minutes after thoroughly mixed. 200 μL of Thioflavin T working solution was added and mixed thoroughly after the reaction completed, 200 μL of the which was placed into a black, clear bottom 96-well plate, and the ThT fluorescence intensity (Ex: 440 nm, Em: 482 nm) was measured to determine the level of Aβ₄₂ aggregation. The value of not reacting with any sample (i.e. only containing 1 μL of Aβ₄₂ and 9 μL of D-PBS, which the final concentration of Aβ₄₂ was 0.25 mg/mL) was a control and set to 100%, and isoacteoside (IsoA) was used as a positive control. The values of the samples were compared to the control and expressed in percentage. The experiment results are shown in FIGS. 4A-4B, which show mean±standard error of eight experimental groups (n=8), and the statistical differences between the control and the testing samples were analyzed by Dunnett's multiple comparison test, which “*” represented p<0.05; “**” represented p<0.01; “***” represented p<0.001; and “****” represented p<0.0001.

FIG. 4A shows the experiment results of Samples 1-9 with a lower concentration in inhibiting Aβ₄₂ accumulation. The concentration of Sample 1 was 10 μM, the concentration of Samples 2-9 was 20 μM, and the concentration of IsoA was 10 μg/mL. The level of Aβ₄₂ accumulation was measured by ThT assay, which the measured value of the control without adding any sample was set to 100%, and other values were adjusted accordingly. FIG. 4B shows the experiment results of Samples 1-9 with a higher concentration in inhibiting Aβ₄₂ accumulation. The concentration of Sample 1 was 100 μM, the concentration of Samples 2-9 was 200 μM, and the concentration of IsoA was 100 μg/mL. The level of Aβ₄₂ accumulation was measured by ThT assay, which the measured value of the control without adding any sample was set to 100%, and other values were adjusted accordingly.

The experiment results shown in FIG. 4A suggested that in the lower concentration, Sample 2 could inhibit about 20% of Aβ₄₂ aggregation in the concentration of 20 μM, and Samples 4 and 8 could inhibit about 50% and 60% of Aβ₄₂ aggregation in the concentration of 20 μM respectively. The experiment results shown in FIG. 4B suggested that after increasing the concentration of the samples, Sample 2 could inhibit about 40% of Aβ₄₂ aggregation in the concentration of 200 μM, Sample 4 could inhibit about 70% of Aβ₄₂ aggregation in the concentration of 200 μM, and Sample 8 could totally inhibit Aβ₄₂ aggregation in the concentration of 200 μM.

Therefore, based on the results of Experimental example 3 and Experimental example 4, the isoacteoside derivative of the embodiments of the present invention does have the efficacy of inhibiting Aβ₄₀ accumulation and Aβ₄₂ accumulation.

Given the above, based on the results of Experimental example 1 to Experimental example 4, Samples 3, 4, and 6 could inhibit Aβ₄₀ formation in cell, which Sample 6 had the best result. As for evaluating whether the samples could inhibit Aβ aggregation, ThT assay was used to measure the level of Aβ aggregation. The experiment results showed that Samples 2, 4, and 8 could effectively inhibit Aβ₄₀ and Aβ₄₂ accumulation, which Sample 8 had the best result. Sample 8 could inhibit about 70% of Aβ₄₂ aggregation and about 100% of Aβ₄₂ aggregation in the concentration of 200 μM.

In addition to β-amyloid peptide, the present invention also used the effects of different oxidative stress to retinal epithelial cells so as to observe the protective effect of the isoacteoside derivative of the present invention on retinal pigment epithelial cells.

Experimental Example 5

Experiment on Aβ Degradation

Experimental example 5 was to confirm that the samples could activate medicine for decomposing Aβ₄₀ enzyme activity extracellularly to improve ability of enzymes for decomposing Aβ₄₀ and to have effects of reducing extracellular Aβ₄₀ level.

Experimental method: 2×10⁷ of mouse neuroblastoma cells (Neuro-2a) were placed on a T175 culture medium, and after overnight, the T175 culture medium was replaced with 30 mL of a chemical-defined medium incubating for 24 hours. After 24 hours, the chemical-defined medium incubated with the cells, which was called a conditioned medium, was centrifuged for 5 minutes at 13,000 rpm, and supernatant liquid was obtained. 10 ng of Aβ₄₀ and testing medicine were added to 300 μL of the conditioned medium, and the mixture was reacted at 37° C. for 24 hours. Immunoassay kits (Human Aβ_1-40 Immunoassay kits, Cat.KHB3482, Life Technologies) were used to measure the remaining amount of Aβ in each reaction to examine whether the medicine can improve the activity for enzyme in the medium to degrade Aβ. One not adding any testing medicine (i.e. only containing 10 ng of Aβ₄₀) was a control, and the measured level of Aβ was set to 100%. The levels of Aβ after treated by the testing medicine were compared to the control and expressed in percentage. The experiment results are shown in FIG. 5, which are mean±standard error of four experimental groups (n=4). The statistical differences between the control and the testing samples were analyzed by Dunnett's multiple comparison test, which “*” represented p<0.05; “**” represented p<0.01; “***” represented p<0.001; and “****” represented p<0.0001.

As the experiment results shown in FIG. 5, the level of Aβ₄₀ for not adding any medicine (C) was set to 100%, and other values were adjusted accordingly and presented in percentage. Sample 9 could effectively improve extracellular Aβ₄₀ degradation in the concentrations of 50 μM and 100 μM.

Therefore, based on the results of Experimental example 5, the isoacteoside derivative of the embodiments of the present invention does have the efficacy of degrading Aβ.

Experimental Example 6

Experiment on Preventing Eye Disease

Human retinal pigment epithelium cells (ARPE-19) were incubated in a DMEM/F12 cell culture medium (Life Technologies) containing 10% of fetal bovine serum (FBS), and were passaged using a 96-well plate after the cell concentration reached 90% full, which each well was seeded with 4.5×10³ cells. Next day, Samples 2 and 8 were diluted with dimethyl sulfoxide (DMSO) to about 200 times of test concentration, and after that, appropriate amount of DMEM/F12 cell culture medium containing 5% fetal bovine serum was added and diluted to twice test concentration. Then, the resultant was mixed with 0.2 mM of tert-butyl hydroperoxide (tBHP, Sigma) in equal proportions to reach the test concentration (containing 0.5% of dimethyl sulfoxide). The diluted sample was added to the plate with the cells, which was placed in an incubator reacted for 24 hours, and the cell viability was analyzed by MTT solution. The absorbance was measured at a wavelength of 570 nm, and the cells not being treated by the medicine was a control, and the average absorbance of which was set to 100%. The cell viability of the cells being treated by the medicine was calculate by the following formula based on the measured absorbance:

Cell viability=(absorbance of the experimental group/average absorbance of the control)×100%.

The tert-butyl hydroperoxide is an organic peroxide, and can be metabolized by free radicals, which causes lipid oxidation covalently bonded with cellular molecules resulting in cell damage. Therefore, the tert-butyl hydroperoxide is widely used in the study of cell damage caused by oxidative stress.

The experiment results are shown in FIGS. 6A-6B, which show mean±standard error of six experimental groups (n=6). The statistical differences between damaging group (i.e. accepting damaging medicine, and no protective medicine) and testing medicine groups and the control group (Control, containing 0.5% of DMSO) were analyzed by Dunnett's multiple comparison test, which “*” represented p<0.05; “**” represented p<0.01; “***” represented p<0.001; and “****” represented p<0.0001.

As the experiment results shown in FIGS. 6A-6B, the human retinal pigment epithelium cells in the existence of tBHP resulted in 30%-40% of cell death. However, after respectively adding Sample 2 (the concentrations were 6.25 μM, 12.5 μM, and 25 μM respectively) and Samples 8 (the concentrations were 8.75 μM, 17.5 μM, and 35 μM respectively), the human retinal pigment epithelium cell death could be significantly inhibited, and the cell viability were even better then the control.

Therefore, based on the results of Experimental example 6, the isoacteoside derivative of the embodiments of the present invention does have a protective effect on the oxidative stress damage of the human retinal pigment epithelium cells caused by tert-butyl hydroperoxide.

Given the above, the present invention provides an isoacteoside derivative, and the drug including the isoacteoside derivative has efficacy of inhibiting amyloid accumulation and preventing eye diseases.

Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

Claims

1. An isoacteoside derivative, having a structure of formula (I):

2. The isoacteoside derivative of claim 1, wherein when at least one of R1 and R2 is the hydrocarboxyl group, the at least one of R1 and R2 is independently selected from an alkoxy group, an alkenyloxy group, or an aryloxy group.

3. The isoacteoside derivative of claim 2, wherein when at least one of R1 and R2 is the alkoxy group, the at least one of R1 and R2 is a methoxy group.

4. The isoacteoside derivative of claim 2, wherein when at least one of R1 and R2 is the alkenyloxy group, the at least one of R1 and R2 is an allyloxy group.

5. The isoacteoside derivative of claim 2, wherein when at least one of R1 and R2 is the aryloxy group, the at least one of R1 and R2 is a benzyloxy group.

6. The isoacteoside derivative of claim 1, wherein when at least one of R3 and R4 is the hydrocarboxyl group, the at least one of R3 and R4 is independently selected from an alkenyloxy group or an aryloxy group.

7. The isoacteoside derivative of claim 6, wherein when at least one of R3 and R4 is the alkenyloxy group, the at least one of R3 and R4 is an allyloxy group.

8. The isoacteoside derivative of claim 6, wherein when at least one of R3 and R4 is the aryloxy group, the at least one of R3 and R4 is a benzyloxy group.

9. The isoacteoside derivative of claim 1, wherein when at least one of R3 and R4 is the acyloxy group, the at least one of R3 and R4 is an acetoxy group.

10. The isoacteoside derivative of claim 1, wherein R3 and R4 are the same substituent.

11. The isoacteoside derivative of claim 1, wherein when R5 is the acyloxy group, R5 is an acetoxy group.

12. The isoacteoside derivative of claim 1, wherein R5 are the same substituent.

13. The isoacteoside derivative of claim 1, wherein the isoacteoside derivative is selected from following structures:

14. A method of preparing a medicine for treating or preventing an amyloid-related disease, comprising providing the isoacteoside derivative of claim 1 to prepare the medicine.

15. The method of claim 14, wherein the amyloid-related disease is a neurodegenerative disease.

16. The method of claim 14, wherein the amyloid-related disease is Alzheimer's disease, mild cognitive impairment, Lewy body dementia, Down's syndrome, hereditary cerebral hemorrhage with amyloidosis-Dutch type, Guam Parkinson-Dementia complex, progressive supranuclear palsy, multiple sclerosis, Creutzfeld Jacob disease, Parkinson's disease, frontotemporal dementia, Pick's disease, amyotrophic lateral sclerosis, inclusion-body myositis, adult-onset diabetes, senile cardiac amyloidosis, or endocrine tumor.

17. The method of claim 14, wherein the amyloid-related disease is an eye disease.

18. The method of claim 14, wherein the amyloid-related disease is neuronal degeneration, visual cortical defect, glaucoma, cataract, ocular amyloidosis, macular degeneration, optic nerve drusen, optic neuropathy, optic neuritis, or lattice corneal dystrophy.

19. The method of claim 14, wherein the amyloid is β-amyloid peptide.

20. A method for forming an isoacteoside derivative, comprising: reacting a compound having a structure of formula (II) with β-D-glucose pentaacetate to form a compound having a structure of formula (III), wherein formula (II) is:

21. The method of claim 20, further comprising reacting the compound having the structure of formula (V-1) with copper(I) chloride and palladium dichloride in a mixture of methanol and water to form a compound having a structure of formula (VI-1), wherein formula (VI-1) is:

22. The method of claim 20, further comprising reacting the compound having the structure of formula (V-2) with methylamine in methanol to form a compound having a structure of formula (VI-1), wherein formula (VI-1) is:

23. The method of claim 20, further comprising reacting the compound having the structure of formula (V-4) with methylamine in methanol to form a compound having a structure of formula (VI-2), wherein formula (VI-2) is: