ABIETANE TYPE DITERPENE COMPOUND, PREPARATION METHOD AND APPLICATION THEREOF

Abstract

Disclosed are an abietane type diterpene compound, a preparation method and an application thereof, relating to the technical field of anti-tumor compounds, where the compound has a chemical structure as shown in the following formula I:

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202211288533.5, filed on Oct. 20, 2022, the contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present application relates to the technical field of anti-tumor compounds, and in particular to an abietane type diterpene compound, a preparation method and an application thereof.

BACKGROUND

Leucosceptrum canum is leaves of the honey plant Leucosceptrum canum Smith belonging to the family Labiatae; the plant has efficacies of cleaning heat and detoxifying, relieving dampness and swelling, and stopping bleeding, and has been found in Sichuan and Yunnan of China.

It has been reported that the abietane type diterpene compound has already been used in pharmacology, examples can be found in the Chinese patent with publication number of CN101633660A, which discloses a new abietane type diterpene compound lushanrubescensin D and its preparation method and application, in addition to the physicochemical properties, optical activity of lushanrubescensin D, and the in vitro activity is screened by 3-(4,5)-dimethylthiahiazo (-z-yl)-3,5-di-phenytetrazoliumromide (MTT) assay, and the results show a significant inhibitory effect on mouse sarcoma cells and mouse liver cancer cells, making the compound possible to serve as a starter compound to develop new anti-tumor drugs, as well as for developing drugs of treating various clinically common and multifocal cancers.

The technical scheme described above provides an abietane type diterpene compound extracted from Rabdosia rubescens for preparing anti-tumor drugs. Currently, more than 60 chemical components, including diterpenoids, sesterterprnoids, flavonoids, phenylethanol glycosides, acyl glycosides and phenols, have been isolated from plants of the genus Leucosceptrum, among which diterpenoids and sesterterprnoids are the main types of structures; however, study on the anti-tumor activity of the chemical components from Leucosceptrum has not yet been reported.

SUMMARY

In view of this, the present application provides an abietane type diterpene compound, its preparation method and application; the abietane type diterpene compound is extracted and prepared from Leucosceptrum canum, and the compound has an inhibitory effect on human lung cancer cells and human promyelocytic leukemia cells.

The objectives of the present application are achieved by technical schemes as follows:

• • one aspect of the present application provides an abietane type diterpene compound Leucosceptrum A, with a chemical name of 11,14-dihydroxy-8,11,13,15-abietatetraen-7-one, and a structure is shown in the following formula I:

Another aspect of the present application provides a preparation method of the abietane type diterpene compound, including:

• • S1, taking air-dried Leucosceptrum canum as raw materials, crushing, leaching with organic solvents, and concentrating under a reduced pressure at low temperature to obtain extract;
  • S2, mixing the extract with water to obtain suspension, adding ethyl acetate for extraction, and concentrating under reduced pressure at a low temperature to obtain ethyl acetate extracting phase;
  • S3, separating the ethyl acetate extracting phase by silica gel column chromatography, and performing gradient elution with petroleum ether-ethyl acetate as eluent, where the petroleum ether and the ethyl acetate are in a volume ratio of 9.8-10.2:1, 4.8-5.2:1, and 2.8-3.2:1; collecting eluent corresponding to the volume ratio of petroleum ether to ethyl acetate of 2.8-3.2:1, followed by thin-layer chromatographic analysis and combining similar fractions to obtain initial components; and
  • S4, separating the initial components by preparative liquid chromatography, and performing isocratic elution by using acetonitrile and water as an eluant to obtain the abietane type diterpene compound Leucosceptrum A as shown in the formula I.

Optionally, the organic solvent in the S1 is ethanol with a volume fraction of more that 90 percent (%), and the ethanol is in a volume-mass ratio of 10-20 milligrams (mL):1 gram (g) to the air-dried Leucosceptrum canum; the leaching is carried out under temperature of 65-75 degree Celsius (° C.) for 2-3 times, each time 4-6 hours (h).

Optionally, concentrating under reduced pressure at a low temperature in both the S1 and the S2 is carried out under a temperature of 40-50° C. with a vacuum degree of 0.07-0.09 Megapascal (MPa).

Optionally, the extract and water in the S2 are mixed in a mass ratio of 1:1-3, the ethyl acetate is in a volume ratio of 0.8-1:1 to the suspension, and the extraction is carried out for 2-4 times.

Optionally, the eluent in the S4 includes 40-50% by volume of acetonitrile, and water for a rest.

The abietane type diterpene compound Leucosceptrum A of the present application is extracted and purified by crushing, extracting, concentrating under reduced pressure, and separating various times using air-dried Leucosceptrum canum as a raw material; for the preparation, air-dried Leucosceptrum canum is used to facilitate the crushing; the eluent with an equal volume of petroleum ether and ethyl acetate is used as a separation system, where elution of single concentration fails to prepare the abietane type diterpene compound Leucosceptrum A since Leucosceptrum canum contains many impurities; moreover, gradient elution with unreasonable concentration arrangement, either too high or too low, leads to insufficient elution of the abietane type diterpene compound Leucosceptrum A. In the absence of reference material providing indications for the extraction of the abietane type diterpene compound Leucosceptrum A, there is a high degree of uncertainty in treating Leucosceptrum canum and obtaining Leucosceptrum A from them.

One aspect of the present application provides an application of the abietane type diterpene compound in preparing anti-tumor drugs.

Optionally, the anti-tumor drugs are applied in inhibiting tumor cells of human lung cancer cell A549 and human promyelocytic leukemia cell HL-60.

The application has the following beneficial effects:

• • the abietane type diterpene compound Leucosceptrum A of the present application is a natural antitumor compound extracted from Leucosceptrum canum; it is effective in inhibiting tumor cells, including human lung cancer cells A549 cells and human promyelocytic leukemia cells HL-60, especially in inhibiting human promyelocytic leukemia cells HL-60; the compound shows a strong antitumor activity and has a very promising application in preparing antitumor drugs, and plays an important role in enhancing the medical and economic value of Leucosceptrum canum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a process of preparing an abietane type diterpene compound Leucosceptrum A.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present application is hereinafter described in detail in conjunction with the embodiments and the enclosed drawing.

Unless otherwise specified, the materials used in the present application are commercially available or commonly used in the art, and the methods in the following embodiments are conventional in the art if not specified.

Embodiment 1 Physical and Chemical Properties Test of Abietane Type diterpene Compound Leucosceptrum A

1.1 Determination of Molecular Structural Formula

The Nuclear Magnetic Resonance (NMR) instrument used is a Bruker AVANCE III 500 NMR instrument manufactured by the Bruker Corporation, and the NMR is performed using the reagent of deuterated CDCl₃ (deuterated chloroform); the hydrogen spectrum and carbon spectrum data of the abietane type diterpene compound Leucosceptrum A is shown in Table 1 below.

TABLE 1
1H-NMR (500 megahertz (MHz)) and 13C-
NMR(125 MHz) data of Leucosceptrum A
S/N	δH	δC
1	1.08, m, α	36.6, CH2
	1.94, m, β
2	1.71, m, α	19.4, CH2
	1.51, m, β
3	2.22, dd (14.0, 6.5), α	41.3, CH2
	1.67, m, β
4	—	33.1, qC
5	1.96, d (14.0)	49.6, CH
6	2.74, m, α	36.1, CH2
	2.72, m, β
7	—	205.8, qC
8	—	115.9, qC
9	—	137.8, qC
10	—	40.2, qC
11	—	144.3, qC
12	6.6, s	124.4, CH
13	—	119.2, qC
14	—	155.7, qC
15	—	143.1, qC
16	5.33, br s	111.2, CH2
	5.02, br s
17	2.10, s	22.0, CH3
18	1.24, s	32.9, CH3
19	1.06, s	21.6, CH3
20	1.25, s	18.0, CH3
Note:
δ stands for a chemical shift; s represents a singlet peak; br s represents a broad singlet peak; m represents multiplet; and dd stands for double of doubles.

1.2 Molecular Weight Test

The compound is determined in terms of exact molecular weight by high-resolution mass spectrometry HR-ESI-MS, and HR-ESI-MS [M−H]⁻ is 313.1804; as determined from the NMR data and mass spectrometry data in Table 1, the abietane type diterpene compound Leucosceptrum A has a molecular formula of C₂₀H₂₆O₃, a molecular weight of 314, an unsaturation of 8, and a chemical name of 11,14-dihydroxy-8,11,13,15-abietatetraen-7-one with the structure shown in formula I.

1.3 Melting Point Test

The melting point is tested by WRS-1C melting point apparatus produced by Shanghai Instrument Physical Optics Instrument Co., Ltd., and it is tested that the melting point of the abietane type diterpene compound Leucosceptrum A is 245-246 degree Celsius (° C.).

Embodiment 2

An abietane type diterpene compound Leucosceptrum A is prepared in the present embodiment; and

• • according to FIG. 1, the compound Leucosceptrum A is prepared as follows:
  • S1, air-drying and crushing 5 kilograms (kg) of Leucosceptrum canum, leaching with ethanol with volume percent of 95%, where the ethanol is added in a mass-volume ratio of Leucosceptrum canum to ethanol of 1 g:10 milliliters (mL), and the leaching is carried out under temperature of 70° C. for 3 times, each time for 5 hours (h); filtering off insoluble substances, combining filtrates, and then evaporating to dryness at a low temperature and under reduced pressure at a vacuum degree of 0.08 Megapascal (MPa) and a temperature of 45° C. to obtain extract;
  • S2, uniformly mixing the obtained extract with water according to a mass ratio of 1:2 to prepare a suspension, extracting with an equal volume of ethyl acetate for 3 times, combining extracted solutions, and evaporating to dryness at a low temperature and under the reduced pressure at a vacuum of 0.08 MPa and a temperature of 45° C. to obtain an ethyl acetate extract phase;
  • S3, evenly mixing the obtained ethyl acetate extract phase with silica gel of a same mass, then placing in a silica gel column for chromatography, and subjecting to gradient elution with petroleum ether-ethyl acetate as the eluent, where the petroleum ether is in volume ratios of 10:1, 5:1, and 3:1 respectively to the ethyl acetate in each gradient; collecting eluent corresponding to the volume ratio of petroleum ether to ethyl acetate of 3:1, followed by thin-layer chromatographic analysis and combining similar fractions to obtain initial components; and
  • S4, separating the obtained initial components by preparative liquid chromatography, and performing isocratic elution by using acetonitrile and water in a volume ratio of 45:55 as the eluant to obtain the abietane type diterpene compound Leucosceptrum A of 16.0 milligrams (mg) with anti-tumor effect as shown in the formula I.

Embodiment 3

The present embodiment prepares an abietane type diterpene compound Leucosceptrum A according to the following steps:

• • S1, air-drying and crushing 5 kg of Leucosceptrum canum, leaching with ethanol with volume percent of 90%, where the ethanol is added in a mass-volume ratio of Leucosceptrum canum to ethanol of 1 g:20 mL, and the leaching is carried out under temperature of 65° C. for 3 times, each time for 4 h; filtering off insoluble substances, combining filtrates, and then evaporating to dryness at a low temperature and under the reduced pressure at a vacuum degree of 0.07 MPa and a temperature of 50° C. to obtain extract;

S2, uniformly mixing the obtained extract with water according to a mass ratio of 1:1 to prepare a suspension, extracting with equal volume of ethyl acetate for 4 times, combining extracted solutions, and evaporating to dryness at a low temperature and under reduced pressure at a vacuum of 0.07 MPa and a temperature of 50° C. to obtain an ethyl acetate extract phase;

• • S3, evenly mixing the obtained ethyl acetate extract phase with silica gel of a same mass, then placing in a silica gel column for chromatography, and subjecting to gradient elution with petroleum ether-ethyl acetate as the eluent, where the petroleum ether is in volume ratios of 9.8:1, 4.8:1, and 2.8:1 respectively to the ethyl acetate in each gradient; collecting eluent corresponding to the volume ratio of petroleum ether to ethyl acetate of 2.8:1, followed by thin-layer chromatographic analysis and combining similar fractions to obtain initial components; and
  • S4, separating the obtained initial components by preparative liquid chromatography, and performing isocratic elution by using acetonitrile and water in a volume ratio of 40:60 as the eluant to obtain the abietane type diterpene compound Leucosceptrum A of 11.4 mg with anti-tumor effect as shown in the formula I.

Embodiment 4

The present embodiment prepares an abietane type diterpene compound Leucosceptrum A according to the following steps:

• • S1, air-drying and crushing 5 kg of Leucosceptrum canum, leaching with the ethanol with volume percent of 95%, where the ethanol is added in a mass-volume ratio of Leucosceptrum canum to ethanol of 1 g:15 mL, and the leaching is carried out under temperature of 75° C. for 2 times, each time for 4 h; filtering off insoluble substances, combining filtrates, and then evaporating to dryness at a low temperature and under the reduced pressure at a vacuum degree of 0.09 MPa and a temperature of 40° C. to obtain extract;
  • S2, uniformly mixing the obtained extract with water according to a mass ratio of 1:1 to prepare a suspension, extracting with equal volume of ethyl acetate for 4 times, combining extracted solutions, and evaporating to dryness at a low temperature and under reduced pressure at a vacuum of 0.071VIPa and a temperature of 50° C. to obtain an ethyl acetate extract phase;
  • S3, evenly mixing the obtained ethyl acetate extract phase with the silica gel of a same mass, then placing in a silica gel column for chromatography, and subjecting to gradient elution with petroleum ether-ethyl acetate as the eluent, where the petroleum ether is in volume ratios of 10.2:1, 5.2:1, and 3.2:1 respectively to the ethyl acetate in each gradient; collecting eluent corresponding to the volume ratio of petroleum ether to ethyl acetate of 3.2:1, followed by thin-layer chromatographic analysis and combining similar fractions to obtain initial components; and
  • S4, separating the obtained initial components by preparative liquid chromatography, and performing isocratic elution by using acetonitrile and water in a volume ratio of 50:50 as the eluant to obtain the abietane type diterpene compound Leucosceptrum A of 8.1 mg with anti-tumor effects as shown in the formula I.

Embodiment 5 Anti-Tumor Performance Test of Abietane Type Diterpene Compound Leucosceptrum A

The abietane type diterpene compound Leucosceptrum A prepared in Embodiment 2 is tested for its anti-tumor ability, with a process as follows:

• • in vitro tumor cell proliferation inhibition assay: exponential phase tumor cells are taken and the cell suspension concentration is adjusted (50,000-100,000 cells/mL), then the cell suspension is inoculated in 96-well plate with 100 microlitres (μL) per well (μL/well), followed by drug administration (100 μL/well) 24 h after inoculation; a blank control group, a cell control group and 6 drug groups with concentrations (3.12, 6.25, 12.5, 25, 50, 100 micromoles per litre (μ mol/L)) are set up respectively, and the drug in the cell control group is cisplatin; after continuous cultivation for 72 h, 100 μL 3-(4,5)-dimethylthiahiazo(-z-yl) -3,5-di-phenytetrazoliumromide (MTT) (1 mg/mL MTT dissolved in Dulbecco's modified eagle medium (DMEM) culture solution) is added to each well, incubated at 37° C. for 4 h, then 150 μL acidified isopropyl alcohol (containing 0.04 mol/L HCl) is added to each well, and kept under darkness for 30 minutes (min); then the absorbance is measured at 570 nanometers (nm) by enzyme-labeled instrument, the inhibition rate of the tested drug on the proliferation of tumor cells and the half inhibition concentration (IC₅₀) of the tested substance on the proliferation of tumor cells (72 h) are calculated respectively; three parallels tests are arranged so as to reduce the influence of experimental errors, and the results are as follows.

5.1 Human Promyelocytic Leukemia Cell HL-60

(1) Tables 2, 3 and 4 illustrate the inhibitory effect of cisplatin on HL-60 cells in the control group.

TABLE 2
Inhibitory effect of parallel test I of cisplatin on HL-60 cells
	HL-60 cell
	quality	Cisplatin concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	−0.001	0.654	0.529	0.471	0.346	0.299	0.043	0.018
2	0.001	0.629	0.635	0.385	0.244	0.208	0.104	0.019
3	0.006	0.619	0.673	0.392	0.346	0.325	0.183	0.027
Average	0.002	0.634	0.6123	0.416	0.312	0.2773	0.11	0.0213
Mean squared	0.0036	0.018	0.0746	0.0478	0.0589	0.0614	0.0702	0.0049
error
Survival	96.57%	65.51%	49.05%	43.57%	17.09%	3.06%

According to Graphpad Prism 6.0, IC₅₀=14.36.

TABLE 3
Inhibitory effect of parallel test II of cisplatin on HL-60 cells
	HL-60 cell
	quality	Cisplatin concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	−0.001	0.515	0.435	0.215	0.185	0.109	0.095	0.033
2	0	0.502	0.465	0.365	0.299	0.121	0.056	0.011
3	−0.002	0.467	0.399	0.327	0.22	0.106	0.077	0.032
Average	−0.001	0.4947	0.433	0.3023	0.2347	0.112	0.076	0.0253
Mean squared	0.001	0.0248	0.033	0.078	0.0584	0.0079	0.0195	0.0124
error
Survival	87.56%	61.20%	47.55%	22.80%	15.53%	5.31%

According to Graphpad Prism 6.0, IC₅₀=10.69.

TABLE 4
Inhibitory effect of parallel test III of cisplatin on HL-60 cells
	HL-60 cell
	quality	Cisplatin concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	−0.002	0.515	0.442	0.391	0.197	0.095	0.038	0.017
2	0	0.536	0.512	0.453	0.201	0.192	0.096	0.019
3	0	0.528	0.509	0.447	0.295	0.202	0.045	0.015
Average	−7E−04	0.5263	0.4877	0.4303	0.231	0.163	0.0597	0.017
Mean squared	0.0012	0.0106	0.0396	0.0342	0.0555	0.0591	0.0317	0.002
error
Survival	92.66%	81.78%	43.96%	31.06%	11.45%	3.35%

According to Graphpad Prism 6.0, IC₅₀=13.16.

IC₅₀=12.74±1.87 of cisplatin is obtained according to the above data.

(2) The inhibitory effect of compound Leucosceptrum A on HL-60 cells is shown in Tables 5, 6 and 7.

TABLE 5
Inhibitory effect of parallel test I of compound Leucosceptrum A on HL-60 cells
	HL-60 cell
	quality	Leucosceptrum A concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0.001	0.556	0.431	0.353	0.164	0.065	0.049	0.035
2	0.002	0.541	0.425	0.366	0.241	0.104	0.054	0.021
3	0	0.536	0.487	0.386	0.258	0.097	0.053	0.035
Average	0.001	0.5443	0.4477	0.3683	0.221	0.0887	0.052	0.0303
Mean squared	0.001	0.0104	0.0342	0.0166	0.0501	0.0208	0.0026	0.0081
error
Survival	82.21%	67.61%	40.49%	16.13%	9.39%	5.40%

According to Graphpad Prism 6.0, IC₅₀=9.58.

TABLE 6
Inhibitory effect of parallel test II of compound Leucosceptrum A on HL-60 cells
	HL-60 cell
	quality	Leucosceptrum A concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0.001	0.541	0.452	0.417	0.177	0.054	0.048	0.043
2	0	0.571	0.417	0.398	0.129	0.055	0.045	0.021
3	0.002	0.488	0.395	0.381	0.239	0.064	0.037	0.032
Average	0.001	0.5333	0.4213	0.3987	0.1817	0.0577	0.0433	0.032
Mean squared	0.001	0.042	0.0287	0.018	0.0551	0.0055	0.0057	0.011
error
Survival	78.96%	74.70%	33.94%	10.64%	7.95%	5.82%

According to Graphpad Prism 6.0, IC₅₀=9.19.

TABLE 7
Inhibitory effect of parallel test III of compound Leucosceptrum A on HL-60 cells
	HL-60 cell
	quality	Leucosceptrum A concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0.001	0.577	0.369	0.352	0.201	0.082	0.053	0.026
2	0.003	0.568	0.365	0.348	0.33	0.068	0.053	0.049
3	0.004	0.564	0.408	0.392	0.312	0.057	0.038	0.042
Average	0.0027	0.5697	0.3807	0.364	0.281	0.069	0.048	0.039
Mean squared	0.0015	0.0067	0.0238	0.0243	0.0699	0.0125	0.0087	0.0118
error
Survival	66.67%	63.73%	49.09%	11.79%	8.00%	6.41%

According to Graphpad Prism 6.0, IC₅₀=8.42.

IC₅₀=9.06±0.59 of Leucosceptrum A is obtained according to the above data.

5.2 Human Lung Cancer Cell A549

(1) The inhibitory effect of cisplatin on human lung cancer cell A549 is shown in Tables 8, 9 and 10.

TABLE 8
Inhibitory effect of parallel test I of cisplatin on A549 cells
	A549 cell
	quality	Cisplatin concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0.001	0.661	0.641	0.489	0.231	0.212	0.205	0.203
2	0.002	0.652	0.642	0.446	0.254	0.288	0.207	0.198
3	0	0.731	0.715	0.391	0.278	0.221	0.196	0.173
Average	0.001	0.6813	0.666	0.442	0.2543	0.2403	0.2027	0.1913
Mean squared	0.001	0.0432	0.0424	0.0491	0.0235	0.0415	0.0059	0.0161
error
Survival	97.75%	64.82%	37.24%	35.18%	29.64%	27.98%

According to Graphpad Prism 6.0, IC₅₀=14.62.

TABLE 9
Inhibitory effect of parallel test II of cisplatin on A549 cells
	A549 cell
	quality	Cisplatin concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0	0.612	0.602	0.431	0.301	0.267	0.213	0.186
2	0.001	0.653	0.647	0.48	0.238	0.234	0.202	0.202
3	0.003	0.626	0.613	0.491	0.239	0.208	0.199	0.179
Average	0.0013	0.6303	0.6207	0.4673	0.2593	0.2363	0.2047	0.189
Mean squared	0.0015	0.0208	0.0235	0.0319	0.0361	0.0296	0.0074	0.0118
error
Survival	98.46%	74.09%	41.02%	37.36%	32.33%	29.84%

According to Graphpad Prism 6.0, IC₅₀=17.85.

TABLE 10
Inhibitory effect of parallel test III of cisplatin on A549 cells
	A549 cell
	quality	Cisplatin concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0	0.71	0.693	0.485	0.262	0.243	0.201	0.146
2	−0.001	0.725	0.686	0.433	0.242	0.217	0.219	0.209
3	0.002	0.665	0.655	0.469	0.292	0.283	0.257	0.252
Average	0.0003	0.7	0.678	0.4623	0.2653	0.2477	0.2257	0.2023
Mean squared	0.0015	0.0312	0.0202	0.0266	0.0252	0.0332	0.0286	0.0533
error
Survival	96.86%	66.03%	37.88%	35.35%	32.21%	28.87%

According to Graphpad Prism 6.0, IC₅₀=15.38.

According to the above data, the IC₅₀ of cisplatin is IC₅₀₌15.95±1.69.

(2) The inhibitory effect of compound Leucosceptrum A on A549 cells is shown in Tables 11, 12 and 13.

TABLE 11
Inhibitory effect of parallel test I of compound Leucosceptrum A on A549 cells
	A549 cell
	quality	Leucosceptrum A concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0	0.843	0.811	0.828	0.635	0.184	0.085	0.078
2	0.002	0.835	0.824	0.791	0.663	0.175	0.074	0.067
3	0.001	0.814	0.81	0.728	0.602	0.189	0.085	0.085
Average	0.001	0.8307	0.815	0.7823	0.6333	0.1827	0.0813	0.0767
Mean squared	0.001	0.015	0.0078	0.0506	0.0305	0.0071	0.0064	0.0091
error
Survival	98.11%	94.17%	76.22%	21.90%	9.68%	9.12%

According to Graphpad Prism 6.0, IC₅₀=17.55.

TABLE 12
Inhibitory effect of parallel test II of compound Leucosceptrum A on A549 cells
	A549 cell
	quality	Leucosceptrum A concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0.003	0.796	0.72	0.711	0.636	0.221	0.077	0.073
2	0.002	0.793	0.753	0.786	0.687	0.182	0.074	0.066
3	0.003	0.865	0.869	0.769	0.683	0.173	0.059	0.058
Average	0.0027	0.818	0.7807	0.7553	0.6687	0.192	0.07	0.0657
Mean squared	0.0006	0.0407	0.0783	0.0393	0.0284	0.0255	0.0096	0.0075
error
Survival	95.42%	92.31%	81.68%	23.22%	8.76%	7.73%

According to Graphpad Prism 6.0, IC₅₀=18.38.

TABLE 13
Inhibitory effect of parallel test III of compound Leucosceptrum A on A549 cells
	A549 cell
	quality	Leucosceptrum A concentrations (μmol/L)
S/N	Blank	control	3.12	6.25	12.5	25	50	100
1	0.001	0.826	0.767	0.822	0.6	0.188	0.071	0.067
2	0	0.867	0.845	0.77	0.587	0.191	0.079	0.067
3	0.002	0.866	0.827	0.791	0.583	0.207	0.088	0.073
Average	0.001	0.853	0.813	0.7943	0.59	0.1953	0.0793	0.069
Mean squared	0.001	0.0234	0.0408	0.0262	0.0089	0.0102	0.0085	0.0035
error
Survival	95.31%	93.11%	69.13%	22.81%	9.19%	7.98%

According to Graphpad Prism 6.0, IC₅₀=16.62.

According to the above data, the IC₅₀ of Leucosceptrum A is IC₅₀₌17.52±0.88.

5.3 The 72-hour IC₅₀ (μmol/L) of Leucosceptrum A and cisplatin on two cancer cells is shown in Table 14.

TABLE 14
72-hour IC50(μmol/L) of Leucosceptrum
A and cisplatin on two cancer cells
	Tumor cells	HL-60 cells	A-549 cells
	Cisplatin	12.74 ± 1.87	15.95 ± 1.69
	Leucosceptrum A	9.06 ± 0.59	17.52 ± 0.88

It can be seen from the above tables 5-7 and 11-13 that the compound Leucoceptrum A with different concentrations has inhibitory effects on human lung cancer cell A549 and human promyelocytic leukemia cell HL-60, and the IC₅₀ values of Leucoceptrum A after 72 h reach 17.52±0.88 and 9.06±0.59 μmol/L, respectively, indicating that Leucoceptum A has a strong inhibitory effect on the growth of the above two tumor cells; specifically, the IC₅₀ value of Leucoceptum A on HL-60 cells is lower than that of control group with cisplatin, which indicates that Leucoceptum A has a very significant inhibitory effect on HL-60 cells.

The above embodiments are only used to illustrate the technical scheme of the present application and not to limit it. Although the present application is described in detail with reference to the preferred embodiments, it should be understood by those of ordinary skill in the art that the technical scheme of the present application may be modified or replaced by the same without departing from the purpose and scope of the technical scheme of the present application, which shall be covered by the scope of the claims of the present application. The technology, shape and construction parts not described in detail in the present application are all prior art.

Claims

1. An abietane type diterpene compound, comprising a chemical structure as shown in a formula I:

2. A preparation method of the abietane type diterpene compound of formula (I):

3. The preparation method of the abietane type diterpene compound according to claim 2, wherein the ethanol in the S1 is in a volume-mass ratio of 10-20 milligrams (mL):1 gram (g) to the air-dried Leucosceptrum canum; and the leaching is carried out under temperature of 65-75 degree Celsius (° C.) for 2-3 times, each time with a duration of 4-6 hours (h).

4. The preparation method of the abietane type diterpene compound according to claim 2, wherein the concentrating under the reduced pressure at the low temperature in both the S1 and the S2 is carried out under a temperature of 40-50° C. with a vacuum degree of 0.07-0.09 Megapascal (MPa).

5. The preparation method of the abietane type diterpene compound according to claim 2, wherein the extract and water in the S2 are mixed in a mass ratio of 1:1-3, the ethyl acetate is in a volume ratio of 0.8-1:1 to the suspension, and the extraction is carried out for 2-4 times.

6. The preparation method of the abietane type diterpene compound according to claim 2, wherein the eluent in the S4 comprises 40-50% by volume of acetonitrile, and water for a rest.

7. An application of the abietane type diterpene compound according to claim 1 in preparing anti-tumor drugs.

8. The application according to claim 7, wherein the anti-tumor drugs are applied in inhibiting tumor cells of human lung cancer cell A549 and human promyelocytic leukemia cell HL-60.