RU2554475C2 - 3-o-propionate allobetulenole (19beta,28-epoxy-18alpha-oleanane-3beta-yl and propionate) immunomodulatory agent - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: immunomodulatory agent contains 3-O-propionate allobetulenole (19beta,28-epoxy-18alpha-oleanane-3beta-yl and propionate) as an active substance. The immunomodulatory agent stimulates a humoral immune response. The T-cell immune response develops in a delayed-type hypersensitivity test of the immunomodulatory agent of 3-O-propionate allobetulenole (19beta,28-epoxy-18alpha-oleanane-3beta-yl and propionate).

EFFECT: reduced oedema.

1 dwg, 2 tbl, 4 ex

Description

The invention relates to chemistry, medicine and pharmaceuticals and relates to a new immunomodulating agent triterpenoid oleanan series 3-O-propionate allobetulinol and its immunomodulating activity. This substance can be used as an immunomodulator for the correction of disorders in the immune system in pathological conditions, as well as an adjuvant in viral diseases.

Allobetulinol 3-O-Propionate (19β, 28-epoxy-18α-oleanan-3β-yl propionate, Allobetulinol 3-O-propionate, AN-12) is an ester of propionic acid and allobetulinol, has the gross formula C ₃₃ H ₅₄ O ₃ and a molecular weight of 498.78 (Fig. 1).

It is known that in medical practice a number of triterpenic preparations are used to treat various diseases, namely, glycyrrhizic acid and its salts, oleanolic acid, asiaticoside, glycyrrhetic acid (Enoxolone) and its salts, sodium carbenoxolone and escin [Encyclopedia of Radar Medicines, 2013; Sweetman SC Martindale: The Complete Drug Reference. London, Chicago, 36 ^th ed., 2009; The European Pharmacopoeia 7 ^th ed., 2010; Sheng H., Sun H. Synthesis, biology and clinical significance of pentacyclic triterpenes: a multi-target approach to prevention and treatment of metabolic and vascular diseases // Nat Prod Rep. 2011. Vol. 28. Number 3. P.543-593; British Pharmacopoeia, 2013]. These funds are of natural and synthetic origin and belong to the triterpenoids of the oleanan series.

Also known are drugs of this group undergoing clinical trials for the treatment of a variety of diseases: escin, glycyrrhizic acid, glycyrrhetic acid, QS-21, bardoxolone (CDDO, RTA-401), methyl bardoxolone (CDDO-Me, RTA-402), boswellic acid, S-0139. Many semi-synthetic oleanan type triterpenoids have high biological activity, improved pharmacokinetic parameters and act as multifunctional (multi-target) agents at different levels of body regulation [Yadav V.R., Prasad S ,, Sung B., Kannappan R., Aggarwal B. B. Targeting inflammatory pathways by triterpenoids for prevention and treatment of cancer // Toxins (Basel). 2010. Vol. 2. No. 10. P.2428-2466; Dehaen W., Mashentseva A.A., Seitembetov T.S. Allobetulin and its derivatives: synthesis and biological activity // Molecules. 2011. Vol.16. Number 3. P.2443-2466; Sheng H., Sun H. Synthesis, biology and clinical significance of pentacyclic triterpenes: a multi-target approach to prevention and treatment of metabolic and vascular diseases // Nat Prod Rep. 2011. Vol. 28. Number 3. P.543-593; Liby K.T., Sporn M.B. Synthetic oleanane triterpenoids: multifunctional drugs with a broad range of applications for prevention and treatment of chronic disease // Pharmacol Rev. 2012. Vol. 64. Number 4. P.972-1003; Patlolla J.M., Rao C.V. Triterpenoids for cancer prevention and treatment: current status and future prospects // Curr Pharm Biotechnol. 2012. Vol.13. No. 1. P.147-155; http://clinicaltrials.gov].

QS-21 (stimulon) - a natural oleanan saponin - is used as an immunological adjuvant for the treatment of various types of cancer. QS-21 is obtained from the bark of a soap tree (Quillaja saponaria) or synthetically [Ragupathi G., Gardner J.R., Livingston P.O., Gin D.Y. Natural and synthetic saponin adjuvant QS-21 for vaccines against cancer // Expert Rev Vaccines. 2011. Vol. 10. Number 4. P.463-470; Garcon N., Van Mechelen M. Recent clinical experience with vaccines using MPL- and QS-21-containing adjuvant systems // Expert Rev Vaccines. 2011. Vol. 10. Number 4. P.471-486].

Allobetulinol (allobetulin, allobetulinol) is an oleanan triterpene monoalcohol with the molecular formula C ₃₀ H ₅₀ O ₂ , contains in its structure an oleanan skeleton, a hydroxyl group at the C-3 position with a β-configuration and a 19β, 28-epoxy group. Allobetulenol was obtained for the first time in 1922 by chemical means, it is extremely rare in natural sources [Kislitsyn AN Extractive substances of birch bark: isolation, composition, properties, application // Chemistry of wood. 1994. No. 3, C.3-28]. Its crystal structure was recently established by [Santos RC, Pinto RM, Matos Beja A., Salvador JA, Paixao JA 19β, 28-Epoxy-18α-olean-3β-ol // Acta Crystallogr Sect E Struct Rep Online. 2009. Vol. 65. Pt. 9. P. o2088-2089].

It should be emphasized that allobetulinol is a promising triterpene platform on an industrial scale in the search for new drugs obtained by chemical modification. Its synthetic analogues exhibit a wide range of biological effects. They have antiviral, immunotropic, antibacterial, antifungal, anti-inflammatory, cytotoxic, antifidant (inhibitory insect nutrition) and glycogen phosphorylase inhibitory activity [Dehaen W., Mashentseva A.A., Seitembetov T.S. Allobetulin and its derivatives: synthesis and biological activity // Molecules. 2011. Vol.16. Number 3. P.2443-2466].

Currently, the progenitor for the production of allobetulinol and its derivatives is naturally available betulenol (3β, 28-di-hydroxy-20 (29) -lupen, betulin, betulinol) - the main component of birch bark of various species. The content of betulenol in the outer bark is up to 35% of the dry weight, and in the refined waste bark of birch during woodworking - up to 24%. Every day, the plywood and pulp and paper industries in the USA, Canada, Finland, China and Russia produce about 40 tons of unprocessed bark (~ 15% birch bark), which consumes approximately 5 tons of betulenol. Given the high yield of the process of its isolation (up to 97% recovery) using a variety of available solvents, betulenol can now be obtained in almost any quantity [Tolstikov GA, Flekhter OB, Schulz E.E., Baltina L .A., Tolstikov A.G. Betulin and its derivatives. Chemistry and biological activity // Chemistry in the interests of sustainable development. 2005. Volume 13. No. 1. S.1-30; Abyshev A.Z., Agaev E.M., Guseinov A.B. Study of the chemical composition of the extract of birch bark Cortex betula sem. Betulaceae // Chem.-farm. Journal. 2007. Volume 41. No. 8. S.22-26. Levdansky V.A., Levdansky A.V., Kuznetsov B.N. The method of producing betulin // RF Patent No. 2458934, Bull. No. 23, 08/20/2012; Krasutsky P.A. Birch bark research and development // Nat Prod Rep. 2006. Vol. 23. No. 6. P.919-942; Sarek J., Svoboda M, Hajduch M. Method of preparation and isolation of betulin diacetate from birch bark from paper mills and its optical processing to betulin // US Patent No. 8093413 B2, 2012].

Methods for producing allobetulinol from betulenol or directly from birch bark are described in [Kislitsyn AN, Trofimov AN The method of producing allobetulin // RF Patent No. 2174126, 09/27/2001; Kuznetsova S.A., Kuznetsov B.N., Redkina E.S., Skvortsova G.P. The method of producing allobetulin // RF Patent No. 2334759, Bull. No. 27, 09/27/2008; Levdansky V.A., Levdansky A.V., Kuznetsov B.N. The method of producing allobetulin // RF Patent No. 2374261, Bull. No. 33, November 27, 2009; Levdansky V.A., Levdansky A.V., Kuznetsov B.N. The method of producing allobetulin // RF Patent No. 2379314, Bull. No. 2, 01/20/2010; Kazakova O.B., Medvedeva N.I., Kazakov D.V., Tolstikov G.A. The method of producing allobetulin // RF Patent No. 2402561, Bull. No. 30, 10.27.2010]. The chemical essence of the known methods for producing allobetulinol is the isomerization (Wagner-Meerwein rearrangement) of betulenol in the presence of an acid catalyst.

Closest to the method for producing allobetulinol of the present invention is the method described in the patent of the Russian Federation No. 2402561 (2010). According to this method, 1 g of FeCl ₃ · 6H ₂ O (3.9 mmol) is added to a suspension of 5.3 g (12 mmol) of betulinol in 300 ml of chloroform. The reaction mass is stirred for 30 min (TLC control), chloroform is evaporated in vacuum water-jet pump. The product is washed with water to remove the iron salt and recrystallized from chloroform-hexane. The yield of allobetulinol is 4.9 g (92%), purity 95%.

This method has the following disadvantages:

- the use of a large amount of a toxic solvent of chloroform (~ 226 ml per 4.0 g of betulenol) during the reaction,

- low degree of purity of the final product. The presence of a trace of the iron salt in allobetulinol can cause the formation of by-products of its oxidation, thereby polluting the target allobetulinol during storage.

In the method for producing allobetulinol of the claimed invention (the first stage of obtaining AN-12) FeCl ₃ · 6H ₂ O is used as an acid catalyst, chloroform is used as a solvent (without preliminary purification and distillation, in the ratio: 60 ml of chloroform per 4.0 g betulenol). The reaction proceeds at the boil under reflux for 30-45 minutes. Removing iron salts during product cleaning is carried out by washing the chloroform phase with water 3-5 times (20 ml of water per 80 ml of chloroform).

Acylation, in particular with the formation of esters, plays an important role in improving the pharmacological properties (increase or formation of new activity, increase bioavailability, decrease toxicity, change the mechanism of action, etc.) of new compounds.

Examples of the synthesis of terpenoid drugs are known: hemisuccinylation of dihydroartemisinin (sesquiterpene group) with the formation of a more effective antimalarial drug artesunate, hemisuccinylation of glycyrrhetic acid (triterpene of the oleanan series) with the formation of carbenoxolone, hemi succination of the naturally occurring (high-acrylephenolate beryolephenol beryolephenol 457) for clinical trials against HIV, or the semisynthesis of the anticancer drug taxol (paclitum sat), which can be regarded as an acylated taxane diterpene type.

It is known that esters of allobetulinol at the C-3 position are obtained by reacting this compound with acid anhydrides or acid chlorides under reaction conditions using a tertiary amine (tributylamine, pyridine) as a catalyst for 6 hours at room temperature [Li T.-S. , Jian-Xin Wang J.-X., Zheng X.-J. Simple synthesis of allobetulin, 28-oxyallobetulin and related biomarkers from betulin and betulinic acid catalysed by solid acids // J. Chem. Soc., Perkin Trans 1. 1998. No. 23. P.3957-3966; Flekhter O.V., Medvedeva N.I., Karachurina L.T., Baltina L.A., Zarudii F.S., Galin F.Z., Tolstikov G.A. Synthesis and antiinflammatory activity of new acylated betulin derivatives // Pharmaceutical Chemistry Journal. 2002. Vol. 36. No. 9. P. 488-491; Kazakova O.V., Khusnutdinova E.F., Tolstikov G.A., Suponitsky K.Yu. Synthesis of new olean-18 (19) -ene derivatives from allobetulin // Russian Journal of Bioorganic Chemistry. 2010. Vol. 36. Number 4. P.512-515].

Prior to the claimed invention, information on the ester of propionic acid allobetulinol (AN-12) has not been described in domestic and foreign literature.

On the other hand, in connection with the general decrease in the immune status of the population, as well as the rapid spread of infectious diseases caused by various viruses (especially the human immunodeficiency virus), the search for new drugs with an immunostimulating effect is currently relevant.

The objective of the invention is the creation of a new effective means-immunomodulator based on 3-O-propionate allobetulinol obtained from natural betulenol simple chemical modification, in order to expand the arsenal of immunomodulating agents.

The essence of obtaining AN-12 is a two-stage synthesis from betulenol.

a) betulinol isomerization

A suspension of betulenol and FeCl ₃ · 6H ₂ O (acid catalyst) in chloroform (solvent) is heated to boiling, maintained at this temperature for 30-45 minutes. The reaction is controlled by TLC in a system of methylene chloride: ethanol: acetic acid - 95: 5: 1. At the end of the reaction, complete dissolution is observed. When processing the reaction, mechanical impurities are removed by filtration through a paper filter, and the soluble part of the iron salt is washed by washing with chloroform water 3-5 times (20 ml of water per 80 ml of chloroform). The product is purified by crystallization from chloroform, ethyl alcohol or a mixture thereof.

b) acylation of the obtained allobetulinol

An excess of propionic acid anhydride (7 equiv.) Is used as an acylating agent, and chloroform is used as a solvent. The catalyst is a tertiary amine: pyridine or DMAP (N, N-dimethylaminopyridine). The reaction is carried out at room temperature for 4 hours under TLC control (Sorbfil UV-254, CTX-1A silica gel) in a methylene chloride: ethanol system; acetic acid - 95: 5: 1. During processing, the tertiary amine is removed by washing with a solution of hydrochloric acid (3%), the product is isolated by extraction with chloroform. Purification of the product AN-12 is carried out by recrystallization from isopropyl alcohol. An AN-12 of the composition C ₃₃ H ₅₄ O ₃ is obtained, mp. 254-256 ° C, Rf 0.75.

The invention is illustrated by examples of the preparation of 3-O-propionate allobetulinol and studies of its immunomodulatory activity.

Example 1. The synthesis of allobetulinol

4.0 g (9.0 mmol) of betulenol are charged into a 100 ml flask equipped with a heater and a refrigerator, 60 ml of chloroform and 1.0 g of FeCl ₃ · 6H ₂ O (3.7 mmol) are added. The reaction mixture is boiled for 30-45 min (until the complete disappearance of the initial betulenol under TLC control). After this, the reaction mixture was cooled to room temperature, filtered off, 60 ml of water was added to the filtrate, the organic layer was separated, the aqueous layer was extracted with 20 ml of chloroform. The organic layers are combined and washed with water 3-5 times (20 ml each) and dried over anhydrous Na ₂ SO ₄ . Solvents were evaporated in vacuo until crystals appeared. Chloroform stripping is used for the following experiments. The yield of chromatographically homogeneous allobetulinol is 3.5 g (87.5%) with mp 264-266 ° C.

The structure of the obtained allobetulinol is confirmed by modern methods: TLC, IR and NMR spectroscopy.

TLC system: methylene chloride: ethanol: acetic acid - 95: 5: 1. TLC plate: Sorbfil PTSX-P-A-UV (silica gel STX-1A, UV-254 nm). Visualization of substances is carried out using iodine vapor. Allobetulinol has an Rf of 0.55. The starting betulenol has an Rf of 0.50.

IR spectrum (KBr, cm ^-1 ): 3431 and 3394 (-OH), 2937-2852 (CH, CH ₂ , CH ₃ ), 1450, 1386, 1041, 1035, 814, 769, 642.

IR spectrum (liquid paraffin, cm ^-1 ): 3429 and 3387 (-OH), 2924-2852 (CH, CH ₂ , CH ₃ ), 1462, 1377, 1039, 814, 769, 721, 642.

¹ H-NMR spectrum (CDCl ₃ , δ, ppm): 0.59-0.97 (m, 24H), 1.00-1.73 (m, 21H), 1.95-2, 06 (m, 1H), 3.07-3.18 (m, 1H, H-3), 3.38 (d, J = 7.78 Hz, 1H, H-28a), 3.47 (s, 1H, H-286), 3.72 (d, J = 7.53 Hz, 1H, H-19).

¹³ C-NMR spectrum (CDCl ₃ , δ, ppm): 13.46, 15.43, 15.66, 16.44, 18.22, 20.93, 24.51, 26.21, 26.39 (2C), 27.36, 27.99, 28.78, 32.67, 33.87, 34.10, 36.20, 36.68, 37.20, 38.85, 38.91 , 40.56, 40.65, 41.41, 46.77, 51.02, 55.47, 71.19 (C-28), 78.64 (C-3), 87.86 (C-19 )

The spectral data given are consistent with those known in the literature [RF patent No. 2379314, RF patent No. 2402561].

Example 2. The method of synthesis of 3-O-propionate allobetulinol (AN-12)

1.0 g (2.3 mmol) of allobetulinol are dissolved in 20 ml of chloroform and 3 ml of pyridine in a 100 ml round bottom flask equipped with a magnetic stir bar, 2.0 ml (15.6 mmol) of propionic anhydride are added. The reaction mixture was constantly stirred at room temperature (20-25 ° C) until the initial allobetulinol completely disappeared under TLC control (~ 4 h). Then the reaction mixture was poured into a glass of water (30 ml) and acidified with 3% HCl solution (~ 70 ml) to pH 2. The organic layer was separated, and the aqueous phase was extracted 2 times with 15 ml of chloroform. The combined extract is washed with water to pH 5 (15 ml, ~ 5 times). After distillation of the solvent and recrystallization from isopropyl alcohol, 0.9 g (79.9%) of 3-O-propionate of allobetulinol (AN-12) gross formula C ₃₃ H ₅₄ O _{3 is} obtained with so pl. 254-256 ° C.

The structure of the obtained 3-O-propionate of allobetulinol was established by modern methods: TLC, IR and NMR spectroscopy.

TLC system: methylene chloride: ethanol: acetic acid - 95: 5: 1. TLC plate: Sorbfil PTSX-P-A-UV (silica gel STX-1A, UV-254 nm). Visualization of substances is carried out using iodine vapor. AN-12 has an Rf of 0.75.

IR spectrum (KBr, cm ^-1 ): 2941, 2851, 1730 (C = O), 1464, 1444, 1390, 1377, 1363, 1194, 1078, 1060, 1035, 1008, 968, 891, 870, 806.

IR spectrum (liquid paraffin, cm ^-1 ): 2924, 2853, 1730 (C = O), 1462, 1388, 1377, 1363, 1194, 1078, 1059, 1035, 1008, 968, 891, 870, 806, 721 .

¹ H-NMR spectrum (CDCl ₃ , δ, ppm): 0.76-1.04 (m, 24H), 1.06-1.77 (m, 24H), 2.32 (q, J = 7.78 Hz, 2H, -CH ₂ COO-), 3.44 (d, J = 7.78 Hz, 1H, H-28a), 3.53 (s, 1H, H-286), 3 77 (d, J = 7.78 Hz, 1H, H-19); 4.41-4.55 (m, 1H, H-3).

¹³ C-NMR spectrum (CDCl ₃ , δ, ppm): 9.34 (propionyl-CH ₃ ), 13.48, 15.71, 16.53 (2C), 18.13, 21.00 23.71 (propionyl-CH ₂ ), 24.54, 26.26, 26.42 (2C), 27.94, 28.06, 28.81, 32.71, 33.84, 34.15, 36.25, 36.75, 37.18, 37.89, 38.58, 40.63, 40.72, 41.46, 46.82, 50.99, 55.57, 71.25 (C- 28), 80.58 (C-3), 87.93 (C-19), 174.24 (C = O).

In the IR spectrum in AN-12 liquid paraffin, there are no absorption bands in the region 3387-3429, characteristic of the secondary alcohol hydroxyl group of the starting allobetulinol, there are absorption bands at 1730 cm ^-1 characteristic of the C = O-ester of the acylation product. In the PMR spectrum of the synthesized compound, a quartet signal of CH ₂ protons _{of the} propionyl group is observed at 2.32 ppm, while proton signals of the skeleton of allobetulinol are retained. Under the influence of the propionyl group, the proton signal at the 3rd position of AN-12 has a chemical. a shift in a weaker field (4.41-4.55 ppm) compared with those of the initial allobetulinol (3.07-3.18 ppm). ¹³ C-NMR spectrum of the product shows that there are additional signals C = O (174.24 ppm), CH ₂ (23.71 ppm) and CH ₃ (9.34 ppm), and the number of carbon atoms in the molecule is 33, thereby fully confirming the structure of AN-12.

Thus, the above chromatographic and spectral data are consistent with the structure of the claimed compound.

Example 3. Evaluation of the humoral immune response (Antibody titer to EB)

In the study, mice were immunized by intraperitoneal administration of a model of an immunological study of the antigen - sheep erythrocytes (EB) [Immunotherapy: a guide. Ed. P.M. Khaitova, R.I. Ataullakhanova. M .: GEOTAR-Media, 2012.672 p.].

On the 7th day after immunization in the blood there is a maximum of IgG specific to the administered red blood cells. In accordance with this, the analysis of the titer of antibodies in serum was performed on the 7th day after immunization. The evaluation was carried out by the hemagglutination reaction method [Herzyk D.J., Bussiere J.L. Immunotoxicology strategies for pharmaceutical safety assessment // John Wiley & Sons - 2008].

The inventive compound AN-12 was administered to mice from 1-7 days subcutaneously in doses of 0.1; one; 10 and 50 mg / kg. For convenience, the results of the study are presented in the form of a median, lower and upper quartile ranges. Statistical differences were determined using the nonparametric Mann-Whitney U test, at p <0.05. The results of the study are presented in table 1.

Table 1 Evaluation of the humoral immune response (titer of antibodies to EB (log2N)), N = 10 Group Dose mg / kg Animal No. / antibody titer Me (Q1; Q2) one 2 3 four 5 control group (DMSO solvent) - 6 6 6 6 6 6 (6; 6) substance AN-12 0.1 6 6 6 6 7 6 (6; 6) substance AN-12 one 6 6 7 6 7 6 (6; 7) substance AN-12 10 7 8 7 8 8 8 (7; 8) * substance AN-12 fifty 9 7 8 9 8 8 (8; 9) * Note - * - the differences are statistically significant in comparison with the control group by the nonparametric Mann-Whitney U-test, at p <0.05

On the 7th day after immunization, the antibody titer in control animals treated with DMSO solvent was 6 (6; 6). Course introduction of the substance AN-12 in doses of 0.1; one; 10 and 50 mg / kg leads to a dose-dependent increase in the titer of antibodies in the blood of laboratory animals, reaching a maximum of 50 mg / kg.

The reaction is the main indicator of the formation of a humoral immune response. The results obtained allow us to conclude that AN-12 has a significant effect on the humoral immune response.

Example 4. Assessment of cellular immune response

To assess the effect of AN-12 on the cellular immune response, a delayed-type hypersensitivity reaction (HRT) was used in mice. This method involves subcutaneous administration to animals of an antigen, usually sheep erythrocytes, in order to activate the immune response. When staging the HRT reaction, sheep erythrocytes were administered twice - for sensitization and resolution.

At the sensitization stage, antigen is presented and a clone of antigen-specific T-lymphocytes-helpers-1 (T × 1) is formed. Presentation of the antigen through MHC class I receptors is carried out by macrophages that have absorbed and processed sheep red blood cells introduced at this stage. Lymphocytes, with their receptors, interact with MHCl and are responsible for the formation of memory T cells that carry antigen information.

At the effector stage, upon repeated encounter with the antigen, the interaction of memory T-lymphocytes and macrophages occurs. The subsequent production of various pro-inflammatory cytokines by lymphocytes and macrophages causes further involvement of specific and non-specific defense cells.

Thus, at the stage of sheep erythrocyte sensitization, the formation of a clone of antigen-specific T-lymphocytes occurs; at the resolution stage, the production of pro-inflammatory cytokines by the lymphocytes occurs. The results of the study are presented in table 2.

table 2 Delayed hypersensitivity reaction in inbred mice with intramuscular injection (M ± m, n = 10) A drug The reaction index,% The control 33.4 ± 2.5 AN-120.1 mg / kg 36.8 ± 2.9 ^* AN-12 1 mg / kg 23.3 ± 2.2 ^* AN-12 10 mg / kg 18.4 ± 1.3 ^* AN-12 50 mg / kg 14.5 ± 1.1 ^* Note: ^* - statistically significantly different from the control according to t student criterion at p <0.05

Course subcutaneous administration to mice AN-12 in doses of 0.1; one; 10 and 50 mg / kg led to a dose-dependent decrease in HRT reaction. At a dose of 50 mg / kg, edema of the affected limb was 2.5 times lower than in the control group.

Analyzing the data obtained, we can conclude that at doses of 0.1, 1, 10 and 50 mg / kg AN-12 has immunomodulating properties: it stimulates a humoral immune response, increasing the concentration of antibodies in the blood by 8 times. With the development of a T-cell immune response in a delayed-type hypersensitivity reaction, the claimed agent provides a reduction in edema. The data obtained can serve as the basis for the use of AN-12 as a candidate for drugs and a promising immunomodulating agent.

Claims (1)

An immunomodulatory agent comprising allobetulinol 3-O-propionate (19β, 28-epoxy-18α-oleanan-3β-yl propionate) as an active substance.

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