6beta-hydroxymaslinic acid, a triterpene from Vochysia ferruginea

J. Braz. Chem. Soc., Vol. 11, No. 3, 241-244, 2000. Printed in Brazil c 2000 Soc. Bras. Química 0103 - 5053 $6.00+0.00 Article 6β β-Hydroxymaslinic Acid, a Triterpene from Vochysia ferruginea a a b c Yasmin L. Zucaro Z. , Reinaldo S. Compagnone , Sonia C. Hess * and Franco Delle Monache ªEscuela de Quimica, Universidad Central de Venezuela, Caracas, Venezuela b Departamento de Hidráulica e Transportes/CCET, Universidade Federal de Mato Grosso do Sul, CP 549, 79070-900, Campo Grande - MS, Brazil c Centro Chimica dei Recettori del C.N.R., Istituto di Chimica e Chimica Clinica, U.C.S.C., Largo Francesco Vito 1, 00168 , Roma, Italy. Um novo ácido triterpenóide pentacíclico foi isolado a partir de folhas e frutos de Vochysia ferruginea. A estrutura do novo composto foi elucidada por espectroscopia de RMN como sendo o ácido 2α,3β,6β-triidroxiolean-12-en-28-óico (ácido 6β-hidroximaslínico, 1). Além do novo triterpenóide, foram isolados das folhas e frutos o glicosídeo de β-sitosterol e três misturas contendo os triterpenóides conhecidos uvaol e eritrodiol, ácidos ursólico e oleanólico e os ácidos 2α,3βdiidroxiurs-12-en-28-óico e o respectivo isômero oleanólico (ácido maslínico ou cratególico). Nos frutos, a bellericagenina A e o seu éster (28 → 1) β-D-glicopiranosílico (bellericasídeo A) estão presentes em elevados teores. A novel oleane acid was isolated from the leaves and the fruits of Vochysia ferruginea. The structure of the new triterpenoid was elucidated by NMR spectroscopy as 2α,3β,6β-trihydroxyolean-12-en-28-oic acid (6β-hydroxymaslinic acid, 1). In addition, β-sitosterol-glucoside and three mixtures containing known triterpenoids, uvaol and erythrodiol, ursolic and oleanolic acids, 2α,3βdihydroxyurs-12-en-28-oic acid and its respective oleanolic isomer (maslinic or crategolic acid), were isolated from the leaves and the fruits of Vochysia ferruginea. In the fruits, bellericageninA and its (28 → 1)β-D-glucopyranosyl ester (bellericaside A) were present in high amount. Keywords: Vochysia ferruginea, Vochysiaceae, pentacyclic triterpenes, 6β-hydroxymaslinic acid Introduction The genus Vochysia (Vochysiaceae) seems to be an abundant source of triterpenoids. Bartogenic and vismiaefolic acids have been reported from V. vismiaefolia1; betulinic, 4-epi-vismiaefolic, and 2α,3β,19α-trihydroxy24-oxo-urs-12-en-28-oic acids from V. piramidalis2. From the stem bark of V. divergens we isolated the terpenoids β-sitosterol, betulinic, sericic, divergioic and 24hydroxytormentic acids, and the (28 → 1) β-D-glucopyranosyl ester of later3-5 . Sericic acid (2α,3β,19,24-tetrahydroxyolean-12-en-28-oic acid) presented antifungal 3 and antibacterial4 activities. 24-Hydroxytormentic acid showed antinociceptive action 6. V. ferruginea is a tree commonly found in wet soils of Venezuelan Amazon7. In this communication we report the structure elucidation of 6β-hydroxymaslinic acid, 1, a novel *e-mail: triterpenoid of the oleane series obtained from the leaves and the fruits of V. ferruginea. β-sitosterol-glucoside and mixtures of uvaol and erythrodiol, ursolic and oleanolic acids, 2α,3β-dihydroxyurs-12-en-28-oic acid and its respective oleanolic isomer (maslinic or crategolic acid) were also obtained. Bellericagenin A and its (28 → 1) β-D-glucopyranosyl ester (bellericaside A) were present in high amount in the fruits. Experimental General experimental procedures Melting points were determined using a Kofler hot-stage instrument and were uncorrected. IR spectra were measured on a Perkin-Elmer 1320 spectrometer. 1H and 13C-NMR spectra were recorded in CDCl3 or in pyridine-d5, using TMS as internal reference, employing a Varian Gemini 300 (1H, 300 MHz; 13C, 75 MHz) spectrometer. Optical rotations were measured in a Polamat A (Carl Zeiss) polarimeter. 242 Zucaro et al. Mass spectra were recorded on a HP 5988A apparatus (EI, 70 eV). Isolation procedures were monitored by employing thin-layer chromatography on pre-coated silica gel plates (Merck, Kieselgel 60 F-254). Plant material Vochysia ferruginea Mart (Vochysiaceae) was collected in the margins of Cataniapo River near Puerto Ayacucho (Amazona State, Venezuela) and identified by Dr. A. Castillo. A voucher specimen is deposited in the Herbarium of the Escuela de Biologia, Universidad Central de Venezuela, Caracas, under number AC 3301. Extraction and isolation Air dried and powdered leaves (400 g) were exhaustively extracted at room temperature with CHCl 3 to give after evaporation a residue (8.0 g), which was purified by CC (SiO2 ; CHCl3 with increasing amounts of MeOH). The first three fractions (eluted with CHCl 3 - MeOH, 49:1, 19:1, and 9:1, respectively) gave unseparated mixtures of uvaol and erythrodiol (38 mg), of ursolic and oleanolic acids (280 mg), and of 2α,3β-dihydroxyurs-12-en-28-oic and 2α,3β-dihydroxyolean-12-en-28-oic acids (maslinic or crategolic acid, 220 mg). After repeated chromathography, the fourth fraction also eluted with CHCl3-MeOH, 9:1, yielded β-sitosterol-glucoside (200 mg) and 6βhydroxymaslinic acid, 1 (92 mg). The crushed fruits (196 g) were exhaustively extracted with hot CHCl 3-EtOH,1:1 in Soxlet apparatus. The residue (5.7 g) was suspended in cold MeOH and filtered. By crystallization (MeOH) the solid material gave bellericagenin A (2.8 g). The MeOH soluble portions (1.6 g) were purified by CC (SiO 2 ; EtOAc with increasing amounts of MeOH). Oleanolic acid (20 mg) and 1 (40 mg) were eluted with EtOAc, further bellericagenin A (1.1 g; total yield, 2% of the fruits) with EtOAc-MeOH, 97:3. The last eluted fraction (EtOAc-MeOH,19:1) yielded bellericaside A after washing with cold acetone (50mg). Methylation of 1 with ethereal diazomethane afforded the monomethyl ester 1a. J. Braz. Chem. Soc Methylation of 1 with ethereal diazomethane, 0o C, afforded the mono methyl ester 1a. EIMS of 1a (70 eV), (m/z, %): 502 (M+, 5), 484 (M-H2O, 4), 442 (M-HCOOMe, 6), 262 (77), 249 (12), 203 (100), 189 (40) (Figure 1); 1H NMR of 1a (300 MHz,CDCl 3) δ 5.33 (H-12), 4.53 (H-6), 3.73 (H-2), 3.63 (OMe), 2.95 (H-3), 2.89 (H-18), 1.37, 1.25, 1.20, 1.10, 1.08, 0.93 and 0.90 (7Me); 13C NMR of 1a (75 MHz, CDCl3) δ 178.2 (C-28), 142.9 (C-13), 122.5 (C-12), 83.7 (C-3), 68.7 (C-2), 68.4 (C-6), 55.6 (C-5), 51.5 (OMe), a48.4 (C-19), 47.8 (C-9), a46.6 (C-1), 45.7 (C-17),42.1 (C14), 41.2 (C-18), 40.6 (C-7), 39.7 (C-8), 38.4, 37.8 (C-10; C-4), 33.8 (C-21), 33.1 (Me-29), 32.3 (C-22), 30.6 (C-20), 28.3 (Me-23), 27.5 (C-15), 25.9 (Me-27), 23.5 (Me-30), 23.3 (C-16), 22.9 (C-11), 18.1 (Me-24, Me-25, Me-26) (a Interchangeable values). 2α,3β,7α,23-Tetrahydroxyolean-12-en-28-oic acid (Bellericagenin A) 1H NMR (300 MHz, C D N) δ 5.57 (br s, H-12), 5.10 5 5 (br s, H-7), 4.41 (m, H-2, H-23 a), 4.25 (d, J 10.4 Hz, H-3), 4.08 (d, J 11.8 Hz, H-23 b), 3.32 (br dd, H-18), 1.78 (Me25), 1.74 (Me-24), 1.63 (Me-26), 1.23 (Me-27), 1.00 (Me30), 0.93 (Me-29) (data not available in the literature, in C 5D5N); 13C NMR (75 MHz, C5D5N) δ 180.0 (s, C-28), 144. 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