【摘要】 <正> 通光藤[Marsdenia tenacissima(Roxb.)Wight et Arn.]系云南民间治疗气管炎和抗癌药用植物。前报我们报告了通光藤甙元甲的结构的部分研究工作。自分离甙元甲的母液中我们又分得了两个少量新甙元——通光藤甙元乙和丙(tenacigenin Band C)。本文报告它们的结构研究,并在此基础上对前报所推定的通光藤甙元甲的六元氧环的立体构型提出修正。更多还原

【Abstract】 Marsdenia tenacissima (Roxb.) Wight et Arn. (Chinese name. Tongguang-teng) is a folk medicine for treating trachitis and antitumor in Yunnan. From the crude glucosides of th steme we isolated three new C21-steroidal compounds: tenaci-genin A(1), B (2) and C (3) by treatment with acid and base.Tenacigenin A (1), mp 255-260℃, C21H32O5 (M+=364). Its NMR spectrum showed signals for three quaternary CH3, its MS peak at m/e 303(M+-HOAc-H) indicated that C20 linked with two oxygen atoms. Reaction of (1) with Ac2O-Py by usual way gave monoacetate (4) and diacetate (5), triacetate (6) could be obtained in sealed tube at high temperature. Therefore (1) has two secondary OH and a tertiary OH, the remaining two oxygen atoms existed as the form of epoxide. ( 1 ) was able to oxidize to monoketone ( 7 ) and diketone ( 8 ) . ( 1 ) reacted with Ac2O-PTS to yield compound(11), its IR and NMR spectra indicated the presence for three OAc and -COCH3, UV and NMR spectra indicated the presence of conjugated double bond at C7,8 and C9,11. Therefore the two epoxy rings of ( 1 ) must be linked with C8 C8, and C20 respectively. The tert. OH attached only to C14 which was due to the fact there appeared a broad double signal of C17-H in NMR of (11). The configulations of 12β-, 14β-OH and two α-aix-membered epoxy rings were determined by the fact that (2) was transformed into (1).Tenacigenin B (2), mp 226-230℃, C21H32O5 (M+=364). Its IR and NMR spectra showed the presence of 17-COCH3 .Reaction of (2) with acetone-CuSO4 afforded major (1) besides monoacetonide (13) .Acetylation of (2)gave triacetate(14) . One oxygen remained could exist in epoxide. Since (2) was treated with dil. acid to yield ( 1 ), with dil. base to yield (15), (l) and little (16), the epoxy ring must be three-menbered which attached to C8 and C14, according to J9,11 and its influence to 18-CH3, the epoxy ring is inferred as β -configuration.Tenacigenin C (3), mp 120-122℃, C21H34O8, its IR and NMR spectra showed the presence of 17-COCH3, reacted with acetone-CuSO4 to yield diacetonide (17), acetylated to yield triacetate (18), therefore the two tert-OH have β-confi-guration.The configuration of 17-COCH3 was inferred as α-eonfiguration bases on the analysis of its NMR (in pyridine-d5).According to the above chemical reactions and spectra data of IR, NMR, UV and MS, the structures of tenacigenin A, B and C have been suggested as (1), ( 2) and (3 ) .更多还原