著者
寺原 昭 羽石 達生 新井 守 桑野 晴光
出版者
天然有機化合物討論会実行委員会
雑誌
天然有機化合物討論会講演要旨集
巻号頁・発行日
vol.18, pp.286-293, 1974

The antifungal metabolite, herbicidin A (C_<23>H_<29>O_<11>N_5) and herbicidin B (C_<18>H_<23>O_9N_5) obtained from Streptmyces saganonensis (Strain No 4075) have a plant growth inhibiting effects against to baryard glass, green panicum, tomato and radish ect., in a concentration 37-300ppm without effect to rice. Basic hydrolysis of herbicidin A affords an unsaturated acid 3 which has been confirmed to be 2-hydroxymethyl-2-butenoic acid, and herbicidin B acid 4. Methanolysis of herbicidin A and B with Amberlyst 15 in methanol affords adenine, and C_<19>H_<28>O_<12> 8 and C_<15>H_<24>O_<10> 5 respectively. On the bases of chemical and physico-chemical evidences of these derivatives, structures of herbicidin A and B have been determined to be nucleosides which consist of adenine and an unusual sugar moiety.
著者
丸山 雅雄 寺原 昭 中平 靖弘 Woods M. C. 板垣 又丕 高木 良子 中西 香爾
出版者
天然有機化合物討論会
雑誌
天然有機化合物討論会講演要旨集
巻号頁・発行日
no.10, pp.238-245, 1966-09-15

From the root bark of Ginkgo biloba L. ("icho" in Japanese), a unique fossil tree which has remained unchanged for 1-2 million years, four bitter principles designated ginkgolides A, B, C and M (for "minor") (abbreviated to GA, GB, GC and GM) have been isolated. Early work was greatly hindered by purification problems and polymorphism, but the molecular formulae were finally settled by high resolution MS of GA dimethyl ether (Fig. 1). As shown in Fig. 2, a tert-Bu group is present; these are the first plant products to contain such a group. Establishing the number of lactone groups presented difficulty, but was achieved by titration according to Method B (Fig. 3). The partial structure comprising rings A/B was elucidated from the data summarized in Figs. 5 and 6. NMR analysis of the isolated 4 proton system E-H (Fig. 7) was simplified in GC because of an additional 2°-OH group. The bislactone system containing H_J was clarified (Figs. 8-10) by an NMR analysis of GA-triether utilizing extensively the techniques of solvent shifts and decoupling, and comparison with the triether-d_6 spectrum which resembles the GA spectrum (Fig. 13). An attempt to determine the number of lactone rings was made by measuring the M^+ and isotope peaks of GA dimethyl ether (Fig. 11), the lactone rings of which had been cleaved and recyclized in the presence of H_2O^<18> as depicted in Fig.13-Method B. However, the MS indicated that only two lactones had incorporated O^<18>; presumably, one of the lactones had been cleaved by O-alkyl fission and recyclized by expulsion of O^<18>H. Alkali fusion of GA gave two important bisnor products, but these are not discussed in the Abstract because of limitations of space. Part structures shown in Fig. 12 are proposed for the ginkgolides.