著者

通 和夫 十倉 一也 岡部 啓 江幡 光雄 大塚 英夫 松下 和弘 Lukacs G.

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.20, pp.24-31, 1976

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Sulfur-containing peptide antibiotics, siomycins (SIM) A, B, and C isolated from Streptomyces sioyaensis are known to have structures quite similar to that of thiostrepton (TST) isolated from S. azureus. The 25-MHz ^<13>C FT NMR and 220-MHz ^1H NMR spectra of TST and SIM's were determined in CDCl_3-CD_3OD (8: 2) at various temperatures to obtain structural relationships between these antibiotics. ^<13>C signals were tentatively assigned by ^1H noise decoupling, single-frequency and noise off-resonance decouplings, and partially-relaxed FT techniques and using known chemical-shift rules, the chemical shifts of amino acids reported, and those observed for thiostreptine and a quinaldic acid derivative. Their ^<13>C spectra quite similar to each other revealed the numbers of carbon atoms and dehydroalanine (Deala) residues. It was found that (1) the signals of the Val-Deala residues in SIM's are changed to those of the Ile-Ala residue in TST, that (2) SIM-B lacks of the terminal Deala-Deala residue in the long side-chain, and that (3) SIM-C has an unknown amino-acid residue instead of the terminal Deala. On the basis of the above spectral and other chemical studies, and a tentative structure (Ia) proposed for TST by an X-ray crystallographic analysis, the structures Ib, II, and III were concluded to be assigned to TST, and SIM-A and -B, respectively.

著者

大村 智 中川 彰 竹嶋 秀雄 宮沢 淳 渥美 清夫 Piriou F. Lukacs G.

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.19, pp.434-441, 1975

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According to previous reports, the aglycone carbons of the 16-membered macrolide antibiotic, magnamycin A, 1 are derived from nine acetates, one propionate and one methionine as shown in Fig. 1. As an application of a recent systematic ^<13>C-NMR study of 16-membered macrolide antibiotic, the validity of these investigation was reexamined on leucomycin A_3 2 which is structurally similar to magnamycin A. It was found that carbons-5, -6, -17 and -18 of leucomycin A_3, 2 were derived from butyrate and carbons-3 and -4 on the aglycone arose from outside of acetate contrary to the proposal in the study on magnamycin biosynthesis. Although the origin of the carbons-3 and -4 is not yet known at present time, this finding let us to investigate the origin for the carbons-3 and -4 of the aglycone of tylosin which has different carbon skeleton from leucomycin or magnamycin (Fig. 3). Consequently, the metabolic origin, acetate, propionate and butyrate was proposed as shown in Fig. 5. The addition of [1-^<13>C]butyrate to a fermentation medium of tylosin showed the enrichment for carbons-3, -7, -11, -13 and -15 of aglycone as like as carbon-5 which is predicted to be enriched by the precursor. On the other hand, carbons-4, -8, -12, -14 and -16 were enriched as like as carbon-19 by [4-^<13>C]2-ethylmalonate. The metabolic pathway is not yet clear, however these precursors are thought to be partially incorporated to the aglycone of tylosin via propionate.