3 カビによるイソプレノイド類の代謝の化学的研究(そのIII)

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We have previously shown that the metabolic transformation of isoprenoids by fungi gave interesting structural modifications on the substrates ; 1) Helminthosporium sativum converts racemic 10,11-epoxyfarnesol into its S(-)-glycol derivatives, and the other fungus, Colletotrichum nicotianae it into the corresponding R(+)-enantiomer, 2) the former fungus catalyzes a trans-cis isomerization of the Δ^<2,3>-double bond of farnesol (Fig. 1). We wish now to report our further advances made on these subjects summerized in the following four parts. 1) C. nicotianae metabolized racemic C_<16>-juvenile hormone (JH) into its R(+)-dihydroxy-derivative, whose enantiomeric composition was determined as 95:5. From this diol metabolites, optically active C_<16>-JH was chemically prepared (Fig. 2). (-)-14,15-epoxygeranylgeraniol, a constituent of the Brazilian plant with a chemoprophylactic activity in shistosomiasis, was synthesized by coupling R(+)-methyl 6,7-dihydroxygeranioate, obtained in pure form as a metabolic product of methyl geranioate by C. nicotianae, with the carboxylic derivative, obtained as a metabolic product of linalool by H. sativum (Fig. 4 and 5), establishing thus the natural product to have the S configuration. 2) Optically pure natural and unnatural C_<16>-JH were prepared in hopes of establishing structure-activity relationship from diastereomers 13 and 12, respectively, which were obtained as a result of complete optical resolution of racemic ethyl 10,11-dihydroxyfarnesoate as its C_<10>-etienyl ester (Fig. 6). 3) 10,11-Epoxysqualene was first found naturally in the mycelial mat of the fungus, Sclerotinia fructicola (Fig. 7). 4) Stereochemistry of the C_1-hydrogen exchange during dehydrogenation-hydrogenation reaction which plays an important role in the trans-cis isomerization of farnesol by H. sativum, was investigated using deuterium-labelled substrates, concluding that the pro R- and not pro S-hydrogen is replaced stereospecifically in this reaction (Fig. 11).
天然有機化合物討論会の論文
1975-10-01

3 カビによるイソプレノイド類の代謝の化学的研究(そのIII)

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