• Bulletin of the Korean Chemical Society
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• v.29 no.8
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• pp.1445-1446
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• 2008

• Archives of Pharmacal Research
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• v.8 no.4
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• pp.229-236
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• 1985

Oxidation of presenegenin dimethyl ester triacetate with chromium trioxide in acetic acid yielded two compounds, 11-ketone (IV) and 12-ketone (IV) derivatives. The latter was a main product. On mild alkaline hydrolysis, IV afforded 11-keto-presenegenin dimethyl ester (V), mp 232-$234^{\circ}$, $C_{32}H_{48}O_{8}$, whereas VI did 12-keto-presenegenin dimethyl ester 12, 27-hemiketal (VIII), mp 240-$242^{\circ}$, $C_{32}H_{50}O_{8}$.

• Journal of Microbiology and Biotechnology
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• v.7 no.4
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• pp.272-277
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• 1997

In the purification of elaiophylin from a culture of Streptomyces hygroscopicus MCY -846, mono- and di-methyl-elaiophylin were obtained through a O-methylation of the hemiketal hydroxy group of elaiophylin. All the three elaiophylins showed cytotoxicity against several human tumor cell lines and murine cell lines. Elaiophylin and monomethyl-elaiophylin also showed antimicrobial activities against gram-positive bacteria and potent inhibitory effects on the activation of B cells by lipopolysaccharide as well as on the proliferation of mouse splenic lymphocytes stimulated by mitogens but dimethyl-elaiophylin did not. This result indicates that elaiophylin and monomethyl-elaiophylin would be strong immunosuppressants. Furthermore this result revealed an interesting structure-activity relationship suggesting that the lack of symmetry and/or the free OH group at C-11 of elaiophylin might be important in conferring biological activities.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.19-26
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• 1996

A phospholipase C (PLC) inhibitor (MT267-2B) was isolated from the culture broth of actinomycetes isolate MT2617-2 by the extraction with n-butanol and column chromatographic techniques. The molecular weight of the inhibitor was 1057, by the spectroscopic analyses of IR, $^{13}C$-and $^{1}H$-NMR and ESI-MS. The chemical structure of MT2617-2B was found to be a macrolide compound consisted of a hemiketal ring, polyhydroxyl and polymethyl groups, which had a malonate and guanidine group as its side chain. MT2617-2B produced its two isomers having the same molecular weight by standing in methanol solution at room temperature. Therefore, MT2617-2B was identified as copiamycin and niphithricin A, macrolide antibiotics. The values of $IC_{50}$ against PLC-${\gamma}$1 and PLC-${\beta}$1 were 25 and 50${\mu}$g/ml, respectively. MT2617-2B had antimicrobial activities against Staphylococcus aureus and Candida albicans, but not against Escherichia coli.