We previously designed and synthesized an NF-B inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), that showed anti-inflammatory activity in vivo. In the present study we looked into its mechanism of inhibi-

Two hundred thirteen cytochrome P450 (P450) genes were collected from bacteria and expressed based on an Escherichia coli expression system to test their hydroxylation ability to testosterone. Twenty-four P450s stereoselectively monohydroxylated testosterone at the 2alpha-, 2beta-, 6beta-, 7beta-, 11beta-, 12beta-, 15beta-, 16alpha-, and 17-positions (17-hydroxylation yields 17-ketoproduct). The hydroxylation site usage of the P450s is not the same as that of human P450s, while the 2alpha-, 2beta-, 6beta-, 11beta-, 15beta-, 16alpha-, and 17-hydroxylation are reactions common to both human and bacterial P450s. Most of the testosterone hydroxylation catalyzed by bacterial P450s is on the beta face.

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The absolute structure of a new antibiotic lactonamycin is described. The NMRstudies deduced one of four possible structures for the aglycon attached by a rhodinose through glycosidic bond. The stereochemistry of the sugar obtained by an acid hydrolysis was determined to be L-form by measuring optical rotation. The stereochemistry of the aglycon was determined by X-ray crystallographic analysis.Lactonamycin 1 has been isolated from a culture broth

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A new structural class of the antibiotic, epoxyquinomicins A, B, C and D were isolated from the culture broth of the strain MK299-95F4,which was related to Amycolatopsis sulphurea. Antimicrobial activity of epoxyquinomicins A and B were weak against Gram-positive bacteria, and epoxyquinomicins C and D showed almost no antimicrobial activity and no cytotoxicity. All these antibiotics showed improvement of collagen induced arthritis in vivo.

Lactonamycin (1) was isolated from a culture broth of Streptomyces risfiiriensis MJ773-88K4. Antibiotic 1 exhibited antimicrobial activities against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA)and vancomycin-resistant Enterococcus (VRE). Methicillin-resistant Staphylococcus aureus (MRSA) has caused a serious problem in clinics since 1980s. Two anti-MRSA agents, vancomycm and arbekacin are used clinically in Japan. But emergence of vancomycinresistant Enterococcus (VRE) reported recently threatened those engaged in medical treatment. So we are devoted to discover antibiotics effective against various bacteria including MRSAand VRE from microbial sources.

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