The chemistry of the leucomycins. I. Partial structure of leucomycin A3

✍ Scribed by Satoshi Ōmura; Haruo Ogura; Toju Hata

• Publisher: Elsevier Science
• Year: 1967
• Tongue: French
• Weight: 229 KB
• Volume: 8
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)90558-6

✦ Synopsis

The leucomycins have been found to be a family of macrolide antibiotics isolated from Streutomvces kitasatoensis Hata by T. Hata et al 1) . In the course of earlier chemical studies, leucomycin AI proved to be an alcohol having a carbonyl group, a conjugated double bond and an epoxide 2)3). In this report, a new component named leucomycin A3 is discussed, which is one of the most effective compounds and closely resembles leucomycin AI. Leucomycin A3 (I) could be separated from the leucomycin complex by chromatography on silicic acid, eluted by benzene-acetone, and crystallized from benzene as colorless prisms, m.p. 120-121°C, (a]U -58.C" (c 2.C, MeOH), -55.4' (c l.S)*", Amax 231.5 rnp @m 351)***, pka' 6.7C.*** Molecular weight determination by titration and osmometry (in chloroform) gave values of 835210 and 850225, respectively, and these values coupled with microanalytical data led to a molecular formula of C4zH69Ci5?: (Calcd. 827). It gives negative ninhydrin and Van Slyke nitrogen tests. The Tollen's and tetrazolium tests are positive. Zeisel determination shows the presence of one methoxyl group. The IR spectrum shows strong peaks at 1728 and 17'cm -1 (carbonyl), 1230 cm -1 (acetyl), and weak peaks at 2725 cm -' (aldehyde) and 1661 cm -1 (double bond).

m~fx Unless otherwise stated, rotations were measured in chloroform solution at 25OC, UV spectra were taken in methanol solution and pka' values were measured in 50% ethanol. Satisfactory analyses were obtained for all compounds for which molecular formulae are given.