abierixin and grisorixin

With addition of methyl oleate, the increased yield of antibiotic production by nigericin-producing Streptomyces hygroscopicus NRRL B-1865 also resulted in the isolation of three additional polyether antibiotics. Two of these are abierixin and epinigericin, as new antibiotics. The third antibiotic is grisorixin. The production of both abierixin (opened ring A and 30-CH2OH) and grisorixin (ring A and 30-CH3) poses the problem of the identity of the last pathway precursor of the major metabolite, nigericin (ring A and 30-CH2OH). Transformation experiments of abierixin by S. hygroscopicus gave negative results. Hydroxylation of grisorixin to nigericin by S. hygroscopicus represents the final step in nigericin biosynthesis.

Topics: Anti-Bacterial Agents; Biotransformation; Fermentation; Hydroxylation; Ionophores; Nigericin; Pyrans; Spectrometry, Mass, Fast Atom Bombardment; Streptomyces

Thin-layer chromatography coupled with flame ionization detection was used to develop a method to separate and to determine simultaneously three polyether carboxylic ionophore antibiotics (abierixin, nigericin and grisorixin) produced by Streptomyces hygroscopicus NRRL B 1865. Various proportions of chloroform, methanol and formic acid (or acetic acid as a substitute for formic acid) were used in the developing solvent to determine changes in RF values of the antibiotics and to allow conditions for maximum resolution to be obtained. Development on Chromarods SII with chloroform-methanol-formic acid (97:4:0.6, v/v/v) gave satisfactory and reliable separations of the three polyether antibiotics. Under these conditions, the internal standard methyl desoxycholate was found to be suitable for their simultaneous determination in the lipid extracts of Streptomyces hygroscopicus NRRL B 1865.

Topics: Calibration; Chromatography, Thin Layer; Flame Ionization; Lipids; Nigericin; Pyrans; Streptomyces