IDENTIFICATION OF ALKALOIDS AND POLYKETIDES IN AN ACTINOMYCETE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH MASS-SPECTROMETRIC AND UV-VISIBLE DETECTION

Analytical HPLC with UV-Vis diode array detection and positive electro spray HPLC-MS were employed to characterise the secondary metabolites of Actinomycetes spec. strain BA 909 in crude mycelial extracts and pr eparative HPLC fractions. It was shown that the strain produced two fa milies of antibiotics previously reported in the literature, namely th e polyketides leptomycin A (1) and B (2), kazusamycins A (3) and B (4) and the alkaloids nybomycin (5) and deoxynybomycin (6), respectively. Compounds 1-4 were identified by comparison of their HPLC-UV and HPLC - MS data with authentic materials obtained from the original producer strain, whereas the identity of the nybomycins 5 and 6 was establishe d by comparison of structural data with those of reference compounds. From HPLC-UV-Vis analyses it was established that both groups of metab olites are produced as complex mixtures of congeners. The employment o f a single HPLC-UV-Vis method, aided by HPLC-MS of selected fractions, allowed fur simultaneous detection of the main metabolites in the cru de extracts during fermentation. Known metabolites could be distinguis hed from tentatively new congeners. For example, the data available fr om HPLC-UV-Vis and HPLC-MS analyses point towards the presence of an a nguinomycin A (7) isomer, two new isomers of kazusamycins A and B (8 a nd 9), and a new nybomycin derivative (10) in addition to the known co mpounds 1-6. The co-occurrence of both leptomycin and nybomycin type m etabolites in the same Actinomycete strain was observed for the first time. (C) 1998 Elsevier Science B.V. All rights reserved.