Résumé
Objective: To investigate the antitumor metabolites of fungal mutants 2-2-3 and PDN-f-2, the two bioactive mutants of Penicillium purpurogenum G59 that do not produce antitumor metabolites. Methods: Bioactive metabolites newly produced by the mutants were isolated by a bioassay-guided separation procedure using iquid-liquid extraction, column chromatography and recrystallization methods through direct comparison with the sample from P. purpurogenum G59. The compounds obtained were identified by spectroscopic methods. The antitumor activity was assayed by the MTT method using K562 cells. Results: Two bioactive metabolites 1 and 2 were isolated from the fermentation products of 2-2-3 and PDN-f-2, respectively, and identified as ergone (1) and citrinin (2). Compounds 1 and 2 inhibited the proliferation of K562 cells with the IC50 values of 7. 4 and 48. 0 μg/ml, respectively. Conclusion: Compounds 1 and 2 are the antitumor metabolites newly produced by he mutants 2-2-3 and PDN-f-2, respectively, and have not been found in the metabolites of P. purpurogenum so far. It is revealed from the present result that the alteration of secondary metabolism of wild-type fungal strains without bioactivity for obtaining bioactive metabolite-producing mutants may become a new route to expand the source of new fungal strains for drug screening.