Two new biological active cyclopentenones VM 4798-1a (1a) and VM 4798-1b (1b) were obtained as a 3:1 inseparable mixture from fermentations of Dasyscyphus sp. A47-98. The mixture of the two isomers showed cytotoxic and weak antibacterial and antifungal properties. VM 4898-1 (2-hydroxy-3, 4-dimethyl-2-cyclopenten-1-one, 4), produced by another Dasyscyphus sp. showed no significant biological activity. The structures were elucidated by NMR techniques.
Japan Antibiotics Research Association