Structure-activity relationships for unsaturated dialdehydes. 10. The generation of bioactive products by autoxidation of isovelleral and merulidial.

The autoxidation of the two mutagenic and antimicrobial sesquiterpenes merulidial (1a) and isovelleral (5) generates a number of bioactive products that are suggested to be partly responsible for the mutagenic and antimicrobial activities of the two compounds. The biological activities of the autoxidation products are, as far as has been possible to assay, of the same order as the parent compounds, and it is shown that they are formed in normal bioassay media. Merulidial (1a) is especially interesting, as its rate of autoxidation is considerably higher compared with non-mutagenic derivatives of 1a. In addition, natural isovelleral [(+/-)-5] was found to be twice as mutagenic as synthetic isovelleral [(+/-)-5], indicating that (-)-isovelleral is only weakly active or inactive, and supporting the suggestion that the interaction of isovelleral (5) and its derivatives with DNA depends on the absolute stereochemistry of the unsaturated dialdehyde moiety.