New bioactive peroxides from marine sponges of the family Plakiniidae

In our continuing program to identify compounds with antifungal properties, the ethanol extracts of two sponges of the family Plakinidae were found to inhibit the growth of the fungal pathogens Candida albicans and Aspergillus fumigatus. From these organisms three new compounds and five known compounds have been identified. A new 1,2-dioxane ring peroxide acid, 1, has been isolated from the sponge Plakortis halichondrioides along with five known compounds. Two new 1,2-dioxolane peroxide acids, 3 and 4, have been isolated from the sponge Plakinastrella onkodes. The structures were established by interpretation of spectral data. The three new compounds exhibit moderate activity against the fungal pathogen C. albicans with MICs of 5, 1.6, and 1.6 mug/mL respectively, for 1, 3, and 4. Compound 1 also showed in vitro inhibition of the fungal pathogen A. fumigatus with an IC90 value of 5.6 mug/mL.