New γ-pyrone propionates from the Indian Ocean sacoglossan Placobranchus ocellatus

Two new γ-pyrone propionates (i.e., 9, relative stereochemistry), characterised by a bicyclo [4.2.0] octane ring, have been isolated from the Indian sacoglossan Placobranchus ocellatus. A sunscreen protective role of compound 9 could be suggested by analogy with photodeoxytridachione previously found in the same mollusc.