Marine natural products: Deodactol,antineoplastic sesquiterpenoid from the sea hare aplysia dactylomela

Deodactol, a halogenated bisabolene-type sesquiterpene alcohol, has been isolated from the sea hare Aplysia dactylomela, and its structure and absolute configuration have been determined by X-ray diffraction. The compound crystallizes in the monoclinic system with the following crystal data: a=6.723(2), b = 11.838(1), c= 10.962(2) Å, β=99.41(2)°, V= 860.7; ?x= 1.669 g cm^?3 at ?135±2°C; space group P2₁. The structure was solved by the heavy-atom method from 3-dimensional diffractometer data collected at ?135±2°C using CuK_α radiation. The final R factor for 1854 reflections is 0.029. The absolute configuration of the molecule was determined by the “R Method” of Hamilton. Deodactol has a strong intramolecular OHO hydrogen bond bridging its tetrahydropyranyl and cyclohexanol rings. The alcohol shows moderate cytotoxic activity. The absolute configuration of deodactol corresponds to that of several halogenated chamigrenes and supports the proposed biogenetic hypothesis linking halogenated bisabolenes and chamigrenes.