An unusual halogenated meroditerpenoid from Stypopodium flabelliforme: Studies by NMR spectroscopic and computational methods

Abstract

Meroditerpenoids, 2-[20(E)-30,70,110,150-tetramethylhexadec-2-en-10-yl]-6-methyl-1,4-benzohydroquinone diacetate and 40-chlorostypotriol triacetate, along with eight known compounds isolated from the dichloromethane extract of the brown alga Stypopodium flabelliforme after peracetylation are reported. One of them, 2-(1-oxo-hexadecyl)-1,3,5-trihydroxybenzene, is described for the first time within this genus. Structural elucidation was carried out on the basis of spectroscopic data and theoretical studies using GIAO/DFT analysis at B3LYP/6-31G(d) and mPW1PW91/6-31G(d) levels of theory for 40- chlorostypotriol. This isomer is the first metabolite from the Stypopodium genus possessing one halogen atom.