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

Meroditerpenoids, 2-[2′(E)-3′,7′,11′,15′-tetramethylhexadec-2-en-1′-yl]-6-methyl-1,4-benzohydroquinone diacetate and 4′-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 4′-chlorostypotriol. This isomer is the first metabolite from the Stypopodium genus possessing one halogen atom.