New Marine Sterols from a Gorgonian Pinnigorgia sp.

Continuous chemical investigation of the gorgonian coral Pinnigorgia sp. resulted in the isolation of two new sterols, 5α,6α-epoxy-(22E,24R)-3β,11-dihydroxy-9,11-secoergosta-7-en-9-one (1) and (22R)-acetoxy-(24ξ)-ergosta-5-en-3β,25-diol (2). The structures of sterols 1 and 2 were elucidated using spectroscopic methods. Sterol 1 displayed inhibitory effects on the generation of superoxide anions and the release of elastase by human neutrophils with IC50 values of 8.65 and 5.86 μM, respectively. The structure of a known metabolite, pubinernoid A (3), is revised as (+)-loliolide (4).