New anti-inflammatory sterols from the Red Sea sponges Scalarispongia aqabaensis and Callyspongia siphonella.

Bioassay-guided fractionation of the anti-inflammation fractions of the Red Sea sponges Scalarispongia aqabaensis and Callyspongia siphonella yielded two new sterols from chloroform fractions of methanol extracts, namely scalaristerol (5alpha,8alpha-dihydroxycholest-6-en-3beta-ol) (1) from Scalarispongia aqabaensis, and callysterol (ergosta-5,11-dien-3beta-ol) (2) from Callyspongia siphonella. Structure determination was based on extensive NMR studies and mass spectrometry. The antiinflammatory activity of compounds 1 and 2 was assessed using the rat-hind paw edema method and by study of their effect on the release of O2(-) and TXB2 from LPS-activated rat neonatal microglia.