Roberto Della Loggia, Laura Casu, G. Altinier, Mariano Casu, Costantino Floris, Filippo Cottiglia, Leonardo Bonsignore, Silvio Sosa, Cottiglia, F., Casu, L., Bonsignore, L., Casu, M., Floris, C., Sosa, Silvio, Altinier, G., and DELLA LOGGIA, Roberto
Bioactivity-guided fractionation of the methanol extract from the leaves of Santolina insularis led to the isolation of one new xanthone, (E)-3-{6-[(E)-3-hydroxy-3-oxo-1-propenyl]-9- oxo-9H-xanthen-2-yl}-2-propenoic acid, together with six known flavonoids: hispidulin, nepetin, cirsimaritin, rhamnocitrin, luteolin and luteolin 7-O-β-ᴅ-glucopyranoside. The structures were elucidated by means of 1D-, 2D-NMR spectroscopy and mass spectrometry. The topical anti-inflammatory activity of all isolated compounds and extracts was investigated employing the croton oil-induced dermatitis in mouse ear. The most active compound, luteolin, showed an ID50 of 0.3 μmol/cm2 and prevented ear oedema more effectively than an equimolar dose of indomethacin within 24 h.