COX-2 inhibitory activity of homoisoflavanones and xanthones from the bulbs of the Southern African Ledebouria socialis and Ledebouria ovatifolia (Hyacinthaceae: Hyacinthoideae)

Abstract

The bulbs of Ledebouria socialis (Hyacinthaceae) yielded the benzocyclobutene homoisoflavonoid, (R)-2′,5-dihydroxy-3′,4′ ,7-trimethoxyspiro{2H-1-benzopyran-3-(4H)-9-bicyclo[4.2.0]octa[1,3,5]triene} -4-one, socialinone (1). Ledebouria ovatifolia yielded (2ε,3R)-2,5- dihydroxy-7-methoxyspiro[2H-1-benzopyran-3(4H), 5′ (6′H)- cyclobuta[f][1,3]benzodioxol]-4-one (2) and the homoisoflavanone, (E)-3-(3′,4′-dihydroxybenzylidene)- 5,7-dihydroxychroman-4-one, ovatifolionone (5), the dihydrochalcone, 4,4′-dihydroxy-2′,6′- dimethoxydihydrochalcone (3), and xanthone, 1,6-dihydroxy-2,3,5-trimethoxy-8- methyl-9H-xanthen-9-one (4) along with 21 known compounds. Structures were determined using spectroscopic techniques. The antiinflammatory activities of the homoisoflavonoids and xanthones isolatedwere evaluated against cyclooxygenase-1 and -2 isoenzymes. (R)-3-(3′,4′-Dihydroxybenzyl)-7- hydroxy-5-methoxychroman-4-one (7), (E)-3-(3′,4′- dihydroxybenzylidene)-7-hydroxy-5-methoxychroman-4-one (10), 1,3,6-trihydroxy-2-methoxy-8-methylxanthen-9-one (6) and ovatifolionone acetate (5Ac) exhibited significant activity against cyclooxygenase- 2 at <10 μM. © 2013 Elsevier Ltd. All rights reserved.