Flavonoid, Iridoid, and Lignan Glycosides from Putoria calabrica

From the aerial parts of Putoria calabrica, two new flavonol triglycosides were isolated and their structures were elucidated as quercetin-3-O-[α-<SCP>l</SCP>-rhamnopyranosyl-(1→2)-α-<SCP>l</SCP>-arabinopyranoside]-7-O-β-<SCP>d</SCP>-glucopyranoside (<BO>1</BO>, calabricoside A) and quercetin-3-O-[4‘ ‘‘-O-caffeoyl-α-<SCP>l</SCP>-rhamnopyranosyl-(1→2)-α-<SCP>l</SCP>-arabinopyranoside]-7-O-β-<SCP>d</SCP>-glucopyranoside (<BO>2</BO>, calabricoside B). Additionally, seven iridoid and three lignan glycosides were isolated and characterized. Radical scavenging activities of all compounds were determined by quantifying their effects on luminol-enhanced chemiluminescence in formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated human polymorphonuclear neutrophils (PMNs). Calabricoside A and B showed strong radical scavenging activity with IC<INF>50</INF> values of 0.25 and 0.3 μM, respectively.