Thotneosides A, B and C: Potent Antioxidants from Nepalese Crude Drug, Leaves of Aconogonon molle

Three new glycosides: thotneoside A (quercetin 3-O-(6″-O-phenylacetyl)-β- D -galactopyranoside) (1), thotneoside B (quercetin 3-O-(6″-O-phenylacetyl)-β- D -glucopyranoside) (2) and thotneoside C (3-methyl-2-butenoic acid 1-O-β- D -glucopyranoside) (3), together with nine known compounds; quercetin (4), quercetin 3-O-β- D -galactopyranoside (5), quercetin 3-O-(6″-O-galloyl)-β- D -galactopyranoside (6), quercetin 3-O-β- D -galacturonopyranoside (7), quercetin 3-O-β- D -glucuronopyranoside (8), quercetin 3-O-α- L -rhamnopyranoside (9), rutin (10), quercetin 3-O-α- L -arabinopyranoside (11) and 2,4,6-trihydroxyacetophenone 2-O-β- D -glucopyranoside (12) have been isolated from the shade dried leaves of Aconogonon molle, commonly known as “Thotne″ in Nepal. The structures were elucidated on the basis of chemical and spectroscopic methods. All of these compounds were isolated for the first time from A. molle and their in vitro antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Quercetin (4) and its glycosides (1–2, 5–11) showed potent free radical scavenging activity.