Acylated anthocyanins from leaves of Oxalis triangularis

The novel anthocyanins, malvidin 3-O-(6-O-(4-O-malonyl-alpha-rhamnopyranosyl)-beta-glueopyranoside)-5-O-beta-glucopyranoside (2), malvidin 3-O-(6-O-beta-rhamnopyranosyl-beta-glucopyranoside)-5-O-(6-O-malonyl-beta-glueopyranoside) (3), malvidin 3-O-(6-O-(4-O-malonyl-alpha-rhaninopyranosyl)-beta-glucopyranoside)-5-O-(6-O-malonyl-beta-glueopyranoside) (4), malvidin 3-O-(6-O-(4-O-malonyl-alpha-rhamnopyranosyl)-beta-glucopyranoside) (5) and malvidin 3-O-(6-O-(Z)-p-coumaroyl-beta-glucopyranoside)-5-O-beta-glucopyranoside (6), in addition to the 3-O-(6-O-alpha-rhamnopyranosyl-beta-glucopyranoside)-5-O-beta-glucopyranoside (1) and the 3-O-(6-O-(E)-p-cournaroyl-beta-glucopyranoside)-5-O-beta-glucopyranoside (7) of malvidin have been isolated from purple leaves of Oxalis triangularis A. St. -Hil. In pigments 2, 4 and 5 a malonyl unit is linked to the rhamnose 4-position, which has not been reported previously for any anthocyanin before. The identifications were mainly based on 2D NMR spectroscopy and electrospray MS. (c) 2005 Elsevier Ltd. All rights reserved.