Malonyltransferase acting on xenobiotic glucosides. Has activity toward 2-Naphthol glucoside (2NAG), 1-Naphthol glucoside (1NAG), kaempferol 7-O-glucoside, kaempferol 3-O-glucoside, hydroxycoumarin glucosides, phenol-glucosides and isoflavone glucoside (daidzin), but not toward 4-coumaroyl glucoside, kaempferol 3,7-O-diglucoside, salicylic acid glucoside and phlorizin. In vivo, seems to be involved in the malonylation of 2-Naphthol glucoside while PMAT2 would be involved in the malonylation of 4-methylumbelliferone glucoside or 4-nitrophenyl glucoside. a flavonol 3-O-beta-D-glucoside + malonyl-CoA = a flavonol 3-O-(6-O-malonyl-beta-D-glucoside) + CoA a flavonol 7-O-beta-D-glucoside + malonyl-CoA = a flavonol 7-O-(6-O-malonyl-beta-D-glucoside) + CoA kcat is 40 sec(-1) for 2-Naphthol glucoside. kcat is 46 sec(-1) for 1-Naphthol glucoside. kcat is 33 sec(-1) for kaempferol 7-O-glucoside. kcat is 120 sec(-1) for 4-nitrophenyl glucoside. kcat is 19 sec(-1) for 4-methylumbelliferone glucoside. kcat is 23 sec(-1) for malonyl-CoA. No visible phenotype, but no malonylation of glucosides. Belongs to the plant acyltransferase family. Phenolic glucoside malonyltransferase subfamily.