Catalyzes the transfer of the p-coumaric and caffeic acids from their CoA esters to the 3-glucosyl moiety of a range of anthocyanidin 3-O-glucosides, 3,5-di-O-glucosides and cyanidin 3-rutinoside. Anthocyanins are ubiquitous colored pigments that are responsible for petal color. Does not act on delphinidin 3,3',7-tri-O-glucoside. Recombinant enzyme can use caffeoyl-CoA but not malonyl-CoA as alternative acyl donor. (E)-4-coumaroyl-CoA + an anthocyanidin 3-O-beta-D-glucoside = an anthocyanidin 3-O-[6-O-(4-hydroxycinnamoyl)-beta-D-glucoside] + CoA + H(+) Pigment biosynthesis; anthocyanin biosynthesis. Detected in the young leaves of perilla red forma. Belongs to the plant acyltransferase family.