Deep blue anthocyanins from blue Dianella berries

Abstract

Three anthocyanins, all acylated delphinidin 3,7,3′,5′-tetraglucosides, and a naphthalene glycoside, 2-acetyl-1,5-dihydroxy-3 methyl-8- O(xylosyl-(1→6)-glucosyl) naphthalene, have been isolated from the berries of two Dianella species, D. nigra and D. tasmanica. The anthocyanins show exceptional blueness at in vivo pH values due to effective intramolecular copigmentation involving p-coumaroyl-glucose units (GC) at the 7, 3′ and 5′ of the delphinidin anthocyanidin. Evidence is presented to show that the effectiveness of the copigmentation can be ranked; 3′,5′ GC>7 GC>3 GC.