Floral anthocyanins in wild taxa of Petunia (Solanaceae)

The flowers of 20 native taxa of Petunia (Solanaceae) were investigated by HPLC for the occurrence of anthocyanins, The investigation revealed the pre sence of at least 24 anthocyanins in their flowers, of which 18 known antho cyanins isolated from the flowers of P. exserta, P. guarapuavensis, P, inte grifolia, P. occidentalis, and P. reitzii were fully identified by chemical and spectral methods to be 3-glucoside of delphinidin; 3-rutinosides of cy anidin, delphinidin, and petunidin; 3-rutinoside-5-glucosides, 3-trans and -cis-p-coumaroylrutinoside-5-glucosides, and 3-trans-caffeoylrutinoside-5-g lucosides of delphinidin, petunidin, and malvidin; and 3-trans-caffeoylgluc osyl-trans-(caffeoyl or p-coumaroyl) rutinoside-5-glucosides of malvidin, S ix novel anthocyanins were isolated from the flowers of P, occidentalis, an d their structures were identified to be 3-glucosyl p-coumaroylrutinoside-5 -glucosides and 3-glucosylcaffeoylrutinosides of petunidin and malvidin, an d also 3-caffeoylglucosylcaffeoylrutinoside-5-glucoside and 3-caffeoylgluco syl p-coumaroylrutinoside-5-glucoside of petunidin. Out of the six pigments , petunidin 3-glucosyl p-coumaroylrutinoside-5-glucoside was unambiguously determined by spectral methods to be petunidin 3-O-[6-O-(4-O-(4-O-(beta-D-g lucopyranosyl)-trans-p-coumaroyl)-alpha-L-rhamnopyranosyl)-beta-D-glucopyra noside]-5-O-[beta-D-glucopyranoside]. The 20 native taxa of Petunia could b e placed into four groups (A, B, C, and D) with one further into five subgr oups (D1-D5) regarding their constituents and contents of major anthocyanin s and also their pigment biosynthesis with respect to the blocks or inhibit ors of the hydroxylation, glucosylation, and acylation reactions in them. T he use of anthocyanins as taxonomic markers in the genus Petunia is discuss ed in relation to the flower colour and possible pollination vectors. (C) 1 999 Elsevier Science Ltd. All rights reserved.