Flavonoids and Condensed Tannins from Leaves of Hawaiian Vaccinium reticulatum and V. calycinum (Ericaceae)

Abstract

The flavonoids and condensed tannins of Hawaiian Vaccinium reticulatum Smith and V. calycinum Smith have been isolated and their structures determined. Flavonoids present in both species were quercetin, quercetin-3- 0-glucoside, quercetin-3-0-galactoside, quercetin-3-0-methyl ether, isorhamnetin, and (-)-epicatechin. The condensed tannin contained procyanidin units with cis stereochemistry only. Extension and terminal units, and number-average molecular weight of the polymer were determined. A large quantity of neochlorogenic acid (a caffeic acid derivative) was also detected. The phenolic compounds of V reticulatum from a population on Mauna Kea and two populations near K11auea, both on the island of Hawai'i, and from one population of V calycinum on Kaua'i were qualitatively identical. The high degree of similarity supports the view that these species are closely related. It is suggested that the phenolic chemistry of the species may have been fixed in the progenitor of the Hawaiian Vaccinium.