Hope H. Lester

Chemical and enzymatic synthesis of monomeric procyanidins (leucocyanidins or 3′,4′,5,7-tetrahydroxyflavan-3,4-diols) from (2R,3R)-dihydroquercetin

Abstract The major product from the reduction of (2 R ,3 R )-dihydroquercetin with sodium borohydride is the 2,3- trans -3,4- trans isomer of leucocyanidin [(2 R ,3 S ,4 R -3,3′,4,4′,5,7-hexahydroxyflavan] whereas the enzymatic reduction product is the 2,3- trans -3,4- cis isomer [(2 R ,3 S ,4 S )-3,3′,4,4′,5,7-hexahydroxyflavan]. The 3,4- trans isomer may be partly converted to the 3,4- cis isomer under mild acid conditions. The 3,4- cis isomer is more acid-labile, and more reactive both chemically with thiols and enzymatically with a diol reductase, than the 3,4- trans isomer.

Histochemical assay of proanthocyanidin heterogeneity in cell cultures

Abstract The distribution patterns and intracellular localization of proanthocyanidins (condensed tannins) were studied microscopically in cell suspension cultures derived from leaves of Ginkgo biloba L., Pseudotsuga menziesii Franco (Douglas fir), and Ribes sanguineum Pursh. (Flowering current) after staining with the nitroso reagent. The specificity and variations of the reaction are discussed.