Anthocyanin profile of Korean cultivated kidney bean (Phaseolus vulgaris L.)

This investigation was conducted to determine the structures and amounts of anthocyanins obtained from seed coats of kidney bean (Phaseolus vulgaris L.) cultivated in Korea. Anthocyanins in the seed coat of kidney bean were extracted with 1% HCI/20% CH3OH, and the crude anthocyanin extracts were purified by semipreparative HPLC. Five major anthocyanins were isolated, and their chemical structures were identified by spectroscopic methods (UV-vis, LC/ES-MS, and H-1 and C-13 NMR). The structures of these five anthocyanins were elucidated as cyanidin 3,5-diglucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, and pelargonidin 3-glucoside. Using RP-HPLC with photodiode array detection, each of the five anthocyanins was separated within 12 min by using a gradient elution. It was proved that the application of RP-HPLC could be an excellent method for determining the composition and contents of anthocyanins in kidney bean. The preponderance of pelargonidin 3-glucoside and delphinidin 3-glucoside are observed in red and black kidney beans, respectively. However, in this study, it is reported for the first time that the contents and composition of anthocyanins in speckled seed depend on the classes of speckle color. The contents of cyanidin 3,5-diglucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, pelargonidin 3-glucoside, and total anthocyanins in seed coats of 16 kidney beans cultivated in Korea were in the ranges of 0-0.04, 0-2.61, 0-0.12, 0-0.17, 0-0.59 and 0-2.78 mg/g of dried seed coats, respectively.