Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Proceedings
Publication Acceptance Date: 11/7/1997
Publication Date: N/A
Interpretive Summary: Flavonoids are compounds found in seedcoats, roots and fruits of many plants. Flavonoids are known to be potent antioxidants. Antioxidants function within human and animal cells to protect them [the cells] from the damaging effects of free radicals which are cellular cancer producing agents. In dry bean, seedcoats that contain color contain a variety of different flavonoids. An experiment was conducted to determine the antioxidant activity of flavonoids in seedcoats of dry bean genetic stocks differing in color. The extracts from seedcoats containing flavonoids all had high antioxidant activity based on standard test for activity. This activity was higher in some of the ethyl acetate extracts compared to the methyl alcohol extracts but both types had high activity. Future work involves the isolation and characterization of pure flavonoids which will enable us to determine the activity associated with each type of flavonoid. Data from our work is new and now gives nutritionists the information for developing guidelines and composition tables of the antioxidant potential of dry bean. Pharmaceutical companies could also benefit because they can extract these naturally occurring compounds and market them as nutritionally important food supplements. Bean growers also benefit because they may be able to obtain a premium from selling bean varieties with a known level of antioxidant potential.
Technical Abstract: Antioxidants protect tissues from the damaging effects of free radicals which can cause cancer in humans. Flavonoids found in seed coats of common bean may affect cooking time, post harvest afterdarkening, and digestibility as well as have antioxidant potency. An experiment was undertaken to identify the flavonoids in bean seed coats from 12 genetic lines in which the color determining loci are known. Seedcoats from the genetic lines were removed, lyophilized, ground to a fine powder and then extracted sequentially with hexane, EtOac, and MeOH. Antioxidant activity of the extracts was tested by fluorescence spectroscopy of liposome oxidation. The hexane extracts showed no activity but the EtOAc extracts from three lines had greater antioxidant activity at 10ppm over a period of 21 min than the MeOH extracts. However, all MeOH extracts from the ten genotypes showed good activity. One flavonoid from the MeOH extract of one genotype has been isolated and identified as kaempferol. Three compounds have been isolated from 'Prim' P. vulgaris L. and identified as kaemferol-3-0-glucoside, kaempferol-3-0-diglycoside and phenolic glycoside.