Anthocyanin, polyphenol, and flavonoid contents and antioxidant activity in Mexican common bean (Phaseolus vulgaris L.) landraces

The aim of this work is to assess and describe a collection of Mexican populations of common bean (Phaseolus vulgaris L.) based on their contents of monomeric anthocyanins, polyphenols, and flavonoids; antioxidant activity; and grain physical characteristics. A collection of 26 bean populations was assembled at five states and regions in Mexico. The beans were cultivated in Santa Cruz Xoxocotlan, Mexico, using a randomized complete block design with four replications. From a sample of seeds per population, the polyphenol and flavonoid contents were evaluated using UV-visible spectroscopy; the anthocyanin content was evaluated based on differential pH; antioxidant activity was measured using the DPPH method; and a morphologic description of the grain was recorded. Analysis of variance was used to determine significant differences (P < 0.01) within and among the population groups for all evaluated variables. Populations from Oaxaca and Puebla presented high anthocyanin contents, 1.6 and 2.1 mg C3GE/g, respectively. Polyphenol content was higher in the seed coat (27.7 to 127.0 mg GAE/g) than in the whole grain (1.3 to 5.4 mg GAE/g). Similar patterns were noted for flavonoids (from 5.9 to 21.5 mg CE/g in the seed coat and from 0.10 to 0.78 mg CE/g in the whole grain) and antioxidant activity (AA; from 132.5 to 1,021.7 μmol ETrolox/g in the seed coat). AA was significantly correlated with anthocyanin and polyphenol contents. Several populations were exceptional regarding the evaluated compounds; these populations were OAX-011-29, OAX-011-30, PUE-011-15, PUE-011-34, EM-01-01 and GRO-10-87. These beans can be used in participatory plant breeding to improve the local beans, and their consumption can be recommended to low income families with poor nutrition.