Polyphenol Content and Antiradical Activity of “Sarconi” Beans (Phaseolus vulgaris L.) Ecotype

The aim of this study was to establish the distribution and content of polyphenols (anthocyans, flavonols and hydroxycinnamic acids) in hulls and seeds of Sarconi beans having different colours and shapes. Sarconi beans are protected by the indication of geographic provenance (IGP) denomination and include different ecotypes. The seeds sampled in the study area (Basilicata, val d’Agri) exhibited different colours from white (Riso bianco) to dark yellow (Tabacchino), to green (Verdolino) and to red (San Michele rosso) with shapes changing from small round to large round-ovoid. The seeds of the four ecotypes were collected from two farms in order to identify differences that could be caused by environmental conditions. Flavonols of some ecotypes of Sarconi beans have already been described, while the anthocyan composition and content have never been reported. In particular, Tabacchino beans contained the highest amount of both flavonols, such as kaempferol and quercetin derivatives (6.342-6.515 mg/g) and hydrxycinnamic acids (1.136-1.636 mg/g), while only San Michele contained anthocyans, such as cyanidin and pelargonidin derivatives (1.118-3.187 mg/g); Riso bianco seeds contained only hydroxycinnamic acids (0.975-1.292 mg/g). Kaempferol derivatives were the most representative flavonols in the seed coat of Sarconi beans and in other Italian landraces they have only been found previously in Zolfino beans. This occurrence could distinguish Italian beans from Brazilian, Peruvian, and Mexican beans. The antiradical activity, as indicated in particular by EC50 values, ranged from 2.78 to 16.93 g sample/mg DPPH• (1,1-diphenyl-2-picrylhydrazil radical) for San Michele and Riso bianco beans, respectively.