Antioxidant Activity of Extracts, Condensed Tannin Fractions, and Pure Flavonoids from Phaseolus vulgaris L. Seed Coat Color Genotypes

Abstract

Twelve different seed coat color genotypes of Phaseolus vulgaris L. were extracted and pure flavonoids isolated from 10 of these. The seed coat methanol extracts, tannin fractions, and pure flavonoids all displayed antioxidant activity in a fluorescence-based liposome assay. The relatively high activity of the condensed tannin (proanthocyanidin) fractions indicates that these may play an important role in the overall activity of the extracts. This activity also indicates that although these polyphenols cause problems in digestibility, they may be important dietary supplements with beneficial health effects. The pure anthocyanins delphinidin 3-O-glucoside (1), petunidin 3-O-glucoside (2), and malvidin 3-O-glucoside (3) and the flavonol quercetin 3-O-glucoside (4) isolated from seed coats also had significantly higher antioxidant activity than the Fe(2+) control. The activity of kaempferol 3-O-glucoside (5) was not different from that of the Fe(2+) control. These findings suggest that variously colored dry beans may be an important source of dietary antioxidants.

Phenolic Acid, Flavonoids and Antioxidant Activity of Common Brown Beans (Phaseolus vulgaris L.) Before and After Cooking

“…The same finding was reported in the study by Beninger and Hosfield [14], who explained their results by noting that the flavonoids present in the crude extract were further concentrated in the extracts; this concentration may have been primarily responsible for the observed antioxidant activity.…”

“…Although Beninger and Hosflied [14] indicated that flavonoids exist mainly in the glycosylated form, the fractions evaluated in this study also contained the aglycone flavonoid.…”

“…The polarity of the compounds in brown beans may affect their extraction from the feedstock [14]. Depending on the polarity of the solvent, more of one or another phenolic compound may be present in food and thus affect the antioxidant capacity of the extract.…”

The polyphenolic profiles of common bean (Phaseolus vulgaris L.)

“…The order of the sugars cannot be determined by LC-DAD-ESI/MS, since the mass spectra did not offer any fragments to indicate the mass of the secondary sugar. Both sugar orders, kaempferol 3-O-glucosylxylose in Montcalm dark kidney beans seed coats (Beninger & Hosfield, 2003;Beninger & Hosfield, 1999) and keampferol 3-Oxylosylglucoside in the Zolfino common bean landraces (P. vulgaris L., cv. Zolfino) (Romani et al, 2004), have been reported.…”

“…There are 10 major US commercial market classes of dry beans: black beans (Aparicio-Fernades et al, 2006;Aparicio-Fernandez, Yousef, Loarca-Pina, Gonzales de Mejia, & Lila, 2005;Takeoka et al, 1997), pinto beans (Beninger et al, 2005;Beninger & Hosfield, 2003), light and dark red kidney beans (Beninger & Hosfield, 1999;Choung, Choi, An, Chu, & Cho, 2003), pink beans, navy beans, great northern beans (Kelly et al, 2003;Luthria & Pastor-Corrales, 2006), alubia beans (Kelly & Copeland, 1998;Kelly, Hosfield, Varner, Uebersax, & Taylor, 1999) cranberry beans (Beaver, 1999), and small red beans, also known as redMexican beans (Hosfield, Varner, Uebersax,& Kelly, 2004). Common dry beans contain a wide range of flavonoids, including flavonols, their glycosides, anthocyanins, proanthocyanidins, and isoflavones, as well as some phenolic acids (Aparicio-Fernades & Garica-Gasca et al, 2006;Aparicio-Fernades & Yousef et al, 2005;Beninger & Hosfield, 1999;Beninger & Hosfield, 2003;Choung et al, 2003;Diaz-Batalla, Widholm, Fahey, Casano-Tostado, & Paredes-López, 2006;Macz-Pop, González-Parama´s, Pérez-Alonso, & Rivas-Gonzalo, 2006;Romani et al, 2004;Takeoka et al, 1997) (Fig. 1).…”