The common bean contains phytochemicals, including phenolic compounds, which can provide health benefits to the consumer. Our objective was to characterize the polyphenolic compounds present in the seed coat of Black Jamapa bean and to test fractionation methods that permit the recovery of polyphenolics in their naturally occurring forms. A 100% methanol extract from seed coats was subjected to different chromatographic fractionation methods. Analysis by HPLC-MS revealed that a better separation of phytochemicals was achieved using direct silica gel fractionation, which allowed more accurate identification of compounds, especially of the flavonols. Anthocyanins, flavanol monomers, and heterogeneous flavanol oligomers up to hexamers were detected. To our knowledge, this is the first time that myricetin glycoside and proanthocyanidin oligomers containing (epi)-gallocatechin have been reported in the black bean. The fractionation methods used in this study produced large quantities of natural mixtures of flavonoids suitable for testing bioactivity and phytochemical interactions.

: Phenolic compounds were extracted from recently harvested or stored black Jamapa beans (Phaseolus vulgaris) that were subjected or not to thermal treatment. The beans studied were cropped in the same area and were from the same lot. The highest amount of condensed tannins (CT) was found in the seed coat of recently harvested beans [222.41 ± 16mg of (+)‐catechin equivalents per gram of seed coat]. After 2 yof storage, the amount of CT dropped significantly [35.8 ± 3.4 mg of (+) ‐catechin equivalents per gram of seed coat]. Thermal treatment significantly reduced the amount of CT in whole beans by approximately 70%. The raw seeds contained 13.76 ±1.2 mg of (+)‐cat‐echin equivalents per gram of seeds and a portion of CT appeared in the broth [9.4 ± 0.1 mg of (+) ‐catechin equivalents per gram of lyophilized broth]. The antimutagenic activity of these extracted phenolic compounds was tested against aflatoxin B1 (AFB1) in the Kado microsuspension assay. Newly harvested beans showed higher antimutagenic activity against AFB1 mutagenicity than stored beans. The results suggest that to take the maximum advantage of components with biological activity present in beans, they must be used fresh.

The antiproliferative effects of 100% methanol crude extract and of Toyopearl and silica gel fractions from the seed coats of black Jamapa beans (Phaseolus vulgaris L.) were evaluated using HeLa, human adenocarcinoma cells, and HaCaT, human premalignant keratinocytes. The 100% methanol crude extract [172.2 microM equiv of (+)-catechin] increased adhesion of HeLa cells; however, 3- and 5-fold higher concentrations decreased the number of cells attached as a function of the treatment time. The highest concentration tested diminished the cell adhesion until 40% (after 24 h) to almost 80% (after 72 h). The IC50 values showed that the 100% methanol crude extract was the most effective inhibitor of HeLa cell proliferation, even when it was dissolved in dimethylsulfoxide (DMSO) [34.5 microM equiv of (+)-catechin] or in medium [97.7 microM equiv of (+)-catechin]. The Toyopearl 5 (TP5) fraction and silica gel 2 (SG2) fraction inhibited 60% of the HeLa cell proliferation. The IC50 was 154 microM equiv of (+)-catechin of the 100% methanol crude extract on HaCaT cells. Toyopearl fractions TP4 and TP6 significantly inhibited HaCaT cell proliferation, but the silica gel fractions did not have a significant effect. The 100% methanol crude extract (35 microg of dry material/mL) decreased the number of HeLa cells in the G0/G1 phase from 68.9% (for control cells) to 51.4% (for treated cells) and increased apoptosis (2.9 and 21.2% for control and treated cells, respectively). The results indicated that black Jamapa beans could be a source of polyphenolic compounds, which have an inhibitory effect toward HeLa cancer cells but are less aggressive on HaCaT premalignant cells.

Jamapa bean is a black Phaseolus vulgaris variety rich in condensed tannins, anthocyanins and flavonols with interesting biological activities. The objective of this work was to evaluate the antiradical capacity (ARC) of a Jamapa bean methanolic extract (BME) and some of the proanthocyanidin-rich fractions derived from it, using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The effect of the BME on some proteins involved in apoptosis on HeLa cells was also evaluated. A strong correlation between proanthocyanidin concentration in BME and antiradical capacity was found, suggesting that these compounds contribute significantly to antiradical activity. BME was a better radical scavenger than butylated hydroxytoluene (45.6 and 33.9% ARC at 400 microM, respectively). Two proanthocyanidin-rich fractions obtained after a preliminary separation of the BME using Toyopearl (TP4 and TP6) exhibited a higher antiradical activity than the parent extract. The treatment of HeLa cells with 35 microg BME/ml/24 h increased the expression of Bax and Caspase-3, pro-apoptotic proteins (6.13 and 1.2 times for Caspase-3 and Bax, respectively). The mechanism of action of some proteins involved in apoptosis was also evaluated, and the results suggest that black Jamapa bean could be an important source of polyphenolic compounds with potential biological use as antioxidant and anticancer agents.

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