The electrooxidative behavior and determination of metformin hydrochloride, anti-hyperglycemic drug, on a pyrogallol modified carbon paste electrode were investigated using cyclic voltammetry and differential pulse voltammetry. Metformin hydrochloride shows an irreversible oxidation behavior over a wide interval of pH (Britton-Robinson buffers, pH 2-9). The peak current varied linearly in the range comprised between 8.0 × 10 -7 and 6.0 × 10 -6 mol/L with detection limit of 6.63 × 10 -8 mol/L and limit of quantification of 2.21 × 10 -7 mol/L. The method was proposed for the determination of metformin hydrochloride in dosage forms and urine.

Legumes are the basic diet in many populations, especially in Africa. They hold high nutritional value and they promote the human health. The aim of this investigation was to study the influence of different processing such as soaking, cooking and germination on chemical composition, phenols, tannins and flavonoids contents, as well as effects on their antioxidant and anticancer activity of black beans. Phenolic compounds of raw and processed black beans was evaluated by HPLC. The antioxidant activity was evaluated by DPPH. Anticancer activities were evaluated on five different cell lines (colon (HCT), breast (MCF7), lung (A549), prostate (PC3) and Hela (HELA). The obtained results indicated that black beans showed high protein, ash and fiber content 26.54, 5.22 and 5.58%, respectively. Total phenols, tannins and isoflavonoids decreased as prolonging soaking time. The reduction percent reached high level in cooked beans. High DPPH antioxidant activity for raw black beans was observed. After 24 h of germination, e-vanellic acid showed the high value 56.4 mg/100 g followed by ferulic acid 45.38 mg/100 g. In soaking plus cooking treatments the level of kaempferol and naringin increased. There were differences in total phenols, flavonoids and tannins content have been observed between raw and processed black beans samples that influence the antioxidant activity. Although antioxidant activity was decreased in the processed samples. Ethanol extracts of different processing exhibited cytotoxicity activities on cancer cell lines, raw sample proved to be the most active in anti-tumoral followed by germinated sample (48 h). This study demonstrated that phenolic compounds of black beans is related with soaking, cooking process and germination, and also with their anticancer activity. Strong anticancer activity toward (MCF7) cell line was observed. Anticancer activity realized a noticeable reduction of tumor inhibition after 48 h of germination.