Objective: The aim of this study was to evaluate the antiradical and inhibitory activity of whole plant extracts of Phyllanthus amarus and Striga hermonthica on α-amylase. Methods: The crude 70% (v/v) hydroethanolic extracts  obtained were used for the assay of polyphenols, the antiradical test with DPPH, the test for the inhibition of α-amylase with DNS (3,5-dinitrosalicylic). The enzyme extracts were obtained from sorghum malt (Sorghum bicolor). Results: It appears from this study that the extract of P. amarus was richer in polyphenols than the extract of S. hermonthica. Regarding the antiradical activity, the extract of S. hermonthica showed an IC50 of 339.06 ± 1.43 µg/mL against 77.74 ±2.73 µg/mL for the extract of   P. amarus. Regarding the anti α-amylase activity, the extract of P. amarus inhibited IMS127 and KMTC 274 respectively 43.64 ±0.59% and 66.28 ±1.97%. On the other hand, the extract of S. hermonthica presented an inhibition of 3.93 ±0.91% on IMS127 and 14.85 ±1.62% on KMTC 274. The extract of P. amarus presents a good antiradical activity and anti α-amylase compared to S. hermonthica extract. In conclusion, these results partly explain the use of these plants in traditional medicine to treat or relieve people suffering from diabetes. Keywords : α-amylase, inhibition, polyphenols, antiradical, diabetes

Objective(s): The aim of this study was to evaluate the antidiabetic potential of Pseudocedrela kotschyi leaf decoction by making a comparison between extracts harvested over three months. Design: This study is done through a few experiences. After the quantification of total polyphenols by folin-Ciocalteu reagent method, the antioxidant activities were tested with ABTS, DPPH and FRAP essays. Then, the glucose oxidase kit was used to determine the glucose adsorption capacity of the extracts. At last, dinitrosalicylic acid method served to evaluate the α-amylase inhibitory activity of the extracts. Results: As results the leaves extracts of Pseudocedrela kotschyi  showed a polyphenol content of 39,97 ± 3,63 mg EAG/g DE for October, 74,2 ± 11,64 for November and 59,45 ± 7,024 for December. For total flavonoids, the content was 4,86 ± 0,29 mg QE/g DE (October) 5,68 ± 0,39 mg QE/g DE (November) and 5,548 ± 0,19 mg QE/g DE (December). In addition, the antioxidant activity was correlated with the phenolic content (r = -0.65 for DPPH IC50, r = -0.84 for ABTS IC50 and r = 0.97 for FRAP). Besides, the extracts exhibited a strong α-amylase inhibitory activity (IC50 = 0,272 mg DE/mL for October, 0,097 mg DE/mL for November and 0,101 mg DE/mL for December) and had a high capacity to adsorb glucose (over 219,98 ±2,54mmol/g DE for a 30mM glucose solution for November). Conclusion: Pseudocedrela kotschyi leaf decoction has the ability to inhibit α-amylase activity and adsorb glucose in glucose concentrated solution. So it possess a high antidiabetic potential. Keywords: Glucose adsorption, α-amylase, Pseudocedrela kotschyi, antioxidant activity.