Étude phytochimique et évaluation de l’activité antioxydante de l'extrait de Trigonella foenum graecum L.

Abstract

Algeria, by its geographical position, is home to an exceptional biodiversity occupied by important medicinal plants. As part of the prospective study of interesting sources of naturally occurring antioxidants, we are interested in Trigonella foenum greacum L is an annual herb belonging to the fabaceae family. This plant is known for its very important medicinal, therapeutic and nutritional properties given the traditional uses and pharmacological activities of the phytochemicals present in the extracts of the seeds of this plant. This work focused on the study of the content of flavonoids and total phenols in the hydro-methanolic extracts of the seeds as well as the evaluation of the antioxidant activity using the methods of the oxidation of the 2,2- radical. diphenyl-1-picrylhydrazyl (DPPH), ABTS test (2, 2'- azynobis- [3-ethylbenzothiazoline-6- sulfonic acid]) and antioxidant power of iron (FRAP) with ascorbic acid, Trolox and (FeSO4)7H20 as the references synthetic successible. With the correlation of antioxidant activity and the correlation between phenols, flavonoids and antioxidant activity (DPPH, ABTS and FRAP).The corresponding amounts of total phenols were reported as the equivalent of one milligram of the standard used per gram of lyophilized extract (701.36 ± 0.01 mg EAG / g) and the flavonoids results were expressed as mg quercetin equivalent per gram of lyophilized extract (206.52 ± 0.03 mg EQ / g). These results obtained show the richness of the extract in flavonoids and total phenols. The evaluation of the antioxidant power showed that the hydro-methanolic extract with very high antioxidant power at 1 mg / ml: IDPPH: 96.45 ± 0.50%; IABTS: 99.27 ± 0.098%; and A FRAP 0.72 ± 0.010% with IC50DPPH inhibition concentrations: 0.44 ± 0.005 mg/ml; IC50ABTS 0.42 ± 0.003 mg/ml and IC50 FRAP 0.49 ± 0.07 mg/ml). With good correlation of DPPH, ABTS and FRAP. Moreover, a strong correlation has been shown between the contents of total phenols and flavonoids and antioxidant activity, the high correlation is (r = 0,922 et r = 0,971) successible. This study confirms, scientifically, the traditional use of this plant.