Determination of Polyphenols and Flavonoids and Evaluation of Antioxidant Activity of Crude Extraction from the Leaves, Seeds, Stems and Roots of Cassia occidentalis

Abstract

In this article, we studied four organs of Cassia occidentalis namely leaves, seeds, stems and roots. Cassia occidentalis is a plant used in traditional Senegalese medicine to treat several pathologies including asthma, malaria, high blood pressure, bronchitis, anemia, stubborn stomach aches, etc. This study focuses on the determination of the antioxidant activity of these extracts. This study focuses on the determination of total polyphenols and flavonoids of different organ extracts (leaves, seeds, stems and roots) of Cassia occidentalis and the determination of the antioxidant activity of these extracts. Total polyphenols are assayed using the Folin-Ciocalteu reagent and total flavonoids using aluminum trichloride (AlCl3). The antioxidant activity of the extracts is evaluated by the DPPH method using TROLOX as reference antioxidant. The results of this study show that leaves and roots are the richest organs in polyphenols with contents ranging from 0.4941 ± 0.0633 mg EAG/g to 11.5114 ± 0.0791 mg EAG/g for leaves and 0.1235 ± 0.0220 mg EAG/g to 4.1968 ± 0.0481 mg EAG/g for roots. These same organs are richer in flavonoids with contents ranging from 1.6645 ± 0.0215 mg EQ/g to 7.2215 ± 0.1728 mg EQ/g for the leaves and 0.0813 ± 0.0022 mg EQ/ g to ​​3.4839 ± 0.0538 mg EQ/g for roots. These contents are higher in the methanolic and aqueous extracts. Total antioxidant capacities are significantly correlated with polyphenol and flavonoid contents. This is because the leaves and roots have more antioxidants that can react with the DPPH radical. This quantity is more noted in the methanolic extracts (14.1502 ± 0.3781 mg ETr/g for the leaves and 7.7042 ± 0.0619 mg ETr/g for the roots). Only the methanolic extracts show remarkable antiradical activities with IC50 values ​​of 0.2409 ± 0.0006 mg/mL for the leaves and 0.1415 ± 0.0005 mg/mL for the roots. IC50 values for other extracts are not available, due to the low total antioxidant capacity. In short, the methanolic extracts of the roots and leaves therefore have an appreciable antioxidant power. This antioxidant power is more significant at the level of the methanolic root extract with the lowest IC50 value. This would justify the use of Cassia occidentalis in traditional Senegalese medicine to fight against several pathologies. This plant would therefore be a good source of natural antioxidants.