Phytochemical Study Assay of Phenolic Compounds and Determination of the Antioxidant Activity of Aqueous Extracts from the Leaves of three Medicinal Plants Used in the Haut-Sassandra Region, Daloa (Côte d'Ivoire)

Cassia occidentalis, Jatropha curcas and Chromoleana odorata are plants used in the treatment of pathologies in Côte d'Ivoire. With the aim of treating pathologies caused by oxidative stress using antioxidants, a study was carried out into the antioxidant activity of aqueous extracts of these plants and to identify the molecules responsible for this effect. After aqueous extraction, the extracts obtained were used to carry out phytochemical tests, phenolic compound assays and antioxidant activity tests using the DPPH• and ABTS+• methods. Phytochemical screening revealed the presence of sterols, polyphenols, flavonoids, alkaloids and saponins. Respective contents of total polyphenols are 3.40 ± 0.04, 3.15 ± 0.03 and 2.80 ± 0.02 mgEAG/g DM for Cassia occidentalis, Jatropha curcas and Chromoleana odorata and those of flavonoids are 54.15 ± 1.2, 50.40 ± 1.2 and 48.50 ± 1.1 mg EqQ/g DM for Cassia occidentalis, Chromoleana odorata and Jatropha curcas. Using the DPPH test, the mean IC50 values were 2.74 ± 0.1 µg/mL for Cassia occidentalis and Chromolaena odorata and 2.73 ± 0.1 µg/mL for Jatropha curcas. ABTS test revealed mean IC50 values of 10.35 ± 0.1 µg/mL for Cassia occidentalis and Chromoaena odorata and 7.01 ± 0.1 µg/mL. Jatropha curcas. These antioxidant powers are thought to be due to the effects of certain phenolic compounds present in these plants, confirming their natural antioxidant activity.