Phytochemical Screening and Antioxidant Potential of Organic Extracts of the Leaves and Flowers of Lippia multiflora Mold from Burkina Faso

Lippia multiflora Moldenke (Mold) is a plant belonging to the Verbenaceae family and is widely used for its therapeutic properties in traditional medicine. The objective of this study was to investigate the phytochemical composition and antioxidant activity of organic extracts from its leaves and flowers. The extracts were obtained by maceration using solvents of increasing polarity. Phytochemical screening was carried out by Thin-Layer Chromatography (TLC) and test-tube assays. Total phenolic compounds (TPC), total flavonoids (TF), and condensed tannins (TC) were measured using colorimetric methods employing Folin-Ciocalteu reagent, aluminium trichloride, and sulfuric vanillin, respectively. The antioxidant activity of the extracts was evaluated using DPPH• and ABTS+• radical scavenging methods. In the leaves, the TPC were 842.40 ± 10.69 μg GAE/mg of dry extract, compared to 870.23 ± 2.41 μg GAE/mg of dry extract in the flowers, for the dichloromethane extracts. Total flavonoid content was 202.78 ± 0.43 μg QE/mg of extract in the ethyl acetate leaf extract versus to 206.05 ± 2.09 μg QE/mg of dry extract of the same solvent in the flowers. Concerning condensed tannins, the content was 333.13 ± 10.91 mg TA/g of dry extract in the methanolic flower extract compared to 525.67 ± 6.46 mg TA/g of dry extract in the ethyl acetate leaf extract. The IC50 values of the methanol extracts were 57.465 ± 0.28 μg/ml and 65.473 ± 2.44 μg/ml for flowers and leaves, respectively, compared to 16.585 ± 0.474 for ascorbic acid using the DPPH method. Using the ABTS method, the ethyl acetate extracts of flowers and leaves showed IC50 values of 37.349 ± 0.301 μg/ml and 39.173 ± 0.390 μg/ml, respectively, compared to 10.864 ± 0.029 μg/ml for ascorbic acid. The flowers were found to be richer in secondary metabolites and antioxidants than leaves, which are nevertheless more commonly used.