Why is Pergularia tomentosa L. absent from the Mauritanian Pharmacopoeia?Evaluation of its antioxidant, antibacterial and antifungal activities

Abstract

To understand the absence of Pergularia tomentosa L. (Apocynaceae) in the Mauritanian pharmacopoeia, we characterized the phytochemical composition, evaluated its biological and antioxidant activities. The phytochemical study shows the presence of flavonoids, tannins, saponins and steroids in the roots and aerial parts. Alkaloids, heterosides and terpenes are absent from the Mauritanian ecotype, although they are well present in P. tomentosa L. according to many studies. Four bacterial strains were tested: Gram positive (Staphylococcus aureus and Citrobacter freundii) and Gram negative (Escherichia coli and Listeria monocytogenes). Only the Staphylococcus aureus strain is sensitive to petroleum ether (PE) and ethyl acetate (EA) extracts from the roots. The diameters of the inhibition zones are 8.3 mm (PE) and 7 mm (EA). The MIC values are 400 µg/mL for PE extract and 200 µg/mL for EA extract. The MBC shows a bacteriostatic effect. For the antifungal activity, five strains of Candida and one of Saccharomyces were tested. No sensitivity of the germs to the tested extracts is revealed. The antioxidant activity assays were determined by in vitro using the DPPH. The IC₅₀ value shows that EA extract is the most effective (1.9 mg/mL). The least effective is obtained with ethanolic extract (3 mg/mL for the aerial parts and 2.4 mg/mL for the roots). This efficiency remains low compared to that of ascorbic acid (IC₅₀ is around 0.15 mg/mL).