Enquêtes ethnobotaniques, phytochimiques et biologiques sur les plantes médicinales les plus courantes dans le Sud-Ouest Algérien.

Abstract

An Ethnobotanical survey of medicinal plants from the Bechar region, as well as phytochemical, antioxidant, antibacterial, and antifungal studies of nine folkloric medicinal plants, widely used in traditional medicine in southwest Algeria, are being actively conducted in this work. The Ethnobotanical survey was undertaken to collect detailed information about the usage of plants in human therapy in the Bechar region. A total of 162 plant species representing 143 genera and 50 families were used in the treatment of various diseases. The most encountered medicinal plant families were Asteraceae (18 spp.), Apiaceae & Lamiaceae (12 spp. each). Plant leaves were the most commonly used plant part. Whereas, decoction and cataplasm were the most common methods of traditional drug preparation. The assessment of phytochemical content, antioxidant potency and antimicrobial activity of the crude aqueous and hydromethanolic extracts of a nine-folkloric medicinal plant from Bechar region (southwest Algeria), namely: A. nardus, A. schoenanthus, G. alypum, two species of H. scoparia green & red, P. laevigata, R. tripartita, T. gallica, and T. nudatum, was conducted. Among all extracts, the aqueous extract of R. tripartita (276.221±0.079 mg GAE/g) and the hydromethanolic extracts of P. laevigata and H. scoparia red (245.095±0.037 and 243.609±0.231 mg GAE/g respectively) showed the highest phenolic content. The hydromethanolic extracts of P. laevigata, R. tripartita, and G. alypum showed the highest flavonoids content (646.531±0.234, 510.531±0.023, and 494.197±0.077 mg QE/g respectively), whereas, the hydromethanolic extracts of A. schoenanthus, R. tripartita, and H. scoparia green showed the highest polysaccharide content (356.609±0.005, 350.440±0.049 and 344.957±0.046 mg GE/g respectively). The antioxidant activity performed by DPPH, FRAP, and TAC shows that the both extracts of R. tripartita exhibited the highest total antioxidant activity with a very low IC50 (15.838 and 19.539 mg/mL respectively). The hydromethanolic extracts of R. tripartita, P. laevigata, T. gallica, and H. scoparia red had the highest ferric reducing antioxidant potency (624.194±0.294, 589.195±0.054, 470.423±0.141, and 436.914±0.153 AAEFRAP/g respectively). Whereas, the aqueous and hydromethanolic extracts of R. tripartita (426.581±0.1812 and 361.507±0.326 mg AAE/g respectively) and the hydromethanolic extracts of T. gallica, H. scoparia red, and P. laevigata (295.166±0.165, 289.673±0.051, and 264.108±0.170 mg AAE/g respectively) had the highest total antioxidant capacity. The maximum antibacterial activity was recorded against the gram-negative reference strains Pseudomonas aeruginosa and Escherichia coli with a maximum inhibition diameter of 15.6±0.5 and 15.0±1.4 mm respectively displayed by the aqueous extract of T. gallica. The antifungal activity revealed that the hydromethanolic extract of R. tripartita and the aqueous extract of T. nudatum were the best to suppress the growth of Aspergillus nidulans (77 and 66% respectively).