The present study aims to develop two medicinal plants used in Benin in the treatment of skin, urinary infections and septicemia. This study consists in determining the chemical composition, evaluating the antibacterial and antioxidant activities of the ethanolic, semi-ethanolic and aqueous extracts of the two plants investigated: Diospyros mespiliformis and Entada africana. The extracts of these plants were obtained by maceration for 72 hours. The identification of secondary metabolites carried out by the method of precipitation and staining in the tubes revealed the presence of tannins, saponosides, flavonoids, anthocyanins; alkaloids, coumarins, sterols and terpenes. The content of total phenolic compounds was estimated by the Folin-Ciocalteu method, it varies from 2455.36 ± 7.05 to 5141.51 ± 98.67 EAG / gMS for extracts of D. mespiliformis and 2261.00 ± 21.14 to 7256.6 ± 24.67 EAG / gMS for extracts of E. africana. The antioxidant activity of the extracts was evaluated by the anti-free radical test using the DPPH radical. The results obtained show that the extracts of E. africana have a higher free radical scavenging power than the extracts of D. mespiliformis. The antibacterial activity of the in vitro extracts against microorganisms is evaluated by two methods: diffusion on disc and microdilution. The results show that the ethanolic extract of D. mespiliformis exerts a bactericidal effect on S. aureus as well as the ethanolic and aqueous extracts of E. africana which have a bactericidal effect on the strains of S. aureus and SCN. These results show that the investigated extracts have antimicrobial properties and could be used in the fight against skin infections and septicemia. This justifies their use in traditional medicine.
The present study was devoted to the chemical analysis of three plants (Anchomanes difformis, Parkia biglobosa and Polyalthia longifolia) commonly used by traditional healers in Benin, for their curative properties in the treatment of certain diseases. After characterization of large chemical groups present in the leaves of these plants, total polyphenols, condensed tannins, total flavonoids, anthocyanins and anthocyanidins were quantified by spectrophotometric methods. The scavenging activity was evaluated by the DPPH method and the volatile compounds in the powders of these plants were determined by SPME-GC/MS. The results showed the presence of several secondary metabolites such as saponins, alkaloids, tannin, mucilages, anthraquinones, leucoanthocyanins, anthocyanins and triterpennoids in varying proportions in the three plants. The levels of condensed tannins, total flavonoids and anthocyanins are respectively higher in leaves of P. longifolia (22.5 mg/g, 15.69 mg / g and 0.94 mg/g) than in those of P. biglobosa (16.48 mg/g, 12.03 mg/g and 0.38 mg/g) and that of A. difformis (9.74 mg/g 4.59 mg/g and 0 mg/g). Against by the total polyphenol content P.longifolia leaves (2.89 mg/g) is between those of A. difformis (2.19 mg/g) and P. biglobosa (4.5 mg/g). It is the same for the contents of anthocyanidins. Three plants studied, P. longifolia proved richest in polyphenols (condensed tannins, total flavonoids, anthocyanidins and anthocyanins) and A. difformis the less rich. This content of polyphenolic compounds would explain the test results of radical scavenging activities with an IC50 of 21.66 mg/mL for P. longifolia, 23.99 mg/mL for P. biglobosa and 26.5 mg/mL for A. difformis. The solid phase micro extraction (SPME) coupled with GC/MS allowed the unambiguous identification of volatile components of each of the three plants.