Antimicrobial investigation of ethnobotanically selected Guinean plant species

Ethnopharmacological relevance: In Guinea, medicinal plants play an important role in the management of infectious diseases including urinary disorders, skin diseases and oral diseases. This study was carried out to collect medicinal plant species employed for the treatment of these diseases and to investigate their antimicrobial potential.

Materials and methods: Based on an ethnobotanical investigation carried out in three Guinean regions, 74 traditional healers and 28 herbalists were interviewed and medicinal plants were collected. The most quoted plant species were evaluated for their antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, and in addition against Plasmodium falciparum.

Results: A total of 112 plant species belonging to 102 genera distributed over 42 botanical families were inventoried. Among the selected plant species, promising activities against C. albicans were obtained for the methanolic extracts of the stem bark of Terminalia albida (IC₅₀ 1.2 μg/ml), the leaves of Tetracera alnifolia (IC₅₀ 1.6 μg/ml) and the root bark of Swartzia madagascariensis (IC₅₀ 7.8 μg/ml). The highest activity against S. aureus was obtained for the dichloromethane extracts of the leaves of Pavetta crassipes (IC₅₀ 8.5 μg/ml) and the root of Swartzia madagascariensis (IC₅₀ 12.8 μg/ml). Twenty one extracts, obtained from twelve plant species, were strongly active against Plasmodium falciparum, including the dichloromethane extracts of the root and stem bark of Terminalia albida root (IC₅₀ 0.6 and 0.8 μg/mL), the leaves of Landolphia heudelotii (IC₅₀ 0.5 μg/mL), the stem bark of Combretum paniculatum (IC₅₀ 0.4 μg/mL) and the leaves of Gardenia ternifolia (IC₅₀ 1.3 μg/mL).

Conclusion: The present study provides a comprehensive overview of medicinal plants employed by Guinean traditional healers for the treatment of various microbial diseases, including urinary disorders, skin diseases and oral diseases. Some of the studied plant species showed promising antimicrobial activity and could be considered as a potential source for the development of new antifungal and/or antimalarial agents.

Keywords: Antimicrobial activity; Guinea; Oral diseases; Skin diseases; Traditional Medicine; Urinary disorders.