Antibacterial Activity and Identification of Phenolic Compounds of Ethanolic Extracts from Pseudocedrela kotschyi Scheinf Harms

Abstract

Pseudocedrela kotchsyi ’ s roots and trunk bark are overused in Togolese traditional medicine to cure various illnesses. Nevertheless, there is currently no scientific proof to support the claim that the leaves of this plant are less useful in herbal medicine than the root and trunk barks. This study aimed to identify the phenolic compounds and compare the antibacterial activities of extracts from the leaf, trunk bark, and root bark of the plant. Each part of the plant was macerated successively in three solvents of increasing polarity: hexane, dichloromethane, and ethanol. Usual methods of characterization were adopted to determine the phytochemical composition of each ethanolic extract. The antibacterial activity of the extracts was evaluated using the diffusion method in solid medium and by microdilution assay in liquid medium, to determine their MIC and MBC, respectively . The phenolic compounds in the extracts were quantified using HPLC-DAD analysis. Then, the identification of compounds in the leaf and root bark extracts was achieved using UHPLC-HRMS analysis. According to the results, the trunk bark yielded the best extraction (12.33 ± 1.43%). Phytochemical screening showed the presence of alkaloids, saponins, phenolic compounds, flavonoids, and tannins in all extracts. The trunk bark showed the most interesting antibacterial activity against three bacterial strains, including Escherichia coli ATCC 22925, Pseudomonas aeruginosa , and Salmonella typhimurium , with MICs ranging from 6.25 to 25 mg/mL and MBCs ranging from 6.25 to 50 mg/mL. Most of the compounds identified by HPLC-DAD and UHPLC-HRMS analyses could be responsible for the antibacterial activities exhibited by the plant extracts. These identified compounds justify the frequent use in traditional medicine of this plant for the treatment of various diseases.