Secondary metabolites and essential oil analysis of Clematis simensis with antioxidant and antibacterial activities

Clematis simensis is one of the most commonly used folk medicines in Ethiopia. This study was aimed to investigate the chemical constituents, antioxidant and antibacterial activities of the aerial part of Clematis simensis, and analysis of the composition of its essential oil. The phytochemical study led to the isolation of five compounds: 1-tricosanol (1), 1-hexacosanol (2), 2-deoxy-D-ribono-1,4-lactone (3), 5-hydroxylevulinic acid (4), and β-sitosterol-3-O-β-D-glucoside (5). Their chemical structures were determined by a comprehensive analysis of HR-ESI-MS, FT-IR, UV-Vis, and 1D/2D NMR experiments. The chemical compositions of the essential oils obtained by hydrodistillation from the aerial part of Clematis semenses were determined by GC-MS, which led to the detection of ten major compounds: (E)-2-nonen-1-ol (38.33%), 4-cyclopentene-1,3-dione (28.69%), cyclofenchene (5.65%), benzene acetaldehyde (4.74%), methyl salicylate (2.77%), salicylaldehyde (2.68%), benzaldehyde (2.60%), α-terpineol (2.10%), eucalyptol (1.21%), and 2,6-dimethylcyclohexanol (1.15%). Compound 4 showed high antioxidant activity (IC50 14.89 μg/mL) but has no antibacterial activity against both Gram-positive and Gram-negative bacterial strains. According to the antimicrobial parameters, crude extract showed very weak activity at 500 mg/mL, 250 mg/mL, and 125 mg/mL. To our knowledge, this is the first report on the isolation of secondary metabolites from Clematis simensis. KEY WORDS: Clematis simensis, Essential oil, Phytochemical investigation, Biological activities Bull. Chem. Soc. Ethiop. 2024, 38(4), 1037-1049. DOI: https://dx.doi.org/10.4314/bcse.v38i4.18