Introduction: Lannea welwitschii is a medicinal plant used in traditional medicine to treat various infectious diseases due to its plethora of bioactive compounds that possess various pharmacological activities. This study aimed to characterize and determine the phytochemical profile and the bioactive compounds responsible for their pharmacological activities. Methods: Phytochemical screening and Gas-Chromatography Mass Spectrometry (GC-MS) analysis were carried out on the ethanolic extract of L. welwitschii to determine the volatile compounds present. Characterization of the crude extract was carried out using Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Energy Dispersive X-ray spectroscopy (EDX). The antioxidant potential of the extract was evaluated using methods such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant Potential (FRAP). The antibacterial activities were determined using the macro-broth dilution technique. Results: Secondary metabolites such as saponins, tannins, alkaloids, reducing sugars, and cardiac glycoside were identified. The GC-MS analysis showed the presence of 48 bioactive compounds, out of which 12 had peak area percentages ≥ 1%. Some of the bioactive compounds identified include 2-butoxy-ethanol, Dodecanoic acid, Stigmasterol, Isopropenyl, and n-hexadecanoic acid, which have been reported with different biological activities. FTIR analysis revealed the presence of various functional groups which showed major compounds in the plant extract. The morphological features showed the spherical shape of the plant extract with several aggregates, while the EDX analysis identified elements such as silicon, oxygen, and silver. The extract demonstrated inhibitory potential against some of the bacterial isolates. However, Bacillus pumilus, Klebsiella quasipneumoniae, Klebsiella aerogenes, and Staphylococcus aureus are more susceptible with MIC of 0.313 and 0.625 mg/ml respectively. Conclusion: The presence of secondary metabolites and bioactive compounds revealed by the characterization and phytochemical analysis provided enough evidence for the usage of the plant in the treatment of infectious diseases and thus might be considered a therapeutic agent.
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