Phytochemical, Antioxidant and Antimicrobial studies of Lannea egregia Engl. & K. Krause (Anacardiaceae) extracts and chromatographic fractions
Screening ‘new’ medicinal plants of traditional importance for bioactive components is a sure way of discovering novel therapeutic agents to treat diseases. This study, therefore investigated the presence of phytochemical, antioxidant and antibacterial components of the extracts of Lannea egregia. Phytochemical screening was done by standard methods. Antibacterial activity of the extracts of Lannea egregia was determined by agar well diffusion method while the minimum inhibitory concentration (MIC) was determined by agar dilution method. The antioxidant capacity of the crude extracts was determined through the evaluation of total flavonoid content, total phenolic content, ferric reducing power, total antioxidant capacity and 2,2-diphenyl-1-picryhydrazyl. The phytochemical screening of the different parts of this plant revealed the presence of tannins, saponins, alkaloids, flavonoids, steroids, terpenoids, emodins, phlobatannins, anthocyanins, coumarins and phenolics. Phlobatannins was observed to be absent in the stem bark. The crude extracts obtained from the leaves, stem bark and roots of this plant exhibited good antibacterial activity against typed strains of Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. The diameter of the zone of inhibition ranged from 9.0 to 26.0 mm at 100 mg/mL for all the plant parts. The ethyl acetate leaf extract of this plant possessed the highest antibacterial activity with MIC and MBC values of the range of (3.125 to ˃50 mg/mL) and (12.5 to ˃50 mg/mL) respectively. The zone inhibition of the chromatographic fractions of both plants ranged 15-23 mm. Antioxidant study of the extracts of the leaf of L. egregia revealed that the ethyl acetate and methanol extracts have good antioxidant potentials comparable to that of ascorbic acid control. This study has revealed that the extracts from different parts of L. egregia possess good antibacterial and antioxidant activities which could be a function of the various phytochemicals detected in the plant.
Keywords: Lannea egregia, Phytochemical, Antibacterial, Antioxidant, Column chromatography.