Chemical Characterization and Anti-Microbial Evaluation of the Eastern Nigerian Specie of African Mistletoe (Loranthus micranthus) Sourced From Citrus sinensis

Abstract

This present study is aimed at determining phytochemical constituents with the aid of GCMS technique and in vitro screening of crude methanol extract of the leaves of Loranthus micranthus Linn parasitic on Citrus sinensis tree sourced from Nsukka, in the eastern part of Nigeria for their antimicrobial activity against six human pathogens. Preliminary phytochemical screening was carried out on the crude extract. The results of the phytochemical analysis showed positive for tannins, flavonoids, steroids, alkaloids, triterpenes/sterols, glycosides and saponins. GCMS analysis revealed nine bioactive compounds in the crude methanol extract of Loranthus micranthus, which includes; Benzoic acid, 3,4,5-trimethoxy-, trimethylsilyl ester, 1,3,5-Triazine, 2,4,6-tris[(trimethylsilyl)oxy]-, Gallic acid, Beta-Amyrin, Beta-Sitosterol, Lup-20( 29)-en-3-one. The crude methanol extract of Loranthus micranthus was subsequently partitioned into four solvents to obtain n-hexane, chloroform, ethyl acetate and methanol fractions respectively. The crude extract and the four fractions were observed for antimicrobial activities on the following pathogens; Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Aspergillums niger, Staphylocoocus aureus and Candida albicans at various concentrations using agar diffusion method. The results of the antimicrobial activity proved the ability of the crude methanol extract and the obtained fractions of Loranthus micranthus to inhibit these pathogens. Different bacterial species and fungi exhibited different sensitivities with variable extent towards the extract/fractions. The order of activity against selected bacteria was Candida albicans> Bacillus subtilis> Staphylococcus aureus> Escherichia coli. Only the crude methanol extract at a concentration of 25 mg/ml inhibited Pseudomonas aeruginosa. While Aspergillums niger was resistant to both the extract and fractions. The n-hexane and the methanol fractions of Loranthus micranthus exerted maximum antimicrobial activity against Candida albicans with an MIC of 1.25 and 0.625 mg/ml respectively. An indication that the plant possesses very potent antifungal activities The MIC for Bacillus subtilis was 1.25 for n-hexane and methanol fractions respectively. There is good evidence that the plant is more active against gram positive bacteria.