Comparative secondary metabolite compositions and anti-microbial properties of n-hexane and ethyl-acetate fractions of Nelsonia campestris

Nelsonia campestris is a medicinal plant commonly used to treat measles caused by morbillivirus. This study assessed the phytochemical composition, in vitro antimicrobial activity of n-hexane and ethyl-acetate fractions of Nelsonia campestris. Phytochemical composition was determined using standard procedures. Antimicrobial test against six microorganisms, including K. pneumonia, S. aureus, B. subtilis, E. coli, P. aeruginosa and S. typhi was investigated using agar diffusion method while minimum inhibitory concentrations were determined by broth micro dilution method. Results revealed the presence of alkaloids, phenols, tannis, flavonoids, saponins and steroids in both n-hexane and ethyl-acetate fraction. Glycoside was present in n-hexane fraction but absent in ethyl-acetate fraction while volatile oil and anthraquinone were completely absent. Quantitatively, n-hexane fraction had higher phenol (57.12±0.01 mg/100g), tannins (19.76±0.04 mg/100g), and saponins (104.78±0.05 mg/100g) while ethyl-acetate had higher flavonoid (27.85±0.50 mg/100g) and alkaloids (16.62±0.01 mg/100g). The ethyl-acetate fraction was highly active against all test organisms with inhibition diameters in the range of 7.50±0.56 mm (P. aeruginosa) to 21.50±0.32 mm (E. coli) The MIC ranges between 2.5-20 mg/mL while the MBC ranged between 5.0-30 mg/ml for the ethyl-acetate fraction. The n-hexane fraction was active only against P. aeruginosa and B. subtilis with inhibition diameters in the range of 12.50±0.10 mm-17.55±1.00 mm. This study has shown that the n-hexane and ethyl-acetate fractions of Nelsonia campestris contain some useful potential bioactive principles that are inhibitory to some pathogenic organisms. The ethyl-acetate fraction was more active than n-hexane fraction and thus could be considered as a natural source of antimicrobials for therapeutic purposes.