Antioxidant and Antimicrobial Activity of Solvent Fractions of Calpurnia aurea (Ait.) Benth. (Fabaceae

Abstract

Background: Calpurnia aurea (Ait.) Benth. leaves are used to treat different diseases like ectoparasite infestation, diarrhea, sores, anthrax, fevers, pain, and snake venom. The leaves of Calpurnia aurea were first extracted by methanol and further fractionated with the help of n-hexane, dichloromethane and ethyl acetate with increasing polarity. Methods: The antibacterial activities of the fractions were evaluated against disease causing bacteria using agar well diffusion. The minimum inhibitory concentrations (MIC) of the fractions were determined by the micro-broth dilution method using tetrazolium salt colorimetric assay. The antioxidant activities of the solvent fractions were determined by phosphomolbedum reduction assay, reducing power assay and hydroxyl radical scavenging activity. Results: The average MIC value of C. aurea fractions ranged from 1.95mg/mL to 31.25mg/ mL, 7.81mg/mL to 31.25mg/mL and 13.02mg/mL to 62.5mg/mL, for ethyl acetate, dichloromethane and n-hexane fractions, respectively. The leaf extracts have a higher antioxidant effect, as shown in the phospho-molbedum reduction assay, reducing power and hydroxyl radical scavenging assay. Conclusion: The ethyl acetate and dichloromethane fractions revealed significant antibacterial effects against the growth of pathogenic bacteria. However, the n-hexane fraction showed the least antibacterial effect against all of the test bacteria. Furthermore, the nhexane fractions of C. aurea showed higher antioxidant activity. Keywords: antimicrobial, antioxidant, Calpurnia aurea, in vitro, solvent fractions