keywords: Phytochemicals, antimicrobial, flavonoids, cytotoxicity, Calotropis procera
The bioactive components of the leaves of Calotropis procera was extracted using aqueous, methanol, and n-hexane and investigated for the presence of secondary metabolites. All the extracts revealed the presence of steroid and saponins while flavonoids are present in aqueous and methanol extracts. The antimicrobial activities of the extracts were tested against fungi, gram positive and gram negative bacteria’s such as Candida albicans, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Salmonela typhi using the agar disk diffusion method. The n-hexane extract demonstrated a significant broad-spectrum antimicrobial activity against S. typhi and S. aureus with the zone of inhibition of 7 and 11 mm. The methanol extract was only active against Gram negative P. aeruginosa with the zone of inhibition of 6, while the aqueous extract was inactive against all the organisms tested. The result of the antioxidant property showed that methanol extract has the highest activity of about 88% while aqueous extract is 37%. The flavonoid content of the extracts was also quantified to be 96.90 and 39.90 mg/g for methanol and aqueous extracts. The crude extracts were also subjected to brine shrimp lethality bioassay and hexane extract showed significant cytotoxicity having LC50 of 2.01 μg/ml.