EVALUATION OF BIOACTIVE COMPOUNDS OF Stevia rebaudiana LEAVES AND CALLUS

Stevia rebaudiana is considered natural antioxidants, which contained phenolic compounds and flavonoides at levels 24.01 18.93 mg/g dry weight basis of leaves and 33.99 30.03 mg/g dry weight basis of callus, these substances have been suggested to play a preventive role-for human health. Antioxidant activity of water and methanolic extracts of stevia leaves and callus equivalent to gallic acid (GA) and butylated hydroxyl anisole (BHA) were determined. GA was the stronger antioxidant in both water and methanol extracts than BHA. Antibacterial and antifungal of stevia leaves and callus extracted by six types of solvent (acetone, chloroform, hexane, methanol, ethyl acetate and water) were studied. Methanol and acetone extracts had greater antibacterial potential for the strains of Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. However, acetone, chloroform, methanol and ethyl acetate had antifungal potential for Asperigiilus ochraceus, Asperigillus parasiticus, Asperigiilus flavus and Fusarium. The results indicate that stevia leaves and callus extracts may be an ideal candidate for further research into their uses for food preservation and pharmaceutical due to their antioxidants and antimicrobial activities.