ANTIOXIDANT, ANTIBACTERIAL AND DNA PROTECTING ACTIVITY OF SELECTED MEDICINALLY IMPORTANT ASTERACEAE PLANTS

Asteraceae is the largest family of flowering plants, traditionally known for its medicinal properties. In the present study antioxidant properties of 10 selected Asteraceae species were assessed by DPPH (1,1-diphenyl-2-picryl-hydrazyl), ABTS (2,2'-azino-bis(3- thylbenzthiazoline-6-sulphonic acid) method. The plants were extracted sequentially in soxhlet apparatus with petroleum ether, hexane, ethyl acetate, chloroform, methanol and water in the increasing order of polarity. These extracts were subjected to find its antioxidant activity and total phenolic contents. Antibacterial activity against some human pathogenic bacteria was tested by agar disk diffusion method. Among all the organic solvent extracts, methanol extracts had very good antioxidant and antibacterial activity. The extracts showed inhibition of human pathogenic bacteria in the order: Escherichia coli > Klebsiella pneumonia > Shigella flexneri > Staphylococcus aureus > Bacillus subtilis > Bacillus cereus . Minimum inhibitory concentration (MIC) was 100 µg/100 µl for many plant extracts, whereas MIC of G. bosvallea and W. trilobata was 70 µg/100 µl for Bacillus subtilis, Klebsiella pneumonia and Shigella flexneri . The extracts were tested for pTZ57R/T plasmid DNA protection against hydroxyl radicals as evidenced by DNA fragmentation assay. Significant and positive linear correlations (R 2 = 0.9294) were found between total antioxidant capacities and phenolic contents indicating that phenolics were the dominant antioxidant constituents in tested medicinal plants which are discussed in this manuscript. Our study clearly demonstrated that the selected plants have good antioxidant, antibacterial and DNA protecting properties.