Antioxidant and antibacterial activities of turkish endemic <i>Sideritis</i> extracts

Abstract

Sideritis species are traditionally used as teas, flavoring agents and for medicinal purposes in Turkey . In this study, the antioxidant and antimicrobial activities of Sideritis condensata Boiss. & Heldr. (SC) and Sideritis eryhrantha v ar. erythrantha Boiss. & Heldr. (SE) endemic species' extracts of Lamiaceae were determined. These extracts were investigated for antibacterial activity by using the agar diffusion method against 15 species of bacteria: Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Enterococcus feacalis, Escherichia coli, Escherichia coli O157:H7, Klebsiella pneumoniae, Mycobacterium smegmatis, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas fluorescens, Salmonella enteritidis, Salmonella typhimurium, Staphylococcus aureus and Yersinia enterocolitica . Statistical differences within bacteria were significant at p<0.05. SC extract was more effective than the other . At all concentrations, although the most sensitive bacteria was P. aeruginosa , the most resistant bacteria were E. feacalis for SC extract and E. feacalis, S. aureus for SE extract. Total phenolics, radical scavenging activity by 1, 1-diphenyl-2-picrylhydrazyl (DPPH) method and the antioxidant capacities by the formation of phosphomolybdenum complex method of the extracts were determined. The total phenolics were found as 247.62 ± 1.91 mg gallic acid equivalent (GAE)/g in SC extract and 217.61 ± 0.95 mg GAE/g in SE extract of dried weight. At 100 ppm concentration, the free radical scavenging activities of SC and SE extracts were found as 72.01 ± 1.93 and 71.48 ± 1.95 %, respectively. The antioxidant activities by phosphomolybdenum method of SC and SE extracts were 279.37 ± 3.61 and 146.11 ± 3.11 mg/g dried extract.