Antioxidant and antibacterial activities of Turkish endemic Sideritis 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 var. 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 faecalis, 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. faecalis for SC extract and E. faecalis, 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.