Date

2011

Author

Barut, Burak

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Staphylococcus aureus is one of the major causes of food-borne pathogenesis. Antibiotic consumption for these pathogens has been increasing year by year world-wide. In order to decrease the use of synthetic antibiotics, fresh fruits and dry herbs consumed as beverages in regular diets were examined as potential natural antibiotics for the treatment of food based infections against Staphylococcus aureus. Herbs consumed as tea infusions including Pimpinella anisum L. (anise), Anthemis arvensis L. (camomile), Rosa canina L. (rosehip), Salvia fruticosa Mill (sage) and fresh fruit juices including Vitis vinifera L. (grape), Citrus sinensis L. (orange), Prunus persica L. (peach) and Punica granatum L. (pomegranate) were selected as samples of hot or cold consumed beverages in our daily diets. Extracts of fresh fruit juices were prepared in methanol, on the other hand, tea infusions of herbs were filtered and lyophilized. Antioxidant capacities of the plant samples were investigated by radical scavenging methods, namely 2’2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) as well as determination of total phenolic and flavonoid contents. Furthermore, antimicrobial activities of plant samples were determined by minimum inhibitory concentration and minimum bactericidal concentration methods along with disc diffusion method. Trolox equivalent antioxidant capacities (TEAC) of the herbal tea infusions obtained by ABTS radical scavenging method were ranged between 48.38 ± 1.242 and 715.73 ± 4.265 (μmol Trolox equivalent (TE)/g of extract) while, TEAC values of fresh fruits juices were between 26.86 ± 0.217 and 73.55 ± 0.973 (μmol Trolox equivalent (TE)/g of extract). Moreover, EC50 values of the tea infusions obtained by DPPH radical scavenging method were ranged between 0.05 ± 0.001 and 1.53 ± 0.004 (mg/mL) while, EC50 values of the fruit juices were 1.6 ± 0.014 and 2 ± 0.093 (mg/mL). Total phenolic content of the plant samples tested in this study were varied from 1.383 (μg gallic acid equivalent (GAE)/mg of extract) to 159.167 (μg gallic acid equivalent (GAE)/mg of extract) and total flavonoid content varied from 0.111 (μg quercetin equivalent (QE)/mg of extract) to 201.15 (μg quercetin equivalent (QE)/mg of extract). Sage, orange and grape displayed higher antimicrobial activities with values of 1.5, 6 and 6 mg/mL minimum inhibitory concentrations and 1.5, 24 and 24 mg/mL minimum bactericidal concentrations, respectively. Inhibition zone diameters of sage, orange and grape were found to be 9, 9 and 11 mm.

Subject Keywords

Staphylococcus aureus infections, Biochemistry.

URI

http://etd.lib.metu.edu.tr/upload/12612999/index.pdf
https://hdl.handle.net/11511/20474

Collections

Graduate School of Natural and Applied Sciences, Thesis