en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <p dir="ltr"><strong>Introduction:</strong> Increasing of food-related diseases has led to the perception of diet importance. Plant-derived products (especially tea) as important sources of antioxidant and antimicrobial compounds play a major role in reducing food pathogens. In this study, total phenolic content, antioxidant and antimicrobial activity of four tea extracts including green tea, white, black and red teas were evaluated. <strong>Methods:</strong> The total phenolic amount was determined using Folin&ndash;Ciocalteu method and 1-diphenyl-2-picryl hydrazyl radical (DPPH) method was used for antioxidant activity measurement. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of tea extracts against eight species of tested bacteria (<em>Staphylococcus aureus</em>, <em>Streptococcus pyogenes</em>, <em>Streptococcus pneumonia</em>, <em>Saprophyticus</em> <em>Staphylococcus</em>, <em>Enterococcus faecali</em>, <em>Acinetobacter baumannii</em>, <em>Proteus mirabilis</em> and <em>Serratia marcescens</em>) were evaluated by microdilution technique. <strong>Results:</strong> The results of this study showed that green tea and white tea extracts had the highest total phenolic content and antioxidant scavenging activity. Also, a strong positive correlation was observed between phenolic content and antioxidant activity in green tea and red tea. <strong>Conclusion:</strong> All four tea extracts showed inhibitions of several microorganisms. However, gram-negative bacteria were more resistant to inhibitory effects of tea extracts. As a result, non-fermented tea extracts showed more antioxidant activity and inhibition effect against tested bacteria.</p> Antioxidants, Phenols, Plant extracts, Tea 57 61 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-105-1&slc_lang=en&sid=1 Barat Ali Fakheri ba_fakheri@yahoo.com No Department of Plant Breeding and Biotechnology, Zabol University, Zabol, Iran Samaneh Bagheri samanehbagheri@uoz.ac.ir Yes Department of Plant Breeding and Biotechnology, Zabol University, Zabol, Iran Nafiseh Mahdi Nezhad nmahdinezhad@uoz.ac.ir No Department of Plant Breeding and Biotechnology, Zabol University, Zabol, Iran