Comparison of chemical compounds, antioxidant and antimicrobial effects of Camellia sinensis black tea and green tea leaf extract on plant pathogenic bacteria (Xanthomonas campestris and Pseudomonas syringae) and human pathogenic b

Identifying and introducing new natural antimicrobial compounds against pathogenic agents is of concern to researchers. The present study was conducted with the aim of comparing the chemical compounds, antimicrobial and antioxidant effects of black and green tea.

Aqueous and methanolic extracts of black and green tea leaves were prepared and the compounds of the methanolic extracts were identified by GC-Mass, antibacterial effects were measured by the disk diffusion method, the minimum inhibitory concentration (MIC) the antioxidant property by the DPPH method.

Caffeine is the main component of green and black tea extracts, and its amount is 82.97% and 86.25% in these extracts, respectively. The minimum inhibitory concentration of green tea extract against Escherichia coli, Staphylococcus aureus, and Pseudomonas syringae is significantly three times higher than that of black tea extract. The inhibitory capacity of green tea extract against Xanthomonas campestris and the inhibitory capacity of black tea extract against Pseudomonas syringae is significantly higher than the other bacteria. Many of the effects related to green and black tea can be considered related to the relatively high capacity of inhibiting free radicals. The results of this research showed that the free radical and antioxidant capacity of green tea is significantly one and a half times higher than black tea. The inhibitory ability of the extract against plant pathogens is relatively and significantly higher than human pathogens. Different products and perhaps the waste of black tea and green tea can be used to control harmful microorganisms.