Antibacterial activity of green tea leaves extracts against specific bacterial strains

Abstract

ObjectivesThere is an increase interest in the beneficial effects of green tea extracts which exhibits great activity against several diseases due to the presence of beneficial bioactive compounds. Green tea extracts were investigated for their anti microbial activity using specified Gram positive and Gram negative bacterial strains by specific methods. Therefore, this study aimed at evaluation of green tea aqueous, ethanol, and methanol extracts efficiency against potential gram positive and gram negative bacterial strains. MethodsFifty grams of dry leaves powder were used to prepare three different solutions with three different solvents; 80% ethanol, methanol, and sterile water; with a final concentration of 20% (g/ml). The flasks were placed for two days in a vibrator at 350 rpm at 15 °C. Four bacterial strains - two of them are gram positive and the other two are gram negative strains- were honored from King Fahd Educational Hospital. Qualitative phytochemical analysis technique was used to insure the presence of active compounds such as flavonoids, saponin, and tannins in plant extracts. Also, Gas chromatography mass spectrometry assay was used to determine extracts bioactive compounds. Seven types of antibiotics were used to determine minimum inhibitory concentration with two-fold dilution of plant extracts, by using agar plate method. While the minimum bactericidal concentration was performed using the pour plate technique. ResultsThe three types of plant extracts showed high effectiveness against pathogenic bacterial strains. The highest value of inhibition was (4.3 ± 0.3) mm with ethanol extract against Bacillus subtilis. Gentamicin, Neomycin and Ciprofloxacin showed good values of inhibition against Gram-positive and gram-negative bacteria, while gram-negative bacteria showed resistance to Chloramphenicol, Methicillin, Vancomycin. On the other hand, Gram positive bacteria showed resistance to the Colistin only. ConclusionGreen tea extracts showed effective anti microbial activity against different types of gram positive and negative bacterial strains as they have a good inhibitory and bactericidal activity due to the presence of special bioactive components such as ECGC and catechins.