Effects of kenyan black tea water soluble components on theaflavins interaction with antibiotics against selected pathogenic bacteria

Abstract

Abstract. Bor A, Kenya E, Mbithi JJN, Mutai C. 2017. Effects of Kenyan black tea water soluble components on theaflavins interaction with antibiotics against selected pathogenic bacteria. Bioteknologi 14: 47-59. This research is intended at differentiating the antibacterial activities of hot water extract of black tea having 18 µg/mL of theaflavins and 18 µg/mL of isolated theaflavins and their blend with antibiotics such as ampicillin. Their blended impacts with antibiotics were resolved by utilizing disk diffusion and modified Checkerboard method. The chi-square test was used to test the null hypothesis, which stated that water soluble components have no effect on theaflavins interaction with antibiotics. The water-soluble components of black tea extract were extracted with hot water, with the theaflavins being measured using the Flavognost method. Similar amounts of theaflavins were extracted using organic solvents and silica gel column chromatography. The concentrates of hot water extract and isolated theaflavins showed synergistic activity with selected antibiotics. However, the level of synergism differed significantly at P<0.05, with isolated theaflavins having a higher level. The difference in inhibitory effect between blended concentrates of hot water extract and isolated theaflavins with MIC (10.4 µg/mL) of ampicillin against Salmonella typhi was significant (?² = 0.56; P<0.05). The differences in inhibitory effect were also significant at (?² = 0.699; P<0.05) between the two black tea extracts blends with MIC (4.3 µg/mL) of norfloxacin against Pseudomonas aeruginosa. The blend of concentrates of hot water extract and isolated theaflavins with MIC (2 µg/mL) of ciprofloxacin differed significantly in level of impediment at (?² = 1.98; P<0.05) against Staphylococcus aureus. When the concentrates of the two black tea extracts were blended with MIC (5.25 µg/mL) of tetracycline, the inhibitory effect differed significantly at (?² = 2.27; P<0.05) against Enterobacter aeruginosa. It was also significant at (?² = 0.4; P<0.05) when concentrates of the two black tea extracts were blended with MIC (12 µg/mL) of chloramphenicol against Escherichia coli. The differences in inhibitory effect were attributed to the interactions within the tea infusion between water soluble components and theaflavins. Theaflavins in black tea infusions are being partially counteracted by one or more chemical components in it and it lowers the overall activity. However, the pattern of activity of isolated theaflavins and hot water extract of black tea were alike. This suggests that the theaflavins are the principal bioactive compounds in black tea infusions, despite the existence of interaction. Isolated theaflavins and hot water extracts of black tea restored the activity of lower concentrations of antibiotics below MIC to vulnerable breakpoints. The two black tea extracts together with antibiotics can be used in the treatment and prevention of bacterial infections.