Abstract:
Tea is a beverage with medicinal properties, produced from the immature leaves of
Camellia sinensis. Tea is categorized into black and green tea depending on
whether it undergoes fermentation or not. Tea waste is produced during the black
tea manufacturing process as a waste product. The objective of the present study
was to determine antibacterial activity of extracts of black tea, green tea and tea
waste of Sri Lanka against multidrug-resistant Staphylococcus aureus (MRSA) and
Mycobacterium smegmatis. From the preliminary antibacterial assays black tea
(grade BOP), tea waste and green tea (grade Fannings) were selected for this study.
Sequential Soxhlet extracts were prepared using hexane, chloroform,
dichloromethane, methanol and ethyl acetate as solvents. Broth microdilution
colorimetric assay was used for the determination of minimum inhibitory
concentrations (MIC). The range of the concentration of extracts which tested were
0.62 -10 mg/ml. Methanol was the best solvent which gave the best extraction
yield in mg/ g 110.88, 146.08 and 68.68 for black, green and tea waste
respectively. Extracts in methanol and ethyl acetate had higher antibacterial
activities compared to extracts in hexane, chloroform and dichloromethene. The
value of 2.5 mg/ml was the best antibacterial activity shown by the methanol
extracts of green and black tea against MRSA. Methanolic extracts of the green tea
yielded 2.5 mg/ml MIC value against M. smegmatis while black and tea waste
yielded 5 and 10 mg/ml respectively. With the hexane and chloroform extracts, a
few dichloromethane extracts and one ethyl acetate extract, MIC values were not
obtained in the tested region (>10 mg/ml) due to low antibacterial activity. From
tested samples, green tea was the best followed by black and tea waste for
antibacterial activity against MRSA and M. smegmatis.
