Abstract:
Tea is one of the most important industries which significantly contribute to
the gross national product (GNP) of Sri Lanka. In order to investigate the
health effects of drinking of Sri Lankan black tea samples, antimicrobial
activity of extracts of BOP (upcountry), BOP (lowcountry), BOPF
(upcountry), BOPI (low-country), Dust (upcountry), and Orange Pekoe I
(lowcountry) was screened against Gram (+) Methicillin resistant
Staphylococcus aureus (MRSA) and Gram (−) Escherichia coli. Out of the
tea samples tested all black tea hot water infusions showed antibacterial
activity against MRSA on agar plates incorporated with different dilutions.
However, no antibacterial activity was observed against E. coli.
Comparatively, upcountry tea samples had a significantly higher inhibitory
activity against MRSA than low country tea. Antibacterial activity of tea
samples against MRSA was further carried out using sequential Soxhlet
extracts of pet-ether, chloroform, ethyl acetate and ethanol of tea samples in
order to investigate which solvent fraction has highest antibacterial activity.
Ethanol and ethyl acetate extracts of the tea samples had higher antibacterial
activity than the other extracts and ethyl acetate extracts showed highest
inhibitory activity against MRSA (at 0.05 probability level). Analysis of
phyto-chemicals of Soxhlet extracts of tea showed that all tea samples were
found to be the same. Aalkaloids, steroids, sterols and triterpenoids, cardiac
glycosides, flavonoids and polyphenols were present in all tea samples
tested, regardless of the geographical region. From the fractions separated,
flavonoids showed considerable inhibitory activity compared to alkaloids
and cardiac glycosides.
