Proceedings of the Wayamba University International Conference, Sri Lanka, 29 - 30 August 2014

ANTIBACTERIAL PROPERTIES OF SELECTED BLACK TEA GRADES GROWN IN

THREE DIFFERENT ELEVATIONS OF SRI LANKA

W.J.S.K. Weerakkody1 D.C. Abeysinghel and W.V.T.D. Amarasinghe2

' Department of Plantation Management, Faculty of Agriculture and Plantation Management,

Wayamba University of Sri Lanka, Makandura, Gonawila (NWP), Sri Lanka; 'Regional Office,

State Timber Corporation, Nuwara Eliya, Sri Lanka

Corresponding author: abeysinghedcayahoo.com

The increase in frequency of drug resistance has discouraged the development of new

synthetic antimicrobial drugs. Natural compounds are a source of various therapeutic

agents. Fresh tea leaves are rich in polyphenols and well conducted systematic studies

could demonstrate clear antimicrobial effect of tea. Sri Lanka plays a vital role in the global

orthodox black tea market as a producer and an exporter. Tea cultivated areas are

distinguished into three elevations as high grown, medium grown and low grown. This

systematic study focused to evaluate the variation of antibacterial properties of Sri Lankan

tea grades from different growing regions. Methanol extracts of 109 samples of selected

tea grades of low grown and mid grown; Flowery Broken Orange Pekoe Fannings

(FBOPF), Flowery Broken Orange Pekoe (FBOP), Orange Pekoe (OP), Orange Pekoe A

(OPA) and selected tea grades of high grown; Broken Orange Peko (BOP), Broken

Orange Peko Fannings (BOPF) and Dust No. 1 were tested against different bacteria;

Staphylococcus aureus, Bacillus cereus, Escherichia co li, Salmonella typhi, Vibrio

parahaemolyticus, Vibrio cholerae by means of zone of inhibition, using agar well

diffusion assay. The antibacterial activity of tea grades were compared with three

standard antibiotics namely Tetracycline, Ampicillin and Penicillin. Antibacterial

properties did not vary based on grades for low grown (p = 0.08 at 0.05 significant level)

and mid grown (p = 0.08 at 0.05 significant level), but varied based on factory and some

bacterial species (S. aureus, B. cereus and V. cholerae). The tea of high grown area

recorded significant variation based on grade, factory and species (S. aureus, B. cereus,

V. cholera and S. typhi). BOP showed the highest antibacterial properties (9.22 mm). The

most susceptible species for tested tea from all three elevations was S. aureus whereas

any of the tested tea did not show a significant effect on E. coli and V.

parahaemolyticus. Although tea grades of low grown and mid grown did not record

clear inhibition on S. typhi, significant inhibition could be observed for high grown tea

grades on S. typhi. When compared with three standard antibiotics used all tea grades

showed higher antibacterial properties than Ampicillin and Penicillin. Tetracycline

recorded higher inhibition on the bacterial species than all tea grades. Further studies are

necessary to explore the variations of antibacterial properties on grades, species and

factories.

Authors wish to acknowledge National Agricultural Research Plan (NARP) of the

National Agricultural Research System of Sri Lanka 2011-2013 for providing grants to conduct the

research project.

Keywords: Antibacterial properties, Black tea, Elevations, Tea grades