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Extraction of tannins from tea:

Weigh for about 0.5g of tea and transfer it into conical flask containing 75ml of water.
Heat the flask gently for 30 minutes, centrifuge the boiled extract at 2000rpm for 20

minutes. Collect the supernatant and add it to 100 ml conical flask and make up the volume.
Transfer the 1ml of sample extract to 100ml flask containing 75ml water. Add about 5ml of

Folin- Denis reagent, 10ml sodium carbonate solution and dilute to 100ml with water and
shaken well. Read the absorbance at 700nm after 30 minutes of incubation. Blank was

made by adding water instead of sample (V. Saxena et al., 2013).

Procedure for quantitative estimation of flavonoids.
A stock of quercetin of 100µg/ml concentration was prepared by adding 10mg of quercetin

to 100ml of methanol in a standard flask. This was used as the standard solution of quercitin.

From this stock solution of quercetin, different concentrations were prepared using methanol.
To each of the sample dilutions made, added 1.5ml methanol, 0.1ml of aluminium

chloride solution, 0.1ml of potassium acetate solution and 2.8ml of distilled water. This
solution was mixed well and absorbance was taken at 415nm after 30 minutes of incubation.

Extraction of flavonoids from tea:
Sample was ground with mortar and pestle in 80% ethanol. The extract was filtered using

Whatman filter paper. The volume was made up to 5ml. Aliquots of 0.5ml extract was taken

and made up the volume to 3ml using methanol. To this 0.1ml of aluminium chloride
(10%),

0.1ml of potassium acetate solution and 2.8ml of distilled water was added and shaken
gently. Absorbance was taken at 415nm after the incubation for 30 minutes.

RESULTS

Antibacterial activity

Antibacterial activity of the tea extracts were studied by agar well diffusion method. It was
observed that the zone of inhibition increased as the concentration of ethanol extract of green

tea was increasing. Maximum zone of inhibition was shown at the concentration of 0.5%
against all 4 bacterial strains (Figure 1). The maximum zone of inhibition was

exhibited against P. aeruginosa in all percentages. And the least inhibition was exhibited
against E.coli. E.coli and K. pneumoniae almost showed the same inhibition of about

(1.3cm, 1.35cm) at

0.5%.

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