Page 16 - Pharmacognosy-I (02-06-06-102)

8. Medicinal leaves affect central nervous system:

TEA LEAVES

Tea is the dried prepared leaves and leaf buds of Camellia sinensis
family Theaceae.

Black tea is prepared by allowing the leaves to be oxidized (by
slowly drying and fermentation of fresh leaves). During this
process, oxidase enzyme present in the tea converts many of the
polyphenolic therapeutic substances to less active compounds
(oxidase enzyme converts the phlobatannins into reddish brown
phlobaphene and as a result, the green color of the leaves changed
into red).

Green Tea is a type of tea that undergone minimal oxidation
during processing. Green Tea is prepared by steaming the fresh-cut
leaf over a mild artificial heat. This process destroys thease
enzyme, therefore oxidation of tannins does not occur with Green
Tea and the leaves retain their green color. The anti-oxidant activity
of Green Tea is six times greater than that of Black Tea.

Constituents:
1. Tea leaves contain 1.00-5.00% total alkaloids; caffeine and
traces of theobromine and theophylline.
2. Polyphenols (green tea with higher amount); mainly tannins and
phenolic carboxylic acids, gallic and chlorogenic acids.
3. It also contains triterpenoid saponins.
(Caffeine is partly combined with tannin. This combination is
decomposed by water during the process of fermentation, leading
to the liberation of free caffeine and its percentage will increase).
Uses:
1. It serves as CNS stimulant, mild astringent and diuretic.
2. green tea has potent antioxidant and anti-cancer properties.
3. Drinking green tea lowers total cholesterol level and is useful for
weight loss management.

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