Abstract:
Some reputed traditional practitioners of Sri Lanka claim that consumption of black tea brew/
infusion (BTB) of Camellia sinensis (L) O. Kuntze (Theaceae) suppresses anxiety. But this claim has not
been scientifically tested and proven. This study therefore investigated the anxiolytic potential of BTB of
Camellia sinensis (with Sri Lankan high grown Dust grade No 1 black tea) in rats using three models of
anxiety (hole-board; neophobia suppression of eating and drinking tests). Different doses of BTB
(equivalent to 1.5, 3, 9, and 24 cups; one cup = 170 mL) or a single (equivalent to 3 cups) of green tea
brew (GTB) of Japanese or Chinese varieties or 2 mL of water were orally administered to different
groups of rats and anxiolytic effects were determined. The results showed that BTB has anxiolytic action
with swift onset (within 1 h) and no accompanying unwanted side effects: muscle relaxation, motor
incoordination, sedation or sleep promotion. The anxiolytic effect of BTB was however inferior to GTB.
Further, decaffetnation of BTB did not impair its anxiolytic action indicating that anxiolysis was not
mediated via caffeine. The anxiolytic action of BTB may be mediated mainly via L-thianine, amino acid
(unique to tea) through GABA-ergic pathways. It is concluded that black tea has mild to moderate oral
anxiolytic activity.
