Sri Lankan orange pekoe grade black tea impairs anxiety

Abstract

There is an unmet need for the development of new herbal pharmaceuticals as anxiolytics. In this context, the present study, investigated the anxiolytic potential of warm black tea brew/ infusion (BTB) of Sri Lankan low grown orthodox Orange Pekoe (O.P.) grade tea made from Camellia sinensis (L) O. Kruntz (Theaceae). This was tested in rats using three models of anxiety (hole-board, neophobic suppression of eating and drinking tests). Different doses [223 mg/kg (equivalent to 1.5 cups), 446 mg/kg (equivalent to 3 cups) and 1339 mg/kg (equivalent to 9 cups)] or water was orally administered to rats (N = 6-10/group) and anxiolytic effects were determined after 1h. The results showed that BTB possesses dose-dependent anxiolytic action with quick onset (1h). This anxiolytic action of BTB was not accompanied with undesirable side effects: muscle relaxation, motor in co-ordination or sedation. In addition, BTB produced no overt signs of toxicity. BTB induced significant increase in the number of entries, time spent in open arms, % open arm entries and % time on open arms and reduced the time spent in closed arms when tested in elevated plus maze model. This suggest that main mode of anxiolytic action of BTB is GABAergic. It is also suggested that, serotoninergic and dopaminergic mechanisms also play a part in mediating anxiolytic action. It is concluded that, O.P. grade Sri Lankan black tea has oral anxiolytic action as claimed in Sri Lankan traditional medicine and consumption of at least 3 cups of BTB may be useful to impair ‘day to day’ anxiety.