Abstract:
Ethnopharmcologicol relevance: Sri Lankan tratiitional practitioners recommend the consumption of black
tea infusion (BTI) made from Camellia sinensis L plant for regulation of glycaemia. However, they do not
specify the grade of tea and their origin (i.e., agroclimatic elevation) and as such many prediabetics and
milddiabetics use BOPF grade tea.
Aim of the study: This study examines the blood glucose lowering potential of Sri Lankan BOPF grade tea
and its potency with respect to agroclimatic elevations.
Materials and methods: Unblended orthodox BOPF grade tea samples were collected from high-, midand
low-grown agroclimatic elevations in Sri Lanka. Different concentrations of w a rm BTI (60, 120
and 480mg/ml). tolbutamide {reference drug: 22.5mg/kg body weight) and water (control) were orally
administered to different groups of rats, and hypoglycaemic and antihypergiycaemic activities were
assessed. Antidiabetic activity was determined using streptozotocin induced diabetic rats. Mechanisms
of blood glucose lowering actions were investigated using several standards techniques.
Results: BTI exhibited significant (P<0.05}, dose-dependent and marked hypoglycaemic and antihypergiycaemic
activities w i th quick onset. These effects did not differ w i th respect to agroclimatic elevation,
although there were differences in the content of phyto-constituents. BTI also showed marked and
quick antidiabetic activity. BTI inhibited intestinal glucose absorption and impaired a-glucosidase and
a-amylase activities. BTI possessed insulinomimetic action, ability to improve insulin sensitivity and
in vivo antioxidant activity. Notably. BTI was nontoxic.
CoficJusions.* BT! of Sri Lankan BOPF grade tea has oral hypoglycaemic. antihypergiycaemic and antidiabetic
actions which are mediated via multiple mechanisms. This study also indicates that, BOPF grade tea
of any agroclimatic elevations in Sri Lanka could be used in the regulation of glycaemia.
