Purple tea: chemical characterization and evaluation as inhibitor of pancreatic lipase and fat digestion in mice

Abstract

A variety of the classic green tea plant, Camellia sinensis, was developed and is exclusive to Kenya. Due to high content of anthocyanin polyphenols in its leaves, the beverage obtained from this variety is purple in color and is the origin of the name purple tea. This work had two main purposes. The first one was to identify and quantify the major anthocyanin polyphenols in a hot water aqueous extract of the purple tea leaves. The second one was to test the hypothesis if this extract is capable of inhibiting triglyceride absorption considering that anthocyanin polyphenolics have been frequently associated to antilipidemic effects. Parallel experiments were always done with a similar green tea extract for comparison purposes. The antioxidant, anti-inflammatory, and cytotoxic activities of both tea varieties are similar. The purple tea extract, however, was strongly inhibitory toward the pancreatic lipase (minimal IC₅₀ = 67.4 μg mL⁻¹), whereas the green tea preparation was a weak inhibitor. Triglyceride digestion in mice was inhibited by the purple tea extract starting at 100 mg kg⁻¹ dose and with a well-defined dose dependence. Green tea had no effect on triglyceride digestion at doses up to 500 mg kg⁻¹. The latter effect is probably caused by several components in the purple tea extract including non-anthocyanin and anthocyanin polyphenols, the first ones acting solely via the inhibition of the pancreatic lipase and the latter by inhibiting both the lipase and the transport of free fatty acids from the intestinal lumen into the circulating blood. The results suggest that the regular consumption of Kenyan purple tea can be useful in the control of obesity.