Isolation and analyses of polymeric polyphenol fractions from black tea

Polymeric polyphenols are the most abundant pigments in black tea. Very limited information is available on the isolation and chemical characterization of these compounds. The present paper reports the comparative yields, physicochemical properties and preliminary biological activities of five polymeric black tea polyphenol (PBP) fractions isolated by liquid–liquid and Soxhlet-based solid (tea powder)–liquid extraction methods. The two methods have also been comparatively evaluated as regards cost, time, labour and practicality of scale-up. Overall, results show that PBP fractions, isolated by both the procedures, were free of other known biologically active monomeric and oligomeric components, and have similar physicochemical properties and biological effect(s). Solid–liquid extraction results in a relatively greater yield of PBP-1 to -3, significant reduction in cost, time and labour and also makes scale-up relatively easier.