Pre-concentration of active principles from different varieties of Camellia sinensis extracts by solid sorbents

In this article we studied the phytochemical composition of leaves extracts of different varieties of Camellia sinensis(L.) Kuntze after treatment with 16 selected solid sorbents (namely hydrotalcites, magnesium oxide and hydroxide, zirconium phosphates, and phyllosilicates). The pre-concentration and selective adsorption of the main active principles of this food and medicinal plant [e.g. gallic acid, (-)-epicatechin, (-)-epicatechin gallate, and caffeine] were investigated. The quantities of phytochemicals adsorbed by solids were measured by HPLC analysis, coupled to photodiode array detection and calculated as the difference between the quantities in the parent untreated extracts and those recorded in the filtrates. Caffeine was selectively adsorbed by bentonite to a large extent, while for the remaining phytochemicals different patterns were recorded depending on the type of leaves extract. A comparison with pure chemicals revealed a strong effect of the phytocomplex composition on the adsorption yields. The methodology outlined herein may be useful to obtain tea extracts enriched in selective active principles also for industrial scopes.