SIMULTANEOUS DETERMINATION OF CATECHINS IN HUMAN SALIVA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Green tea extracts have been suggested to possess a preventive effect against dental caries. A quantitative method for their anticariogenic substances, catechins, was developed to evaluate their concentrations in human saliva after mouthrinsing with green tea extract. Salivary ca techins were extracted to the organic phase after forming a complex wi th diphenylborate and an ion-pair with tetra-n-butylammonium, and then back-extracted to the acidic aqueous phase. The extract was analyzed by high-performance liquid chromatography using diode array detection at absorption wavelengths ranging from 269 to 278 nm. In reversed-phas e chromatography by a gradient elution, eight catechins originating fr om green tea and an internal standard were separated in 15 min without interfering peaks. All the catechins were simultaneously and selectiv ely determined in the concentration range 0.05-25.0 mu g/ml. In replic ate spiking experiments with standards, the mean recovery ranged betwe en 86 and 99%, and both intra-and inter-assay C.V.s were within 2.3%. When mouthrinsing with an aqueous solution of green tea extract (5.0 m g/ml) containing eight catechins, the quantitative results revealed th at each catechin was retained at mu g/ml levels in saliva for up to 60 min. (C) 1997 Elsevier Science B.V.