The effect of green tea formulated with vitamin C and xylitol on intestinal cell transport of gallated and nongallated catechin was studied. The transport of catechins from both apical to basolateral and basolateral to apical directions was measured. The effect of vitamin C (4, 10, 20 ppm), xylitol (11, 27.5, 55 ppm), and combinations of both on the intestinal transport rate of catechins was examined. The efflux value (Pb→a/Pa→b) of (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG), (-)-epicatechin (EC), and (-)-epicatechin gallate (ECG) was 0.26, 0.22, 1.22, and 0.17, respectively, indicating that EC appeared to be less absorbed compared with other catechins. The addition of xylitol (11, 27.5, 55 ppm) and vitamin C (4, 10, 20 ppm) and in combination enhanced transport rate of nongallated catechins such as EC and EGC. For EC, vitamin C was revealed to be the most effective on intestinal transport, implying the inhibition of the efflux transport mechanism of EC. Intestinal transport of gallated catechins significantly increased from catechins formulated with vitamin C and xylitol in a dose-dependent manner compared to the catechin-only formulation. Results provide a potential strategy to enhance the delivery and bioavailability of catechins in humans by modulating green tea formulation with vitamin C and xylitol.

The hypothesis was that green tea catechins (GTCs) formulated with vitamin C and xylitol followed by enteric coating with hydroxypropyl methyl cellulose phthalate (HPMCP) or encapsulated into γ-cyclodextrin (γ-CD) could enhance intestinal absorption of GTCs. Surface morphology and size obtained by SEM were different. Digestive stability of GTCs encapsulated into γ-CD or coated with HPMCP was enhanced up to 65.56% or 57.63%, respectively. When GTCs were formulated, the digestive stability was greater than the one not formulated. Formulated GTCs followed by encapsulation into γ-CD significantly increased intestinal transport. Absorption of GTCs was 2.8%, 9.64%, 11.97%, 8.41% and 14.36% for only GTCs, GTCs encapsulated into γ-CD, formulated GTCs encapsulated into γ-CD, GTCs coated with HPMCP and formulated GTCs coated with HPMCP, respectively. This study suggests that GTCs, formulated with vitamin C and xylitol followed by γ-CD encapsulation or HPMCP enteric coating, provide combinational effect to increase bioavailability of GTCs.

BackgroundThe purpose of this study was to investigate the effect of hydroxypropyl methyl cellulose phthalate (HPMCP) coating on the digestive stability and intestinal transport of green tea catechins (GTCs).MethodsTwo types of HPMCP coating were prepared: one type with size smaller than 500 μm (S-HPMCP) and the other with size larger than 500 μm (L-HPMCP). An in vitro gastrointestinal model system coupled with Caco-2 cells was used for estimating the bioavailability of GTCs. Ultraperformance liquid chromatography with a photodiode array detector was performed to analyze GTCs.ResultsThe digestive stability of GTCs was enhanced up to 33.73% and 35.28% for S-HPMCP and L-HPMCP, respectively. Intestinal transport of the GTCs was increased to 22.98% and 23.23% for S-HPMCP and L-HPMCP, respectively. Overall, the bioavailability of GTCs increased by 4.08 and 11.71 times for S-HPMCP and L-HPMCP, respectively.ConclusionThe results of this study confirm that coating with HPMCP could be a way to improve the digestive stability and intestinal transport of GTCs.

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