Epigallocatechin-3-gallate + L-theanine/β-cyclodextrin inclusion complexes enhance epigallocatechin-3-gallate bioavailability and its lipid-lowering and weight loss effects

Epigallocatechin-3-gallate (EGCG) and L-theanine (LTA), which are active ingredients in green tea, can inhibit fat accumulation; however, EGCG bioavailability is <5%. Here, we aimed to improve EGCG bioavailability and efficacy by preparing EGCG + LTA/β-cyclodextrin (βCD) inclusion complexes by freeze-drying EGCG + LTA at their mass ratio (5:1) in green tea. Physicochemical characterisation revealed that the supramolecular EGCG + LTA/βCD inclusion complexes had distinct crystal structures formed via intermolecular hydrogen bonding. The inclusion complexes prevented simulated EGCG digestion in vitro while increasing its bioaccessibility and antioxidant activity (p < 0.05). In rats fed a high-fat diet, EGCG + LTA/βCD inclusion complexes significantly increased gut microflora diversity and the abundance of lipid metabolism-related genera but decreased the abundance of EGCG catabolism-related genera. Furthermore, the inclusion complexes significantly enhanced the lipid-lowering and weight loss effects of EGCG in vivo (p < 0.05), likely by improving gut microflora and EGCG bioavailability.