Tannase Treatment of TSA to Obtain Theasinensins B and C

To obtain mass spectrometric information of theasinensin B (TSB, single degalloylation product of TSA) and theasinensin C (TSC, double degalloylation product of TSA), TSA was degallolylated with tannase. A 500 μL aqueous TSA solution (1.0 mmol/L) was incubated with 500 μL tannase (0.15 U/mL, from Aspergillus ficuum, Sigma Aldrich) for 30 min at room temperature. The resulting mixture, containing TSB and TSC, was analyzed by UHPLC-Q-Orbitrap-MS. In addition, to obtain solely TSC, an excess of tannase (900 μL, 0.15 U/mL) was added to an aqueous TSA solution (100 μL, 1.0 mmol/L) for 24 h at room temperature. The resulting solution was used as a TSC standard for identification and quantification.