EGC reference standard from Sigma-Aldrich Corp. (Product No. E3768) and tea extract.

(a) HPLC chromatogram of EGC reference standard from Sigma-Aldrich Corp.; (b) HPLC chromatogram of green tea extract. Peak identification: (1) L-theanine; (2) (–)-epigallocatechin (EGC); (3) caffeine; (4) (–)-epicatechin (EC); (5) (–)-epigallocatechin gallate (EGCG); (6) (–)-epicatechin gallate (ECG); and (c) ¹H-NMR spectrum, record in CD₃OD at 400 MHz, and with peak suppression of the HOD peak at approximately 4.87 ppm, at 25°C, of supposed EGC (ca. 5 mg/mL) from Sigma-Aldrich Corp. (Product No. E3768).