Characterization and Quantitation of Anthocyanins of the Pigmented Tea Cultivar TRI 2043 (Camellia sinensis L.) from Sri Lanka

Abstract

Tea leaves are rich in diverse bioactive compounds. The tea accession TRI 2043 is unique due to its pigmented leaves caused by anthocyanins, clonal origin, resistance to blister blight disease, and high pubescence density. Because of its peculiarity, TRI 2043 is used to produce high-quality silver tip tea, a premium type of tea that commands high prices. This study was carried out to clarify and elucidate the types of anthocyanins in this particular accession. Four different anthocyanin species were identified and quantitated as cyanidin-3-O-β-d-galactoside and delphinidin-3-O-β-d-galactoside equivalents for leaf blades and stems of the cultivar TRI 2043. The characterization was performed by comparison with commercially available reference substances and further confirmed using ion mobility high-resolution time-of-flight-mass spectrometry (IMS-HRTOF-MS). Quantitation was carried out using ultra-high-performance liquid chromatography ultraviolet–visible detection (UHPLC-UV-vis) with cyanidin-3-O-β-d-glucoside as an internal standard. E- and Z-geometric isomers of 6-p-coumaroyl derivates of delphinidin and cyanidin-3-O-β-d-galactopyranosides were observed, and collision cross section (CCS) values were determined for all four different anthocyanidin species. The content of anthocyanins in leaf blades of cultivar TRI 2043 was 856.32 ± 41.56 µg/g dry weight, with cyanidin being the more abundant anthocyanin (69.8%). Conversely, the stem material contained an anthocyanin amount of 459.5 ± 44.7 µg/g dry weight, with a higher content of delphinidin (69.6%). In summary, an enrichment strategy using analytical membrane chromatography was established to fully elucidate and quantify the anthocyanin profile of plant samples such as the special tea variety TRI 2043.