Establishment of anthocyanin fingerprint in black wolfberry fruit for quality and geographical origin identification

Black wolfberries (Lycium ruthenicum Murray) establish various biological activities, owing to anthocyanins, polysaccharides, pectin and so on. However, minor appearance differences are found in black wolfberries from different geographical origins. Thus, in this study, total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) were determined in black wolfberries from four provinces in China (Xinjiang, Qinghai, Gansu, Ningxia Provinces) for obtaining a distinguishable chemical index. Compared with TPC and TFC, TAC largely was affected by environment conditions, and thus, it may be a good chemical marker for geographical origin identification. Then, anthocyanin profiles were analysed by ultra-performance liquid chromatography (UPLC) coupled with triple quadrupole (triple Q)-time-of-flight mass spectrometry (TOF-MS), and principal component analysis (PCA) was applied for geographical origin identification based on anthocyanin fingerprints. A total of 17 anthocyanins were tentatively determined including two new individual anthocyanins, delphinidin-3-rutinoside (cis-p-coumaroyl)-5-O-diglucoside and delphinidin-3-rutinoside (trans-p-coumaroyl)-5-O-diglucoside. PCA indicated that individual anthocyanin contents calculated according to HPLC data and raw HPLC data both allowed a clear separation of geographical origins of black wolfberry fruits, explaining more than 95% of information of the samples. The present study could provide a scientific guidance for distinguishing the black wolfberry from different geographical origins.