UPLC-Orbitrap-MS/MS combined with chemometrics establishes variations in chemical components in green tea from Yunnan and Hunan origins.

Multi-components of green tea from different origins were identified by UPLC-Orbitrap-MS/MS, including alkaloids, amino acids, catechins, flavones, flavone glycosides, phenolic acids and theaflavins. Quantitative chemical profiles of 72 samples of Yunnan green tea (YGT) and Hunan green tea (HGT) established the influence of origin on green tea. In addition, three variable selection methods, based on partial least squares-discriminant analysis (PLS-DA), were employed to screen characteristic components of YGT and HGT. The results of variable importance on projection (VIP) method showed better performance than coefficients ß and the least absolute shrinkage and selection operator (LASSO) for this dataset. Three characteristic components, named, gallocatechin gallate (GCG), epicatechin-(4ß → 8)-epigallocatechin-3-O-gallate, and vitexin were selected by VIP, with a correct rate of 98.61% and an AUC value of 0.9706. The results indicated that the combination of UPLC-Orbitrap-MS/MS and chemometrics could serve as a valid strategy to analyze complex analytical objects, such as green tea.

Comprehensive characterization and identification of antioxidants in Folium Artemisiae Argyi using high-resolution tandem mass spectrometry.

Antioxidants from natural sources, such as vegetables and fruits, are attracting more and more interest. In this work, we evaluated the antioxidant potential of Folium Artemisia Argyi, a traditional Chinese herb medicine and food supplement. The total phenolic content, total flavonoid content, and antioxidant ability of the crude extracts and fractions obtained from consecutively partition of n-hexane, ethyl acetate, and n-butanol were measured and compared. Ethyl acetate fraction shows the highest total phenolic and flavonoid contents and highest antioxidant capability with regard to DPPH, ABTS, superoxide anion free radical scavenging ability, and ferric-reducing antioxidant power. In addition, the potential antioxidant components were screened by DPPH-UHPLC-MS experiments and subsequently characterized by using high-resolution tandem mass spectrometry. This work finally identified 45 antioxidants, including organic acids, phenolic compounds, flavonoids, and methoxylated flavonoids. The results suggested that Folium Artemisiae Argyi is a potential inexpensive resource of natural antioxidants.

Combined application of chromatographic techniques for the separation of phenolic compounds from Stenoloma chusanum Ching.

High-speed countercurrent chromatography combined with preparative high-performance liquid chromatography was successfully used to separate seven phenolic compounds from Stenoloma chusanum Ching. A biphasic solvent system composed of hexane/ethyl acetate/methanol/water (1:2:1:2, v/v) was used for the first step high-speed countercurrent chromatography separation in elution-extrusion mode. A mobile phase composed of acetonitrile (18%) and pure water (82%) was used for further preparative high-performance liquid chromatography purification. In total, the combined separation yielded seven compounds, including 3,4-dihydroxy benzoic acid, 3,4-dihydroxy benzaldehyde, esculetin, caffeic acid, syringic acid, luteolin, and apigenin, at a purity of over 90%. Esculetin was separated from Stenoloma chusanum Ching for the first time. The results suggest that the proposed combination method is a useful strategy for separating compounds from complex samples.