Quality Assessment and Quantitative Analysis of Flavonoids from Tea Samples of Different Origins by HPLC-DAD-ESI-MS

Abstract

Components of green tea ( Camellia sinensis) have been of considerable interest in recent years because of their potential utility as pharmaceutical agents, particularly for their antioxidant and anticarcinogenic activity. Responding to the increasing scientific validation of numerous health benefits of tea, a comprehensive approach was adopted to carry out analysis for the quality assessment of flavonoids in tea samples of different origins. For this purpose, extraction, separation, and mass spectrometric parameters were optimized. Extraction methods evaluated include reflux extraction, a modified accelerated solvent extraction (ASE), namely, Aquasolv extraction, and microwave-assisted extraction (MAE) using different percentages of solvents. Separation was performed by a specifically developed reversed phase high-performance liquid chromatography (RP-HPLC) method using different C18 and C8 stationary phases. Optimization of extraction techniques clearly proved the performance of MAE, which delivered highest yields in a very short time. Additionally, the comparison with Aquasolv extraction provided new insights, as variations in quantified amounts of target compounds between the extracts could be explained on the basis of thermal degradation and epimerization phenomena. Especially the epimerization phenomenon for catechin/epicatechin oligomers, that is, of procyanidins P 2 and P 3, was observed for the first time. Finally, an optimized extraction and separation system was used for qualitative and quantitative investigations of compounds from different green tea samples from Ceylon (cultivated under biologically controlled conditions), Japan, India, and China as well as from one black tea sample from India.

Distribution patterns of polyphenols and alkaloids in instant coffee, soft and energy drinks, and tea

“…In this regard, EGC was the main flavan-3-ol found in most samples; the highest concentration of individual flavan-3-ols was found in sample WT2, which is a blend of tea (white, green, and red tea). The second major compound found in the samples was EGCG in most cases, although it was not possible to determine a clear trend for flavan-3-ols due Sultana et al (2008) in green tea where high concentrations of EGCG and EGC were reported. EGCG levels ranged between 20.3 and 42.6 mg/g and EGC levels between 19.0 and 34.6 mg/g.…”

“…In another study, the main flavan-3-ol occurring in 14 different tea samples was also EGC, where its concentration ranged from 8.0 mg/g to 83.3 mg/g, depending of the type of tea and cultivation site (Lin et al 2003). Altogether, differences in the reported levels can be attributed to variety, cultivation site, processing conditions and to the analytical methodology used for the determination of present phytochemicals; the concentration in the final extract was reported to be different depending on extraction conditions (Sultana et al 2008). Since compounds have different polarity and because they are subjected to different interactions in the sample matrix, one solvent may be effective for the extraction of one class of compounds and need not be effective to others.…”

Quantification of methyl esters of fatty acids in the oil of Physalis minima by GC-MS

“…Qualitative and quantitative evaluation of the chemical constituents is vital for establishing the quality control profile and standardization of herbal extracts [1][2][3][4][5][6]. This makes a base for the investigation of metabolites which have various biological and pharmacological importance [1,4,7,8].…”

Microwave‐assisted water extraction of green tea polyphenols

“…The current interest in the health eff ects of green tea has stimulated the development of new processes for the extraction of the polyphenolic fraction (Gulati et al, 2003;Pan et al, 2003;Sultana et al, 2008). Indeed, the quality of polyphenol extracts and their antioxidant activity depend not only on the quality of the starting material (geographic origin, climatic conditions, harvesting date, storage conditions), but also on the technological processes involved in its manufacture.…”

“…Using microwaves, fully reproducible extractions could be completed in minutes, thereby leading to reduced solvent and energy consumption, simplifi ed manipulation and work-up, higher purity of the fi nal product and eliminating the post-treatment of waste water. Several classes of natural products such as essential oils (Lucchesi et al, 2004), bioactive compounds from herbs (Hao et al, 2002), GTPs and caff eine (Gulati et al, 2003;Pan et al, 2003;Sultana et al, 2008) as well as environmental contaminants (Vidal et al, 2007) have been effi ciently extracted from a variety of matrices.…”