ABSTRACT
Recently, 9,10-anthraquinone (AQ) contamination in Chinese Liupao tea has attracted much attention because the tea for export must meet the EU limit (10 µg kg-1). In this study, a method was developed in which the sample was extracted with n-hexane-acetone solution, then purified with Florisil adsorbent, detected by GC-MS/MS and contamination levels of AQ determined using an internal standard. This method was found to be more suitable for Liupao tea and other dark tea complex substrates than the QuEChERS procedure. The sample pre-treatment method was optimized with respect to extraction reagent and clean-up column adsorbent and n-hexane-acetone selected as the optimal extraction solvent. When the content of Florisil in the column was 1.0 g, the optimum clean-up was achieved. The new method reduced the limit of quantification (LOQ) of AQ to 10 µg kg-1, and accuracy was also further improved. The recovery of AQ-fortified tea samples containing 20-100 µg·kg-1 was 94.5-100.4%, and the relative standard deviation (RSD) was less than 1.3%. In a small survey, 98 Liupao tea samples on the market were tested by the new method. It was found that 61 samples were positive (occurrence rate 63.3%), and thus exceeded the EU limit (10 µg kg-1). This study also found that the contamination of AQ in Liupao tea increased with the length of ageing. The source of AQ in the Liupao tea ageing process will be the focus of further research.
Subject(s)
Camellia sinensis , Tandem Mass Spectrometry , Tea , Acetone , Camellia sinensis/chemistry , Tandem Mass Spectrometry/methods , Tea/chemistry , China , Food Contamination , Food Handling , AdsorptionABSTRACT
Tea plant (Camellia sinensis) is a typical fluoride (F) hyperaccumulator enriching most F in old leaves. There is association between the risk of fluorosis and excessive consumption of teas prepared using the old leaves. It is meaningful to develop methods for controlling F levels in tea leaves. We generated a comprehensive RNA-seq dataset from tea plants grown at various F levels for different durations by hydroponics, aiming at providing information on mechanism of F metabolism in tea plant. Besides raw reads of the RNA-seq dataset, we present assembled unigenes and aligned unigenes with annotations versus the Gene Ontology (GO) databases, Kyoto Encyclopaedia of Genes and Genomes (KEGG) databases, and Nonredundant (Nr) protein databases with low e-values. 69,488 unigenes were obtained in total, in which 40,894 were given Nr annotations.
Subject(s)
Camellia sinensis/genetics , RNA, Plant , Sequence Analysis, RNA , Transcriptome , Camellia sinensis/chemistry , Fluorides , Fluorine/chemistryABSTRACT
Tea plant is a typical fluorine (F) accumulator. F concentration in mature tea leaves is several hundred times higher than that in normal field crops. Long-term consumption of teas with high level F will increase the risks of dental and skeletal fluorosis. The mechanism of F accumulation in tea stands unclear. RNA-Seq and digital gene expression (DGE) techniques were used to investigate the effect of F on the differential expressions of transcriptome in tea plant. The results showed that F content in mature tea leaves was increased with increase in F concentration of cultural solution and duration of F treatment time. Based on comparison with data of GO, COG, KEGG and Nr databases, 144 differentially expressed unigenes with definite annotation were identified. Real-time reverse transcription PCR (qRT-PCR) was used to validate the effect of F on expression of 5 unigenes screened from the 144 unigenes. F treatment induced the expression of defense genes such as receptor-like kinases (RLKs) and U-box domain-containing protein. Based on the present study, F uptake is considered to be related to calcium-transporting ATPase, especially autoinhibited Ca2+ ATPase (ACAs) which was activated by the RLKs and worked as a carrier in uptake of F by tea plant.
Subject(s)
Camellia sinensis/genetics , Fluorides/pharmacology , Gene Expression Regulation, Plant/drug effects , Camellia sinensis/metabolism , Computational Biology/methods , Gene Expression Profiling , Gene Ontology , High-Throughput Nucleotide Sequencing , Molecular Sequence Annotation , Plant Leaves/genetics , Reproducibility of Results , Tea/genetics , TranscriptomeABSTRACT
Diabetes mellitus (DM) is a chronic endocrine disease resulted from insulin secretory defect or insulin resistance and it is a leading cause of death around the world. The care of DM patients consumes a huge budget due to the high frequency of consultations and long hospitalizations, making DM a serious threat to both human health and global economies. Tea contains abundant polyphenols and caffeine which showed antidiabetic activity, so the development of antidiabetic medications from tea and its extracts is increasingly receiving attention. However, the results claiming an association between tea consumption and reduced DM risk are inconsistent. The advances in the epidemiologic evidence and the underlying antidiabetic mechanisms of tea are reviewed in this paper. The inconsistent results and the possible causes behind them are also discussed.