Alantolactone attenuates high-fat diet-induced inflammation and oxidative stress in non-alcoholic fatty liver disease.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a chronic disease with an increasing incidence, which can further develop into liver fibrosis and hepatocellular carcinoma at the end stage. Alantolactone (Ala), a sesquiterpene lactone isolated from Asteraceae, has shown anti-inflammatory effects in different models. However, the therapeutic effect of Ala on NAFLD is not clear. METHODS: C57BL/6 mice were fed a high-fat diet (HFD) to induce NAFLD. After 16 weeks, Ala was administered by gavage to observe its effect on NAFLD. RNA sequencing of liver tissues was performed to investigate the mechanism. In vitro, mouse cell line AML-12 was pretreated with Ala to resist palmitic acid (PA)-induced inflammation, oxidative stress and fibrosis. RESULTS: Ala significantly inhibited inflammation, fibrosis and oxidative stress in HFD-induced mice, as well as PA-induced AML-12 cells. Mechanistic studies showed that the effect of Ala was related to the induction of Nrf2 and the inhibition of NF-κB. Taken together, these findings suggested that Ala exerted a liver protective effect on NAFLD by blocking inflammation and oxidative stress. CONCLUSIONS: The study found that Ala exerted a liver protective effect on NAFLD by blocking inflammation and oxidative stress, suggesting that Ala is an effective therapy for NAFLD.

Candida albicans Infection Disrupts the Metabolism of Vaginal Epithelial Cells and Inhibits Cellular Glycolysis.

Vulvovaginal candidiasis (VVC) is a common gynecologic disorder caused by fungal infections of the vaginal mucosa, with the most common pathogen being Candida albicans (C. albicans). Exploring metabolite changes in the disease process facilitates further discovery of targets for disease treatment. However, studies on the metabolic changes caused by C. albicans are still lacking. In this study, we used C. albicans-infected vaginal epithelial cells to construct an in vitro model of VVC, analyzed the metabolites by UHPLC-Q-Exactive MS, and screened the potential metabolites based on metabolomics. The results showed that C. albicans infection resulted in significant up-regulation of D-arabitol, palmitic acid, adenosine, etc.; significant down-regulation of lactic acid, nicotinamide (NAM), nicotinate (NA), etc.; and disruption of amino acid metabolism, and that these significantly altered metabolites might be potential therapeutic targets of VVC. Further experiments showed that C. albicans infection led to a decrease in glycolytic enzymes in damaged cells, inhibiting glycolysis and leading to significant alterations in glycolytic metabolites. The present study explored the potential metabolites of VVC induced by C. albicans infection based on metabolomics and verified the inhibitory effect of C. albicans on vaginal epithelial cell glycolysis, which is valuable for the diagnosis and treatment of VVC.

Macrophage-specific FGFR1 deletion alleviates high-fat-diet-induced liver inflammation by inhibiting the MAPKs/TNF pathways.

Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disease that is substantially associated with obesity-induced chronic inflammation. Macrophage activation and macrophage-medicated inflammation play crucial roles in the development and progression of NAFLD. Furthermore, fibroblast growth factor receptor 1 (FGFR1) has been shown to be essentially involved in macrophage activation. This study investigated the role of FGFR1 in the NAFLD pathogenesis and indicated that a high-fat diet (HFD) increased p-FGFR1 levels in the mouse liver, which is associated with increased macrophage infiltration. In addition, macrophage-specific FGFR1 knockout or administration of FGFR1 inhibitor markedly protected the liver from HFD-induced lipid accumulation, fibrosis, and inflammatory responses. The mechanistic study showed that macrophage-specific FGFR1 knockout alleviated HFD-induced liver inflammation by suppressing the activation of MAPKs and TNF signaling pathways and reduced fat deposition in hepatocytes, thereby inhibiting the activation of hepatic stellate cells. In conclusion, the results of this research revealed that FGFR1 could protect the liver of HFD-fed mice by inhibiting MAPKs/TNF-mediated inflammatory responses in macrophages. Therefore, FGFR1 can be employed as a target to prevent the development and progression of NAFLD.

Study on the association between the polymorphism of MCP-1 rs1024611 and the genetic susceptibility of type 2 diabetes with sepsis.

Monocyte chemoattractant protein-1 (MCP-1) rs1024611 (-2518 A > G) polymorphism are associated with inflammatory diseases. In this study, we investigate the relationship between MCP-1 rs1024611 polymorphism and genetic susceptibility of type 2 diabetes mellitus (T2DM) with sepsis. Two hundred eighty-five patients with T2DM are divided into the diabetes with sepsis group (combined group, 113 cases) and the diabetes group (172 cases). Blood samples and corresponding clinical data were collected. MCP-1 rs1024611 polymorphism in blood samples was detected by pyrosequencing. Meanwhile, the expressions of MCP-1, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1ß, and IL-6 in blood samples were detected by real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The relationship between different genotypes of MCP-1 rs1024611 polymorphic locus and T2DM with sepsis was analyzed by combining with the clinical data of the patients. The frequencies of rs1024611 AG/GG genotypes and G allele in T2DM with sepsis group were significantly higher than those in T2DM patients without sepsis (P = .004 for AG/GG vs AA genotypes; P = .037 for G allele vs A allele). Subgroup analysis showed that the rs1024611 G allele frequency in the septic shock group was significantly higher than the general sepsis group (P = .02). The expressions of MCP-1 and TNF-α in GG genotypes in T2DM with sepsis group were significantly higher than AA or GA genotypes (P < .05). This study preliminarily showed that the rs1024611 A > G polymorphism within the promoter region of MCP-1 gene can upregulate the expression of MCP-1 gene and proinflammatory cytokine TNF-α, which ultimately contributed to the predisposition and progression of T2DM with sepsis.

Kaempferol attenuates streptozotocin-induced diabetic nephropathy by downregulating TRAF6 expression: The role of TRAF6 in diabetic nephropathy.

ETHNOPHARMACOLOGICAL RELEVANCE: Kaempferia rhizome is a famous traditional herbal medical in tropical and subtropical areas. Kaempferol (KPF) is one of the main bioactive compounds in Kaempferia rhizome, with anti-oxidant/anti-inflammatory effects demonstrated in various disease models, including cancers, obesity and diabetes. AIM OF THE STUDY: Inflammation plays an important role in the pathogenesis of diabetic nephropathy (DN). TRAF6 functions as a signal transducer in toll-like receptor 4 and NF-κB pro-inflammatory signaling pathway. We aimed at investigate whether KPF is able to mitigate inflammatory responses by regulating TRAF6 in DN. MATERIAL AND METHODS: C57BL/6 mice were injected with streptozotocin to induce type 1 DN. NRK-52E, a tubular epithelial cell line, was used for in vitro analysis. TRAF6 was knockdown using siRNA in vitro and AAV2/2-shRNA in vivo. The anti-DN and inflammatory effects of KPF or knockdown of TRAF6 were evaluated by investigating renal filtration index, pathological changes of kidney tissue. Proinflammatory cytokine levels were detected using ELISA. NF-κB pathway and protein levels of related pathways were detected through Western blot. RESULTS: KPF significantly reduced renal inflammation, fibrosis, and kidney dysfunction in diabetic mice. These effects were associated with a downregulation of TRAF6 in diabetic mouse kidneys, indicating the potential role of TRAF6. Knockdown of TRAF6 in mice through AAV2-shTRAF6 confirmed the importance of TRAF6 in DN. In vitro, treatment of KPF in NRK-52E cells attenuated high glucose (HG)-induced inflammatory and fibrogenic responses, associated with downregulated TRAF6 expression. The conclusion was further confirmed in NRK-52E cells by knocking down the expression and by overexpression of TRAF6. CONCLUSION: Our findings provide direct evidence that TRAF6 mediates diabetes-induced inflammation leading to renal dysfunction. We also show that KPF is a potential therapeutic agent to reduce inflammatory responses in DN. Also, TRAF6 may represent an interesting target to combat DN.

Allylated Curcumin Analog CA6 Inhibits TrxR1 and Leads to ROS-Dependent Apoptotic Cell Death in Gastric Cancer Through Akt-FoxO3a.

BACKGROUND: Gastric cancer is one of the leading causes of cancer-related deaths. Allylated monocarbonyl analogs of curcumin (MACs) have been reported to selectively inhibit a broad range of human cancers including gastric cancer. However, the precise molecular mechanisms underlying the inhibitory activities of MACs are not fully known. METHODS: In this study, we examined the anti-tumor activities of an allylated MAC, CA6, on gastric cancer cells and gastric cancer xenograft mouse model. The potential molecular anti-tumor mechanisms of CA6 were also elucidated. RESULTS: Our data show that CA6 exhibited significant cytotoxicity in gastric cancer cells, which was seen as an induction of G2/M cell cycle arrest and apoptosis. These activities were mediated through an elaboration of ROS levels in gastric cancer cells and induction of endoplasmic reticulum stress. CA6 increased ROS levels through directly binding to and inhibiting thioredoxin reductase R1 (TrxR1). Also, CA6-generated ROS inhibited Akt and activated forkhead O3A (FoxO3a), causing cytotoxicity in gastric cancer cells. Finally, CA6 treatment dose-dependently reduced the growth of gastric cancer xenografts in tumor-bearing mice, which was associated with reduced TrxR1 activity and increased ROS in the tumor. CONCLUSION: In summary, our studies demonstrate that CA6 inhibited gastric cancer growth by inhibiting TrxR1 and increasing ROS, which in turn activated FoxO3a through suppressing Akt. CA6 is a potential candidate for the treatment of gastric cancer.

Metabolic changes in primary, secondary, and lipid metabolism in tobacco leaf in response to topping.

As an important cultivation practice used for flue-cured tobacco, topping affects diverse biological processes in the later stages of development and growth. Some studies have focused on using tobacco genes to reflect the physiological changes caused by topping. However, the complex metabolic shifts in the leaf resulting from topping have not yet been investigated in detail. In this study, a comprehensive metabolic profile of primary, secondary, and lipid metabolism in flue-cured tobacco leaf was generated with use of a multiple platform consisting of gas chromatography-mass spectrometry, capillary electrophoresis-mass spectrometry, and liquid chromatography-mass spectrometry/ultraviolet spectroscopy. A total of 367 metabolites were identified and determined. Both principal component analysis and the number of significantly different metabolites indicated that topping had the greatest influence on the upper leaves. During the early stage of topping, great lipid level variations in the upper leaves were observed, and antioxidant defense metabolites were accumulated. This indicated that the topping activated lipid turnover and the antioxidant defense system. At the mature stage, lower levels of senescence-related metabolites and higher levels of secondary metabolites were found in the topped mature leaves. This implied that topping delayed leaf senescence and promoted secondary metabolite accumulation. This study provides a global view of the metabolic perturbation in response to topping. Graphical abstract Metabolic alterations in tobacco leaf in response to topping using a multiplatform metabolomics.

Comprehensive investigation of tobacco leaves during natural early senescence via multi-platform metabolomics analyses.

Senescence is the final stage of leaf growth and development. Many different physiological activities occur during this process. A comprehensive metabolomics analysis of tobacco middle leaves at 5 different developmental stages was implemented through multi-platform methods based on liquid chromatography, capillary electrophoresis and gas chromatography coupled with mass spectrometry. In total, 412 metabolites were identified, including pigments, sterols, lipids, amino acids, polyamines, sugars and secondary metabolites. Dramatic metabolic changes were observed. Firstly, membrane degradation and chlorophyll down-regulation occurred after the 50% flower bud stage. Levels of major membrane lipids decreased, including those of the glycolipids in chloroplast thylakoids and phospholipids in membrane envelopes. Clear decreases in free sterols and acylated sterol glucosides were detected along with the accumulation of sterol esters. The accumulation of alkaloids was found. The amino acid levels were significantly decreased, particularly those of N-rich amino acids (glutamine and asparagine), thus reflecting N translocation. Subsequently, the antioxidant system was activated. Sugar alcohols and polyphenols accumulated when the lower leaves turned yellow. These results comprehensively revealed the metabolic changes that occur during tobacco leaf development and senescence under natural conditions.

Effect of Inhaled Budesonide on Interleukin-4 and Interleukin-6 in Exhaled Breath Condensate of Asthmatic Patients.

BACKGROUND: Studies of interleukin (IL)-4 and IL-6 in the exhaled breath condensate (EBC) of asthmatic patients are limited. This study was to determine the effect of inhaled corticosteroid (ICS) treatment on IL-4 and IL-6 in the EBC of asthmatic patients. METHODS: In a prospective, open-label study, budesonide 200 µg twice daily by dry powder inhaler was administered to 23 adult patients with uncontrolled asthma (mean age 42.7 years) for 12 weeks. Changes in asthma scores, lung function parameters (forced expiratory volume in 1 s [FEV1], peak expiratory flow [PEF], forced expiratory flow at 50% of forced vital capacity [FEF50], forced expiratory flow at 75% of forced vital capacity, maximum mid-expiratory flow rate) and the concentrations of IL-4 and IL-6 in EBC were measured. RESULTS: Both asthma scores and lung function parameters were significantly improved by ICS treatment. The mean IL-4 concentration in the EBC was decreased gradually, from 1.92 ± 0.56 pmol/L before treatment to 1.60 ± 0.36 pmol/L after 8 weeks of treatment (P < 0.05) and 1.54 ± 0.81 pmol/L after 12 weeks of treatment (P < 0.01). However, the IL-6 concentration was not significantly decreased. The change in the IL-4 concentration was correlated with improvements in mean FEV1, PEF and FEF50 values (correlation coefficients -0.468, -0.478, and -0.426, respectively). CONCLUSIONS: The concentration of IL-4 in the EBC of asthmatic patients decreased gradually with ICS treatment. Measurement of IL-4 in EBC could be useful to monitor airway inflammation in asthmatics.

A Novel Strategy for Large-Scale Metabolomics Study by Calibrating Gross and Systematic Errors in Gas Chromatography-Mass Spectrometry.

Metabolomics is increasingly applied to discover and validate metabolite biomarkers and illuminate biological variations. Combination of multiple analytical batches in large-scale and long-term metabolomics is commonly utilized to generate robust metabolomics data, but gross and systematic errors are often observed. The appropriate calibration methods are required before statistical analyses. Here, we develop a novel correction strategy for large-scale and long-term metabolomics study, which could integrate metabolomics data from multiple batches and different instruments by calibrating gross and systematic errors. The gross error calibration method applied various statistical and fitting models of the feature ratios between two adjacent quality control (QC) samples to screen and calibrate outlier variables. Virtual QC of each sample was produced by a linear fitting model of the feature intensities between two neighboring QCs to obtain a correction factor and remove the systematic bias. The suggested method was applied to handle metabolic profiling data of 1197 plant samples in nine batches analyzed by two gas chromatography-mass spectrometry instruments. The method was evaluated by the relative standard deviations of all the detected peaks, the average Pearson correlation coefficients, and Euclidean distance of QCs and non-QC replicates. The results showed the established approach outperforms the commonly used internal standard correction and total intensity signal correction methods, it could be used to integrate the metabolomics data from multiple analytical batches and instruments, and it allows the frequency of QC to one injection of every 20 real samples. The suggested method makes a large amount of metabolomics analysis practicable.

Metabolic Profiling with Gas Chromatography-Mass Spectrometry and Capillary Electrophoresis-Mass Spectrometry Reveals the Carbon-Nitrogen Status of Tobacco Leaves Across Different Planting Areas.

The interaction between carbon (C) and nitrogen (N) metabolism can reflect plant growth status and environmental factors. Little is known regarding the connections between C-N metabolism and growing regions under field conditions. To comprehensively investigate the relationship in mature tobacco leaves, we established metabolomics approaches based on gas chromatography-mass spectrometry (GC-MS) and capillary electrophoresis-time-of-flight-mass spectrometry (CE-TOF-MS). Approximately 240 polar metabolites were determined. Multivariate statistical analysis revealed that the growing region greatly influenced the metabolic profiles of tobacco leaves. A metabolic correlation network and related pathway maps were used to reveal the global overview of the alteration of C-N metabolism across three typical regions. In Yunnan, sugars and tricarboxylic acid (TCA) cycle intermediates were closely correlated with amino acid pools. Henan tobacco leaves showed positive correlation between the pentose phosphate pathway (PPP) intermediates and C-rich secondary metabolism. In Guizhou, the proline and asparagine had significant links with TCA cycle intermediates and urea cycle, and antioxidant accumulation was observed in response to drought. These results demonstrate that combined analytical approaches have great potential to detect polar metabolites and provide information on C-N metabolism related to planting regional characteristics.

A metabolomics study delineating geographical location-associated primary metabolic changes in the leaves of growing tobacco plants by GC-MS and CE-MS.

Ecological conditions and developmental senescence significantly affect the physiological metabolism of plants, yet relatively little is known about the influence of geographical location on dynamic changes in plant leaves during growth. Pseudotargeted gas chromatography-selected ion monitoring-mass spectrometry and capillary electrophoresis-mass spectrometry were used to investigate a time course of the metabolic responses of tobacco leaves to geographical location. Principal component analysis revealed obvious metabolic discrimination between growing districts relative to cultivars. A complex carbon and nitrogen metabolic network was modulated by environmental factors during growth. When the Xuchang and Dali Districts in China were compared, the results indicated that higher rates of photosynthesis, photorespiration and respiration were utilized in Xuchang District to generate the energy and carbon skeletons needed for the biosynthesis of nitrogen-containing metabolites. The increased abundance of defense-associated metabolites generated from the shikimate-phenylpropanoid pathway in Xuchang relative to Dali was implicated in protection against stress.

[Metabolic profiling analysis of amino metabolites in plant extract based on pre-column derivatization-ultra high performance liquid chromatography-mass spectrometry].

Amino metabolites are important compounds that play a key role in plant growth and development. A metabolic profiling analysis method of amino metabolites in plant extract was developed based on pre-column derivatization-ultra high performance liquid chromatography- mass spectrometry. Using the tobacco leaf as an example, a total of 87 amino metabolites, including amino acids, amines, peptides, alkaloids etc. were detected. The repeatability of the method was good with RSDs of 85 amino metabolites between 1. 5% and 18. 8%. Forty-three amino metabolites validated by standard samples showed good linearity with the correlation coefficients of 0.993-0.999, covered linear range of four orders of magnitude. The limits of detection were 0.03-6.58 ng/mL. The intra-day and inter-day precisions were 0.7%-15.6% and 0.8%-22.9%, respectively. The recoveries were 74.4%-122.7%. The influence of topping on metabolic profiling of amino metabolites in fresh tobacco was investigated using the developed method. The results showed that the amino metabolites in the upper tobacco leaves were most affected than those in the middle and lower leaves. Metabolism of amino metabolites in the upper leaves after topping was mainly towards the alkaloid synthesis. The method integrated the advantages of triple quadrupole mass spectrometry and high resolution quadrupole-time of flight mass spectrometry. It can be used for metabolic profiling analysis of amino metabolites in plant extract with high sensitivity and selectivity.

[Analysis of factors associated with decline of FEV1 among community population in urban area of Beijing].

OBJECTIVE: To investigate risk factors correlated to the decline of FEV1among community population in the urban area of Beijing. METHOD: Subjects no younger than 40 years old were recruited from three communities in the urban area of Beijing. All of them were asked to fill in a questionnaire in regard to general health conditions, past medical history, medication usage, smoking history, etc. FEV1and FEV6 were measured by Vitalograph COPD-6 spirometer using the standard protocol. Two years after the first visit, questionnaire survey and spirometry were repeated. RESULT: Four hundred and fifty two subjects fulfilled the inclusion criteria and finished the 2nd visit, with an average age of (58.8 ± 8.6) years, 29% male and 71% female. The mean decline rate of FEV1in the cohort was (43 ± 114) ml per year. There was no significant difference of mean FEV1decline between different gender and age groups. A mean decline of FEV1by (64 ± 125) ml per year was observed in smokers (including former smokers and current smokers) whereas the decline rate in non-smokers was (36 ± 109) ml per year (P = 0.030). There was no significant statistical difference among current smokers, former smokers, passive smokers and subjects who never smoke. A higher decline rate of FEV1was observed in subjects with a history of COPD or airway hyperreactivity, chronic cough, diabetes, hypertension and coronary heart disease. The difference, however, was not statistically significant. Binary logistic regression was used to screen risk factors affected the FEV1decline rate between rapid decline (ΔFEV1 ≥ 30 ml/y) and non-rapid decline (ΔFEV1 < 30 ml/y), and found smoking was an independent risk factor of FEV1decline rate. CONCLUSION: The mean rate of FEV1 decline in 2.6 years in the surveyed community population in the urban area of Beijing was (43 ± 114) ml per year; Smoking is an independent risk factor of FEV1decline.

Lipidome and metabolome analysis of fresh tobacco leaves in different geographical regions using liquid chromatography-mass spectrometry.

The combination of the lipidome and the metabolome can provide much more information in plant metabolomics studies. A method for the simultaneous extraction of the lipidome and the metabolome of fresh tobacco leaves was developed. Method validation was performed on the basis of the optimal ratio of methanol to methyl tert-butyl ether to water (37:45:68) from the design of experiments. Good repeatability was obtained. We found that 92.2% and 91.6% of the peaks for the lipidome and the metabolome were within a relative standard deviation of 20%, accounting for 94.6% and 94.6% of the total abundance, respectively. The intraday and interday precisions were also satisfactory. A total of 230 metabolites, including 129 lipids, were identified. Significant differences were found in lipidomic and metabolomic profiles of fresh tobacco leaves in different geographical regions. Highly unsaturated galactolipids, phosphatidylethanolamines, predominant phosphatidylcholines, most of the polyphenols, amino acids, and polyamines had a higher content in Yunnan province, and low-unsaturation-degree galactolipids, triacylglycerols, glucosylceramides with trihydroxy long-chain bases, acylated sterol glucosides, and some organic acids were more abundant in Henan province. Correlation analysis between differential metabolites and climatic factors indicated the vital importance of temperature. The fatty acid unsaturation degree of galactolipids could be influenced by temperature. Accumulation of polyphenols and decreases in the ratios of stigmasterols to sitosterols and glucosylstigmasterols to glucosylsitosterols were also correlated with lower temperature in Yunnan province. Furthermore, lipids were more sensitive to climatic variations than other metabolites.

Study of metabolite differences of flue-cured tobacco from different regions using a pseudotargeted gas chromatography with mass spectrometry selected-ion monitoring method.

A pseudotargeted method based on gas chromatography and mass spectrometry with selected-ion monitoring was established to investigate the metabolite differences of flue-cured tobacco from three different growing regions. The mixed solvent of acetonitrile/isopropanol/water (3:3:2, v/v/v) was chosen as the optimal extraction system based on the good repeatability and extraction efficiency. A self-developed software coupled with commercial software was used to establish the pseudotargeted method including 289 peaks and 47 groups. Multivariable statistical analysis indicated that tobacco samples can be obviously separated based on the geographical origins. On the basis of a Mann-Whitney U test, organic acids, phenols, and alkaloids had higher levels in Hunan province. In contrast, a large proportion of amino acids (including L-tyrosine, L-proline, and serine), sucrose, and linoleic acid were the highest in Yunnan province. Meanwhile, multiple metabolic pathways (including carbohydrate metabolism, tricarboxylic acid cycle, and nitrogen metabolism) were influenced by growing regions. Twenty-eight differential metabolites, which had great contributions to the classification of tobacco samples of three growing regions, were further defined. The results demonstrated that the developed pseudotargeted method was a powerful tool to investigate the metabolic profiling of tobacco leaves and discriminate tobacco leaves of different growing regions.

[Determination of phenolic compounds in fresh tobacco leaves by high performance liquid chromatography-ultraviolet/mass spectrometry].

Twenty-five phenolic compounds in tobacco were analyzed using high performance liquid chromatography-ultraviolet/mass spectrometry (HPLC-UV/MS), including absolute quantification of 11 main phenols by HPLC-UV and relative quantification of other 14 phenols by SHPLC-MS. The validation results of this method were satisfactory. Eleven phenol standards showed good linearity with correlation coefficients (r2) of 0.999 3 - 0.999 9 over the mass concentration range from 0.90 mg/L to 99.00 mg/L (the range of chlorogenic acid and rutin was from 0.95 mg/L to 380.00 mg/L). The recoveries of the 11 phenol standards were 91.0% - 112.4% with the RSDs of 0.33% - 8.11% at the three spiked levels of 22.5 - 24.8, 45.0 - 49.5 and 67.5 - 74.3 mg/L. The reproducibility of the method was good with the RSDs of 1.48% - 13.40%. In addition, the intra-day and inter-day precisions were also satisfactory with the RSDs of 0.35% - 15.54%. Mature fresh tobacco leaves from Yunnan, Henan and Guizhou Provinces, China were analyzed using this method. The results showed that the total amount of main phenols was Guizhou > Yunnan > Henan and there was significant difference between Guizhou and Henan. The amount of rutin was Yunnan > Guizhou > Henan, and there were significant differences among them each other. The method is reproducible with a simple pretreatment covering a wide range of phenols, and can be applied in batch analysis of tobacco leaves.

Metabolomics study of cured tobacco using liquid chromatography with mass spectrometry: method development and its application in investigating the chemical differences of tobacco from three growing regions.

Cured tobacco is an important plant material. Component studies are a big challenge for its significantly diverse chemical properties and vastly different concentrations. In this work, liquid chromatography with quadrupole time-of-flight mass spectrometry was used to perform a metabolomics study of cured tobacco owing to its efficient separation and detection of semipolar metabolites. A solvent of methanol/water (8:2, v/v) and 30 min of ultrasound time were found to be optimal to perform extraction. 95, 92, and 93% of metabolite features had within 20% of coefficient of variation for repeatability, intraday and interday precision analysis, respectively, indicating a good stability of the method developed. 113 metabolites were identified in cured tobacco based on accurate mass, retention time, and MS/MS fragments. The developed method was applied to a metabolomics study of cured tobacco from three growing regions. Forty three metabolites were found to be contributed to the classification. It is shown that the developed method can be applied to metabolomics analysis of plant materials.

Investigation of the relationship between the metabolic profile of tobacco leaves in different planting regions and climate factors using a pseudotargeted method based on gas chromatography/mass spectrometry.

An improved pseudotargeted method using gas chromatography/mass spectrometry (GC/MS) was developed to investigate the metabolic profile of tobacco leaves from three planting regions (Yunnan, Guizhou, and Henan provinces). The analytical characteristics of the method with regard to reproducibility, precision, linearity, and stability were satisfactory for metabolic profiling study. Partial least-squares-discriminant analysis and hierarchical cluster analysis demonstrated that the metabolic profiles of tobacco from the Yunnan and Guizhou regions were different from that from the Henan province. The amino acid (e.g., phenylalanine, leucine, and tyrosine) and carbohydrate (e.g., fructose, trehalose, and sucrose) contents were the highest in Henan tobacco. The highest contents of organic acids (e.g., isocitrate, citrate, and fumarate) of the TCA cycle and antioxidants (e.g., quinate, chlorogenic acid, and ascorbate) were found in Guizhou tobacco. The correlation coefficients between metabolite content and climate factors (rainfall, sunshine, and temperature) demonstrated that drought facilitated the accumulation of sugars and amino acids. The content of TCA cycle intermediates could be influenced by multiple climate factors. This study demonstrates that the pseudotargeted method with GC/MS is suitable for the investigation of the metabolic profiling of tobacco leaves and the assessment of differential metabolite levels related to the growing regions.

Analysis of free amino acids in flue-cured tobacco leaves using ultra-high performance liquid chromatography with single quadrupole mass spectrometry.

Amino acids are one of the most important metabolites of organisms. They play an important role in plant growth, development, and product quality. A method based on RP ultra-performance LC with single quadrupole MS and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate precolumn derivatization was developed for the analysis of free amino acids in flue-cured tobacco leaves. Unlike the corresponding UV detection method, this method avoids matrix interference of complicated tobacco components, and the quantitative accuracy and resolution were improved. Twenty free amino acids were detected in flue-cured tobacco leaves. The method showed a good linearity with correlation coefficients of 0.9966-0.9998. The LODs for derivatized amino acids were 0.2-9.7 fmol/µL. Good repeatability with an RSD of 2.5-8.6% and satisfactory intra- and interday precisions were obtained. The developed method was used to investigate free amino acids in flue-cured tobacco leaves in China. The effects of aroma type, variety, and growing regions on free amino acids were investigated. The results showed that free amino acids in tobacco were affected by growing regions and varieties.