Study on the correlation between the dominant microflora and the main flavor substances in the fermentation process of cigar tobacco leaves.

The flavor of cigar tobacco leaf determines the quality of finished cigar tobacco, and the enhancement of flavor generally relies on microbial fermentation. In this paper, the correlation between the dominant microorganisms and the main flavor substances of cigar tobacco leaves during fermentation and the correlation between the two were investigated to reveal the correlation between microorganisms and flavor and the metabolic pathways of microorganisms affecting the flavor substances. During the fermentation process, the main flavors of cigar tobacco leaves were sweet, light and grassy, with hexanal, 2,6-dimethylpyridine, nonanal, phenylacetaldehyde, naphthalene, and methyl benzoate as the main constituents, and the key microorganisms Haloferax mediterranei, Haloterrigena limicola, Candidatus Thorarchaeota archaeon SMTZ-45, the genera Methyloversatilis, Sphingomonas, Thauera, Pseudomonas, Penicillium, and Aspergillus. Correlation analysis revealed that fungi were negatively correlated with the main aroma and inhibited the main flavor substances, while bacteria were positively correlated with Benzoic acid, methyl ester in the main flavor substances, which was conducive to the accumulation of green aroma. Functional analysis revealed that the dominant bacterial population was producing aroma by metabolizing glycoside hydrolases and glycosyltransferases, performing amino acid metabolism, carbohydrate metabolism and film transport metabolism. The present study showed that the bacterial and fungal dominant microorganisms during the fermentation of cigar tobacco were influencing the production and degradation of the main flavor substances through the enzyme metabolism by the occurrence of the Merad reaction.

Changes in volatile profile and related gene expression during senescence of tobacco leaves.

BACKGROUND: Volatile organic compounds are critical for food flavor and play important roles in plant-plant interactions and plants' communications with the environment. Tobacco is well-studied for secondary metabolism and most of the typical flavor substances in tobacco leaves are generated at the mature stage of leaf development. However, the changes in volatiles during leaf senescence are rarely studied. RESULTS: The volatile composition of tobacco leaves at different stages of senescence was characterized for the first time. Comparative volatile profiling of tobacco leaves at different stages was performed using solid-phase microextraction coupled with gas chromatography/mass spectrometry. In total, 45 volatile compounds were identified and quantified, including terpenoids, green leaf volatiles (GLVs), phenylpropanoids, Maillard reaction products, esters, and alkanes. Most of the volatile compounds showed differential accumulation during leaf senescence. Some terpenoids, including neophytadiene, ß-springene, and 6-methyl-5-hepten-2-one, increased significantly with the progress of leaf senescence. Hexanal and phenylacetaldehyde also showed increased accumulation in leaves during senescence. The results from gene expression profiling indicated that genes involved in metabolism of terpenoids, phenylpropanoids, and GLVs were differentially expressed during leaf yellowing. CONCLUSION: Dynamic changes in volatile compounds during tobacco leaf senescence are observed and the integration of gene-metabolites datasets offers important readouts for the genetic control of volatile production during the process of leaf senescence. © 2023 Society of Chemical Industry.

Antagonistic Activity of Volatile Organic Compounds Produced by Acid-Tolerant Pseudomonas protegens CLP-6 as Biological Fumigants To Control Tobacco Bacterial Wilt Caused by Ralstonia solanacearum.

Tobacco bacterial wilt, which is caused by Ralstonia solanacearum, is a devastating soilborne disease of tobacco worldwide and is widespread in the continuously acidic fields of southern China. Here, the fumigation activity under different pH conditions, component identification, and bioactivity of the volatile organic compounds (VOCs) produced by an acid-tolerant strain, Pseudomonas protegens CLP-6, were investigated. There was a wide antimicrobial spectrum of the VOCs against phytopathogens, including four bacteria, eight fungi, and two oomycetes. The antagonistic activity of the VOCs against R. solanacearum was proportionally correlated with the concentration of the inoculum, amount, culture time, and culture pH for CLP-6. The number of gene copies of R. solanacearum was significantly inhibited by VOCs produced at pH 5.5 in vivo. The control effect of VOCs emitted at pH 5.5 was 78.91% for tobacco bacterial wilt, which was >3-fold greater than that at pH 7.0. Finally, the main volatile compounds were identified by solid-phase microextraction (SPME)-gas chromatography-mass spectroscopy (GC-MS) as S-methyl thioacetate, methyl thiocyanate, methyl disulfide, 1-decene, 2-ethylhexanol, 1,4-undecadiene, 1-undecene, 1,3-benzothiazole, and 2,5-dimethylpyrazine, and the inhibition rates of 1,3-benzothiazole, 2-ethylhexanolmethyl thiocyanate, dimethyl disulfide, and S-methyl thioacetate were 100%, 100%, 88.91%, 67.64%, and 53.29%, respectively. S-Methyl thioacetate was detected only at pH 5.5. In summary, VOCs produced by P. protegens CLP-6 had strong antagonistic activities against phytopathogens, especially R. solanacearum, under acidic conditions and could be used to develop a safe and additive fumigant against R. solanacearum on tobacco and even other Solanaceae crop bacterial wilt diseases in acidic fields. IMPORTANCE VOCs produced by beneficial bacteria penetrate the rhizosphere to inhibit the growth of plant-pathogenic microorganisms; thus, they have the potential to be used as biological agents in controlling plant diseases. Tobacco bacterial wilt, which is caused by the acidophilic pathogen R. solanacearum, is a major bacterial disease in southern China and is prevalent in acidic soil. In this study, we discovered that the VOCs produced by P. protegens CLP-6 had excellent inhibitory effects on important plant pathogens. Moreover, two of the VOCs, namely, 1,3-benzothiazole and 2-ethylhexanol, had excellent inhibitory effect on R. solanacearum, and another VOC substance, methyl thiocyanate, was produced only at pH 5.5. The VOCs produced by the acid-tolerant strain P. protegens CLP-6 may have potential as environment-friendly microbial fumigant agents for bacterial wilt of tobacco or even other Solanaceae crops in acidic soils in China.

Exercise serum regulates uric acid transporters in normal rat kidney cells.

Hyperuricemia (HUA) refers to a physiological condition of high serum uric acid (SUA) level in the body, which may cause an increased risk of several chronic diseases. The kidney's impaired uric acid (UA) metabolism is an important reason for HUA. In this study, we tested the hypothesis that circulating factors produced during exercise regulate the expression of ABCC4, ABCG2, URAT1, and GLUT9 in normal rat kidneys and normal rat kidney cells (NRK-52E) and their relationship with NF-κB and NRF-2. NRK-52E cells were separately cultured by serum from 10 healthy SD rats who did not exercise (CON) and 10 healthy SD rats who did aerobic treadmill exercise for 6 weeks. Cells cultured by serum from rats who did aerobic treadmill exercise for 6 weeks were separated by without NRF-2 inhibitor (EXE) and with NRF-2 inhibitor (EXE + ML). SUA level of rats was tested by using dry chemical assays, xanthine oxidase (XOD) activity in serum and liver were tested by using enzyme colorimetry assays, protein expression in kidney and NRK-52E cells were tested by using Western-blot, and UA levels in the upper or lower chamber were tested by colorimetry assays. Aerobic exercise reduced SUA levels in rats but did not significantly affect on liver xanthine oxidase. It also increased the expression of some UA transporters in the kidney and NRK-52E cells and increased the cells' ability in UA excretion. When the NRF-2 was inhibited, the NF-κB and ABCG2 increased, and the expression of ABCC4, URAT1, and GLUT9 decreased. In conclusion, this study suggested that 6 weeks of aerobic treadmill exercise intervention may help to improve the excretion of UA in renal cells, suggesting that long-term aerobic exercise may be a means to prevent hyperuricemia.

[Protective effects of Lycium ruthenicum Murr. juice on alcoholic liver injury in rats].

Objective: To study the protective effects of Lycium ruthenicum Murr. juice on alcoholic liver injury in rats and explore the regulatory mechanism of toll-like receptors 4 (TLR4)/p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway in this process. Methods: Sixty male SD rats were randomly divided into control group (C), model group (M), low-dose Lycium ruthenicum Murr. juice group (LLM), medium-dose Lycium ruthenicum Murr. juice group (MLM) and high-dose Lycium ruthenicum Murr. juice group (HLM), 12 rats in each group. The group M, LLM, MLM and HLM were treated with 20 ml/kg (8 g/(kg·d)) ethanol (400 g/L) intragastrically and the gavage was divided into two sessions, group C was treated with an equal volume of distilled water at the same time point. Four hours before the first alcohol gavage session, rats in each dose group of Lycium ruthenicum Murr. juice were administered with 2.4, 4.8, 9.6 ml/(kg·d) Lycium ruthenicum Murr. juice respectively, and the other groups were given equal volume of distilled water at the corresponding time points. Four weeks later, the rats were sacrificed 24 hours after the end of the last experiment, blood and liver were collected. The liver index was calculated. The morphology of the liver was observed by HE staining. The expressions of hepatic TLR4, p38 MAPK and phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) were detected by immunohistochemistry. The activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were detected by colorimetry. The levels of hepatic tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-10 (IL-10) and interleukin-18 (IL-18) were detected by enzyme linked immunosorbent assay. Results: Compared with group C, the alcoholic liver injury model was established successfully in Group M. Compared with group M, related indicators in each dose group of Lycium ruthenicum Murr. juice were improved, the improvement of hepatic morphology in group HLM was the most significant, the liver index, the levels of serum ALT, AST and hepatic TLR4, p38 MAPK/p-p38 MAPK ratio, TNF-α, IL-1ß, IL-18 were decreased (P＜ 0.05 or P＜0.01), while the level of hepatic IL-10 was increased (P＜0.01). Comparison among the dose groups of Lycium ruthenicum Murr. juice, the levels of liver index, serum AST and hepatic TLR4, p38 MAPK/p-p38 MAPK ratio, TNF-α, IL-18 in HLM were lower than those in LLM (P＜0.05 or P＜0.01); the level of hepatic IL-10 in HLM was higher than that in LLM and MLM (P＜0.05 or P＜0.01); the other indicators in each dose group had no statistical difference (P＞0.05). Conclusion: Lycium ruthenicum Murr. juice can improve the inflammatory stress by regulating TLR4/p38 MAPK signaling pathway, relieve alcoholic liver injury in rats, and the effect of high-dose group is better than the others.

Biocontrol potential of Bacillus velezensis EM-1 associated with suppressive rhizosphere soil microbes against tobacco bacterial wilt.

Tobacco bacterial wilt caused by Ralstonia solanacearum is one of the most devastating diseases. Microbial keystone taxa were proposed as promising targets in plant disease control. In this study, we obtained an antagonistic Bacillus isolate EM-1 from bacterial wilt-suppressive soil, and it was considered rhizosphere-resident bacteria based on high (100%) 16S rRNA gene similarity to sequences derived from high-throughput amplicon sequencing. According to 16S rRNA gene sequencing and MLSA, strain EM-1 was identified as Bacillus velezensis. This strain could inhibit the growth of R. solanacearum, reduce the colonization of R. solanacearum in tobacco roots, and decrease the incidence of bacterial wilt disease. In addition, strain EM-1 also showed a strong inhibitory effect on other phytopathogens, such as Alternaria alternata and Phytophthora nicotianae, indicating a wide antagonistic spectrum. The antimicrobial ability of EM-1 can be attributed to its volatile, lipopeptide and polyketide metabolites. Iturin A (C14, C15, and C16) was the main lipopeptide, and macrolactin A and macrolactin W were the main polyketides in the fermentation broth of EM-1, while heptanone and its derivatives were dominant among the volatile organic compounds. Among them, heptanones and macrolactins, but not iturins, might be the main potential antibacterial substances. Complete genome sequencing was performed, and the biosynthetic gene clusters responsible for iturin A and macrolactin were identified. Moreover, strain EM-1 can also induce plant resistance by increasing the activity of CAT and PPO in tobacco. These results indicated that EM-1 can serve as a biocontrol Bacillus strain for tobacco bacterial wilt control. This study provides a better insight into the strategy of exploring biocontrol agent based on rhizosphere microbiome.

Effects of a vegetarian diet combined with exercise on lipid profiles and blood pressure: A systematic review and meta-analysis.

We aimed to evaluate the combined effects of a vegetarian diet (VD) and exercise on total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), systolic blood pressure (SBP), and diastolic blood pressure (DBP) parameters. A literature search was conducted in electronic databases from build to February 27, 2022. Data were synthesized using random effects model and were ＿expressed as standardized mean difference (SMD)/weighted mean difference (WMD) and 95% confidence interval (CI). Overall, 27 trials with 9,251 participants were included. Pooled results indicated that the combination of a VD and exercise significantly reduced TC (SMD: -0.524; 95% CI: -0.602, -0.446; p < 0.001), LDL-C (SMD: -0.379; 95% CI: -0.471, -0.287; p < 0.001), HDL-C (SMD: -0.213; 95% CI: -0.299, -0.126; p < 0.001), TG (SMD: -0.090; 95% CI: -0.160, -0.020; p = 0.012), SBP (WMD: -7.664 mm Hg; 95% CI: -9.219, -6.109 mm Hg; p < 0.001), and DBP (WMD: -4.347 mm Hg; 95% CI: -5.099, -3.596 mm Hg; p < 0.001). These parameters were reduced more following a low-fat VD, or a mixed high-frequency exercise, especially under strict supervision. Surprisingly, the decreased HDL-C due to VD was observed to recover with the prolongation of exercise.

Virtual reality-based targeted cognitive training program for Chinese older adults: A feasibility study.

OBJECTIVE: To investigate the acceptance and tolerance of a targeted cognitive training program with virtual reality (VR) in Chinese older adults. METHODS: We developed a VR-based program consisting of five games for cognitive training. Fourteen older adults voluntarily participated in the VR training program from January 1 to 22, 2022. The tolerance of the participants and acceptance of the video-based training were assessed after training. RESULTS: Of the participants, 8 (57.1%) had normal cognitive function, and 6 (42.9%) had cognitive impairment. The participants tolerated the program well with a total SSQ (simulated sickness questionnaire) score of 10.42±12.97. Regarding acceptance, 97.6% of subjects found VR equipment to be easy to use, 76.2% said it was a positive experience, and 57.1% thought VR devices were attractive. CONCLUSION: This study shows that VR-based cognitive training was well tolerated by Chinese older adults, without major or severe adverse events.

Characterization of trichome-specific BAHD acyltransferases involved in acylsugar biosynthesis in Nicotiana tabacum.

Glandular trichomes of tobacco (Nicotiana tabacum) produce blends of acylsucroses that contribute to defence against pathogens and herbivorous insects, but the mechanism of assembly of these acylsugars has not yet been determined. In this study, we isolated and characterized two trichome-specific acylsugar acyltransferases that are localized in the endoplasmic reticulum, NtASAT1 and NtASAT2. They sequentially catalyse two additive steps of acyl donors to sucrose to produce di-acylsucrose. Knocking out of NtASAT1 or NtASAT2 resulted in deficiency of acylsucrose; however, there was no effect on acylsugar accumulation in plants overexpressing NtASAT1 or NtASAT2. Genomic analysis and profiling revealed that NtASATs originated from the T subgenome, which is derived from the acylsugar-producing diploid ancestor N. tomentosiformis. Our identification of NtASAT1 and NtASAT2 as enzymes involved in acylsugar assembly in tobacco potentially provides a new approach and target genes for improving crop resistance against pathogens and insects.

Efficacy of an improved method to screen semiochemicals of insect.

BACKGROUND: A combination of gas chromatography-electroantennographic detection (GC-EAD) and gas chromatography-mass spectrometry (GC-MS) is typically used to screen active compounds that play a role in the regulation of insect behavior. This method uses two kinds of gas chromatography (GC) equipment and needs to compare compounds between the two chromatograms, and it is tedious and costly. To improve detection efficiency, as well as reduce costs and the rate of missed detection, we designed a system connecting gas chromatography (GC), electroantennography (EAG), and mass spectrometry (MS), with MS used instead of the flame ionization detector (FID) as the GC-EAD detector. To verify the feasibility of the improved method, we compare two methods-GC-EAG-MS and GC-EAD-through a series of experiments. Some researchers made similar improvements, but these were not compared with GC-EAD, and their method needed to be improved in the synchronization and split ratio. Our method has been optimized and improved in these aspects. METHODS: Helicoverpa armigera was the test organism; the improved method and conventional method were used to detect known and unknown compounds, as well as screen out active compounds that could generate responses in H. armigera antennae. RESULTS: Screening known single compounds using the two methods, the active compound benzaldehyde was detected in all seven concentrations of solution. By using the two methods, the five same active compounds of Helicoverpa armigera were detected in high concentration solution of the mixed compounds (100 mg L-1, 50 mg L-1); the four same active compounds were detected at 20 mg L-1 concentration; two identical same compounds were detected in low concentration solution (concentrations of 10 mg L-1 and below). By using the two methods, six identical active compounds of Helicoverpa armigera were detected in unknown compounds. CONCLUSION: The improved method was consistent with the conventional method in terms of accuracy and sensitivity. However, compared with the traditional methods, Gas chromatography-electroantennographic-mass spectrometry (GC-EAG-MS) saved the cost of GC and FID equipment, thereby greatly lowering the experimental cost. In the experiment, GC-EAG-MS combined the two experimental operations of screening active substances by GC-EAD and identifying active substances by GC-MS into one, which not only reduced the experimental steps, but also avoided the false positive caused by the comparison of the two chromatograms, and it greatly reduced the difficulty level of the overall experimental analysis. GC-EAG-MS is more convenient, efficient, economical, and practical, and could confidently replace traditional methods. With further optimization, it could be widely applied in the study of plant and insect chemical ecology.

Purification and characterization of a fucoidan from the brown algae Macrocystis pyrifera and the activity of enhancing salt-stress tolerance of wheat seedlings.

A fuciodan (Mw = 11.1 kDa) was obtained and purified from Macrocystis pyrifera (MPF). MPF was an acid heteropolysaccharide including fucose, mannose, xylose, galactose, rhamnose, glucuronic acid, and glucose in a molar ratio of 3.1:1.0:0.86:0.63:0.25:0.33:0.11. Sulfate content in MPF was 28.6%, and the molar ratio of fucose to sulfate (Fuc:SO42-) was 1.0:0.58. The structure of MPF was mainly consist of repeating →3)-ß-L-Fucp (2SO3-)-(1→ and →4)-ß-D-Xylp-(1→3)-ß-L-Fucp(2SO3-)-(1→ and with α-L-Fucp-(1→ and →6)-α-D-Galp-(1→ in branches. Moreover, the effects of different MPF concentrations on plant salt tolerance were investigated. The results indicated that MPF could improve the salt tolerance of wheat seedlings. Among the five concentrations (0.05, 0.1, 0.5, 1, and 2 mg/ml), 0.5 and 1 mg/ml MPF were optimal for effective plant salt-resistance activity. These results suggested that MPF extracted from brown seaweed show potential as plant stimulators that may be used to improve salt resistance of plants.

Comparative Evaluation of Key Aroma-Active Compounds in Sweet Osmanthus (Osmanthus fragrans Lour.) with Different Enzymatic Treatments.

Sweet osmanthus (Osmanthus fragrans Lour.) (OF) is one of the ten most famous flowers in China for its unique and delicate fragrance. A combined solid-phase microextraction and solvent-assisted flavor evaporation method was used to accurately capture the overall aromatic profile and characterize the predominant odorants of fresh osmanthus with the help of gas chromatography (GC)-olfactometry and comprehensive two-dimensional GC-quadrupole time-of-flight mass spectrometry (GC × GC-QTOF-MS). Twenty-six volatiles were identified for the first time in OF. A total of 23 potent odorants, dominated by monoterpene oxides and C6 aliphatic aldehydes, were identified. The efficacy of pectinase, ß-glucosidase, and their combination on the aroma enhancement of OF was evaluated by quantitation of the target aroma components using GC-triple quadrupole-MS. The total concentration of key aroma components increased in all three enzyme treatment groups, and the increase was more significant in two ß-glucosidase-treated groups. Changes in odor activity values and odor spectrum values of key odorants indicated that the pectinase-treated sample had more prominent floral, green, and potato-like scents. In contrast, the ß-glucosidase-treated sample had more dominant floral, woody, almond-like, and fruity notes but less green odor, which was confirmed by sensory evaluation. ß-Glucosidase and pectinase complement one another very well, and together, promote a remarkable aroma enhancement in OF.

Rootstock-Scion Interaction Affects the Composition and Pathogen Inhibitory Activity of Tobacco (Nicotiana tabacum L.) Root Exudates.

The composition and allelopathy to Phytophthora nicotianae (the causal agent of tobacco black shank disease) of root exudates from a resistant tobacco (Nicotiana tabacum L.) cultivar Gexin 3, a susceptible cultivar Xiaohuangjin 1025 and their reciprocal grafts were investigated. Grafting with disease-resistant rootstock could improve resistance to black shank; this is closely related to the allelopathy of root exudates. The root exudates from the resistant cultivar inhibited the growth of P. nicotianae, while those from the susceptible cultivar promoted the growth; the grafting varieties had intermediate properties. The root exudate composition differed among cultivars. Gexin 3 was rich in esters and fatty acids, while Xiaohuangjin 1025 contained more hydrocarbons and phenolic acids. The composition of root exudates of grafted cultivars as well as their allelopathy to P. nicotianae were altered, and tended to be close to the composition of cultivar used as rootstock. Eugenol, 4-tert-butylphenol, mono (2-ethylhexyl) phthalate, 4-hydroxybenzoic acid, 2,6-di-tert-butylphenol, dipropyl phthalate, and methyl myristate were identified as the main compounds contributing to inhibitory properties of root exudates. Sorbitol was suggested to play a role in disease induction. Overall, rootstock-scion interaction affected the composition of tobacco root exudates, which may be attributed to the different disease resistance among grafted plants, rootstock and scion.

[Effects of aerobic exercise combined with Lycium ruthenicum on some indicators of myocardial lipid metabolism in rats with high-fat diet].

OBJECTIVE: To study the effects of aerobic exercise combined with Lycium ruthenicumon on some indicators of myocardial lipid metabolism in rats with high-fat diet. METHODS: Fifty-five male Wistar rats were subjected to adaptive feeding for 4 days and weight-free swimming training for 3 days, 20 min/d. After eliminating 5 rats that were not suitable for swimming training, the others were randomly divided into 5 groups according to their weight: regular diet + quiet control group (RDC), high fat diet + quiet control group (HDC), high-fat diet + Lycium ruthenicum quiet control group (HDLC), high fat diet + aerobic exercise group (HDM), high fat diet + Lycium ruthenicum + aerobic exercise group (HDLM), 10 in each group. Group HDM and HDLM did 60 min/d swimming training for 6 weeks with no-bearing. Group C were fed regular diet; The other groups were fed with high-fat diet; Group HDLC and HDLM were intragastrically treated with Lycium ruthenicum at the dose of 4.48 g/(kg·d), and the volume was 5 mL/kg, and the other groups were given equivalent distilled water. The Lee's index, serum and myocardial biochemical indexes were measured after 6 weeks. RESULTS: Compared with group RDC, Lee's index, serum free fatty acids (FFA), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), myocardial FFA and intercellular adhesion molecule-1 (ICAM-1) increased significantly (P＜0.01), serum level of high-density lipoprotein cholesterol (HDL-C) decreased significantly (P＜0.01) in group HDC. Compared with group HDC, Lee's index, serum FFA, IL-6, TNF-α, TC, TG, LDL-C, myocardial FFA and ICAM-1 decreased significantly (P＜0.05 or P＜0.01), serum HDL-C levels increased significantly (P＜0.05 or P＜0.01) in group HDLC, HDM and HDLM. Compared with group HDLC and HDM, Lee's index, serum FFA, IL-6, TNF-α, TC, TG, LDL-C, myocardial FFA and ICAM-1 decreased significantly (P＜0.05), serum HDL-C level increased significantly (P＜0.05) in group HDLM. CONCLUSION: Aerobic exercise and/or Lycium ruthenicum can improve lipid metabolism in rats with high-fat diet, reduce lipotoxicity caused by obesity. Combined intervention is more effective.

Coupled multidimensional GC and odor activity value calculation to identify off-odors in thermally processed muskmelon juice.

Predominant contributors to thermally-induced off-notes in muskmelon juice were investigated by combination of sensory evaluation, GC-olfactometry (GC-O), multidimensional GC, odor activity value (OAV) calculation and addition experiments. "Fermented" and "sulfurous" were revealed as the dominant heat-induced offensive off-notes, and fundamental heat-led changes in odorant compositions were observed. Comparative aroma extract dilution analysis revealed that the off-flavors were mainly caused by newly heat-formed compounds with extremely low odor threshold and unpleasant smells. These included volatile sulfur compounds with "rotten" odors, Strecker aldehydes having "fermented" notes, and heterocyclics exhibiting "roasted" smells. Specifically, dimethyl sulfide, methional, methanethiol, dimethyl trisulfide, dimethyl disulfide, and acetaldehyde were identified as the predominant off-note contributors, among which DMS was the most important one, showing the highest OAV. Multiple extraction techniques, GC-O coupling to GC × GC-QTOF-MS and OAV calculation are powerful tools for accurate location and reliable identification of trace and key off-odorants in natural complex matrices.

Essential oil of Chrysanthemum indicum L.: potential biocontrol agent against plant pathogen Phytophthora nicotianae.

Phytophthora nicotianae is currently considered one of the most devastating oomycete plant pathogens, and its control frequently relies solely on the use of systemic fungicides. There is an urgent need to find environment-friendly control techniques. This study examined the chemical composition, inhibitory activity, and possible modes of action of the essential oil of Chrysanthemum indicum L. (EOC) flower heads against P. nicotianae. The EOC was obtained using hydrodistillation at a 0.15% yielded. It inhibited mycelial growth and spore germination of P. nicotianae at a minimum inhibitory concentration (MIC) of 200 µL/L, and exhibited fumigation effects (92.68% inhibition at 157.48 µL/L). Marked deformation of P. nicotianae mycelia included deformed tip enlargement, shrinkage, and rupture. Further, 55 and 47 compounds were identified using gas chromatography-mass spectrometry (GC-MS) and headspace solid-phase microextraction (HS-SPME) GC-MS analyses, representing 88.2% and 98.91% of the total EOC, respectively. Monoterpenes (25.77%) and sesquiterpenes (54.14%) were the major components identified using GC-MS, whereas monoterpenes were the main constituents in the HS-SPME GC-MS analysis. The higher proportions of sesquiterpenes and monoterpenes could be responsible for the inhibitory activity of EOC, which increased mycelia membrane permeability and the content of mycelial malondialdehyde (MDA) in a dose-dependent manner. Cell death also occurred. Thus, destruction of the cell wall and membrane might be two modes of action of EOC. Our results would be useful for the development of a new plant source of fungicide for P. nicotianae-induced disease.

[Regulatory effects of curcumin on spleen apoptosis in overtraining rats and its mechanism].

OBJECTIVE: To study the mechanisms of curcumin alleviating oxidative stress and spleen apoptosis induced by overtraining in rats by regulating Kelch-like ECH-associated protein-1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) signaling pathway. METHODS: Male Wistar rats of 7 weeks old were divided into control group (C group, 12), overtraining group (OM group, 11), curcumin + overtraining group (COM group, 14). The C Group did not undergo any exercise intervention. The OM and COM group underwent 8-week incremental load swimming training. During the training, rats in the COM group were treated with curcumin at the dose of 200 mg/(kg·d) in the volume of 5 ml/kg by gavage, and rats in the other groups were given an equal volume of solvent, 0.5% sodium carboxymethylcellulose. Twenty-four hours after the last training, the spleen index was calculated by weighing, the pathological changes of the spleen were observed by light microscopy, and the biochemical indicators of blood and spleen were detected. RESULTS: The spleen structure of C group was normal under light microscope; the spleen index of OM group was significantly lower than that of C group (P＜0.01) and pathological changes were obvious; the spleen index of COM group was significantly higher than that of OM group (P＜0.05) and histomorphological changes were relieved. Compared with C group, in OM group, serum corticosterone (Cor) level, spleen apoptosis level, malondialdehyde (MDA) concentration and the expression of proapoptotic Bcl-2 associated X protein (Bax) in spleen were increased (P＜0.05 or P＜0.01); the body weight, serum testosterone (T), superoxide dismutase (SOD) activity, the expressions of heme oxygenase-1 (HO-1) and anti-apoptotic B cell lymphoma-2 protein (Bcl-2) in spleen were decreased (P＜0.05 or P＜0.01); the expression of Nrf2 was not changed significantly (P＞ 0.05). Compared with OM group, in COM group, there were no significant changes in body weight (P＞0.05), serum T level, SOD activity, the expressions of Bcl-2, Nrf2 and HO-1 in spleen were increased (P＜0.05 or P＜0.01); serum Cor level, spleen apoptosis level, MDA concentration and the expression of Bax were decreased (P＜0.05 or P＜0.01). The change trend of T/Cor ratio between groups was consistent with the change of testosterone, and the change trend of Bcl-2/Bax ratio was consistent with the change of Bcl-2. CONCLUSION: The 8-week incremental load excessive swimming training aggravated spleen apoptosis, led to pathological changes and dysfunction of spleen. Curcumin can up-regulate expression of Nrf2 and HO-1, alleviate oxidative stress induced by overtraining, enhance Bcl-2 expression and attenuate Bax expression, thereby inhibiting excessive spleen apoptosis of rats, protecting the structure and function of spleen.

A new method for hydroxyl radical detection by chemiluminescence of flue-cured tobacco extracts.

Chemiluminescence (CL) reactions usually take place in a severely restricted pH regime, thereby confining their application in media at different pH. In this paper, the CL behavior of tobacco-methanol extract (TME) was explored. Surprisingly, TME exhibited CL behavior upon mixing with Fe2+/H2O2, HRP/H2O2 and gold nanoparticles/H2O2 oxidation systems, i.e., in acidic, neutral and alkaline solution respectively. Addition of different reactive oxygen species scavengers verified that the hydroxyl radical (OH) triggers TME CL reactions. Then, the CL behavior of TME was applied to determine OH in tetrachloro-1,4-benzoquinone (TCBQ)/H2O2 system in acidic, neutral and alkaline solutions. CL intensity correlated most strongly (R2 = 0.99) with TCBQ concentration, which was used as a means to indirectly denote OH concentration. This implies that OH could be determined by a TME CL method in a semi-quantitative way regardless of pH value. Therefore, the TME CL method may be a promising method for OH determination in various OH-generating systems.