Purification and characterization of limonin D-ring lactone hydrolase from sweet orange (Citrus sinensis (L.) Osbeck) seeds.

BACKGROUND: Citrus products often suffer from delayed bitterness, which is generated from the conversion of non-bitter precursors (limonoate A-ring lactone, LARL) to limonin under the catalysis of limonin D-ring lactone hydrolase (LDLH). In this study, LDLH was isolated and purified from sweet orange seeds, and a rapid and accurate high-performance liquid chromatography method to quantify LARL was developed and applied to analyze the activity and enzymatic properties of purified LDLH. RESULTS: Purified LDLH (25.22 U mg-1) showed bands of 245 kDa and 17.5 kDa molecular weights in native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate PAGE analysis respectively. After a 24 h incubation under strongly acidic (pH 3) or strongly alkaline (pH 9) conditions, LDLH still retained approximately 100% activity. Moreover, LDLH activity was not impaired by thermal treatment at 50 °C for 120 min. Enzyme inhibition assays showed that LDLH was inactivated only after ethylenediaminetetraacetic acid treatment, and other enzyme inhibitors showed no significant effect on its activity. In addition, the LDLH activity of calcium ion (Ca2+) intervention was 108% of that in the blank group, and that of zinc ion (Zn2+) intervention was 71%. CONCLUSION: LDLH purified in this study was a multimer containing 17.5 kDa monomer with a wide pH tolerance range (pH 3-9) and excellent thermal stability. Moreover, LDLH might be a metallopeptidase, and its activity was stimulated by Ca2+ and significantly inhibited by Zn2+. These findings improve our understanding of LDLH and provide some important implications for reducing the bitterness in citrus products in the future. © 2024 Society of Chemical Industry.

Characterizing and decoding the key odor-active compounds in fresh, pasteurized, and high pressure processing sea buckthorn (Hippophae rhamnoides L.) juice.

The non-thermal and thermal effects on aroma of sea buckthorn juice have rarely been investigated. In this study, 57 odor compounds were identified in fresh sea buckthorn juice (FSBJ), high pressure processing sea buckthorn juice (HSBJ), and pasteurized sea buckthorn juice (PSBJ), including 29 esters, 8 aldehydes, 1 ketone, 5 alcohols, 5 acids, 6 terpenoids, and 3 others. Ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, and ethyl 2-hydroxy-3-methylbutanoate with flavor dilution factors ranging from 729 to 59,049 contributed to the fruity odors of FSBJ and HSBJ. Besides, the formation of off-odor compounds including hexanal, nonanal, furfural, 3-methylbutanoic acid, and dimethyl disulfide with odor activity values ≥ 1, imparts fatty, roasted, sweaty, and cooked odor in PSBJ. The variations of vitamin C and reducing sugar are significantly associated with changes in odor-active compounds during pasteurized processing. These findings provide new insights that high pressure processing minimizes the adverse effects of pasteurization.

Prognostic significance of nadir platelet count in patients with heatstroke: A multi-center retrospective study.

BACKGROUND: Heatstroke (HS), associated with the early activation of the coagulation system and frequently presenting with thrombocytopenia, poses a significant healthcare challenge. Understanding the relationship of nadir platelet count (PLT) within 24 h for adverse outcomes in HS patients is crucial for optimizing management strategies. METHODS: This retrospective cohort study, conducted in six tertiary care hospitals, involved patients diagnosed with HS and admitted to the emergency departments. The primary and secondary outcomes included in-hospital mortality and various acute complications, respectively, with logistic regression models utilized for assessing associations between nadir PLT and outcomes. The PLT count change curve was described using a generalized additive mixed model (GAMM), with additional analyses involving body temperature (BT) at 2 h also conducted. RESULTS: Of the 152 patients included, 19 (12.5%) died in-hospital. The median nadir PLT within 24 h was 99.5 (58.8-145.0)*10^9/L. Notably, as a continuous variable (10*10^9/L), nadir PLT was significantly associated with in-hospital mortality (OR 0.76; 95% CI 0.64-0.91; P = 0.003) and other adverse outcomes like acute kidney and liver injury, even after adjustment for confounders. GAMM revealed a more rapid and significant PLT decline in the non-survival group over 24 h, with differential PLT dynamics also observed based on BT at 2 h. CONCLUSIONS: Nadir PLT within 24 h were tied to in-hospital mortality and various adverse outcomes in HS patients. Early effective cooling measures demonstrated a positive impact on these associations, underscoring their importance in patient management.

Structural and functional properties of whey protein isolate-inulin conjugates prepared with ultrasound or wet heating method.

BACKGROUND: Whey protein isolate (WPI) generally represents poor functional properties such as thermal stability, emulsifying activity and antioxidant activity near its isoelectric point or high temperatures, which limit its application in the food industry. The preparation of WPI-polysaccharide covalent conjugates based on Maillard reaction is a promising method to improve the physical and chemical stability and functional properties of WPI. In this research, WPI-inulin conjugates were prepared through wet heating method and ultrasound method and their structural and functional properties were examined. RESULTS: In conjugates, the free amino acid content was reduced, the high molecular bands were emerged at sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), new C-N bonds were formed in Fourier-transform infrared (FTIR) spectroscopy, and fluorescence intensity was reduced compared with WPI. Furthermore, the result of circular dichroism (CD) spectroscopy also showed that the secondary structure of conjugates was changed. Conjugates with ultrasound treatment had better structural properties compared with those prepared by wet heating treatment. The functional properties such as thermal stability, emulsifying activity index (EAI), emulsion stability (ES) and antioxidant activity of conjugates with wet heating treatment were significantly improved compared with WPI. The EAI and ES of conjugates with ultrasound treatment were the highest, but the thermal stability and antioxidant activity were only close to that of the conjugates with wet heating treatment for 2 h. CONCLUSION: This study revealed that WPI-inulin conjugates prepared with ultrasound or wet heating method not only changed the structural characteristics of WPI but also could promote its functional properties including thermal stability, EAI, ES and antioxidant activity. © 2024 Society of Chemical Industry.

Recent advances in the contribution of glucosinolates degradation products to cruciferous foods odor: factors that influence degradation pathways and odor attributes.

As one of the most important vegetables and oils consumed globally, cruciferous foods are appreciated for their high nutritional value. However, there is no comprehensive knowledge to sufficiently unravel the "flavor mystery" of cruciferous foods. The present review provides a comprehensive literature on the recent advances regarding the contribution of glucosinolates (GSL) degradation products to cruciferous foods odor, which focuses on key GSL degradation products contributing to distinct odor of cruciferous foods (Brassica oleracea, Brassica rapa, Brassica napus, Brassica juncea, Raphanus sativus), and key factors affecting GSL degradation pathways (i.e., enzyme-induced degradation, thermal-induced degradation, chemical-induced degradation, microwave-induced degradation) during different processing and cooking. A total of 93 volatile GSL degradation products (i.e., 36 nitriles, 33 isothiocyanates, 3 thiocyanates, 5 epithionitriles, and 16 sulfides) and 29 GSL (i.e., 20 aliphatic, 5 aromatic, and 4 indolic) were found in generalized cruciferous foods. Remarkably, cruciferous foods have a distinctive pungent, spicy, pickled, sulfur, and vegetable odor. In general, isothiocyanates are mostly present in enzyme-induced degradation of GSL and are therefore often enriched in fresh-cut or low-temperature, short-time cooked cruciferous foods. In contrast, nitriles are mainly derived from thermal-induced degradation of GSL, and are thus often enriched in high-temperature, long-time cooked cruciferous foods.

Processing and cooking can cause degradation of glucosinolates and formation of volatiles.Structure­odor relationship of glucosinolates degradation products is discussed.Nitriles, isothiocyanates, and sulfides play an important role in cruciferous foods odor.Both enzyme- and thermal-induced degradation of glucosinolates is strongly pH-dependent.

Anisotropic materials based on carbohydrate polymers: A review of fabrication strategies, properties, and applications.

Anisotropic structures exist in almost all living organisms to endow them with superior properties and physiological functionalities. However, conventional artificial materials possess unordered isotropic structures, resulting in limited functions and applications. The development of anisotropic structures on carbohydrates is reported to have an impact on their properties and applications. In this review, various alignment strategies for carbohydrates (i.e., cellulose, chitin and alginate) from bottom-up to top-down strategies are discussed, including the rapidly developed innovative technologies such as shear-induced orientation through extrusion-based 3D/4D printing, magnetic-assisted alignment, and electric-induced alignment. The unique properties and wide applications of anisotropic carbohydrate materials across different fields, from biomedical, biosensors, smart actuators, soft conductive materials, to thermal management are also summarized. Finally, recommendations on the selection of fabrication strategies are given. The major challenge lies in the construction of long-range hierarchical alignment with high orientation degree and precise control over complicated architectures. With the future development of hierarchical alignment strategies, alignment control techniques, and alignment mechanism elucidation, the potential of anisotropic carbohydrate materials for scalable manufacture and clinical applications will be fully realized.

Glasgow Coma Scale on admission as predictor of neurological sequelae at discharge and acute respiratory failure in patients with heatstroke.

BACKGROUND: Transient neuronal dysfunction may occur in most brain regions with heatstroke (HS). This study aimed to explore the prognostic significance of initial Glasgow Coma Scale (GCS) scores in HS. METHODS: Retrospective data regarding HS were obtained from six hospitals. The primary outcome was neurological sequelae at discharge. Secondary outcomes included acute respiratory failure (ARF) and intensive care unit (ICU) admission. Logistic regression models and random forest imputation were used to assess the independent association between GCS score and outcomes. Interaction and stratified analyses of body temperature (BT) at 0.5 hours were also conducted. Receiver operating characteristic curves and decision curve analysis were used to estimate prognostic values. RESULTS: Of 206 patients, 44 (21.36%) had neurological sequelae at discharge. The mean ± standard deviation initial GCS score was 8.17 ± 4.05. After adjustment for confounders, GCS, as a continuous variable, was significantly related to neurological sequelae at discharge [odds ratio (OR): 0.65; 95% confidence interval (CI): 0.50-0.85; P = 0.002], ARF (OR: 0.76; 95% CI: 0.66-0.87; P = 0.001), and ICU admission (OR: 0.68; 95% CI: 0.53-0.87; P = 0.003). These relationships were consistent in the random forest imputation cohort. The OR between GCS and neurological sequelae at discharge was much lower (P = 0.048) in participants with BT at 0.5 hours ≤39°C than in those with BT at 0.5 hours >39°C. The GCS and National Early Warning Score (NEWS) had similar prognostic ability for all outcomes, whereas the net benefits were greater with the GCS compared with the NEWS. CONCLUSIONS: Initial GCS score was an independent prognostic factor for neurological sequelae at discharge in HS. Rapid cooling played a positive role in this relationship. Key messages What is already known on this topic Brain damage caused by heatstroke (HS) can be transient or result in irreversible injury. Early recognition of those at risk of death or developing neurological complications is very important for improving the outcomes of HS. What this study adds Initial Glasgow Coma Scale (GCS) score was an independent prognostic factor for neurological sequelae at discharge, acute respiratory failure, and intensive care unit (ICU) admission in HS. Rapid cooling played a positive role in this relationship. How this study might affect research, practice, or policy The GCS upon emergency department admission can be a useful predictor of prognosis in patients with HS.

Effects of Capsaicin on Glucose Uptake and Consumption in Hepatocytes.

Obesity represents a major health challenge because it substantially increases the risk of metabolic diseases. Capsaicin, the major active ingredient of Capsicum spp., has been reported to possess anti-obesity activity. Hereon, the effect of capsaicin on glucose uptake and consumption in hepatocytes was extensively studied. Capsaicin was shown to accelerate the glucose uptake/consumption and the ATP production of hepatocytes. The elevation of intracellular Ca2+ was thought to be a potential mechanism. By transcriptome analysis, 78, 146 and 507 differentially expressed genes (DEGs) were identified between capsaicin and the control group for 4 h, 12 h and 24 h treatments. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that most of the DEGs were involved in canonical pathways, like MAPK and PI3K-AKT signaling pathways. Clustering analysis showed that many DEGs were associated with glucose and amino acid metabolism. The variation trend in genes related to glucose and amino acid metabolism (like CTH, VEGFA, PCK2 and IGFBP3) in the quantitative PCR (q-PCR) assay was consistent with the transcriptome data. These results demonstrated that capsaicin efficiently accelerated the glucose uptake and consumption of hepatocytes.

Identification of glucosinolates and volatile odor compounds in microwaved radish (Raphanus sativus L.) seeds and the corresponding oils by UPLC-IMS-QTOF-MS and GC × GC-qMS analysis.

The effect of microwave treatment on the content of glucosinolates (GSL) in radish seeds and volatile odor compounds in the microwaved radish seed oils (MRSO) is still unclear. In this study, a total of 13 GSL were identified and quantified in five radish seed varieties by UPLC-IMS-QTOF-MS, among which glucoraphenin, glucoraphasatin, glucoerucin accounting for up to 90 %. Total GSL decreased by 47.39-67.88% after microwave processing. Moreover, 58 odor compounds were identified in MRSO, including 6 sulfides, 12 nitriles, 2 isothiocyanates, 10 alcohols, 12 aldehydes, 5 ketones, 6 acids, and 5 others. The major odor compounds were (methyldisulfanyl)methane, dimethyltrisulfane, (methylsulfinyl)methane, 3-(methylsulfanyl)-1-propanol, methyl thiocyanate, hexanenitrile, 5-(methylsulfanyl)pentanenitrile, and 4-isothiocyanato-1-butene with odor activity value (OAV) higher than 1. The principal components analysis (PCA) results can distinguish MRSO from five different radish seed varieties, three of which (H20-18, H20-19 and H20-28) were in one group and other two (H20-23 and H20-26) were in another group. In addition, aliphatic GSL showed positive correlations with sulfides, isothiocyanates, and nitriles, while negative correlations with alcohols. This work provides a new insight into the odor contribution of GSL degradation products.

Inulin: properties and health benefits.

Inulin, a soluble dietary fiber, is widely found in more than 36 000 plant species as a reserve polysaccharide. The primary sources of inulin, include Jerusalem artichoke, chicory, onion, garlic, barley, and dahlia, among which Jerusalem artichoke tubers and chicory roots are often used as raw materials for inulin production in the food industry. It is universally acknowledged that inulin as a prebiotic has an outstanding effect on the regulation of intestinal microbiota via stimulating the growth of beneficial bacteria. In addition, inulin also exhibits excellent health benefits in regulating lipid metabolism, weight loss, lowering blood sugar, inhibiting the expression of inflammatory factors, reducing the risk of colon cancer, enhancing mineral absorption, improving constipation, and relieving depression. In this review paper, we attempt to present an exhaustive overview of the function and health benefits of inulin.

Structural characteristics and gel properties of pectin from citrus physiological premature fruit drop.

This study is the first to extract and characterize pectin from citrus physiological premature fruit drop. The extraction yield of pectin reached 4.4 % by acid hydrolysis method. The degree of methoxy-esterification (DM) of citrus physiological premature fruit drop pectin (CPDP) was 15.27 %, indicating it was low-methoxylated pectin (LMP). The monosaccharide composition and molar mass test results showed CPDP was a highly branched macromolecular polysaccharide (ß: 0.02, Mw: 2.006 × 105 g/mol) with rich rhamnogalacturonan I domain (50.40 %) and long arabinose and galactose side chain (32.02 %). Based on the fact that CPDP is LMP, Ca2+ was used to induce CPDP to form gels. Textural and rheological tests showed that the gel strength and storage modulus of CPDP were higher than commercial citrus pectin (CP) used in this paper due to the lower DM and rich neutral sugar side chains of CPDP. Scanning electron microscope (SEM) results showed CPDP had stable gel network structure.

Isolation, purification, and mass spectrometry identification of the enzyme involved in citrus flavor (+)-valencene biotransformation to (+)-nootkatone by Yarrowia lipolytica.

BACKGROUND: (+)-Nootkatone is a highly valuable sesquiterpene compound that can be used as an aromatic in the food industry because of its grapefruit flavor and low sensory threshold. The unconventional yeast Yarrowia lipolytica has many unique physical and chemical properties, metabolic characteristics, and genetic structure, which has aroused the interest of researchers. Previous research showed that Y. lipolytica possesses the ability to transform the sesquiterpene (+)-valencene to (+)-nootkatone. The aim of this study was to isolate, purify, and identify the enzyme involved in the (+)-valencene bioconversion to (+)-nootkatone by Y. lipolytica. RESULTS: In this study, ultrasonic-assisted extraction, ammonium sulfate precipitation, anion-exchange chromatography, and gel-filtration chromatography were used to separate and purify the enzyme involved in the (+)-valencene bioconversion by Y. lipolytica. The protein was identified as aldehyde dehydrogenase (ALDH) (gene0658) using sodium dodecyl sulfate polyacrylamide gel electrophoresis and liquid chromatography-tandem mass spectrometry analysis. The ALDH had the highest activity when the pH value was 6.0 and the temperature was 30 °C. The activity of ALDH was significantly stimulated by ferrous ions and inhibited by barium, calcium, and magnesium ions. CONCLUSION: This is the first time that ALDH was found to participate in (+)-valencene biotransformation by Y. lipolytica. It may be involved in regulating the microbial transformation of (+)-valencene to (+)-nootkatone through redox characteristics. This study provides a theoretical basis and reference for the biological synthesis of citrus flavor (+)-nootkatone. © 2023 Society of Chemical Industry.

Effect of different ways of ingesting orange essential oil on blood immune index and intestinal microflora in mice.

BACKGROUND: Studies have found that the addition of plant essential oils to feed had a positive effect on intestinal microflora and immunity in mice. However, the effect of different ways of ingestion of orange essential oil on mice has seldom been reported. In the present study, we investigated the effects of ingestion of orange essential oil by gavage, sniffing and feeding on intestinal microflora and immunity in mice. RESULTS: The results obtained showed that a low concentration of essential oil feeding significantly increased the spleen index of mice (P < 0.05). The effect of different ways of ingestion on the thymus index, immunoglobulin G and immunoglobulin M of mice was not significant (P > 0.05). High and medium concentrations of essential oil feeding increased the level of interleukin-2 in mice (P < 0.05). H+ K+ -ATPase activity was significantly increased in mice fed with gavage and different concentrations of essential oil feed compared to the control group (P < 0.05). The analysis of the results of the microflora in the cecum and colon of mice indicated that the medium concentration of essential oil feeding group and the sniffing group significantly changed the structure of the flora and increased the diversity of the intestinal microflora. All three essential oil ingestion methods increased the abundance of Bacteroidetes and Lactobacillus in the intestine of mice. CONCLUSION: Compared with gavage and feeding, sniffing had a significant effect on immunoglobulins in mice. All the three ingestion methods could affect the intestinal microflora of mice and increase the abundance of Lactobacillus. © 2022 Society of Chemical Industry.

Chemical constitutes and anti-obesity potential of seedlings of purple-leafed rice in high-fat diet induced obese mice.

The seedlings of purple leafed rice (SPLR) are characterized by high contents of anthocyanins and various polyphenols, whose total anthocyanin content can reach 15.16 mg g-1, indicating that SPLR may have many bioactivities. Therefore, in order to evaluate the anti-obesity potential value of SPLR, the nutrient components were first identified, and the anti-obesity effect of SPLR was evaluated with a high-fat diet (HFD) induced obese mouse model for 12 weeks. The results demonstrated that SPLR supplementation could alleviate HFD-induced obesity and suppress pro-inflammatory cytokine production and macrophage infiltration in epididymal white adipose tissue of HFD-induced obese mice. The findings indicated that supplementation with SPLR may contribute to preventing obesity and related complications.

Citrus juice off-flavor during different processing and storage: Review of odorants, formation pathways, and analytical techniques.

As the most widespread juice produced and consumed globally, citrus juice (mandarin juice, orange juice, and grapefruit juice) is appreciated for its attractive and distinct aroma. While the decrease of characteristic aroma-active compounds and the formation of off-flavor compounds are easy to occur in processing and storage conditions. This review provides a comprehensive literature of recent research and discovery on citrus juice off-flavor, primarily focusing on off-flavor compounds induced during processing and storage (i.e., thermal, storage, light, oxygen, package, fruit maturity, diseases, centrifugal pretreatment, and debittering process), formation pathways (i.e., terpene acid-catalyzed hydration, caramelization reaction, Maillard reaction, Strecker degradation, and other oxidative degradation) of the off-flavor compounds, effective inhibitor pathway to off-flavor (i.e., electrical treatments, high pressure processing, microwave processing, ultrasound processing, and chemical treatment), as well as odor assessment techniques based on molecular sensory science. The possible precursors (terpenes, sulfur-containing amino acids, carbohydrates, carotenoids, vitamins, and phenolic acids) of citrus juice off-flavor are listed and are also proposed. This review intends to unravel the regularities of aroma variations and even off-flavor formation of citrus juice during processing and storage. Future aroma analysis techniques will evolve toward a colorimetric sensor array for odor visualization to obtain a "marker" of off-flavor in citrus juice.

(1) Processing and storage can cause the degradation of nutrients in citrus juice and the formation of off-flavor compounds.(2) Terpene degradation products, sulfur-containing compounds, phenols, acids, and furans are contributed to citrus juice off-flavor.(3) Nonthermal techniques such as electrical treatments, high pressure, microwave, and ultrasound processing is beneficial to preservation of the original aroma and sensory qualities of citrus juice.(4) Potential off-flavor compounds (especially trace level) explored by molecular sensory science also significantly impact the aroma of citrus juice.

Separation and purification of nootkatone from fermentation broth of Yarrowia lipolytica with high-speed counter-current chromatography.

Nootkatone is an important functional sesquiterpene, which can be obtained by the biotransformation of valencene. It is increasingly important because of its pleasant citrus aroma and physiological effects. Yarrowia lipolytica is beneficial for biotechnology applications and has ability to transform valencene to nootkatone. High-speed counter-current chromatography (HSCCC) was used to isolate and purify the product of nootkatone in this study. The suitable two-phase solvent system was selected and the optimum separation conditions were determined. The partition coefficients of nootkatone and the separation factor between nootkatone and valencene were considered as the indexes. The results showed that there were numerous products during the transformation of valencene by Yarrowia lipolytica, and the content of nootkatone was 13.75%. The obtained nootkatone was separated by HSCCC with a solvent system n-hexane/methanol/water (5/4/1, v/v). The final purity of nootkatone was 91.61 ± 0.20% and the elution time was 290-310 min. The structure of nootkatone was identified by gas chromatography-mass spectrometry (GC-MS), infrared spectrum and nuclear magnetic resonance hydrogen spectroscopy (1H NMR). This was the first report on the separation of nootkatone from the fermentation broth by HSCCC. This study proved that HSCCC could be used as an effective method to separate and purify the nootkatone from valencene transformed by Yarrowia lipolytica with n-hexane/methanol/water (5/4/1, v/v).

Differential proteomic analysis of citrus flavor (+)-valencene biotransformation to (+)-nootkatone by Yarrowia lipolytica.

Natural products (+)-nootkatone is an important sesquiterpene compound and is widely used in pharmaceutical, cosmetic, agricultural and food industries. The aim of this study was to analyze the differentially expressed proteins (DEPs) during citrus aroma compound (+)-valencene biotransformation to (+)-nootkatone by Yarrowia lipolyticaby with high-throughput LC-MS/MS. A total of 778 proteins were differentially expressed, 385 DEPs were significantly up-regulated and 393 DEPs were markedly down-regulated. It was found that the enzymes transformed (+)-valencene to (+)-nootkatone were mainly existed in yeast intracellular and precipitated under the condition of 30-40 % ammonium sulfate. Most DEPs involved in amino acid and fatty acid metabolism were down-regulated during (+)-valencene biotransformation. The DEPs related to the carbohydrate metabolism, energy metabolism and most of transporter proteins were significantly up-regulated. Furthermore, the key enzymes involved in (+)-valencene transformation might be related to cytochrome P450s (gene2215 and gene2911) and dehydrogenases (gene6493). This is the first time that proteomics was used to investigate the metabolism mechanism of Yarrowia lipolytica during (+)-valencene biotransformation. The proteomic analysis of Yarrowia lipolytica provided a foundation for the molecular regulatory mechanism in the biotransformation to (+)-nootkatone from (+)-valencene.

Genomic and transcriptomic analysis screening key genes for (+)-valencene biotransformation to (+)-nootkatone in Yarrowia lipolytica.

Yarrowia lipolytica is a kind of unconventional yeast, which is widely used in food industry because of its safety. (+)-Nootkatone, the ketone derivatives of (+)-valencene, possesses typical grapefruit aroma and is used as aromatics and medicines. It was found that Yarrowia lipolytica was an efficient biocatalyst for the transformation of (+)-valencene to (+)-nootkatone. Thus, it was meaningful to explore the genome features and the gene expression differences of strain Yarrowia lipolytica during (+)-valencene biotransformation, and to study the detailed bioconversion pathways. The results showed that the Yarrowia lipolytica genome was about 20.49 Mb, which encoded 6 137 protein coding genes. There were 1 167 differentially expressed genes (DEGs) in Y_V_36h ((+)-valencene-treated condition) compared to Y_36h ((+)-valencene-untreated blank). During biotransformation, the expression of genes related to the biosynthesis of secondary metabolites and most of ATP-binding cassette (ABC) transporters were significantly up-regulated. In addition, the expression of genes involved in energy metabolism decreased. Moreover, the enzymes participated in (+)-valencene biotransformation were inducible and they were inhibited by cytochrome P450 inhibitors. Several differentially expressed genes related to cytochrome P450 and dehydrogenase (gene2800, gene2911 and gene3152) were significantly up-regulated and might be responsible for converting (+)-valencene to (+)-nootkatone. The RT-qPCR experiment of ten DEGs were further verified and confirmed the reliability of transcriptome results. This study provided a basis for exploring the related genes and molecular regulatory mechanism of (+)-nootkatone biosynthesis from (+)-valencene by Yarrowia lipolytica.

Protective effect of orange essential oil on the formation of non-alcoholic fatty liver disease caused by high-fat diet.

The purpose of this study was to investigate the protective effect of sniffing orange essential oil (OEO) on the formation of non-alcoholic fatty liver disease (NAFLD) caused by a high-fat diet. The results confirmed that sniffing OEO could reduce obesity caused by a high-fat diet (HFD) by reducing the levels of triglycerides (TGs), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). In addition, the observation of liver tissue sections showed that sniffing OEO could reduce lipid accumulation in liver cells. Further analysis by western blot analysis showed that OEO treatment made the expression levels of acetyl-CoA carboxylase (ACC) and Cytochrome P450 2E1 (CYP2E1) down-regulated and the expression levels of peroxisome proliferator-activated receptor-α (PPAR-α) and carnitine palmitoyltransferase-1 (CPT-1) up-regulated. These results indicate that the treatment of sniffing OEO could enhance the antioxidant capacity of mice and reduce liver damage caused by a high-fat diet. Furthermore, sniffing OEO could inhibit lipid synthesis and oxidative stress stimulated by a high-fat diet. Overall, OEO treatment had a certain protective effect on NAFLD-related diseases caused by a high-fat diet. Therefore, aromatherapy may be introduced as a treatment of long-term chronic diseases.