Efficacy of ergosterol peroxide obtained from the endophytic fungus Acrophialophora jodhpurensis against Rhizoctonia solani.

AIM: To investigate antifungal activity of the extract and major metabolite of the endophytic fungus Acrophialophora jodhpurensis (belonging to Chaetomiaceae) against crown and root rot caused by Rhizoctonia solani (teleomorph: Thanatephorus cucumeris), as an important pathogen of tomato. METHODS AND RESULTS: The endophytic fungus A. jodhpurensis, has high inhibitory effect against R. solani AG4-HG II in vitro and in vivo. The media conditions were optimized for production of the endophyte's metabolites. The highest amounts of secondary metabolites were produced at pH 7, 30°C temperature, and in the presence of 0.5% glucose, 0.033% sodium nitrate, and 1 gl-1 asparagine as the best carbon, nitrogen, and amino acid sources, respectively. The mycelia were extracted by methanol and the obtained extract was submitted to various chromatography techniques. Phytochemical analysis via thin-layer chromatography (TLC) and nuclear magnetic resonance (NMR) spectroscopy showed that ergosterol peroxide was the major component in the extract of this endophyte. Antifungal activities of the methanolic extract and ergosterol peroxide in the culture media were studied against R. solani. Minimum inhibitory concentrations of the extract and ergosterol peroxide against the pathogen were 600 and 150 µg ml-1, respectively. Ergosterol peroxide revealed destructive effects on the pathogen structures in microscopic analyses and induced sclerotia production. Histochemical analyses revealed that it induced apoptosis in the mycelia of R. solani via superoxide production and cell death. Application of ergosterol peroxide in the leaf disc assay reduced the disease severity in tomato leaves. CONCLUSIONS: Antifungal metabolites produced by A. jodhpurensis, such as ergosterol peroxide, are capable of controlling destructive Rhizoctonia diseases on tomato.

Antifungal activity and potential mechanism of action of Huangqin decoction against Trichophyton rubrum.

Introduction. Trichophyton rubrum is a major causative agent of superficial dermatomycoses such as onychomycosis and tinea pedis. Huangqin decoction (HQD), as a classical traditional Chinese medicine formula, was found to inhibit the growth of common clinical dermatophytes such as T. rubrum in our previous drug susceptibility experiments.Hypothesis/Gap Statement. The antifungal activity and potential mechanism of HQD against T. rubrum have not yet been investigated.Aim. The aim of this study was to investigate the antifungal activity and explore the potential mechanism of action of HQD against T. rubrum.Methodology. The present study was performed to evaluate the antifungal activity of HQD against T. rubrum by determination of minimal inhibitory concentrations (MICs), minimal fungicidal concentrations (MFCs), mycelial growth, biomass, spore germination and structural damage, and explore its preliminary anti-dermatophyte mechanisms by sorbitol and ergosterol assay, HPLC-based ergosterol test, enzyme-linked immunosorbent assay and mitochondrial enzyme activity test.Results. HQD was able to inhibit the growth of T. rubrum significantly, with an MIC of 3.125 mg ml-1 and an MFC of 12.5 mg ml-1. It also significantly inhibited the hyphal growth, conidia germination and biomass growth of T. rubrum in a dose-dependent manner, and induced structural damage in different degrees for T. rubrum cells. HQD showed no effect on cell wall integrity, but was able to damage the cell membrane of T. rubrum by interfering with ergosterol biosynthesis, involving the reduction of squalene epoxidase (SE) and sterol 14α-demethylase P450 (CYP51) activities, and also affect the malate dehydrogenase (MDH), succinate dehydrogenase (SDH) and ATPase activities of mitochondria.Conclusion. These results revealed that HQD had significant anti-dermatophyte activity, which was associated with destroying the cell membrane and affecting the enzyme activities of mitochondria.

Phytoconstituents and Ergosterol Biosynthesis-Targeting Antimicrobial Activity of Nutmeg (Myristica fragans Houtt.) against Phytopathogens.

In recent years, nutmeg (Myristica fragans Houtt.) has attracted considerable attention in the field of phytochemistry due to its diverse array of bioactive compounds. However, the potential application of nutmeg as a biorational for crop protection has been insufficiently explored. This study investigated the constituents of a nutmeg hydroethanolic extract via gas chromatography-mass spectrometry and vibrational spectroscopy. The research explored the extract's activity against phytopathogenic fungi and oomycetes, elucidating its mechanism of action. The phytochemical profile revealed fatty acids (including tetradecanoic acid, 9-octadecenoic acid, n-hexadecanoic acid, dodecanoic acid, and octadecanoic acid), methoxyeugenol, and elemicin as the main constituents. Previously unreported phytochemicals included veratone, gelsevirine, and montanine. Significant radial growth inhibition of mycelia was observed against Botrytis cinerea, Colletotrichum acutatum, Diplodia corticola, Phytophthora cinnamomi, and especially against Fusarium culmorum. Mode of action investigation, involving Saccharomyces cerevisiae labeled positively with propidium iodide, and a mutant strain affected in ERG6, encoding sterol C-24 methyltransferase, suggested that the extract induces a necrotic type of death and targets ergosterol biosynthesis. The evidence presented underscores the potential of nutmeg as a source of new antimicrobial agents, showing particular promise against F. culmorum.

Antifungal Constituents of Piper crocatum and Their Activities as Ergosterol Biosynthesis Inhibitors Discovered via In Silico Study Using ADMET and Drug-Likeness Analysis.

Along with the increasing resistance of Candida spp. to some antibiotics, it is necessary to find new antifungal drugs, one of which is from the medicinal plant Red Betel (Piper crocatum). The purpose of this research is to isolate antifungal constituents from P. crocatum and evaluate their activities as ergosterol biosynthesis inhibitors via an in silico study of ADMET and drug-likeness analysis. Two new active compounds 1 and 2 and a known compound 3 were isolated, and their structures were determined using spectroscopic methods, while their bioactivities were evaluated via in vitro and in silico studies, respectively. Antifungal compound 3 was the most active compared to 1 and 2 with zone inhibition values of 14.5, 11.9, and 13.0 mm, respectively, at a concentration of 10% w/v, together with MIC/MFC at 0.31/1.2% w/v. Further in silico study demonstrated that compound 3 had a stronger ΔG than the positive control and compounds 1 and 2 with -11.14, -12.78, -12.00, and -6.89 Kcal/mol against ERG1, ERG2, ERG11, and ERG24, respectively, and also that 3 had the best Ki with 6.8 × 10-3, 4 × 10-4, 1.6 × 10-3, and 8.88 µM. On the other hand, an ADMET analysis of 1-3 met five parameters, while 1 had one violation of Ro5. Based on the research data, the promising antifungal constituents of P. crocatum allow P. crocatum to be proposed as a new antifungal candidate to treat and cure infections due to C. albicans.

Sterols Content of Fruiting Bodies of Medicinal Artist's Bracket Mushroom Ganoderma applanatum (Agaricomycetes) Collected in Armenia.

The qualitative analysis of hexane extracts obtained from different trama layers (WT, T1-T4) of dried fruiting bodies of medicinal bracket fungus Ganoderma applanatum collected in the Tavoush region of North-East Armenia was performed by GC-MS analysis. Three sterols [(7.22-ergostadienon, ergosterol and ergosta-14.22-diene-3-ol (3ß, 5α, 22E)] have been identified. The results have shown that the content and ratio of sterols differ in analyzed trama samples. The highest amount of sterols was detected in middle parts of T2 and T3 layers, while content of sterols gradually decreased to the upper cortical (T4) and lower hymenial (T1) layers. The chromatographic profiles of identified compounds indicate that different sterols dominated in each layer: 7.22-ergostadienon in T4, ergosterol in T3, T2, and T1. The average weight loss of analyzed trama samples during six days of drying was about 40 wt.% (37.0-43.49 wt.%) of the total weight of basidiome, which decreased up to 5 wt.% in the next two days. The complete extraction of sterols lasted six days. Its further prolongation leads to stationary phase without an increase in the amount of extracted sterols.

Understanding the Immune-Endocrine Effects of Vitamin D in SARS-CoV-2 Infection: A Role in Protecting against Neurodamage.

Calcitriol and hydroxyderivatives of lumisterol and tachisterol are secosteroid hormones with immunomodulatory and anti-inflammatory properties. Since the beginning of the COVID-19 pandemic, several studies have correlated deficient serum concentrations of vitamin D3 (calcifediol) with increased severity of the course of SARS-CoV-2 infection. Among systemic complications, subjective (anosmia, ageusia, depression, dizziness) and objective (ischemic stroke, meningoencephalitis, myelitis, seizures, Guillain-Barré syndrome) neurological symptoms have been reported in up to 80% of severe COVID-19 patients. In this narrative review, we will resume the pathophysiology of SARS-CoV-2 infection and the mechanisms of acute and chronic neurological damage. SARS-CoV-2 can disrupt the integrity of the endothelial cells of the blood-brain barrier (BBB) to enter the nervous central system. Invasion of pro-inflammatory cytokines and polarization of astrocytes and microglia cells always in a pro-inflammatory sense together with the pro-coagulative phenotype of cerebral endothelial cells in response to both SARS-CoV-2 and immune cells invasion (immunothrombosis) are the major drivers of neurodamage. Calcitriol and hydroxyderivatives of lumisterol and tachisterol could play an adjuvant role in neuroprotection through mitigation of neuroinflammation and protection of endothelial integrity of the BBB. Dedicated studies on this topic are currently lacking and are desirable to confirm the link between vitamin D3 and neuroprotection in COVID-19 patients.

Mechanisms of Antioxidant Dipeptides Enhancing Ethanol-Oxidation Cross-Stress Tolerance in Lager Yeast: Roles of the Cell Wall and Membrane.

High concentrations of ethanol could cause intracellular oxidative stress in yeast, which can lead to ethanol-oxidation cross-stress. Antioxidant dipeptides are effective in maintaining cell viability and stress tolerance under ethanol-oxidation cross-stress. In this study, we sought to elucidate how antioxidant dipeptides affect the yeast cell wall and membrane defense systems to enhance stress tolerance. Results showed that antioxidant dipeptide supplementation reduced cell leakage of nucleic acids and proteins by changing cell wall components under ethanol-oxidation cross-stress. Antioxidant dipeptides positively modulated the cell wall integrity pathway and up-regulated the expression of key genes. Antioxidant dipeptides also improved the cell membrane integrity by increasing the proportion of unsaturated fatty acids and regulating the expression of key fatty acid synthesis genes. Moreover, the addition of antioxidant dipeptides significantly (p < 0.05) increased the content of ergosterol. Ala-His (AH) supplementation caused the highest content of ergosterol, with an increase of 23.68 ± 0.01% compared to the control, followed by Phe-Cys (FC) and Thr-Tyr (TY). These results revealed that the improvement of the cell wall and membrane functions of antioxidant dipeptides was responsible for enhancing the ethanol-oxidation cross-stress tolerance of yeast.

Ganodermasides E-H, four new ergosterol derivatives from the endophytic fungus Epicoccum poae DJ-F associated with Euphorbia royleana.

Ganodermasides E-H (1-4), four new ergosterol derivatives and two known ones (5 and 6) were isolated from the fermentation of the endophytic fungus Epicoccum poae DJ-F in the stems of Euphorbia royleana Boiss. Their structures were elucidated by spectroscopic analysis, including extensive 1D NMR, 2D NMR, and HRESIMS techniques. All the isolated compounds were tested for their vitro antibacterial activity. Compounds 1-6 showed weak inhibitory effects on Staphylococcus epidermidis, Pseudomonas syringae, and Ralstonia solanacearum with MIC values ranging from 0.4 to 3.6 mM.

Impact of ergosterol content on acetic and lactic acids toxicity to Saccharomyces cerevisiae.

Organic acid stress often represents a major hurdle in industrial bio-based microbial processes. Organic acids can be released from lignocellulosic feedstocks pretreatment and can also be desirable products obtained by microbial fermentation with applications in different industrial sectors. Yeasts are prominent cell factories. However, the presence of organic acids can compromise yeast metabolism, impairing fermentation performances and limiting the economic feasibility of the processes. Plasma membrane remodeling is deeply involved in yeast tolerance to organic acids, but the detailed mechanisms and potentials of this phenomenon remain largely to be studied and exploited. We investigated the impact of ergosterol on Saccharomyces cerevisiae tolerance against organic acid stress by coupling in vitro and in vivo assays. In the in vitro assay, synthetic lipid vesicles were prepared containing different concentrations of ergosterol. We observed changes in organic acids diffusion through the membrane as a function of ergosterol content. Then, we extended our approach in vivo, engineering S. cerevisiae with the aim of changing the ergosterol content of cells. We focused on ECM22, an important transcription factor, involved in the regulation of ergosterol biosynthesis. The overexpression of ECM22 was sufficient to increase ergosterol levels in S. cerevisiae, resulting in an enhanced tolerance toward lactic acid stress. In this work we propose an in vitro approach, using synthetic lipid vesicles, as a complementary method to be used when studying the impact of the plasma membrane lipid composition on the diffusion of organic acids.

Development of skin-permeable flexible liposome using ergosterol esters containing unsaturated fatty acids.

Ergosterol (Ergo) and cholesterol contribute to performances of liposomes by increasing membrane packing density and physical stability. However, as these sterols can reduce membrane flexibility, they can lower skin permeability of liposomes. We synthesized ergosterol ester (Ergo-Est) containing unsaturated fatty acid different from Ergo in size and physical properties. In this work, we investigated effects of Ergo-Est and Ergo on physical properties of liposomes. We incorporated Ergo, Ergo-oleate (EO18:1), Ergo-linoleate (EL18:2), and Ergo-linolenate (ELn18:3) into the liposomal membrane of egg phosphatidylcholine and soybean lecithin. Ergo-Est did not reduce membrane fluidity as much as Ergo. Nevertheless, Ergo-Est increased membrane packing density and physical stability of liposomes. EL18:2 and ELn18:3 almost maintained membrane flexibility and skin permeability of liposomes, while Ergo significantly reduced them. Skin permeation test demonstrated that EL18:2 and ELn18:3 liposomes permeated to the dermis, whereas Ergo liposome mostly remained in the stratum corneum. This is the first report to show that EL18:2 and ELn18:3 can be efficient sterol compounds for flexible liposome formulation.

GC-MS and NMR spectroscopy based metabolite profiling of Panchvalkal kwath (polyherbal formulation).

Panchvalkal kwath (PK) is a bark formulation of five pharmacologically important plants, i.e., Ficus benghalensis, Ficus racemosa, Ficus religiosa, Thespesia populnea, and Ficus lacor. The Ayurvedic formulation is being used since ancient times to cure diabetes, bacterial infections and heal wounds. The present study aims to identify the metabolite profiles of PK which could explain its properties and its mode of action against specific diseases and disorders. The aqueous extract of Panchvalkal is prepared through a hot maceration process. The extract is subjected to preliminary identification of phytoconstituents and FTIR spectroscopy to recognize functional groups. GC-MS analysis reveals that the extract is enriched with 24-Norursa-3,12-diene (25.16%); Lup-20(29)-en-3-one (16.76%); 2-methyl-3-(4-propan-2-ylphenyl) propanal (7.04%); 2-(hydroxymethyl)-2-nitropropane-1,3-diol (11.21%) and 3,5-dihydroxy-6-methyl-2,3-dihydropyran-4-one (4.15%). The presence of three new phytocompounds that are 4-(hydroxymethyl)-7-methyl-1,3-dioxepane-5,6-diol; 1-(4-isopropylphenyl)-2-methylpropylacetate and 4,4,6 A,6B,8A,11,11,14B-octamethyl-1,4,4A,5,6,6A,8,8a,910,11,12,12a,12b,13,14,14a,14b-ctadecahydro-3(2H)-picenone are detected in the extract. Metabolite profiles of the extract also constitute isoeugenol, stigmasterol, ergosterol, ocimene, myrcene, squalene, sphingosine, betulin, methyl ferulate and cis-jasmone, which are unraveled by 1 D 1H and 2 D 1H-13C HSQC NMR spectroscopy. This article focuses on the presence of different phytocompounds in PK in order to demonstrate its efficacy as a therapeutic formulation for a variety of diseases.

Novel CYP11A1-Derived Vitamin D and Lumisterol Biometabolites for the Management of COVID-19.

Vitamin D deficiency is associated with a higher risk of SARS-CoV-2 infection and poor outcomes of the COVID-19 disease. However, a satisfactory mechanism explaining the vitamin D protective effects is missing. Based on the anti-inflammatory and anti-oxidative properties of classical and novel (CYP11A1-derived) vitamin D and lumisterol hydroxymetabolites, we have proposed that they would attenuate the self-amplifying damage in lungs and other organs through mechanisms initiated by interactions with corresponding nuclear receptors. These include the VDR mediated inhibition of NFκß, inverse agonism on RORγ and the inhibition of ROS through activation of NRF2-dependent pathways. In addition, the non-receptor mediated actions of vitamin D and related lumisterol hydroxymetabolites would include interactions with the active sites of SARS-CoV-2 transcription machinery enzymes (Mpro;main protease and RdRp;RNA dependent RNA polymerase). Furthermore, these metabolites could interfere with the binding of SARS-CoV-2 RBD with ACE2 by interacting with ACE2 and TMPRSS2. These interactions can cause the conformational and dynamical motion changes in TMPRSS2, which would affect TMPRSS2 to prime SARS-CoV-2 spike proteins. Therefore, novel, CYP11A1-derived, active forms of vitamin D and lumisterol can restrain COVID-19 through both nuclear receptor-dependent and independent mechanisms, which identify them as excellent candidates for antiviral drug research and for the educated use of their precursors as nutrients or supplements in the prevention and attenuation of the COVID-19 disease.

Hepatoprotective Constituents of Macrocybe gigantea (Agaricomycetes) from India.

Non-alcoholic fatty liver disease (NAFLD) is one of the most frequent, chronic liver diseases worldwide and currently has no specific therapy. Our previous study indicated the anti-NAFLD effect of Macrocybe gigantea (Massee) Pegler & Lodge in high-fat diet-fed animals. This study aimed to isolate and identify the active hepatoprotective constituents from M. gigantea using fatty acid induced steatotic HepG2 cells as in vitro model. The effect of the test materials on the viability of HepG2 cells was analyzed using MTT assay. The HepG2 cells were treated with a mixture of palmitate-oleate to induce steatosis; after 24 h of treatment with the test materials, the intracellular lipid content was estimated using Oil Red O staining. The levels of transaminases were also estimated in the spent media. Bioassay-guided isolation of hepatoprotective constituents from M. gigantea yielded two compounds viz., ergosterol and linoleic acid; their structures were confirmed using spectroscopic data. Among these two compounds, ergosterol significantly lowered the levels of intracellular triglyceride content of fatty acid induced HepG2 cells; it also lowered the leakage of transaminases. The reductions caused by linoleic acid were not statistically significant at the tested concentrations. Detailed investigations on efficacy and safety of these compounds and M. gigantea might yield some useful leads for the management of NAFLD.

Structural basis for activation of fungal sterol receptor Upc2 and azole resistance.

Fungal transcription factor Upc2 senses ergosterol levels and regulates sterol biosynthesis and uptake. Constitutive activation of Upc2 causes azole resistance in Candida species. We determined the structure of ergosterol-bound Upc2, revealing the ligand specificity and transcriptional regulation. Ergosterol binding involves conformational changes of the ligand-binding domain, creating a shape-complementary hydrophobic pocket. The conserved helix α12 and glycine-rich loop are critical for sterol recognition by forming the pocket wall. The mutations of the glycine-rich loop inhibit ligand binding by steric clashes and constitutively activate Upc2. The translocation of Upc2 is regulated by Hsp90 chaperone in a sterol-dependent manner. Ergosterol-bound Upc2 associates with Hsp90 using the C-terminal tail, which retains the inactive Upc2 in the cytosol. Ergosterol dissociation induces a conformational change of the C-terminal tail, releasing Upc2 from Hsp90 for nuclear transport by importin α. The understanding of the regulatory mechanism provides an antifungal target for the treatment of azole-resistant Candida infections.

Chemical fingerprinting, comparative in vitro antioxidant properties, and biochemical effects of ginger and bitterleaf infusion.

Botanicals with remarkable pharmacological properties include Zingiber officinale Roscoe [Zingiberaceae] (ginger) and Gymnanthemum amygdalinum (Delie) Sch. Bip [Asteraceae] (bitterleaf). The plants are frequently used as teas and decoctions, and have been studied in the treatment of various illnesses. Thus, this study investigated the in vitro antioxidant activities and chemical fingerprints of ginger and bitter leaf infusions separately and as a combination. In addition, we assessed the effects of the tea infusions on rat liver and kidney indices. The findings from this study showed that the bitterleaf infusion had the highest phenolic content (21.77 ± 3.140 µg gallic acid equivalent/mg) in comparison with that of ginger (15.17 ± 1.50 µg gallic acid equivalent/mg) and their combination (8.81 ± 0.48 µg gallic acid equivalent/mg). The ginger infusion had the highest flavonoid content (547.15 ± 1.17 µg quercetin equivalent/mg), which was preceded by bitterleaf (473.02 ± 10.48 µg quercetin equivalent/mg) and the ginger and bitterleaf infusion (415.08 ± 4.15 µg quercetin equivalent/mg). Furthermore, our results showed that the tea infusions had no significant effect on the liver function indices (ALT and AST) compared to the control. In contrast, the rat plasma urea significantly increased in the groups given bitterleaf and a combination of ginger and bitterleaf infusions, while creatinine significantly decreased in the group that received the combined form of the infusion. The GC-MS analysis of ginger and bitterleaf infusions revealed that n-hexadecanoic acid, oleic acid, and ergosterol were most abundant in the bitterleaf infusion. At the same time, gingerol, 2-butanone, and 4-(4-hydroxy-3-methoxyphenyl) were the most abundant in the ginger infusion. Together, the findings are not only evidence in support of the medicinal value of these plants but also reinforce their prospects as nutriceuticals.

Design, Synthesis, and Biological Evaluation of Dual-Target COX-2/CYP51 Inhibitors for the Treatment of Fungal Infectious Diseases.

The design of novel dual-target (COX-2/CYP51) inhibitors was proposed in the study, and three series of compounds were constructed though the pathway of skeleton screening and combination; their molecular structures were synthesized and evaluated. Most of the compounds exhibited significant antifungal ability. Among them, potential compounds (10a-2, 16b-3) with excellent antifungal and anti-drug-resistant fungal ability (MIC50, 0.125-2.0 µg/mL) were selected for the subsequent mechanistic study. On the one hand, these compounds could block the ergosterol biosynthesis pathway by inhibiting CYP51 and influence the internal physiological function of fungal cells, which included the increase of the ROS level, the anomaly of ΔΨm, and the emergence of an apoptotic state. On the other hand, these compounds also effectively showed COX-2 inhibition ability, eliminated the inflammatory reaction of the infected region, and activated the body's immune function. In summary, this study not only provided a novel antifungal drug design pathway but also discovered excellent target compounds.

The induced cryptic metabolites and antifungal activities from culture of Penicillium chrysogenum by supplementing with host Ziziphus jujuba extract.

The productions of cryptic metabolites including three undescribed drimane sesquiterpenoids, penicichrins A-C, and three known compounds from Penicillium chrysogenum were activated by the host Ziziphus jujuba medium. The structures were established by comprehensive analysis of spectroscopic data. The spiro ß-lactone, and gem-dimethyl dihydroxylation in induced penicichrins A-C were rare in natural products. Cryptic metabolites, monaspurpurone was first found in Penicillium. 4-Methoxy-3-methylgoniothalamin, and 2-hydroxy-l-phenyl-l,4-pentanedione were second example of isolation. Penicichrin A, monaspurpurone, 4-methoxy-3-methylgoniothalamin, physcion, ergosterol, and ergosta-7,22-dien-3ß-ol had antifungal activities against phytopathogens, P. chrysogenum, Alternaria alternata and Aspergillus fumigatus with MICs ≤2 µg/mL, and 2-hydroxy-l-phenyl-l,4-pentanedione had flowering activity. So the chemical constituents from Z. jujuba could induce the productions of cryptic metabolites with plant growth-promoting activity from endophyte P. chrysogenum.

An Integrated Transcriptomics and Lipidomics Analysis Reveals That Ergosterol Is Required for Host Defense Against Bacterial Infection in Drosophila.

Animals adjust their lipid metabolism states in response to pathogens infection. However, the underlying molecular mechanisms for how lipid metabolism responds to infection remain to be elusive. In this study, we assessed the temporal changes of lipid metabolism profiles during infection by an integrated transcriptomics and lipidomics analysis. Ergosterol is identified to be required for proper host defense to pathogens. Notably, ergosterol level is increased in the hemolymph upon bacterial infection. We show that the increase of ergosterol level by food supplement or genetic depletion of Acsl, a long-chain fatty acid-CoA synthetase, promotes host survival against bacterial challenges. Together, our results suggest a critical role of lipid metabolism adaption in the process of host defense against invading pathogens.

Improved osmotic stress tolerance in brewer's yeast induced by wheat gluten peptides.

The influences of three wheat gluten peptides (WGP-LL, WGP-LML, and WGP-LLL) on the osmotic stress tolerance and membrane lipid component in brewer's yeast were investigated. The results demonstrated that the growth and survival of yeast under osmotic stress were enhanced by WGP supplementation. The addition of WGP upregulated the expressions of OLE1 (encoded the delta-9 fatty acid desaturase) and ERG1 (encoded squalene epoxidase) genes under osmotic stress. At the same time, WGP addition enhanced palmitoleic acid (C16:1) content, unsaturated fatty acids/saturated fatty acids ratio, and the amount of ergosterol in yeast cells under osmotic stress. Furthermore, yeast cells in WGP-LL and WGP-LLL groups were more resistant to osmotic stress. WGP-LL and WGP-LLL addition caused 25.08% and 27.02% increase in membrane fluidity, 22.36% and 29.54% reduction in membrane permeability, 18.38% and 14.26% rise in membrane integrity in yeast cells, respectively. In addition, scanning electron microscopy analysis revealed that the addition of WGP was capable of maintaining yeast cell morphology and reducing cell membrane damage under osmotic stress. Thus, alteration of membrane lipid component by WGP was an effective approach for increasing the growth and survival of yeast cells under osmotic stress. KEY POINTS: •WGP addition enhanced cell growth and survival of yeast under osmotic stress. •WGP addition increased unsaturated fatty acids and ergosterol contents in yeast. •WGP supplementation improved membrane homeostasis in yeast at osmotic stress.