Ester-related volatile compounds reveal the diversity and commonalities of different types of late-ripening peaches.

To recognize the key ester-related volatile compounds, 5 types of peaches including 54 late-ripening peach materials were examined by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry and E-nose. Here, a large number of esters were identified to be released by ripe peach fruits and were mainly characterized by fruity, green, and fatty notes. The variety and content of esters had greatly changed within or between cultivars, indicating that the fruit volatiles were highly differentiated depending on the specific genotypes and cultivation conditions. The ester types showed that fatty acid-derived C6 alcohols and methyl-/ethyl- short-chain alcohol were the main ester precursors, which were more likely to be utilized and well selected by alcohol acyltransferases, whereas the preference of acyl donors was not observed. The common peach type, which exhibited a unique volatile profile, displayed broader diversity and more abundant characteristics in ester-related volatiles than the other four types. A total of 19 key esters were identified as the main components and the content of most esters showed no significant difference among different peach types. Some key esters had even been enriched in nectarines. Moreover, the multiple discriminant analysis revealed a possible relationship between peach types and the domestication of the peach evolution. This study investigated ester-related volatiles released by different types of peach fruits and can be further used to evaluate the peach qualities, providing an important reference for peach breeding and processing.

Proteomic insights into the response of Halomonas sp. MNB13 to excess Mn(â ¡) and the role of H2S in Mn(â ¡) resistance.

Halomonas spp. are moderately halophilic bacteria with the ability to tolerate various heavy metals. However, the role of basic cellular metabolism, particularly amino acid metabolism, has not been investigated in Halomonas spp. under excess Mn(Ⅱ). The strain Halomonas sp. MNB13 was isolated from a deep-sea ferromanganese nodule and can tolerate 80 mM Mn(Ⅱ). To comprehensively explore the mechanisms underlying its resistance to excess Mn(Ⅱ), we conducted a comparative proteome analysis. The data revealed that both 10 mM and 50 mM Mn(Ⅱ) significantly up-regulated the expression of proteins involved in Mn(Ⅱ) transport (MntE), oxidative stress response (alkyl hydroperoxide reductase and the Suf system), and amino acid metabolism (arginine, cysteine, methionine, and phenylalanine). We further investigated the role of cysteine metabolism in Mn(Ⅱ) resistance by examining the function of its downstream product, H2S. Consistent with the up-regulation of cysteine desulfurase, we detected an elevated level of H2S in Halomonas sp. MNB13 cells under Mn(Ⅱ) stress, along with increased intracellular levels of H2O2 and O2•-. Upon exogenous addition of H2S, we observed a significant restoration of the growth of Halomonas sp. MNB13. Moreover, we identified decreased intracellular levels of H2O2 and O2•- in MNB13 cells, which coincided with a decreased formation of Mn-oxides during cultivation. In contrast, in cultures containing NaHS, the residual Mn(Ⅱ) levels were higher than in cultures without NaHS. Therefore, H2S improves Mn(Ⅱ) tolerance by eliminating intracellular reactive oxygen species rather than decreasing Mn(Ⅱ) concentration in solution. Our findings indicate that cysteine metabolism, particularly the intermediate H2S, plays a pivotal role in Mn(Ⅱ) resistance by mitigating the damage caused by reactive oxygen species. These findings provide new insights into the amino acid mechanisms associated with Mn(Ⅱ) resistance in bacteria.

Chemical components of Fu brick tea and its potential preventive effects on metabolic syndrome.

As living standards advance, an escalating emphasis is placed on health, particularly in relation to prevalent chronic metabolic disorders. It is necessary to explore safe and effective functional foods or drugs. Fu brick tea (FBT) is a kind of dark tea fermented by fungi. The extracts are rich in compounds that can effectively relieve metabolic diseases such as hyperglycemia and hyperlipidemia, protect the liver, improve human immunity, enhance antioxidant activity, and regulate intestinal flora. This paper summarizes the biological activities and mechanisms of the extracts, polysaccharides, and small molecular compounds of FBT, which provides a certain theoretical basis for the rational, systematic, comprehensive development and utilization of the FBT resources. It is expected to develop and apply these active substances in health care products and natural medicines and provide more beneficial and diversified FBT products for human beings.

Recent Updates on the Antimicrobial Compounds from Marine-Derived Penicillium fungi.

In this review, 72 compounds isolated from marine-derived Penicillium fungi and their antimicrobial activities are reviewed from 2020 to 2023. According to their structures, these compounds can be divided into terpenoids, polyketides, alkaloids and other structural compounds, among which terpenoids and polyketides are relatively large in number. Some compounds have powerful inhibitory effects against different pathogenic bacteria and fungi. This review aims to provide more useful information and enlightenment for further efficient utilization of Penicillium spp. and their secondary metabolites.

2-Heptanone, 2-nonanone, and 2-undecanone confer oxidation off-flavor in cow milk storage.

Flavor sensation is one of the most prevalent characteristics of food industries and an important consumer preference regulator of dairy products. So far, many volatile compounds have been identified, and their molecular mechanisms conferring overall flavor formation have been reported extensively. However, little is known about the critical flavor compound of a specific sensory experience in terms of oxidized off-flavor perception. Therefore, the present study aimed to compare the variation in sensory qualities and volatile flavors in full-fat UHT milk (FFM) and low-fat UHT milk (LFM) samples under different natural storage conditions (0, 4, 18, 25, 30, or 37°C for 15 and 30 d) and determine the main component causing flavor deterioration in the FFM and LFM samples using sensory evaluation, electronic nose, and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). In addition, the Pearson correlation between the volatile flavor components and oxidative off-flavors was analyzed and validated by sensory reconstitution studies. Compared with the LFM samples, the FFM samples showed a higher degree of quality deterioration with increased storage temperature. Methyl ketones of odd carbon chains (i.e., 2-heptanone, 2-nonanone, 2-undecanone, 2-tridecanone, and 2-pentadecanone) reached a maximum content in the FFM37 samples over 30 d storage. The combined results of the Pearson correlation and sensory recombination study indicated that 2-heptanone, 2-nonanone, and 2-undecanone conferred off-flavor perception. Overall, the present study results provide potential target components for detecting and developing high-quality dairy products and lay a foundation for specific sensory flavor compound exploration in the food industry.

Killing of Staphylococcus aureus persisters by a multitarget natural product chrysomycin A.

Staphylococcus aureus poses a severe public health problem as one of the vital causative agents of healthcare- and community-acquired infections. There is a globally urgent need for new drugs with a novel mode of action (MoA) to combat S. aureus biofilms and persisters that tolerate antibiotic treatment. We demonstrate that a benzonaphthopyranone glycoside, chrysomycin A (ChryA), is a rapid bactericide that is highly active against S. aureus persisters, robustly eradicates biofilms in vitro, and shows a sustainable killing efficacy in vivo. ChryA was suggested to target multiple critical cellular processes. A wide range of genetic and biochemical approaches showed that ChryA directly binds to GlmU and DapD, involved in the biosynthetic pathways for the cell wall peptidoglycan and lysine precursors, respectively, and inhibits the acetyltransferase activities by competition with their mutual substrate acetyl-CoA. Our study provides an effective antimicrobial strategy combining multiple MoAs onto a single small molecule for treatments of S. aureus persistent infections.

New bisabolane-type sesquiterpenoid from Aspergillus sydowii BTBU20213012.

A new bisabolane-type sesquiterpenoid, named (+)-8-dehydroxylaustrosene (1), along with ten known compounds, penicibisabolanes E (2) and G (3), (+)-austrosene (4), (S)-(+)-11-dehydrosydonic acid (5), sydonic acid (6), (7S,11S)-(+)-12-hydroxysydonic acid (7), (-)-(R)-hydroxysydonic acid (8), pseudaboydin A (9), (-)-(7 R,10R)-iso-10-hydroxysydowic acid (10), lumichrome (11), were identified from the fungus Aspergillus sydowii BTBU20213012 isolated from a marine sediment sample from the Western Pacific. The structures of the compounds were identified by HRESIMS and NMR data analysis. Compound 11 showed weak antimicrobial activity against Staphylococcus aureus with MIC value of 200 µg/mL.

Enhanced Transdermal Peptide-Modified Flexible Liposomes for Efficient Percutaneous Delivery of Chrysomycin A to Treat Subcutaneous Melanoma and Intradermal MRSA Infection.

Superficial skin diseases, including skin infections and tumors, are common healthcare burdens. In this study, the in vivo activity of chrysomycin A (CA) is explored, and a transdermal liposomal CA formulation is further constructed for the simultaneous treatment of cutaneous melanoma and cutaneous methicillin-resistant Staphylococcus aureus (MRSA) infection. The prepared liposomes (TD-LP-CA) display a strong antitumor effect with an IC50 value of less than 0.1 µm in B16-F10 cells, suppress the proliferation of MRSA with a minimum inhibitory concentration (MIC) of 1 µm, and eradicate established MRSA biofilms at 10× MIC in vitro. More importantly, TD-LP-CA shows enhanced stratum corneum (SC) penetration, reaching more than 500 µm beneath the skin's surface due to modification with the TD peptide, and demonstrates excellent subcutaneous tumor penetration after skin application in vivo. TD-LP-CA displays an excellent therapeutic effect against intradermal MRSA infection in mice after topical dermal administration, as well as a moderate inhibitory effect on subcutaneous melanoma with a 75% tumor inhibition rate. The liposomes prepared herein can be a promising carrier for transcutaneous CA transfer for the treatment of superficial diseases such as skin tumors and infections due to their ability to overcome the skin barrier.

Chrysomycin A Regulates Proliferation and Apoptosis of Neuroglioma Cells via the Akt/GSK-3ß Signaling Pathway In Vivo and In Vitro.

Glioblastoma (GBM) is a major type of primary brain tumor without ideal prognosis and it is therefore necessary to develop a novel compound possessing therapeutic effects. Chrysomycin A (Chr-A) has been reported to inhibit the proliferation, migration and invasion of U251 and U87-MG cells through the Akt/GSK-3ß signaling pathway, but the mechanism of Chr-A against glioblastoma in vivo and whether Chr-A modulates the apoptosis of neuroglioma cells is unclear. The present study aims to elucidate the potential of Chr-A against glioblastoma in vivo and how Chr-A modulates the apoptosis of neuroglioma cells. Briefly, the anti-glioblastoma activity was assessed in human glioma U87 xenografted hairless mice. Chr-A-related targets were identified via RNA-sequencing. Apoptotic ratio and caspase 3/7 activity of U251 and U87-MG cells were assayed via flow cytometry. Apoptosis-related proteins and possible molecular mechanisms were validated via Western blotting. The results showed that Chr-A treatment significantly inhibits glioblastoma progression in xenografted hairless mice, and enrichment analysis suggested that apoptosis, PI3K-Akt and Wnt signaling pathways were involved in the possible mechanisms. Chr-A increased the apoptotic ratio and the activity of caspase 3/7 in U251 and U87-MG cells. Western blotting revealed that Chr-A disturbed the balance between Bax and Bcl-2, activating a caspase cascade reaction and downregulating the expression of p-Akt and p-GSK-3ß, suggesting that Chr-A may contribute to glioblastoma regression modulating in the Akt/GSK-3ß signaling pathway to promote apoptosis of neuroglioma cells in vivo and in vitro. Therefore, Chr-A may hold therapeutic promise for glioblastoma.

Co-functional Group Conducting Hydrogels Inspired by Ligament for Flexible Electronic Devices.

The application of conductive hydrogels in flexible electronics has attracted much interest in recent years due to their excellent mechanical properties and conductivity. However, the development of conductive hydrogels combining with superior self-adhesion, mechanical properties, antifreeze, and antibacterial activity is still a challenge. Herein, inspired by the structure of the ligament, a multifunctional conductive hydrogel is constructed to address the issue by introducing collagen into the polyacrylamide. The obtained conductive hydrogel exhibits outstanding conductivity (52.08 mS/cm), ultra-stretchability (>2000%), self-adhesion, and antibacterial properties. More significantly, the supercapacitor based on this hydrogel electrolyte achieves a desirable capacitance (514.7 mF·cm-2 at 0.25 mA·cm-2 current density). As a wearable strain sensor, the obtained hydrogel can rapidly detect different movements of the body such as finger, wrist, elbow, and knee joints. It is conceived that this study would provide a potential approach for the preparation of conductive hydrogels in the application of flexible electronics.

Marine Aspergillus: A Treasure Trove of Antimicrobial Compounds.

Secondary metabolites from marine organisms are diverse in structure and function. Marine Aspergillus is an important source of bioactive natural products. We reviewed the structures and antimicrobial activities of compounds isolated from different marine Aspergillus over the past two years (January 2021-March 2023). Ninety-eight compounds derived from Aspergillus species were described. The chemical diversity and antimicrobial activities of these metabolites will provide a large number of promising lead compounds for the development of antimicrobial agents.

Assessing Sensory Attributes and Properties of Infant Formula Milk Powder Driving Consumers' Preference.

Infant formula milk powder (IFMP) is an excellent substitute for breast milk. It is known that the composition of maternal food during pregnancy and lactation and exposure level to food during infancy highly influence taste development in early infancy. However, little is known about the sensory aspects of infant formula. Herein, the sensory characteristics of 14 brands of infant formula segment 1 marketed in China were evaluated, and differences in preferences for IFMPs were determined. Descriptive sensory analysis was performed by well-trained panelists to determine the sensory characteristics of evaluated IFMPs. The brands S1 and S3 had significantly lower astringency and fishy flavor compared to the other brands. Moreover, it was found that S6, S7 and S12 had lower milk flavor scores but higher butter scores. Furthermore, internal preference mapping revealed that the attributes fatty flavor, aftertaste, saltiness, astringency, fishy flavor and sourness negatively contributed to consumer preference in all three clusters. Considering that the majority of consumers prefer milk powders rich in aroma, sweet and steamed flavors, these attributes could be considered for enhancement by the food industry.

The Hypolipidemic Characteristics of a Methanol Extract of Fermented Green Tea and Spore of Eurotium cristatum SXHBTBU1934 in Golden Hamsters.

Fuzhuan brick tea (FBT), a distinctive Chinese dark tea with the predominant fungus of Eurotium cristatum, offered significant health benefits to Chinese people. In the current study, the in vivo bioactivities of E. cristatum (SXHBTBU1934) fermented green tea and spores of E. cristatum fermented on wheat were investigated, respectively. The methanol extract of fermented green tea and spore of E. cristatum both showed potent lipid-lowering activity in the blood of a high-fat diet induced hyperlipidemia model in golden hamsters and significantly reduced the accumulation of fat granules in the liver. These results indicated that the key active components were produced by E. cristatum. Chemical investigations suggested similar components in the two extracts and led to the identification of a new alkaloid, namely variecolorin P (1), along with four known structurally related compounds, (-)-neoechinulin A (2), neoechinulin D (3), variecolorin G (4), and echinulin (5). The structure of the new alkaloid was elucidated by HRESIMS, 1H, 13C, and 2D NMR analysis. The lipid-lowering activity of these compounds was evaluated using an oleic acid-induced HepG2 cell line model. Compound 1 significantly reduced the lipid accumulation in the HepG2 cell line with an IC50 value of 0.127 µM.

A new phenyl 6,7-dihydroxygeranyl ether derivative from a marine-derived fungus strain of Penicillium arabicum ZH3-9.

A new phenyl 6,7-dihydroxygeranyl ether derivative, named (Z)-4-((6,7-dihydroxy-3,7-dimethyloct-2-en-1-yl)oxy)benzoic acid (1), and 8 known compounds (2-9) were characterized from a marine-derived fungus strain of Penicillium arabicum ZH3-9 isolated from a mud sample collected from the coast of Zhuhai, Guangdong Province, China. The structure of 1 was elucidated by HRESIMS, 1 D and 2 D NMR. All compounds were evaluated antimicrobial activities against Candida albicans, Staphylococcus aureus, and Escherichia coli. Compounds 4-6 displayed antibacterial activity against S. aureus with minimum inhibitory concentrations of 50, 12.5, and 50 µg/mL.

Comparative Transcriptome Analysis of Two Chrysomycin-Producing Wild-Type and Mutant Strains of Streptomyces sp. 891.

Chrysomycin A (CA), a promising antibiotic agent, usually coexists with two analog chrysomycins B (CB) and C (CC) produced by several wild-type (WT) Streptomyces strains. With the aim to increase CA production, UV mutagenesis-based breeding had been employed on a marine-derived strain Streptomyces sp. 891 in our previous study and afforded an improved strain 891-B6 with enhanced CA yield. By comparative transcriptome analysis, significant differences in chrysomycin BGC-related gene expression between the WT strain 891 and the mutant strain 891-B6 were unveiled in the current study. Among 25 up-regulated genes in mutant 891-B6, chryA, chryB, chryC, chryF, chryG, chryK, chryP, and chryQ, responsible for the biosynthesis of benzonaphthopyranone aglycone, and chryD, chryE, and chryU in charge of production of its deoxyglycoside, were characterized. Furthermore, the expression of genes chryOII, chryOIII, and chryOIV responsible for the formation of 8-vinyl in CA from 8-ethyl in CB were greatly enhanced in strain 891-B6. These findings provide molecular mechanisms for increased yield of CA and decreased yield of CB for mutant 891-B6, which has potential application in industrial CA production.

Antimicrobial Natural Products.

Infectious diseases, resulting from microbial pathogens, are one of the major causes of morbidity and mortality worldwide [...].

Investigation on the chemical constituents of the marine-derived fungus strain Aspergillus brunneoviolaceus MF180246.

Aspergillus have been proven to be excellent resources for new natural products. During our systematic biodiversifying new compounds from marine derived fungi, one novel compound, asperbrunneo acid (1), along with seven bistetrahydroxanthone analogues, secalonic acid D (2), secalonic acid F (3), secalonic acid F1 (4), secalonic acid H (5), penicillixanthone A (6), chrysoxanthone C (7), and asperdichrome (8), one ketodivinyllactonic steroid, herbarulide (9), as well as one tyrosine-derived compound, aspergillusol A (10), were isolated from the marine-derived fungus Aspergillus brunneoviolaceus MF180246. These structures were elucidated by HRMS, 1 D and 2 D NMR analysis. Compound 1 possessed the first reported new carbon skeleton natural product. Compounds 1, 4, 5, 6, 7 and 8 showed antibacterial activity against Staphylococcus aureus with minimum inhibitory concentration values of 200, 25, 50, 6.25, 50, and 25 µg/ml, respectively.

Chrysomycin A Inhibits the Proliferation, Migration and Invasion of U251 and U87-MG Glioblastoma Cells to Exert Its Anti-Cancer Effects.

Chrysomycin A (Chr-A), an antibiotic from Streptomyces, is reported to have anti-tumor and anti-tuberculous activities, but its anti-glioblastoma activity and possible mechanism are not clear. Therefore, the current study was to investigate the mechanism of Chr-A against glioblastoma using U251 and U87-MG human cells. CCK8 assays, EdU-DNA synthesis assays and LDH assays were carried out to detect cell viability, proliferation and cytotoxicity of U251 and U87-MG cells, respectively. Transwell assays were performed to detect the invasion and migration abilities of glioblastoma cells. Western blot was used to validate the potential proteins. Chr-A treatment significantly inhibited the growth of glioblastoma cells and weakened the ability of cell migration and invasion by down regulating the expression of slug, MMP2 and MMP9. Furthermore, Chr-A also down regulated Akt, p-Akt, GSK-3ß, p-GSK-3ß and their downstream proteins, such as ß-catenin and c-Myc in human glioblastoma cells. In conclusion, Chr-A may inhibit the proliferation, migration and invasion of glioblastoma cells through the Akt/GSK-3ß/ß-catenin signaling pathway.

Biocontrol of Candida albicans by Antagonistic Microorganisms and Bioactive Compounds.

Candida albicans is an endogenous opportunistic pathogenic fungus that is harmless when the host system remains stable. However, C. albicans could seriously threaten human life and health when the body's immune function declines or the normal flora is out of balance. Due to the increasing resistance of candidiasis to existing drugs, it is important to find new strategies to help treat this type of systemic fungal disease. Biological control is considered as a promising strategy which is more friendly and safer. In this review, we compare the bacteriostatic behavior of different antagonistic microorganisms (bacteria and fungi) against C. albicans. In addition, natural products with unique structures have attracted researchers' attention. Therefore, the bioactive nature products produced by different microorganisms and their possible inhibitory mechanisms are also reviewed. The application of biological control strategies and the discovery of new compounds with antifungal activity will reduce the resistance of C. albicans, thereby promoting the development of novel diverse antifungal drugs.

Comparative transcriptomic analysis of Stenotrophomonas sp. MNB17 revealed mechanisms of manganese tolerance at different concentrations and the role of histidine biosynthesis in manganese removal.

Bacteria possess protective mechanisms against excess Mn(Ⅱ) to reduce its toxicity. Stenotrophomonas sp. MNB17 showed high Mn(Ⅱ) removal capacity (92.24-99.16 %) by forming Mn-precipitates (MnCO3 and Mn-oxides), whose Mn-oxides content increased with increasing Mn(Ⅱ) concentrations (10-50 mM). Compared with 0 mM Mn(Ⅱ)-stressed cells, transcriptomic analysis identified genes with the same transcriptional trends in 10 mM and 50 mM Mn(Ⅱ)-stressed cells, including genes involved in metal transport, cell envelope homeostasis, and histidine biosynthesis, as well as genes with different transcriptional trends, such as those involved in oxidative stress response, glyoxylate cycle, electron transport, and protein metabolism. The upregulation of histidine biosynthesis and oxidative stress responses were the most prominent features of these metabolisms under Mn(Ⅱ) stress. We confirmed that the increased level of reactive oxygen species was one of the reasons for the increased Mn-oxides formation at high Mn(Ⅱ) concentrations. Metabolite analysis indicated that the enhanced histidine biosynthesis rather than the tricarboxylic acid cycle resulted in an elevated level of α-ketoglutarate, which helped eliminate reactive oxygen species. Consistent with these results, the exogenous addition of histidine significantly reduced the production of reactive oxygen species and Mn-oxides and enhanced the removal of Mn(Ⅱ) as MnCO3. This study is the first to correlate histidine biosynthesis, reactive oxygen species, and Mn-oxides formation at high Mn(Ⅱ) concentrations, providing novel insights into the molecular regulatory mechanisms associated with Mn(Ⅱ) removal in bacteria.