Yuele Lu

Objective: The study aims to tackle the limitation of natural plant‐based oils in insufficient potency for addressing complex skin issues and explore a strategy to enhance the value of natural oils in skincare. A dihydroquercetin (DHQ) enriched eleven‐seed fermented oil (DrEFO) was achieved by fermenting an eleven‐seed oil (ESO). Materials and Methods: The distinctive antioxidant property of DHQ was first measured by DPPH radical scavenging experiment to evaluate its long‐term antioxidant capacity and its continuous antioxidant effect. To assess the distinctive long‐term antioxidation property of DHQ, DHQ was subjected to harsh real‐life conditions such as UV stress and thermal attack and monitored its antioxidant activity. To determine its continuous antioxidant effect, DPPH was continuously introduced into the system and the antioxidation result was measured. Then, a S. cerevisiae strain was engineered via synthetic biology approaches to produce DHQ, which was then used for large‐scale fermentation of DrEFO. The antioxidant property of DrEFO was tested by measuring the DPPH radical scavenging rate, as well as scavenging rates against ABTS, hydroxyl, superoxide anion, PTIO, and ROS radicals. The collagen synthesis boosting effect was also evaluated in cell models. Results: When exposed to harsh daily‐life conditions like UV stress and thermal attack, DHQ impressively retained its ability to combat oxidative stress over an extended period, clearly showcasing its long‐term protective effect. More significantly, DHQ was able to continuously neutralize DPPH radicals as they were introduced into the system. Thorough fermentation, more than 1000 ppm of DHQ was detected in DrEFO. DrEFO also showed outstanding antioxidant properties. Its DPPH radical scavenging rate was 4.3 times that of ESO, and it had high scavenging rates against multiple other radicals. In cell models, DrEFO significantly boosted collagen synthesis. Conclusion: These findings highlight DrEFO's potential as an effective skincare solution for various skin concerns. Moreover, this research pioneers a new way to enhance the value of natural oils in skincare by leveraging the power of fermentation. It transforms the capabilities of traditional natural oils to meet the diverse needs of consumers.

Pesticide residues on vegetables may affect microbes and metabolites during the fermentation process, leading to effects and potential risks. Here, the enantioselective effects and potential risks of chiral penflufen on pickled cowpea were investigated by using microbiome and metabolomics analyses. Correlation analysis was conducted to construct bacterial-metabolite interaction networks. Penflufen enantiomers were degraded little during the fermentation process. Rac-penflufen treatment significantly decreased the relative abundance of Lactiplantibacillus while increasing Weissella, but the opposite effects were found in R- and S-penflufen treatments. These shifts were linked to content and functional changes of metabolites. R-/S-/Rac-penflufen upregulated rose aroma metabolites (e.g., β-damascenone), while R- and S-penflufen downregulated floral aroma metabolites (e.g., β-ionone, 2-nonenal) and green leaf aroma metabolites (e.g., (E)-2-hexenal). S-Penflufen reduced alcohols and increased esters more significantly, and altered a higher number of volatile organic compounds (VOCs) and chiral amino acids than R-penflufen, showing a greater risk to food flavor and nutritional quality.

Cyclodextrin glycosyltransferase (CGTase) can catalyze the glycosylation of hesperidin, resulting in α-glycosyl hesperidin with significantly improved water solubility. In this study, a rational design of CGTase to improve its hesperidin glycosylation activity was investigated. The strategy we employed involved docking hesperidin in its near-attack conformation and virtually mutating the surrounding residues, followed by calculating the changes in binding energy using Rosetta flex-ddG. The mutations with a stabilization effect were then subjected to an activity assay. Starting from CGTase-Y217F, we obtained three double-point mutants, Y217F/M351F, Y217F/M351L, and Y217F/D393H, with improved hesperidin glycosylation activities after screening twenty variants. The best variant, Y217F/D393H, exhibited a catalytic activity of 1305 U/g, and its kcat/KmA is 2.36 times higher compared to CGTase-Y217F and 15.14 times higher compared to the wild-type CGTase. Molecular dynamic simulations indicated that hesperidin was repulsed by CGTase-Y217F when bound in a near-attack conformation. However, by introducing a second-point mutation with a stabilization effect, the repulsion effect is weakened, resulting in a reduction in the distances between the bond-forming atoms and, thus, favoring the reaction.

The application of pesticides is critical during the growth of high-quality grape for wine making. However, pesticide residues have significant influence on the wine flavor. In this study, gas chromatography-mass spectrometry (GC-MS) was performed and the obtained datasets were analyzed with multivariate statistical methods to investigate changes in flavor substances in wine during fermentation. The principal component analysis (PCA) score plot showed significant differences in the metabolites of wine treated with various pesticides. In trials using five pesticides (hexaconazole, difenoconazole, flutriafol, tebuconazole, and propiconazole), more than 86 metabolites were changed. Most of these metabolites were natural flavor compounds, like carbohydrates, amino acids, and short-chain fatty acids and their derivatives, which essentially define the appearance, aroma, flavor, and taste of the wine. Moreover, the five pesticides added to grape pulp exhibited different effects on the metabolic pathways, involving mainly alanine, aspartate and glutamate metabolism, butanoate metabolism, arginine, and proline metabolism. The results of this study will provide new insight into the potential impact of pesticide residues on the metabolites and sensory profile of wine during fermentation.

2-O-α-d-Glucopyranosyl-l-ascorbic acid (AA-2G) is an ideal substitute for l-ascorbic acid because of its remarkable stability and improved biological activity, which can be easily applied in cosmetic, food, and medicine fields. However, impurity identification and control are significant procedures during the manufacturing of AA-2G. This study assessed a manufacturing routine of AA-2G synthesized by sucrose phosphorylase (SPase). First, three unknown process-related impurities were observed, which were further identified as 3-O-α-d-glucopyranosyl- l-ascorbic acid (impurity I), 2-O-α-d-glucopyranosyl-l-dehydroascorbic acid (impurity II), and 13-O-α-d-glucopyranosyl-2-O-α-d-glucopyranosyl-l-ascorbic acid (impurity III), respectively. Second, a comprehensive formation pathway of impurities was elucidated, and specific strategies corresponding to controlling each impurity were also proposed. Specifically, the content of impurity I can be reduced by 50% by fine tuning reaction conditions. The impurity II-free purification process was also achieved by applying a low concentration of alkali. Finally, a semi-rational design was introduced, and a single mutant L343F was obtained by site-directed mutagenesis, which reduced impurities I and III by 63.9 and 100%, respectively, without affecting the transglycosylation activity. It is expected that the reported impurity identification and control strategies during the AA-2G production will facilitate its industrial production.

The enantioselective behaviors of chiral pesticides would affect the accuracy of risk assessment. This study evaluated the enantioselectivity of chiral triticonazole (a widely used fungicide) in three kinds of fruits. Firstly, the enantioseparation of triticonazole enantiomers was carried out within 1.2 min utilizing CHIRALPAK OJ-3 column with a mixture of CO₂ and methanol (93:7, v/v) using SFC-MS/MS. Secondly, field trials were conducted to clarify the enantioselective degradation and residue of S-( +)-triticonazole and R-(–)-triticonazole in fruits. The initial concentrations of rac-triticonazole were 25.1–93.1 ng/g, and enantioselective degradation was observed in pear, peach, and jujube after 2 h, 10 days, and 3 days, respectively. The degradation of S-( +)-triticonazole was fastest in pear (T_1/2, 2.01 days), while the T_1/2 of R-(–)-triticonazole was 5.02 days. The residue concentrations of rac-triticonazole were less than the MRL set by EU (10 ng/g) on the 3rd and 21st day in pear and peach, respectively, which were lower than 10 ng/g in jujube on the 30th day (no MRL). Finally, we found that the dietary intake risks of rac-triticonazole in fruits were low for 2–7 age, 20–50 age/female, and 20–50 age/male. The current study could provide complimentary references for the rational usage, MRL formulation, and risk assessment of chiral triticonazole.

A novel strain with antifungal activity against Sclerotinia sclerotiorum was isolated from soil, and identified as Streptomyces sp. ZJUT-IFE-354 using morphological and 16S rDNA sequence analysis. The bioactive metabolite produced by strain ZJUT-IFE-354 was identified and characterized as valinomycin by spectroscopic and chemical methods. The yield of valinomycin was 191.26 mg/L from the culture of Streptomyces sp. ZJUT-IFE-354, which was the highest yield to our knowledge. The in vitro antifungal activity of valinomycin against S. sclerotiorum was investigated as 0.056 ± 0.012 (EC₅₀) and 0.121 ± 0.023 μg/mL (EC₉₅), respectively, which was approximately 10.696- and 30.960-fold more active than that of carbendazim. The results from scanning electron microscopy, cell membrane permeability, and _D-sorbitol and ergosterol assay indicated that valinomycin exerted the antifungal activity probably by increasing permeability of fungal cell membrane, leading to mycelial electrolyte leakage, and eventually resulting in the death of S. sclerotiorum. Thus, valinomycin may be a promising antifungal agent to control S. sclerotiorum.

l-Menthyl α-D-glucopyranoside (α-MenG) is a glycoside derivative of l-menthol with improved water-solubility and new flavor property as a food additive. α-MenG can be synthesized through biotransformation, but its scale-up production was rarely reported. In this study, the properties of an α-glucosidase from Xanthomonas campestris pv. campestris 8004 (Agl-2) in catalyzing the glucosylation of menthol was investigated. Agl-2 can almost completely glycosylate l-menthol (> 99%) when using 1.2 M maltose as glycosyl donor. Accumulated glucose resulted from maltose hydrolysis and transglycosylation caused the inhibition of the glucosylation rate (40% reduction of the glucosylation rate in the presence of 1.2 M glucose) which can be avoided through whole-cell catalysis with recombinant E. coli. Interestingly, in spite of the poor solubility of menthol, the productivity of α-MenG reached 24.7 g/(L·h) in a 2 L catalyzing system, indicating industrialization of the reported approach.

Natural compounds bearing maleimide rings are a series of secondary metabolites derived from fungi/marine microorganisms, which are characterized by a general structure –CO–N(R)–CO–, and the R group is normally substituted with alkyl or aryl groups. Maleimide compounds show various biological activities such as antibacterial, antifungal, and anticancer activity. In this review, the broad-spectrum antimicrobial activities of 15 maleimide compounds from natural sources and 32 artificially synthesized maleimides were summarized, especially against Candida albicans, Sclerotinia sclerotiorum, and Staphylococcus aureus. It highlights that maleimide scaffold has tremendous potential to be utilized in the development of novel antimicrobial agents. Graphical abstract

Chitin is an important part of the fungal cell wall, but is not found in plants and mammals, so chitin synthase (CHS) can be a green fungicide target. In this paper, 35 maleimide compounds were designed and synthesized as CHS inhibitors. All the screened compounds showed different degrees of CHS inhibitory activity and antifungal activity in vitro. In particular, the half–inhibitory concentration (IC₅₀) value of compound 20 on CHS was 0.12 mM, and the inhibitory effect was better than that of the control polyoxin B (IC₅₀ = 0.19 mM). At the same time, this compound also showed good antifungal activity and has further development value.