Antioxidant Capacity Research Articles

Biological activities, Peptidomics and in silico analysis of low-fat Cheddar cheese after in vitro digestion: Impact of blending camel and bovine Milk

Cheesemaking with camel milk (CM) presents unique challenges and additional health benefits. This study involved preparing low-fat Cheddar cheese (LFCC) by blending bovine milk (BM) with varying levels of CM. Control cheese was made exclusively with BM. After 180 days of ripening, LFCC samples underwent in vitro digestion to determine antioxidant capacities, α-amylase and α-glucosidase inhibition, and angiotensin-converting enzyme inhibition. The peptide profile of LFCC treatments was analyzed using liquid chromatography-quadrupole-time of flight-mass spectrometry. Antioxidant and biological activities were influenced by BM-CM blends and digestion. At days 120 and 180, the number of αs1-casein-derived peptides increased in all samples except for LFCC made with 15% CM. Generally, 88 peptides exhibited ACE inhibition activity after 120 days of ripening, increasing to 114 by day 180. These findings suggest that ripening time positively affects the health-promoting aspects of functional cheese products.

Investigation of the extraction efficiency and antioxidant capacity of deep eutectic solvent-enhanced Paeonia lactiflora

Study has demonstrated that Paeonia lactiflora contains a significant number of polyphenolic compounds; however, there is little research literature focus on phenolic acids in Paeonia lactiflora. In this study, an ultrasound-assisted extraction method based on ternary DESs was developed for the extraction of biologically active polyphenols in Paeonia lactiflora. The results indicated that the ternary solvent composed of choline chloride, DL-lactic acid, and 1,2-propanediol in a molar ratio of 1:4:2 achieved a superior extraction of polyphenols than that of conventional solvents and other ternary solvents. Subsequently, the response surface method was used to optimize the selected parameters of solid–liquid ratio, extraction time, and temperature for the extraction of phenolic by the DES, and the optimal extraction conditions were as follows: a solid–liquid ratio of 1:13.8 g/mL, an extraction time of 47.5 min, and an extraction temperature of 34.5 °C, with a total polyphenol yield of 79.77 mg/g, which is 1.09 times that of the traditional solvent. Furthermore, the extract of Paeonia lactiflora obtained through the DES method exhibited promising in vitro antioxidant activity and reducing ability. Studies have shown that DES is an efficient and environmentally friendly extraction solvent for extracting polyphenols from natural products, providing a new direction for the development and industrial production of Paeonia lactiflora.

Comparative study on the biological activity of bovine and ovine PP3 and of their hydrolysates

This study investigated the bioactivity of bovine and ovine proteose-peptone (PPT) fractions, specifically the proteose-peptone component 3 (PP3) and its enzymatic hydrolysate. The antioxidant capacity of the above fractions and their activity against Cronobacter sakazakii and rotavirus were evaluated. Results revealed strong interspecies differences on their bioactivity. Thus, antioxidant activity of bovine PPT decreased with the fractionation but increased for ovine PPT, the latter being more active in all cases. Moreover, the antibacterial activity of hydrolyzed bovine PP3 showed high concentration-dependence reaching a maximum of 6.82 logarithmic cycle reduction at 4 mg mL-1, for 24 h of incubation. Conversely, neither intact nor hydrolyzed ovine PP3 were able to reduce the bacterial growth. Finally, both bovine and ovine PP3 neutralized rotavirus in a dose-response way, the former being more effective. Interestingly, the antiviral activity of bovine PP3 increased after hydrolysis, whereas the ovine counterpart lost almost all of its antirotaviral capacity.

Effects of rosmarinic acid covalent conjugation on the allergenicity and functional properties of egg white protein

Polyphenols can form complexes with proteins, potentially enhancing the properties of egg white protein (EWP) by altering its structure. This study aimed to explore the effect of covalent conjugating with rosmarinic acid (RA), a bioactive polyphenol found in various edible Lamiaceae herbs, on the structure, allergenicity, and functional properties of EWP. The successful preparation of EWP-RA conjugates was confirmed through RA binding equivalent analysis. Fluorescence spectroscopy, Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD), and ultraviolet (UV) absorption spectroscopy collectively indicated that the covalent conjugation with RA led to significant structural alterations in EWP. Furthermore, the conjugation of RA markedly enhanced the antioxidant capacity of EWP, as evidenced by its improved ability to scavenge DPPH and ABTS+ radicals. Enzyme-linked immunosorbent assay (ELISA) results indicated a substantial reduction in the binding capacity of EWP-RA conjugates to IgG and IgE, indicating a decrease in the allergenic potential of EWP. Moreover, the incorporation of RA was associated with an increase in the absolute zeta potential, protein flexibility, and free sulfhydryl content of EWP, alongside a reduction in surface hydrophobicity. The findings also revealed that RA enhanced the emulsifying activity, emulsion stability, foaming ability and foaming stability of EWP. Furthermore, the storage performance of EWP improved after conjugation with RA. In conclusion, the covalent conjugation of EWP with RA not only diminished its allergenic potential but also improved its functional properties through structural modification. This study posits that such an approach could be an effective strategy for enhancing the functional properties of EWP while concurrently mitigating its allergenic potential, thereby offering promising applications in the formulation of future food products.

Effect of sequential fermentation with indigenous non-Saccharomyces cerevisiae combinations and Saccharomyces cerevisiae on the chemical composition and aroma compounds evolution of kiwifruit wine

To unlock the potential of indigenous non-Saccharomyces cerevisiae and develop novel starters to enhance the aromatic complexity of kiwifruit wine, Zygosaccharomyces rouxii, Pichia kudriavzevii and Meyerozyma guilliermondii were pairwise combined and then used in sequential fermentation with Saccharomyces cerevisiae. The impact of different starter cultures on the chemical composition and flavor profile of the kiwifruit wines was comprehensively analyzed, and the aroma evolution during alcoholic fermentation was investigated by examining the changes in key volatiles and their loss rates. Compared with Saccharomyces cerevisiae, mixed starter cultures not only improve antioxidant capacity but also increase esters and alcohols yields, presenting intense floral and fruity aromas with high sensory acceptability. The results indicated that sequential inoculation of non-Saccharomyces cerevisiae combination and Saccharomyces cerevisiae promoted the development of volatiles while maintaining the stability of key aroma compounds in the winemaking environment and reducing the aroma loss rates during alcoholic fermentation.

Inoculation of Paraburkholderia sp. GD17 improves seedling growth and tolerance to Cadmium in Chinese cabbage

This study provided evidence at the first time showing that root inoculation with the plant growth-promoting rhizobacteria Paraburkholderia sp. GD17 improved the growth and tolerance to Cd stress in Chinese cabbage seedlings. Under normal conditions, the shoot fresh and dry weight of GD17-inoculated 30-day-old plants increased by about 29% and 33%, and their root fresh and dry weight by 104% and 67%, respectively, compared with their non-inoculated partners. The GD17-mediated growth promotion could be attributed to its facilitating influence on plant acquisition of nutrient elements and photosynthetic efficiency, and decreasing abscisic acid production. Under Cd stress, an effective alleviation in Cd-induced growth inhibition was observed in GD17 plants relative to non-inoculated control, suggesting that the root inoculation with GD17 played a systemic protective role. The Cd concentration in plant aerial tissues was comparable between GD17 plants and non-inoculated ones, but it was substantially decreased in GD17 plant roots. In response to Cd, GD17-inoculated plants generally showed a stronger ability to absorb and transport nutrient elements to shoots. The GD17-conferred plant tolerance to Cd was also associated with an increased antioxidative capacity companied by declined oxidative damage, optimal levels of phytohormones, increased flavonoid synthesis as indicated by significantly upregulated expression of related genes and activity of phenylalanine ammonia-lyase. Additionally, root inoculation with GD17 effectively mitigated the Cd-induced decline in photosynthetic efficiency. Collectively, this study firstly showed that GD17-conferred growth-promotion and Cd-tolerance in Chinese cabbage was correlated with multiple regulatory roles in plant metabolism, which, in most cases, was involved in the regulation at the transcription levels of relevant genes.

Upcycling of melon seed (Cucumis melo L.) oil processing by-product: evaluation of functional properties and nutritional components as novel ingredient

BackgroundDefatted melon seed, a major by-product from melon oil processing chain, is scarcely utilsed. However, it has high potential value and can be used as novel ingredient in food products production. In line with zero waste policy and food sustainability, exploring and utilisation of this oil processing by-product can reduce food waste, and is key to moving towards a more sustainable food system. Therefore, this study aimed to assess the nutritional profile and functional properties of three varieties of defatted melon seeds (Galia, Cantaloupe, and Honeydew), and then compare them with defatted pumpkin seeds (as control group).ResultsIn this study, three varieties of melon seeds (Galia, Cantaloupe, and Honeydew) and pumpkin seeds (as control group) were defatted using Soxhlet extraction with petroleum ether; subsequently, their functional properties and nutritional components were assessed. The defatted melon seeds contained high level of protein (51.1–54.2%, w/w), dietary fibre (29.4–33.2%, w/w), potassium (1181.0–2373.1 mg/100 g), and GABA (γ-aminobutyric acid, 1.4–4.3 mmol/kg), whereas in terms of anti-nutritional compounds, they contained a relatively high amount of phytic acid (5.0%—5.8%, w/w). They also exhibited good in water/oil absorption capacity and emulsifying capacity. The phenolics were mainly free phenolics (FP) fraction (75%–77%), followed by the conjugated phenolics (CP) fraction (15%–16%), and the bound phenolics (BP) fraction (about 8%); the antioxidant capacity of each fraction followed the same sequence (FP > CP > BP).ConclusionConsidering the nutritional composition, functional properties, and the presence of potentially bioactive compounds, defatted melon seeds have considerable potential to be used as a functional food ingredient for the reformulation of foods.Graphical

In vitro digestion and functional properties of bovine β-casein: A comparison between adults and infants

Gastrointestinal digestibility behavior, structural and functional characteristics of bovine β-casein (β-CN) were studied in vitro under infant and adult conditions. This direct comparison helps reveal the effects of different physiological stages on the digestive behavior of β-CN. Not only was the degree of hydrolysis (DH) of β-CN analyzed, but also the changes in its digestive morphology, microstructure, and secondary structure during digestion were explored in depth. Meanwhile, we focused on the physicochemical properties of β-CN digesta, including solubility, emulsifying and foaming properties, as well as their functional properties, such as antimicrobial and antioxidant activities. Key results showed that β-CN underwent more extensive hydrolysis in the adult digestion model, with approximately twice the DH compared to the infant model. The adult model exhibited faster digestion kinetics, less protein flocculation, and a more loosened secondary structure, indicating a more efficient digestion process. Notably, the digesta from the adult model displayed significantly improved solubility and emulsifying properties, and also enhanced antioxidant capacities, with significantly better inhibition of two common pathogenic bacteria than the infant model, and an average increase in the diameter of the inhibition zone of approximately 2 mm. These findings underscore the differential digestive behavior and functional potential of β-CN across physiological stages. This comprehensive assessment approach contributes to a more comprehensive insight into the digestive behavior of β-CN. Therefore, we conclude that producing products from unmodified β-CN may be more suitable for the adult population, and that the digesta in the adult model exhibit higher functional properties.

Structure Identification and Activity Evaluation of Polysaccharide from Codonopsis pilosula (C. pilosula Nannf. var. Modesta (Nannf.) L. T. Shen)

Codonopsis pilosula is a medicinal plant with properties related to food, and the antioxidant and hypoglycemic components of its natural polysaccharides, as well as their related mechanisms, have not been fully understood. This study examined the physicochemical properties and structure of C. pilosula polysaccharide (WCP) using an orthogonal extraction method involving hot water-alcohol precipitation, high-resolution spectroscopy, and microscopic imaging technology. The antioxidant and hypoglycemic activities of the polysaccharides were assessed. Six fractions (WCP1, WCP2, WCP3, WCP4, WCP5, and WCP6) were identified through purification using a DEAE-cellulose column and Sephadex G-100 gel column. Mannose, glucose, and arabinose were identified as the primary monosaccharide components of WCPs through Gas Chromatography (GC). The polysaccharide exhibited a crystal structure composed of irregularly entangled pyranose particles of WCPs as revealed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The polysaccharide decomposed into smoother triple-helix fibrous flocs as indicated by Congo red analysis and circular dichroism analysis (CD). The antioxidant capacity of the polysaccharides against various free radicals was evaluated, with WCP4 demonstrating a significant reducing capacity. Moreover, WCP3 and WCP5 displayed notable inhibition rates of α-amylase and α-glucosidase, respectively. Molecular docking studies indicated the interaction of WCP5 with two enzymes, forming multiple hydrogen bonds through specific amino acids. In the gromacs simulation, both composite systems maintained a steady state in terms of root mean square deviation (RMSD), root mean square fluctuation (RMSF), and radius of gyration, providing strong support for their potential as a reference for the developing novel therapeutic approaches to diabetes.

Heat hardening enhances the energy metabolism activity and oxidative defense ability of Manila clam Ruditapes philippinarum under different thermal stress

Heat-hardening treatment can improve the thermal tolerance of aquatic organisms, likely due to enhanced antioxidant capacity and energy metabolism. In this study, the Heat-hardened Manila clam exhibited an increase in survival rate ranging from 15.5% to 80% compared to Non-hardened Manila clam under acute heat stress. Under chronic heat stress, following sub-lethal heat shock treatment, the activities of antioxidant enzymes-Catalase (CAT), Glutathione peroxidase (GSH-PX), Superoxide dismutase (SOD) in Heat-hardened Manila clam was significantly elevated in comparison to the control group (P < 0.05). Compared with the non-hardened Manila clam, the activity of energy metabolism enzymes - Na+/K+-ATPase (NKA), Ca2+/Mg2+-ATPase (CMA) of heat-hardened Manila clam decreased after the first sublethal heat shock treatment, and increased during recovery treatment, and the total ATPase activity significantly increased. Within 7 days of chronic heat stress, the activities of CAT and SOD in the Heat-hardened group higher than that in the non-hardened group. The balance between antioxidant ability and energy metabolism may be critical for the enhanced thermal tolerance observed in the Heat-hardened Manila clam. These findings indicated that Heat-hardening treatment is likely to enhance the resistance of Manila clam to high temperature in the natural environment. Such insights could be advantageous in aquaculture to protect Manila clam from the detrimental effects of heat stress.

Melatonin alleviates brain injury in copper-laden rats: Underlying benefits for Wilson’s disease

Copper serves as an indispensable cofactor for all living organisms, and its excessive accumulation has been associated with a variety of diseases. Wilson’s disease (WD) serves as an illustrative example of copper toxicity in humans, frequently presenting with liver and/or neuropsychiatric symptoms. The current therapeutic drugs, penicillamine (PA) and zinc gluconate (ZnG), have constraints, and research on their combination efficacy remains insufficient. It has been reported that melatonin (MLT) plays a vital role in binding to transition metals and exhibits strong antioxidant capacity. To investigate the therapeutic efficacy of MLT and combined treatment, rats were randomly divided into the following seven groups: the control (Con) group, copper-laden model rat (Mod) group, PA-treated group, ZnG-treated group, MLT- treated group, PA-ZnG-treated group, and PA-MLT-treated group. Then potential mechanisms and targets were investigated using a combination of metabolomics and network pharmacology and verified by molecular docking and qPCR. The findings revealed that MLT and the combination significantly improved behavior, pathology and copper levels in copper-laden rats. The results of the metabolomics study showed that profoundly altered metabolites were identified, and alanine, aspartate and glutamate metabolism, pyruvate metabolism, citrate cycle (TCA cycle), and glycolysis/gluconeogenesis were explored. In addition, molecular docking showed that MLT had high binding affinity with key targets, and qPCR results revealed that MLT could reverse the mRNA expression of targets GOT2 and PKM2. It was concluded that MLT effectively improves brain injury in copper-laden rats, and this effect was linked with the altered features of the metabolite profiles.

Precise evaluation of the nutritional value of yeast culture and its effect on pigs fed low-protein diets

The purpose of the present study was to assess the nutritional value of yeast culture (YC) and to explore the effect of YC on growth performance and health of piglets fed low-protein (LP) diets. In Exp.1, 12 growing barrows were allocated into control diet and YC diet treatments to determine the available energy of YC. Results showed that the digestible energy and metabolizable energy of YC are 12.12 and 11.66 MJ/kg dry matter (DM), respectively. In Exp.2, 12 growing barrows were surgically equipped with a T-cannula near the distal ileum and were assigned to 2 dietary treatments (nitrogen-free diet and YC diet), and the amino acid digestibility of YC was determined. In Exp.3, a total of 96 weaned piglets were randomly divided into 4 treatments, including LP basal diet (Basal), Basal+0.5% YC (0.5%YC), Basal+1.0% YC (1%YC), and Basal+1.5% YC (1.5%YC). The results were as follows: YC supplementation linearly improved the weight gain and feed intake ratio (P < 0.001), linearly increased the activity of glutathione peroxidase on d 14 (P = 0.032) and linearly decreased the concentration of malondialdehyde on d 14 (P = 0.008) and d 32 (P = 0.004) in serum, and linearly decreased the concentration of total short-chain fatty acid on d 14 in feces (P = 0.045). Compared with other treatments, 1.5%YC group showed a greater abundance of various probiotics, such as Prevotellaceae, Prevotella and Turicibacter. In Exp.4, twelve growing barrows with an ileal T-cannula were randomly assigned to Control and 1.5%YC treatments to clarify the impact of YC supplementation on nitrogen balance and nutrient digestibility. Results showed that YC had no significant effect on nitrogen efficiency and nutrient digestibility, except for trend of reducing the total tract digestibility of organic matter (P = 0.067). In conclusion, the present study assessed the digestible and metabolizable energy values (12.12 and 11.66 MJ/kg DM, respectively) and standardized ileal digestibility of amino acid (from 43.93% to 82.65%) of YC in pig feed and demonstrated that moderate supplementation of YC (1.5% of diet) can effectively improve feed conversion efficiency, enhance antioxidant capacity, and promote a balanced gut microbiota in piglets.

Structural characterization and antioxidant activity mechanism of the ferulic acid-rich subfraction from sugar beet pectin

The feruloylated sugar chain in sugar beet pectin (SBP) is a natural polyphenol-polysaccharide complex. Its low abundance often leads to be neglected, thereby hindering its bioactivity and mechnism research. In this study, SBP-3 A, a novel feruloylated polysaccharide fragment, was isolated from sugar beet pectin utilizing enzymatic digestion. The presence of ferulic acid on SBP-3 A was confirmed through high-performance liquid chromatography (HPLC), with a mass fraction of 22.5 μg/mg. The average molecular weight was determined to be 33.31 kDa. Methylation analysis, and nuclear magnetic resonance (NMR) spectra revealed that SBP-3 A is a heteroglycan with the main chain structure of →2)-α-Rhap-(1 → 4)-α-GalpA-(1 → 2)-α-Rhap-(1→, and the branched chain structure of ferulic acid (FA) → 3,4)-β-Galp-(1 → 2,4)-α-Rhap-(1→. Subsequently, the antioxidant activity of SBP-3 A was evaluated using the Caenorhabditis elegans (C. elegans). SBP-3 A improved antioxidant enzymes and non-enzymatic defense system, decreased reactive oxygen species levels, and up-regulated the mRNA expression of sod-3, skn-1, and daf-16, while down-regulated the expression of age-1 in C. elegans. Moreover, SBP-3 A modulated the gut flora by favorably affecting the abundances of Lactobacillus, Ligilactobacillus, and Akkermansia, thereby enhancing antioxidant capacity in C. elegans. Consequently, the aforementioned findings support the potential application of SBP-3 A as a functional food for treating oxidative stress-related illnesses.

Second-generation snacks prepared from quinoa with probiotic. Physicochemical properties, in vitro digestibility, antioxidant activity and consumer acceptability

Food security is a pressing issue, emphasizing the necessity for food designs that address the current geopolitical and geoeconomic challenges. This study evaluates the impact of including different percentages (10 %, 20 %, 30 %, and 60 %) of high protein quinoa flour (HPQF) in the development of a new rice-based snack. The aim is to create four snack formulations with a protein content enriched with probiotics, surpassing those currently available in the market. Probiotics Bacillus coagulans were added at a 0.1 % concentration. Once the rice flour and quinoa flour are mixed, they are mixed with the probiotic, to move on to the extrusion process. Following the incorporation of probiotics, the snacks were packaged in a modified atmosphere, and their physicochemical properties, Bacillus coagulans probiotic viability, tolerance to artificial gastroenteric juice (TAGJ), starch digestibility, and sensory acceptance were assessed.Significant differences were observed in the expansion index, with the 60 % inclusion snack exhibiting the least expansion. Despite having a higher density, this snack reached a porosity index similar to that of the 20 % HPQF snack. Achieving a 17 % protein content in the snacks was possible with a 60 % inclusion rate. Texture was notably affected by the inclusion of HPQF, with snacks having higher inclusion levels showing increased hardness. Probiotic viability evaluation consistently remained above 106 UFC/g of snack, while TAGJ exhibited a viability of 75 %. Although HPQF inclusion led to a decrease in the glycemic index (GI), snacks still maintained a GI above 70 %. Regarding antioxidant properties, snacks with 60 % HPQF inclusion displayed superior results, reaching 35.29, 5.52, and 13.74 μmol of AA/g, measured via ABTS, DPPH, and FRAP methods, respectively. These findings demonstrate a heightened antioxidant capacity compared to other formulations. Our results indicate that the new probiotic snack serves as a rich source of protein and probiotics and is well-received sensorially. However, it is worth noting that it falls within the category of high GI foods, prompting the need for future studies aimed at reducing this parameter.

A Nanozyme-Boosted MOF-CRISPR Platform for Treatment of Alzheimer's Disease.

Rectifying the aberrant microenvironment of a disease through maintenance of redox homeostasis has emerged as a promising perspective with significant therapeutic potential for Alzheimer's disease (AD). Herein, we design and construct a novel nanozyme-boosted MOF-CRISPR platform (CMOPKP), which can maintain redox homeostasis and rescue the impaired microenvironment of AD. By modifying the targeted peptides KLVFFAED, CMOPKP can traverse the blood-brain barrier and deliver the CRISPR activation system for precise activation of the Nrf2 signaling pathway and downstream redox proteins in regions characterized by oxidative stress, thereby reinstating neuronal antioxidant capacity and preserving redox homeostasis. Furthermore, cerium dioxide possessing catalase enzyme-like activity can synergistically alleviate oxidative stress. Further in vivo studies demonstrate that CMOPKP can effectively alleviate cognitive impairment in 3xTg-AD mouse models. Therefore, our design presents an effective way for regulating redox homeostasis in AD, which shows promise as a therapeutic strategy for mitigating oxidative stress in AD.

Biosynthesis and characterization of gold nanoparticles from citrullus colocynthis (L.) schrad pulp ethanolic extract: Their cytotoxic, genotoxic, apoptotic, and antioxidant activities

The age-old discipline of plant therapy has gained renewed importance through the utilization of plants for the synthesis of metal nanoparticles. However, toxicity testing and characterization of the recently synthesized nanomaterials are essential to evaluating their appropriate application. Citrullus colocynthis is a medicinal plant with several health benefits. Herein, we used its ethanolic pulp extract (PE) to manufacture gold nanoparticles (PE-AuNPs). Various approaches were employed to assess the MTT50 and NR50 values of PE and PE-AuNPs at different concentrations in the human hepatocarcinoma cell line (HepG2). The study aimed to assess the genotoxic effects and in vivo toxicity of PE and PE-AuNPs at MTT50 dosages. The quasi-spherical, cubic/triangular prisms, and nail-looking particles exhibited no antioxidant properties. They had an absorbance peak between 540 and 560 nm, diameters of less than 20 nm, hydrodynamic diameters of 177.9 nm, and a negative surface charge (−10.3 mV). The significant role of plant phytochemicals in the formation of metal nanoparticles is confirmed by the diminished antioxidant capacity of extract residues following PE-AuNP synthesis. PE-AuNPs exhibited in vivo and cytotoxic effects at relatively lower concentrations compared to PE. In contrast to PE, PE-AuNPs exhibited lower genotoxic at MTT50 dosages. Despite having MTT50 values of approximately 1.95 ± 0.06 and 0.89 ± 0.03 mg/ml, PE and PE-AuNPs can still be considered biocompatible. Nonetheless, our results suggest that the characteristics of recently produced nanoparticles can differ from those of the matching plant. Further investigation can provide a better understanding of the possible therapeutic and pharmacological impacts of PE-AuNPs.

CIPK11 phosphorylates GSTU23 to promote cold tolerance in Camellia sinensis.

Cold stress negatively impacts the growth, development, and quality of Camellia sinensis (Cs, tea) plants. CBL-interacting protein kinases (CIPK) comprise a pivotal protein family involved in plant development and response to multiple environmental stimuli. However, their roles and regulatory mechanisms in tea plants (Camellia sinensis (L.) O. Kuntze) remain unknown. Here we show that CsCBL-interacting protein kinase 11 (CsCIPK11), whose transcript abundance was significantly induced at low temperatures, interacts and phosphorylates tau class glutathione S-transferase 23 (CsGSTU23). CsGSTU23 was also a cold-inducible gene and has significantly higher transcript abundance in cold-resistant accessions than in cold-susceptible accessions. CsCIPK11 phosphorylated CsGSTU23 at Ser37, enhancing its stability and enzymatic activity. Overexpression of CsCIPK11 in Arabidopsis thaliana resulted in enhanced cold tolerance under freezing conditions, while transient knockdown of CsCIPK11 expression in tea plants had the opposite effect, resulting in decreased cold tolerance and suppression of the C-repeat-binding transcription factor (CBF) transcriptional pathway under freezing stress. Furthermore, the transient overexpression of CsGSTU23 in tea plants increased cold tolerance. These findings demonstrate that CsCIPK11 plays a central role in the signaling pathway to cold signals and modulates antioxidant capacity by phosphorylating CsGSTU23, leading to improved cold tolerance in tea plants.

The key role of iroBCDN-lacking pLVPK-like plasmid in the evolution of the most prevalent hypervirulent carbapenem-resistant ST11-KL64 Klebsiella pneumoniae in China

AimsHypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP), coharboring hypervirulence and carbapenem-resistance genes mediated by plasmids, causes infections with extremely high mortality and seriously impacts public health. Exploring the transfer mechanisms of virulence/carbapenem-resistance plasmids, as well as the formation and evolution pathway of hv-CRKP is of great significance to the control of hv-CRKP infections. MethodsIn this study, we identified the predominant clone of hv-CRKP in China and elucidated its genomic characteristics and formation route based on 239 multicenter clinical K. pneumoniae isolates and 1014 GenBank genomes by using comparative genomic analysis. Further, we revealed the factors affecting the transfer of virulence plasmids, and explained the genetic foundation for the prevalence of Chinese predominant hv-CRKP clone. ResultsST11-KL64 is the predominant clone of hv-CRKP in China and primarily evolved from ST11-KL64 CRKP by acquiring the pLVPK-like virulence plasmid from hvKP. Significantly, the virulence gene cluster iroBCDN was lost in the virulence plasmid of ST11-KL64 hv-CRKP but existed in that of hvKP. Moreover, the absence of iroBCDN didn’t decrease the virulence of hv-CRKP, which was proved by bacterial test, cell-interaction test and mice infection model. On the contrary, loss of iroBCDN was observed to regulate virulence/carbapenem-resistance plasmid transfer and oxidative stress-related genes in strains and thus promoted the mobilization of nonconjugative virulence plasmid from hvKP into ST11-KL64 CRKP, forming hv-CRKP which finally had elevated antioxidant capacity and enhanced survival capacity in macrophages. The loss of iroBCDN increased the survival ability of hv-CRKP without decreasing its virulence, endowing it with an evolutionary advantage. ConclusionsOur work provides new insights into the key role of iroBCDN loss in convergence of CRKP and hvKP, and the genetic and biological foundation for the widespread prevalence of ST11-KL64 hv-CRKP in China.

Polymethoxylated flavone variations and in vitro biological activities of locally cultivated Citrus varieties in China

Citrus peels are rich in polymethoxylated flavones (PMFs), which have beneficial health and pharmacological properties. In this study, the profiles, variations, and biological activities of PMFs in the peel extracts of 27 Citrus varieties (eight species) native to China were investigated. UPLC-QTOF-MS/MS analysis revealed that mandarin accumulated more diversity and higher detectable PMF contents. Wangcangzhoupigan (ZPG) possessed the highest antioxidant capacity. Gailiangcheng (GLC) and Bingtangcheng (BTC), sweet oranges showed excellent inhibitory effects against pancreatic lipase and α-glucosidase, respectively. Most citrus extracts effectively inhibited the production of ROS and pro-inflammatory cytokines, while increasing the accumulation of anti-inflammatory cytokines. In addition, Limeng (LM), Goushigan (GSG), and Yanxiwanlu (YXWL) showed anti-proliferative effects against DU145 and PC3 cancer cells. This study provides a comprehensive PMF profile and biological activities of various citrus species and will benefit future functional citrus breeding practices aimed at designing plants rich in total or specific PMFs for health benefits.

Integrated gold nanorods-based dual-signal platform for accurate total antioxidant capacity assessment in food samples

Accurate assessment of Total Antioxidant Capacity (TAC) in food is crucial for evaluating nutritional quality and potential health benefits. This study aims to enhance the sensitivity and reliability of TAC detection through a dual-signal method, combining colorimetric and photothermal signals. Gold nanorods (AuNRs) were utilized to establish a dual-signal method duo to the colorimetric and photothermal properties. Fenton reaction can etch the AuNRs from the tips, as a result, a blue shift in the longitudinal LSPR absorption peak was obtained, leading to significant changes in color and photothermal effects, facilitating discrimination through both visual observation and thermometer measurements. In the presence of antioxidants, the Fenton reaction was suppressed or inhibited, protecting the AuNRs from etching. The colorimetric and photothermal signals were therefore positively correlated with TAC levels, enabling dual-signal detection of TAC. The linear range of AA was 4–100 μM in both colorimetry and photothermal modes, with detection limits of 1.60 μM and 1.38 μM, respectively. This dual-signal approach achieves low detection limits, enhancing precision and sensitivity. The method thus has the potential to act as a promising candidate for TAC detection in food samples, contributing to improved food quality and safety assessment.