Obesity is a metabolic disease associated with gut microbiota and low-grade chronic inflammation. Tremella fuciformis is a medicinal and edible fungus; polysaccharide (TP) is the main active component, which has a variety of biological activities, such as hypoglycemic and hypolipidemic. However, the anti-obesity effects and potential mechanisms of TP have never been reported. This study was conducted to elucidate the inhibitory effect of TP on high-fat diet (HFD)-induced obesity in mice. Mice were split into five groups: normal chow diet (NCD) group, NCD_TP_H group, HFD group, HFD_TP_L group and HFD_TP_H group. Our study showed that TP inhibited high-fat diet-induced weight gain and fat accumulation in mice and reduced blood glucose, hyperlipidemia and inflammation. TP also improved gut microbiota disorders by reducing the Firmicutes/Bacteroidetes ratio and modulating the relative abundance of specific gut microbiota. We also found that the anti-obesity and gut microbiota-modulating effects of TP could be transferred to HFD-fed mice via faecal microbiota transplantation (FMT), confirming that the gut microbiota was one of the targets of TP for obesity inhibition. Further studies showed that TP increased the production of short-chain fatty acids and the secretion of intestinal hormones. Our studies showed that TP inhibited obesity by modulating inflammation and the microbe-gut-brain axis, providing a rationale for developing TP to treat obesity and its complications.

SBFI26, an inhibitor of FABP5, has been shown to suppress the proliferation and metastasis of tumour cells. However, the underlying mechanism by which SBFI26 induces ferroptosis in breast cancer cells remains largely unknown. Three breast cancer cell lines were treated with SBFI26 and CCK‐8 assessed cytotoxicity. Transcriptome was performed on the Illumina platform and verified by qPCR. Western blot evaluated protein levels. Malondialdehyde (MDA), total superoxide dismutase (T‐SOD), Fe, glutathione (GSH) and oxidized glutathione (GSSG) were measured. SBFI26 induced cell death time‐ and dose‐dependent, with a more significant inhibitory effect on MDA‐MB‐231 cells. Fer‐1, GSH and Vitamin C attenuated the effects but not erastin. RNA‐Seq analysis revealed that SBFI26 treatment significantly enriched differentially expressed genes related to ferroptosis. Furthermore, SBFI26 increased intracellular MDA, iron ion, and GSSG levels while decreasing T‐SOD, total glutathione (T‐GSH), and GSH levels.SBFI26 dose‐dependently up‐regulates the expression of HMOX1 and ALOX12 at both gene and protein levels, promoting ferroptosis. Similarly, it significantly increases the expression of SAT1, ALOX5, ALOX15, ALOXE3 and CHAC1 that, promoting ferroptosis while downregulating the NFE2L2 gene and protein that inhibit ferroptosis. SBFI26 leads to cellular accumulation of fatty acids, which triggers excess ferrous ions and subsequent lipid peroxidation for inducing ferroptosis.

The anti-PD-L1 monoclonal antibody (mAb) targeting PD-1/PD-L1 immune checkpoint has achieved outstanding results in clinical application and has become one of the most popular anti-cancer drugs. The mechanism of molecular recognition and inhibition of PD-L1 mAbs is not yet clear, which hinders the subsequent antibody design and modification. In this work, the trajectories of PD-1/PD-L1 and nanobody/PD-L1 complexes were obtained via comparative molecular dynamics simulations. Then, a series of physicochemical parameters including hydrogen bond, dihedral angle distribution, pKa value and binding free energy, and so forth, were all comparatively analyzed to investigate the recognition difference between PD-L1 and PD-1 and nanobody. Both _LR113 (the amino acid residues in PD-L1 are represented by the lower left sign of L) and _LR125 residues of PD-L1 undergo significant conformational change after association with mAbs, which dominates a strong electrostatic interaction. Solvation effect analysis revealed that solvent-water enhanced molecular recognition between PD-L1 and nanobody. By combining the analyses of the time-dependent root mean squared fluctuation (RMSF), free energy landscape, clustering and energy decomposition, the potential inhibition mechanism was proposed that the nanobody competitively and specifically bound to the β-sheet groups of PD-L1, reduced the PD-L1’s flexibility and finally blocked the formation of PD-1/PD-L1 complex. Based on the simulation results, site-directed mutagenesis of _ND99 (the amino acid residues in Nano are displayed by the lower left sign of N) and _NQ116 in the nanobody may be beneficial for improving antibody activity. This work offers some structural guidance for the design and modification of anticancer mAbs based on the structure of the PD-1/PD-L1 complex.

Polysaccharides derived from Auricularia auricula exhibit diverse biological activities and hold significant potential for commercial utilization as functional food ingredients. In this investigation, polysaccharides from A. auricula were obtained using six extraction techniques (ammonium oxalate solution extraction, sodium hydroxide solution extraction, hot water extraction, pectinase and cellulase-assisted extraction, ultrasonic-assisted extraction, and microwave-assisted extraction). Subsequently, a comprehensive comparison was conducted to evaluate their physicochemical properties and biological functionalities. The ammonium oxalate solution extraction method yielded a higher extraction rate (11.76%) and polysaccharide content (84.12%), as well as a higher uronic acid content (10.13%). Although the six Auricularia polysaccharides had different molecular weight distributions, monosaccharide molar ratios, similar monosaccharide compositions, and characteristic functional groups of polysaccharides, they exhibited different surface morphology. In vitro assays showed that polysaccharides extracted by ammonium oxalate solution possessed good scavenging ability against DPPH free radical, hydroxyl free radical and superoxide anion free radical as well as reduction power of iron ion. At the same time, both polysaccharides extracted by ammonium oxalate solution and sodium hydroxide solution promoted NO production in mouse macrophages along with the secretion of cytokines TNF-α, IL-1β, and IL-6. These results indicated significant differences in the structure and characteristics among Auricularia polysaccharides prepared by various extraction methods, which may be related to the variety or origin of A. auricula; furthermore, their bioactivities varied accordingly in vitro assays where the ammonium oxalate solution extraction method was found more beneficial for obtaining high-quality bioactive Auricularia polysaccharides.

The dried flower (corolla) of Abelmoschus manihot (L.) Medicus, known as Abelmoschi Corolla, contains polysaccharides with therapeutic potential for immunopotentiation; however, the underlying mechanisms remain unclear. This study aimed to systematically investigate the efficacy and molecular mechanisms through which acidic Abelmoschi Corolla polysaccharides (S-AMFP) reverse cyclophosphamide (CTX)-induced immunosuppression, using integrated analyses of intestinal microbiology, metabolomics, histology, and biochemistry. We isolated and purified S-AMFP from Abelmoschi Corolla and subjected it to preliminary structural characterisation. An immunosuppressive mouse model was established through intraperitoneal injection of cyclophosphamide (CTX). The immunorestorative effects of S-AMFP were evaluated using gut microbiomics, non-targeted metabolomics, histopathology, and molecular biology techniques. Immune organ indices, including spleen and thymus weights, were measured in BALB/c mice. Cytokine and immunoglobulin levels (TNF-α, IL-4, IL-6, IgG, IgA, and IgM) were quantified using enzyme-linked immunosorbent assay; T-lymphocyte subsets (CD3⁺/CD4⁺ percentages and CD4⁺/CD8⁺ ratios) were analysed using flow cytometry. Splenic histopathological changes were examined using haematoxylin and eosin staining. Gut microbiota composition was profiled by 16S rDNA sequencing, whereas serum metabolites were analysed through non-targeted metabolomics. Faecal short-chain fatty acids (SCFAs) were quantified using gas chromatography-mass spectrometry. Mitogen-activated protein kinase pathway activity and intestinal barrier integrity were evaluated using reverse transcription quantitative polymerase chain reaction and Western blot. S-AMFP is a pectin-based polysaccharide primarily composed of rhamnose and galacturonic acid. S-AMFP restored body weight, thymic and splenic indices, serum cytokines, immunoglobulin levels, and rectified T lymphocyte dysfunction by rebalancing CD4⁺/CD8⁺ ratios. It improved intestinal barrier function by up-regulating tight junction proteins (Claudin-1 and Occludin), activating the MAPK pathway, and reshaping gut microbiota. S-AMFP increased beneficial bacteria, including Lactobacillus and Lachnospiraceae_NK4A136_group, reduced pathogenic Enterobacteriaceae, elevated SCFA levels, and alleviated CTX-induced metabolic disturbances in amino acid, lipid, and energy pathways. S-AMFP mitigates CTX-induced immunosuppression by restoring intestinal barrier integrity, modulating gut microbiota composition, and enhancing metabolic homeostasis. These findings advance current understanding of polysaccharide-mediated immunomodulation and highlight S-AMFP's potential as a dietary supplement or adjunctive agent for mitigating drug-induced immunosuppression, particularly through gut ecological and metabolic regulation.

Umami is a fundamental taste sensation, often described as a delicious and pleasant flavor perception. To enhance or complement the original flavor and meet the tastes of diverse regions, umami dipeptides have been extensively utilized in global food manufacturing. Currently, the application and purification techniques of dipeptides are relatively mature, while their umami mechanisms and molecular modification are both scarce. In this work, the 3D structure of the umami dipeptide target T1R1/T1R3 was first obtained through sequence alignment and homology modeling, then followed by the successful construction of a database containing 400 samples of dipeptides. Subsequently, the complex models of T1R1/T1R3, respectively, with DG (Asp-Gly) and EK (Glu-Lys) (i.e., T1R1_DG/T1R3, T1R1/T1R3_DG, T1R1_EK/T1R3, and T1R1/T1R3_EK) were obtained via molecular docking and virtual screening. Finally, based on comparative molecular dynamics (MD) simulation trajectories, the binding free energy was calculated to investigate receptor–ligand recognition and conformational changes, providing some implications for potential modifications of umami dipeptides. T1R1 tends to bind relatively small umami dipeptides, whereas T1R3 does the opposite, both of which favor the recognition of acidic and hydrophilic dipeptides. By comparing strategies such as hydroxyl introduction and chain length alteration, electrostatic effects may be more important than non-polar effects in molecular design. This work not only explores the recognition mechanism of umami dipeptides with the receptor T1R1/T1R3 showing certain theoretical significance, but also provides feasible suggestions for dipeptide screening and modification having certain application value.