Zhiyong Xie’s research while affiliated with Sun Yat-sen University and other places

Advances in techniques for quality analysis allow for a more detailed examination of drug impurities. High‐resolution mass spectrometry (HRMS) contributes to detecting both known and unknown impurities. In this study, a combination of a nontargeted and targeted screening approach was established and applied to the detailed degradation profile of the losartan potassium (LP) drug substance. Through general unknown comparative screening (GUCS), 35 degradation products (DPs) were detected; of these, 10 DPs were confirmed with reference substances. DP‐1, DP‐2, DP‐3, and DP‐6 were the first characterized, as per previous studies; the other twenty‐four were newly identified. In addition, a liquid chromatography‐tandem mass spectrometry method was developed for the determination of the ten DPs. It was sensitive, with the limit of quantitation of analytes ranging from 0.01 to 0.5 ng mL ⁻¹ . Two newly characterized DPs, DP‐1 and DP‐2, were determined in active pharmaceutical ingredient solutions. This study introduced a new approach using broad screening to analyze degradation impurity profiles in LP drug substance, aiding in the identification of low‐level impurities or those without reference substances. Additionally, the sensitive determination method developed allows for the precise quantification and control of ten DPs at trace levels in LP drug substances or products.

Small molecule‐responsive tags for targeted protein degradation are valuable tools for fundamental research and drug target validation. Here, we show that genetically incorporated unnatural amino acids bearing a strained alkene or alkyne functionality can act as a minimalist tag for targeted protein degradation. Specifically, we observed the degradation of strained alkene‐ or alkyne‐containing kinases and E2 ubiquitin‐conjugating enzymes upon treatment with hydrophobic tetrazine conjugates. The extent of the induced protein degradation depends on the identity of the target protein, unnatural amino acid, and tetrazine conjugate, as well as the site of the unnatural amino acid in the target protein. Mechanistic studies revealed proteins undergo proteasomal degradation after tetrazine tethering, and the identity of tetrazine conjugates influences the dependence of ubiquitination on protein degradation. This work provides an alternative approach for targeted protein degradation and mechanistic insight, facilitating the future development of more effective targeted protein degradation strategies.

Background Recurrent pregnancy loss (RPL) affects women's reproductive health seriously, with immune dysfunction playing a key role in its cause, yet the exact mechanisms remain elusive. We aim to investigate potential mechanisms and identify biomarkers linked to RPL. Methods Immune cytokine testing and metabolomic profiling were conducted on the serum of 34 RPL patients and 30 healthy individuals. The metabolic pathways of the differential metabolites were analyzed, and specific metabolites were validated through targeted profiling. Potential biomarkers were identified, and the relationships between immune cytokines and differential metabolites were explored. Results In the RPL group, serum interleukin-6 and interleukin-10 levels were significantly higher, while interleukin-2 and interferon-γ were significantly lower. A total of 296 differential metabolites were detected by untargeted metabolomic profiling between the RPL and control groups, with most linked to amino acid metabolism. Targeted metabolomic profiling of amino acid metabolism revealed upregulation of indole-3-acetic acid, tyrosine, glycine, isoleucine, tryptophan, lysine, aspartic acid, arginine, leucine, threonine, glutamic acid, cystine, and phenylpyruvic acid (PPA) in the RPL group. Moreover, PPA and 5-hydroxy-L-tryptophan showed great potential in predicting RPL in a diagnostic model. Cystine and tyrosine were associated with immune cytokines in correlation analysis. Conclusion The study highlights the role of amino acid metabolism in RPL pathogenesis, suggesting that PPA and 5-HTP may be potential predictive indicators, while cystine and tyrosine may potentially regulate immune responses related to RPL. Further investigation into the molecular mechanisms underlying these findings could potentially result in the creation of novel diagnostic and therapeutic approaches for RPL.

Chickpea is rich in protein and has been demonstrated to possess hypoglycaemic effects. However, the specific bioactive ingredients and mechanisms underlying their hypoglycaemic effects remain unclear. In this study, enzymatic hydrolysis and gel permeation chromatography were used to extract chickpea bioactive peptide (CBP) from chickpea protein. One of the products, CBP-75-3, was found to inhibit α-glucosidase (GAA) activity and significantly increase the viability of insulin resistant (IR) cells. Moreover, CBP-75-3 significantly increased the rate of glucose consumption and glycogen synthesis in IR-HepG2 cells. Moreover, CBP-75-3 decreased the levels of malondialdehyde and increased the levels of superoxide dismutase, glutathione, and glutathione peroxidase. Subsequently, 29 novel bioactive peptides in CBP-75-3 were identified by LC‒MS/MS, and the potential hypoglycaemic targets of these novel bioactive peptides were investigated using molecular docking. Based on the results, the residues of the novel bioactive peptides interact with GAA through hydrogen bonding (especially LLR, FH, RQLPR, KGF and NFQ by binding to the substrate binding pocket or the active centre of GAA), thereby inhibiting GAA activity and laying a foundation for its hypoglycaemic activity. In short, the novel bioactive peptides isolated and identified from chickpea can effectively exert hypoglycaemic effects and increase the antioxidant capacity of IR-HepG2 cells. This study reveals that CBP-75-3, a natural hypoglycaemic ingredient, has potential for applications in functional foods and provides a theoretical basis for the development and application of CBP in the future.