Evaluating toxicity and decoding the underlying mechanisms of active compounds are crucial for drug development.In this study,we present an innovative,integrated approach that combines air flow-assisted desorption electrospray ionization mass spectrometry imaging(AFADESI-MSI),time-of-flight secondary ion mass spectrometry(ToF-SIMS),and spatial metabolomics to comprehensively investi-gate the nephrotoxicity and underlying mechanisms of nitidine chloride(NC),a promising anti-tumor drug candidate.Our quantitive AFADESI-MSI analysis unveiled the region specific of accumulation of NC in the kidney,particularly within the inner cortex(IC)region,following single and repeated dose of NC.High spatial resolution ToF-SIMS analysis further allowed us to precisely map the localization of NC within the renal tubule.Employing spatial metabolomics based on AFADESI-MSI,we identified over 70 discriminating endogenous metabolites associated with chronic NC exposure.These findings suggest the renal tubule as the primary target of NC toxicity and implicate renal transporters(organic cation transporters,multidrug and toxin extrusion,and organic cation transporter 2(OCT2)),metabolic en-zymes(protein arginine N-methyltransferase(PRMT)and nitric oxide synthase),mitochondria,oxidative stress,and inflammation in NC-induced nephrotoxicity.This study offers novel insights into NC-induced renal damage,representing a crucial step towards devising strategies to mitigate renal damage caused by this compound.

Polygala tenuifolia,commonly known as Yuanzhi(YZ)in Chinese,has been shown to possess anti-insomnia properties.However,the material basis and the mechanism underlying its sedative-hypnotic effects remain unclear.Herein,we investigated the active components and neurochemical mechanism of YZ extracts using liquid chromatography tandem mass spectrometry(LC-MS/MS)-based pharmaco-metabolomics and mass spectrometry imaging(MSI)-based spatial resolved metabolomics.According to the results,17 prototypes out of 101 ingredients in the YZ extract were detected in both the plasma and brain,which might be the major components contributing to the sedative-hypnotic effects.Network pharmacology analysis revealed that these prototypes may exert their effects through neuroactive ligand-receptor interaction,serotonergic synapse,dopaminergic synapse,and dopaminergic synapse,among other pathways.LC-MS/MS-based targeted metabolomics and Western blot(WB)revealed that tryptophan-serotonin-melatonin(Trp-5-HT-Mel)and tyrosine-norepinephrine-adrenaline(Tyr-Ne-Ad)are the key regulated pathways.Dopa decarboxylase(DDC)upregulation and phenylethanolamine N-methyltransferase(PNMT)downregulation further confirmed these pathways.Furthermore,MSI-based spatially resolved metabolomics revealed notable alterations in 5-HT in the pineal gland(PG),and Ad in the brainstem,including the middle brain(MB),pons(PN),and hypothalamus(HY).In summary,this study illustrates the efficacy of an integrated multidimensional metabolomics approach in unraveling the sedative-hypnotic effects and neurochemical mechanisms of a Chinese herbal medicine,YZ.

Three-dimensional(3D)cell spheroid models combined with mass spectrometry imaging(MSI)enables innovative investigation of in vivo-like biological processes under different physiological and patho-logical conditions.Herein,airflow-assisted desorption electrospray ionization-MSI(AFADESI-MSI)was coupled with 3D HepG2 spheroids to assess the metabolism and hepatotoxicity of amiodarone(AMI).High-coverage imaging of＞1100 endogenous metabolites in hepatocyte spheroids was achieved using AFADESI-MSI.Following AMI treatment at different times,15 metabolites of AMI involved in N-desethylation,hydroxylation,deiodination,and desaturation metabolic reactions were identified,and according to their spatiotemporal dynamics features,the metabolic pathways of AMI were proposed.Subsequently,the temporal and spatial changes in metabolic disturbance within spheroids caused by drug exposure were obtained via metabolomic analysis.The main dysregulated metabolic pathways included arachidonic acid and glycerophospholipid metabolism,providing considerable evidence for the mechanism of AMI hepatotoxicity.In addition,a biomarker group of eight fatty acids was selected that provided improved indication of cell viability and could characterize the hepatotoxicity of AMI.The combination of AFADESI-MSI and HepG2 spheroids can simultaneously obtain spatiotemporal infor-mation for drugs,drug metabolites,and endogenous metabolites after AMI treatment,providing an effective tool for in vitro drug hepatotoxicity evaluation.

Deconvolution of potential drug targets of the central nervous system (CNS) is particularly challenging because of the complicated structure and function of the brain. Here, a spatiotemporally resolved metabolomics and isotope tracing strategy was proposed and demonstrated to be powerful for deconvoluting and localizing potential targets of CNS drugs by using ambient mass spectrometry imaging. This strategy can map various substances including exogenous drugs, isotopically labeled metabolites, and various types of endogenous metabolites in the brain tissue sections to illustrate their microregional distribution pattern in the brain and locate drug action-related metabolic nodes and pathways. The strategy revealed that the sedative-hypnotic drug candidate YZG-331 was prominently distributed in the pineal gland and entered the thalamus and hypothalamus in relatively small amounts, and can increase glutamate decarboxylase activity to elevate γ-aminobutyric acid (GABA) levels in the hypothalamus, agonize organic cation transporter 3 to release extracellular histamine into peripheral circulation. These findings emphasize the promising capability of spatiotemporally resolved metabolomics and isotope tracing to help elucidate the multiple targets and the mechanisms of action of CNS drugs.

Developing analytical methods for the chemical components of natural medicines remains a challenge due to its diversity and complexity. Miao-Fu-Zhi-Tong (MFZT) granules, an ethnic Yi herbal prescription, comprises 10 herbs and has been clinically applied for gouty arthritis (GA) therapy. Herein, a series of chemical profiling strategies including in-house library matching, molecular networking and MS/MS fragmentation behavior validation based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) were developed for qualitative analysis of MFZT granules. A total of 207 compounds were identified or characterized in which several rare guanidines were discovered and profiled into alkyl substituted or cyclic subtypes. Moreover, network pharmacology analysis indicated that MFZT's anti-gout mechanism was mostly associated with the nuclear factor kappa-B (NF-κB) signaling, nucleotide oligomerization domain (NOD)-like signaling and rheumatoid arthritis pathways, along with the synergistic effect of 84 potential active compounds. In addition, a quantitative analytical method was developed to simultaneously determine the 29 potential effective components. Among them, berberine, pellodendrine, 3-feruloylquinic acid, neoastilbin, isoacteoside and chlorogenic acid derivatives at higher concentrations were considered as the chemical markers for quality control. These findings provide a holistic chemical basis for MFZT granules and will support the development of effective analytical methods for the herbal formulas of natural medicines.
Humans ; Chromatography, High Pressure Liquid/methods* ; Tandem Mass Spectrometry/methods* ; Drugs, Chinese Herbal/chemistry* ; Quality Control ; Arthritis, Gouty

Diabetic cardiomyopathy(DCM)is a metabolic disease and a leading cause of heart failure among people with diabetes.Mass spectrometry imaging(MSI)is a versatile technique capable of combining the molecular specificity of mass spectrometry(MS)with the spatial information of imaging.In this study,we used MSI to visualize metabolites in the rat heart with high spatial resolution and sensitivity.We optimized the air flow-assisted desorption electrospray ionization(AFADESI)-MSI platform to detect a wide range of metabolites,and then used matrix-assisted laser desorption ionization(MALDI)-MSI for increasing metabolic coverage and improving localization resolution.AFADESI-MSI detected 214 and 149 metabolites in positive and negative analyses of rat heart sections,respectively,while MALDI-MSI detected 61 metabolites in negative analysis.Our study revealed the heterogenous metabolic profile of the heart in a DCM model,with over 105 region-specific changes in the levels of a wide range of metabolite classes,including carbohydrates,amino acids,nucleotides,and their derivatives,fatty acids,glycerol phospholipids,carnitines,and metal ions.The repeated oral administration of ferulic acid during 20 weeks significantly improved most of the metabolic disorders in the DCM model.Our findings provide novel insights into the molecular mechanisms underlying DCM and the potential of ferulic acid as a therapeutic agent for treating this condition.

Multicellular tumor spheroids (MCTS) can simulate the structure and metabolic characteristics of tumors in vivo, which is of great significance to study the metabolic phenotype of tumor cells and the mechanism of drug intervention. In this study, esophageal cancer MCTS were constructed, and MCTS frozen sections were prepared after treated with different formulations of paclitaxel (PTX) including common PTX injection, PTX liposome and albumin bound PTX. MCTS mass spectrometry imaging analysis method was established by using air flow assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI). The visualization of the permeation and enrichment process of PTX in MCTs after PTX treatment was realized, and the spatially resolved metabolomics of PTX injection group was studied. The results showed that the permeation and enrichment behavior of PTX in MCTs model were related to the formulations. The changes of endogenous metabolites in MCTs of esophageal cancer after treated with PTX injection had temporal and spatial characteristics. The metabolic changes of MCTS during the initial 0-4 hours were dominated by the down-regulation of middle-high polarity metabolites and some lipids in the central region of MCTS, while the metabolic changes of MCTS during 8-72 hours were mainly up-regulated by lipid metabolites in the peripheral region of MCTS. The combination of in vivo tumor-associated MCTs model with label free, highly sensitive and high coverage mass spectrometry imaging technology provided a new method and strategy for the study of pharmacometabolomics.

Objective:To investigate the functional imaging parameters that effectively distinguish isocitrate dehydrogenase (IDH) gene mutation status in clinical practice with long echo time (TE) point-resolved spectroscopy (PRESS) MRS.Methods:Totally 25 patients with suspected diagnosis of low grade gliomas(LGGs; Grade II) were recruited prospectively and divided into IDH mutation group and IDH wild group according to pathological results in the study. All patients were scanned with long TE PRESS MRS. In addition, IDH mutational status was determined by post-operation Sanger sequencing. The t test or Mann-Whitney U test was used to analyze the differences of 2-hydroxyglutarate (2HG), Glutamate (Glu), Glutamine (Gln) and 2HG/Glu+Gln between the IDH mutation group and the IDH wild group, then ROC curve was plotted with statistically significant indexes to obtain the efficacy of predicting IDH mutation status. Results:Of the 25 patients, 19 had IDH mutant gliomas and 6 had IDH wild-type gliomas. 2HG, Glu, Gln and 2HG/Glu+Gln in IDH mutated group were 1.42 (1.09, 1.93)mmol/L, (1.74±1.31)mmol/L, (1.68±0.66)mmol/L, 0.55 (0.28, 0.77), respectively; while the corresponding values were 0.00 (0.00, 1.30)mmol/L, (3.28±1.02)mmol/L, (2.55±1.47)mmol/L, 0.00 (0.00, 0.26) in IDH gene wild type group, respectively. The differences of 2HG, Glu, and 2HG/Glu+Gln between the two groups were statistically significant ( P values were 0.030, 0.016, 0.004, respectively). The area under the ROC curve of 2HG/Glu+Gln was the largest (0.877), and the sensitivity was the highest (84.2%). Conclusion:The integration of 2HG with Glu and Gln can effectively realize the noninvasive assessment of IDH mutation status.

Detailed knowledge on tissue-specific metabolic reprogramming in diabetic nephropathy (DN) is vital for more accurate understanding the molecular pathological signature and developing novel therapeutic strategies. In the present study, a spatial-resolved metabolomics approach based on air flow-assisted desorption electrospray ionization (AFADESI) and matrix-assisted laser desorption ionization (MALDI) integrated mass spectrometry imaging (MSI) was proposed to investigate tissue-specific metabolic alterations in the kidneys of high-fat diet-fed and streptozotocin (STZ)-treated DN rats and the therapeutic effect of astragaloside IV, a potential anti-diabetic drug, against DN. As a result, a wide range of functional metabolites including sugars, amino acids, nucleotides and their derivatives, fatty acids, phospholipids, sphingolipids, glycerides, carnitine and its derivatives, vitamins, peptides, and metal ions associated with DN were identified and their unique distribution patterns in the rat kidney were visualized with high chemical specificity and high spatial resolution. These region-specific metabolic disturbances were ameliorated by repeated oral administration of astragaloside IV (100 mg/kg) for 12 weeks. This study provided more comprehensive and detailed information about the tissue-specific metabolic reprogramming and molecular pathological signature in the kidney of diabetic rats. These findings highlighted the promising potential of AFADESI and MALDI integrated MSI based metabolomics approach for application in metabolic kidney diseases.

Understanding of the nephrotoxicity induced by drug candidates is vital to drug discovery and development. Herein, an metabolomics method based on air flow-assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI) was established for direct analysis of metabolites in renal tissue sections. This method was subsequently applied to investigate spatially resolved metabolic profile changes in rat kidney after the administration of aristolochic acid I, a known nephrotoxic drug, aimed to discover metabolites associated with nephrotoxicity. As a result, 38 metabolites related to the arginine-creatinine metabolic pathway, the urea cycle, the serine synthesis pathway, metabolism of lipids, choline, histamine, lysine, and adenosine triphosphate were significantly changed in the group treated with aristolochic acid I. These metabolites exhibited a unique distribution in rat kidney and a good spatial match with histopathological renal lesions. This study provides new insights into the mechanisms underlying aristolochic acids nephrotoxicity and demonstrates that AFADESI-MSI-based metabolomics is a promising technique for investigation of the molecular mechanism of drug toxicity.