Comparison of 3-nitrophenylhydrazine, O-benzyl hydroxylamine, and 2-picolylamine derivatizations for analysis of short-chain fatty acids through liquid chromatography coupled with tandem mass spectrometry.

Short-chain fatty acids (SCFAs) are metabolites derived from gut microbiota and implicated in host homeostasis. Hence, the profiling SCFAs from biological samples plays an important role in revealing the interaction between gut microbiota and pathogens. Previous studies, liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with various derivatization strategies have been performed to obtain the SCFA profiles from biological samples. However, it is poor evidence to compare these derivatization regents and conditions. Thus, we present the evaluation of three major derivatization reagents, namely 3-nitrophenylhydrazine (3-NPH), O-benzylhydroxylamine (O-BHA), and 2-picolylamine (2-PA), for the analysis of eight SCFAs classified as C2-C5 isomers using LC-MS/MS. First, in a reversed-phase LC separation, 3-NPH showed good retention capacity. Although O-BHA derivatization showed higher sensitivity and good retention capacity than 2-PA, only 2-PA derivatization could successfully separate eight SCFAs. The matrix effects in human serum ranged 77.1-99.0% (RSD ≤ 3.4%, n = 6) for 3-NPH derivatives, 91.0-94.6% (RSD ≤ 5.4%, n = 6) for O-BHA derivatives, 81.6-99.5% (RSD ≤ 8.0%, n = 6) for 2-PA derivatives. These compared results showed each characteristic of 3-NPH, O-BHA, and 2-PA for SCFA derivatization based on LC-MS/MS approaches.

Sustainable chromatographic purification of milbemectin: Application of high-speed countercurrent chromatography coupled with off-line atmospheric pressure solid analysis probe-high resolution mass spectrometry.

Isolation of valuable chemicals is an important process in reagent manufacturing for the pharmaceutical and food science industries. This process is traditionally time-consuming, expensive, and consumes vast amounts of organic solvents. Considering green chemistry and sustainability concerns, we sought to develop a sustainable chromatographic purification methodology for obtaining antibiotics by focusing on the reduction of organic solvent waste generation. Milbemectin (mixture of milbemycin A3 and milbemycin A4) was successfully purified using high-speed countercurrent chromatography (HSCCC) and pure fractions (>98% purity, HPLC) could be identified using the organic solvent fee atmospheric pressure solid analysis probe mass spectrometry (ASAP-MS). The organic solvents required for HSCCC could be redistilled and recycled for continued HSCCC purification, thus reducing the consumption of organic solvent (n-hexane/ethyl acetate) by 80+%. Optimization of the two-phase solvent system (n-hexane/ethyl acetate/methanol/water, 9/1/7/3, v/v/v/v) for HSCCC was assisted computationally, thereby reducing solvent waste from an experimental determination. Our proposal application of HSCCC and offline ASAP-MS provides proof of concept for a sustainable, preparative scale, chromatographic purification methodology for obtaining antibiotics in high purity.

Short-chain fatty acids profiling in biological samples from a mouse model of Sjögren's syndrome based on derivatized LC-MS/MS assay.

An analytical platform is required to characterize the short-chain fatty acids (SCFAs) in a mouse model of pathological immune conditions. Therefore, liquid chromatography tandem mass spectrometry combined with 2-picolylamine derivatization and a comprehensive study of SCFAs distribution based on serum, saliva, feces, liver, and brain from a mouse model of Sjögren's syndrome (SS) is performed. The design of experiments is used to achieve efficient 2-picolylamine derivatization, and optimize the reaction conditions. Twelve SCFAs are derivatized, and separated on a reversed-phase C18 column. All SCFAs show high linearity (r2 > 0.995) and intra/inter-day accuracy values from 71.6% to 115.6% (precision < 13.7%). This method was used to determine SCFAs concentrations in the serum, saliva, feces, liver, and brain of an SS model mice, and isobutyric acid, valeric acid, isovaleric acid, and 2-methylbutyric acid in liver from SS were significantly different compared with control group. Moreover, the preliminary evaluation of propionic acid, butyric acid, isobutyric acid, valeric acid, and isovaleric acid in saliva is conducted based on the respective SS stages and are correlated with these histological scores. This analytical platform for the widely SCFAs profiling in several tissues can be a clue for studying unclear immune pathophysiology.

Experimental design of a stable isotope labeling derivatized UHPLC-MS/MS method for the detection/quantification of primary/secondary bile acids in biofluids.

An efficient analytical platform is required to characterize the human metabolome in pathology. For this purpose, ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) combined with chemical derivatization stands out as one of the most powerful techniques. A targeted metabolomics platform for 11 bile acids (BAs) profiling in human serum and bile samples using a stable isotope labeling derivatization (SILD) was applied. For SILD, the design of experiments (DoE) was employed to optimize the reaction conditions such five factors in three levels. The sample preparation built upon a liquid-liquid extraction requiring small volumes (20 µL). In application, the relation between the BA and short-chain fatty acid levels in human serum and bile samples from patients with bile duct diseases were investigated. The proposed method offers significant utility in the large-scale biological analyses of hepato-biliary-pancreatic-related diseases.

Verification of the Impact of Blood Glucose Level on Liver Carcinogenesis and the Efficacy of a Dietary Intervention in a Spontaneous Metabolic Syndrome Model.

Metabolic syndrome (MS) is a risk factor for type 2 diabetes mellitus, vascular inflammation, atherosclerosis, and renal, liver, and heart diseases. Non-alcoholic steatohepatitis (NASH) is a progressive representative liver disease and may lead to the irreversible calamities of cirrhosis and hepatocellular carcinoma. Metabolic disorders such as hyperglycemia have been broadly reported to be related to hepatocarcinogenesis in NASH; however, direct evidence of a link between hyperglycemia and carcinogenesis is still lacking. Tsumura Suzuki Obese Diabetic (TSOD) mice spontaneously develop metabolic syndrome, including obesity, insulin resistance, and NASH-like liver phenotype, and eventually develop hepatocellular carcinomas. TSOD mice provide a spontaneous human MS-like model, even with significant individual variations. In this study, we monitored mice in terms of their changes in blood glucose levels, body weights, and pancreatic and liver lesions over time. As a result, liver carcinogenesis was delayed in non-hyperglycemic TSOD mice compared to hyperglycemic mice. Moreover, at the termination point of 40 weeks, liver tumors appeared in 18 of 24 (75%) hyperglycemic TSOD mice; in contrast, they only appeared in 5 of 24 (20.8%) non-hyperglycemic mice. Next, we investigated three kinds of oligosaccharide that could lower blood glucose levels in hyperglycemic TSOD mice. We monitored the levels of blood and urinary glucose and assessed pancreatic lesions among the experimental groups. As expected, significantly lower levels of blood and urinary glucose and smaller deletions of Langerhans cells were found in TSOD mice fed with milk-derived oligosaccharides (galactooligosaccharides and lactosucrose). At the age of 24 weeks, mild steatohepatitis was found in the liver but there was no evidence of liver carcinogenesis. Steatosis in the liver was alleviated in the milk-derived oligosaccharide-administered group. Taken together, suppressing the increase in blood glucose level from a young age prevented susceptible individuals from diabetes and the onset of NAFLD/NASH, as well as carcinogenesis. Milk-derived oligosaccharides showed a lowering effect on blood glucose levels, which may be expected to prevent liver carcinogenesis.

Association of Short-Chain Fatty Acids in the Gut Microbiome With Clinical Response to Treatment With Nivolumab or Pembrolizumab in Patients With Solid Cancer Tumors.

Importance: Immunotherapy using immune checkpoint inhibitors has been remarkably effective for treating multiple cancer types, and the gut microbiome is a possible factor affecting immune checkpoint inhibitor efficacy. However, the association between the gut microbiome and immune status of the tumor microenvironment remains unclear. Short-chain fatty acids (SCFAs) are major end product metabolites produced by the gut microbiota and have wide-ranging impacts on host physiology. Objective: To evaluate fecal and plasma SCFAs in patients with solid cancer tumors treated with programmed cell death-1 inhibitors (PD-1i). Design, Setting, and Participants: This was a prospective cohort biomarker study of patients with cancer who planned therapy with PD-1i at Kyoto University Hospital between July 2016 and February 2019. Data were analyzed from October 2019 to February 2020. Exposures: Patients who were treated with nivolumab or pembrolizumab were classified into 2 groups based on their treatment response using Response Evaluation Criteria in Solid Tumors version 1.1: responders who achieved an objective response and nonresponders. Dietary information in terms of intake frequency was obtained. Concentrations of SCFAs in fecal and plasma samples collected before PD-1i administration were measured using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. Main Outcomes and Measures: The concentration of SCFAs and progression-free survival. Results: Among 52 patients enrolled, the median (range) patient age was 67 (27-84) years, and 23 (44%) were women. Median (range) duration of follow-up of the survivors after administration of PD-1i was 2.0 (0.4-4.1) years. The overall response rate was 28.8%. High concentrations of some SCFAs were associated with longer progression-free survival. These included fecal acetic acid (hazard ratio [HR], 0.29; 95% CI, 0.15-0.54), propionic acid (HR, 0.08; 95% CI, 0.03-0.20), butyric acid (HR, 0.31; 95% CI, 0.16-0.60), valeric acid (HR, 0.53; 95% CI, 0.29-0.98), and plasma isovaleric acid (HR, 0.38; 95% CI, 0.14-0.99). Conclusions and Relevance: Results of this study suggest that fecal SCFA concentrations may associated with PD-1i efficacy; thus, SCFAs may be the link between the gut microbiota and PD-1i efficacy. Because fecal examinations are completely noninvasive, they may be applicable for routine monitoring of patients.

Effect of coffee or coffee components on gut microbiome and short-chain fatty acids in a mouse model of metabolic syndrome.

We previously showed that male Tsumura Suzuki obese diabetes (TSOD) mice, a spontaneous mouse model of metabolic syndrome, manifested gut dysbiosis and subsequent disruption of the type and quantity of plasma short-chain fatty acids (SCFAs), and daily coffee intake prevented nonalcoholic steatohepatitis in this mouse model. Here, we present a preliminary study on whether coffee and its major components, caffeine and chlorogenic acid, would affect the gut dysbiosis and the disrupted plasma SCFA profile of TSOD mice, which could lead to improvement in the liver pathology of these mice. Three mice per group were used. Daily intake of coffee or its components for 16 wk prevented liver lobular inflammation without improving obesity in TSOD mice. Coffee and its components did not repair the altered levels of Gram-positive and Gram-negative bacteria and an increased abundance of Firmicutes in TSOD mice but rather caused additional changes in bacteria in six genera. However, caffeine and chlorogenic acid partially improved the disrupted plasma SCFA profile in TSOD mice, although coffee had no effects. Whether these alterations in the gut microbiome and the plasma SCFA profile might affect the liver pathology of TSOD mice may deserve further investigation.

Application of 2-Picolylamine Derivatized Ultra-high Performance Liquid Chromatography Tandem Mass Spectrometry for the Determination of Short-chain Fatty Acids in Feces Samples.

We present a sensitive and selective method for the simultaneous determination of short-chain fatty acids (SCFAs), such as acetic acid (AA), propionic acid, butyric acid (BA), isobutyric acid, valeric acid, isovaleric acid, hydroangelic acid, caproic acid, 4-methylvaleric acid and succinic acid (SA) in feces samples using a ultra-high performance liquid-chromatography tandem mass spectrometry (UHPLC-MS/MS) with simple derivatization of 2-picolylamine. The main SFCAs were derivatized in the same condition, and showed the specific product ion (m/z 109) in the electrospray positive mode regarding to 2-picolylamine. The derivatized SA showed a different pattern of the product ion (m/z 191). The derivatized analytes showed LOD < 75 nM, LOQ < 100 nM and r2 in the calibration curve > 0.991. The QuEChERS was used for sample preparation of feces samples. In the recovery test, the recovery values appeared from 89.7 to 100.2% (RSD: 2.1 to 9.2%, n = 6). This developed method was applied to evaluate obese diabetes model mice. In the result, the branched-chain SCFAs levels in feces from model mice of spontaneous obese type II diabetes were on a declining trend compared with normal. The AA levels from model mice with high-calorie/fat diet are owed a declining trend for 3 to 9 months. The BA levels showed that normal mice were increasing, and model mice had decreased tendency for breeding months. High-calorie/fat diet showed that the SA levels increased.

Analysis of the gut microbiome and plasma short-chain fatty acid profiles in a spontaneous mouse model of metabolic syndrome.

Male Tsumura Suzuki obese diabetes (TSOD) mice spontaneously develop obesity and obesity-related metabolic syndrome. Gut dysbiosis, an imbalance of gut microbiota, has been implicated in the pathogenesis of metabolic syndrome, but its mechanisms are unknown. Short-chain fatty acids (SCFAs) are the main fermentation products of gut microbiota and a link between the gut microbiota and the host's physiology. Here, we investigated a correlation among gut dysbiosis, SCFAs, and metabolic syndrome in TSOD mice. We detected enriched levels of Gram-positive bacteria and corresponding decreases in Gram-negative bacteria in 24-wk-old metabolic syndrome-affected TSOD mice compared with age-matched controls. The abundance of Bacteroidetes species decreased, the abundance of Firmicutes species increased, and nine genera of bacteria were altered in 24-wk-old TSOD mice. The total plasma SCFA level was significantly lower in the TSOD mice than in controls. The major plasma SCFA-acetate-decreased in TSOD mice, whereas propionate and butyrate increased. TSOD mice had no minor SCFAs (valerate and hexanoate) but normal mice did. We thus concluded that gut dysbiosis and consequent disruptions in plasma SCFA profiles occurred in metabolic syndrome-affected TSOD mice. We also propose that the TSOD mouse is a useful model to study gut dysbiosis, SCFAs, and metabolic syndrome.

Disruption of ins-11, a Caenorhabditis elegans insulin-like gene, and phenotypic analyses of the gene-disrupted animal.

The insulin/insulin-like growth factor-I signaling (IIS) pathway regulates larval diapause, adult lifespan, fat metabolism, and stress-resistance in the nematode Caenorhabditis elegans. One of 38 C. elegans insulin-like genes, ins-11, was disrupted and phenotypic analyses of the gene-disrupted animal were performed. The gene-disruption exhibited a significant influence on the adult lifespan. It antagonized the lifespan extension induced by RNAi knockdown of another insulin-like gene, ins-7. Hence ins-11 appears to be necessary for lifespan extension caused by a decrease in the IIS pathway. This is the first description of gene-disruption of the C. elegans insulin-like gene that suppresses the lifespan extension.