Optimization and validation of direct gas chromatography-mass spectrometry method for simultaneous quantification of ten short-chain fatty acids in rat feces

Solanum nigrum L. berries extract ameliorated the alcoholic liver injury by regulating gut microbiota, lipid metabolism, inflammation, and oxidative stress

Solanum nigrum L. (SN) berry is an edible berry containing abundant polyphenols and bioactive compounds, which possess antioxidant and antiinflammatory properties. However, the effects of SN on alcohol-induced biochemical changes in the enterohepatic axis remain unclear. In the current study, a chronic ethanol-fed mice ALD model was used to test the protective mechanisms of SN berries. Microbiota composition was determined via 16S rRNA sequencing, we found that SN berries extract (SNE) improved intestinal imbalance by reducing the Firmicutes to Bacteroides ratio, restoring the abundance of Akkermansia microbiota, and reducing the abundance of Allobaculum and Shigella. SNE restored the intestinal short-chain fatty acids content. In addition, liver transcriptome data analysis revealed that SNE primarily affected the genes involved in lipid metabolism and inflammatory responses. Furthermore, SNE ameliorated hepatic steatosis in alcohol-fed mice by activating AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), peroxisome proliferator-activated receptor α (PPAR-α). SNE reduced the expression of toll-like receptor 4 (TLR4), myeloid differentiation factor-88 (MyD88) nuclear factor kappa-B (NF-κB), which can indicate that SNE mainly adjusted LPS/TLR4/MyD88/NF-κB pathway to reduce liver inflammation. SNE enhanced hepatic antioxidant capacity by regulating NRF2-related protein expression. SNE alleviates alcoholic liver injury by regulating of gut microbiota, lipid metabolism, inflammation, and oxidative stress. This study may provide a reference for the development and utilization of SN resources.

Short-chain fatty acid levels in stools of patients with inflammatory bowel disease are lower than those in healthy subjects

OBJECTIVE

Short-chain fatty acids (SCFAs) are produced when the microbiota in the large intestine cause fermentation of dietary carbohydrates and fibers. These fatty acids constitute the primary energy source of colon mucosa cells and have a protective effect in patients suffering from inflammatory bowel disease (IBD). This study aimed to compare the SCFA levels in the stools of patients with IBD and healthy controls.

METHOD

Healthy controls and patients with IBD aged 18 and over were included in the study. Stool samples from all patients and healthy controls were collected, and stool acetic acid, propionic acid, and butyric acid levels were measured using a gas chromatography-mass spectrometry measurement method.

RESULTS

In this study, 64 participants were divided into two groups: 34 were in IBD (Crohn disease and ulcerative colitis) and 30 were in healthy control group. When fecal SCFA concentrations of IBD and healthy control groups were compared, a statistically significant difference was observed between them. When the fecal SCFA concentrations of Crohn's disease and ulcerative colitis patients in the IBD group were compared, however, no statistically significant difference was observed between them. Furthermore, when the participants' diet type (carbohydrate-based, vegetable-protein-based and mixed diet) and the number of meals were compared with fecal SCFA concentrations, no statistically significant difference was observed between them.

CONCLUSION

In general, fecal SCFA levels in patients with IBD were lower than those in healthy controls. Moreover, diet type and the number of meals had no effect on stool SCFA levels in patients with IBD and healthy individuals.

Sample preparation for fatty acid analysis in biological samples with mass spectrometry-based strategies

Fatty acids (FAs) have attracted many interests for their pivotal roles in many biological processes. Imbalance of FAs is related to a variety of diseases, which makes the measurement of them important in biological samples. Over the past two decades, mass spectrometry (MS) has become an indispensable technique for the analysis of FAs owing to its high sensitivity and precision. Due to complex matrix effect of biological samples and inherent poor ionization efficiency of FAs in MS, sample preparation including extraction and chemical derivatization prior to analysis are often employed. Here, we describe an updated overview of FA extraction techniques, as well as representative derivatization methods utilized in different MS platforms including gas chromatography-MS, liquid chromatography-MS, and mass spectrometry imaging based on different chain lengths of FAs. Derivatization strategies for the identification of double bond location in unsaturated FAs are also summarized and highlighted. The advantages, disadvantages, and prospects of these methods are compared and discussed. This review provides the development and valuable information for sample pretreatment approaches and qualitative and quantitative analysis of interested FAs using different MS-based platforms in complex biological matrices. Finally, the challenges of FA analysis are summarized and the future perspectives are prospected.

Microbiome metabolite quantification methods enabling insights into human health and disease

Many of the health-associated impacts of the microbiome are mediated by its chemical activity, producing and modifying small molecules (metabolites). Thus, microbiome metabolite quantification has a central role in efforts to elucidate and measure microbiome function. In this review, we cover general considerations when designing experiments to quantify microbiome metabolites, including sample preparation, data acquisition and data processing, since these are critical to downstream data quality. We then discuss data analysis and experimental steps to demonstrate that a given metabolite feature is of microbial origin. We further discuss techniques used to quantify common microbial metabolites, including short-chain fatty acids (SCFA), secondary bile acids (BAs), tryptophan derivatives, N-acyl amides and trimethylamine N-oxide (TMAO). Lastly, we conclude with challenges and future directions for the field.

HiSorb sorptive extraction for determining salivary short chain fatty acids and hydroxy acids in heart failure patients

Variations in salivary short-chain fatty acids and hydroxy acids (e.g., lactic acid, and 3-hydroxybutyric acid) levels have been suggested to reflect the dysbiosis of human gut microbiota, which represents an additional factor involved in the onset of heart failure (HF) disease. The physical-chemical properties of these metabolites combined with the complex composition of biological matrices mean that sample pre-treatment procedures are almost unavoidable. This work describes a reliable, simple, and organic solvent free protocol for determining short-chain fatty acids and hydroxy acids in stimulated saliva samples collected from heart failure, obese, and hypertensive patients. The procedure is based on in-situ pentafluorobenzyl bromide (PFB-Br) derivatization and HiSorb sorptive extraction coupled to thermal desorption and gas chromatography-tandem mass spectrometry. The HiSorb extraction device is completely compatible with aqueous matrices, thus saving on time and materials associated with organic solvent-extraction methods. A Central Composite Face-Centred experimental design was used for the optimization of the molar ratio between PFB-Br and target analytes, the derivatization temperature, and the reaction time which were 100, 60 °C, and 180 min, respectively. Detection limits in the range 0.1-100 µM were reached using a small amount of saliva (20 µL). The use of sodium acetate-1-13C as an internal standard improved the intra- and inter-day precision of the method which ranged from 10 to 23%. The optimized protocol was successfully applied for what we believe is the first time to evaluate the salivary levels of short chain fatty acids and hydroxy acids in saliva samples of four groups of patients: i) patients admitted to hospital with acute HF symptoms, ii) patients with chronic HF symptoms, iii) patients without HF symptoms but with obesity, and iv) patients without HF symptoms but with hypertension. The first group of patients showed significantly higher levels of salivary acetic acid and lactic acid at hospital admission as well as the lowest values of hexanoic acid and heptanoic acid. Moreover, the significant high levels of acetic acid, propionic acid, and butyric acid observed in HF respect to the other patients suggest the potential link between oral bacteria and gut dysbiosis.

Structure-specific antitumor effects and potential gut microbiota-involved mechanisms of ginseng polysaccharides on B16F10 melanoma-bearing mice

Ginseng polysaccharides (GPs) have shown gut microbiota-related antitumor effects. However, the relation between their structures and antitumor functions remains unknown. Here, crude polysaccharide (GP-c) and its fractions neutral polysaccharide (GP-n) and pectin (GP-a) were prepared for structure characterization and anti-B16F10 melanoma effect evaluation, and their influence on gut microbiota diversities and short-chain fatty acids (SCFAs) were also analyzed. Spearman correlations among the altered gut microbiota, SCFAs, and antitumor effects were conducted to elucidate the structure-function relationships. It was shown that the structures of GP-c, GP-n, and GP-a varied in monosaccharide composition and molecular weight distribution. GP-n and GP-c showed anti-melanoma effects, whereas GP-a promoted its growth slightly. GP-n and GP-c restored SCFAs levels such as acetic acid and butyric acid; moreover, it improved the gut microbiota ecosystem by upregulating the abundance of Allobaculum and Bifidobacterium. However, the restoration effect of GP-a was weak, or even worse. In addition, these two bacteria were negatively correlated with the tumor weight and related with the altered SCFAs. In conclusion, GP-n is essential for the anti-melanoma effects of GP, and the potential mechanisms might be related with its specific regulation of Allobaculum and Bifidobacterium abundance, and tumor-associated SCFAs levels. The outcomes highlighted here enable a deeper insight into the structure-function relationship of GP and propose new opinions on its antitumor effect.

Comparative effects of different enzymatic hydrolysates of konjac glucomannan on gut flora and constipation rats

This study aimed to compare the effects of different hydrolysates (named GKOS and MKOS) on constipated rats, which were degraded to obtain from konjac glucomannan by β-glucanase and β-mannanase, respectively....