The intestine is considered to be a vital digestive organ to absorb nutrients and is the largest immune organ, while numerous microorganisms coexist with the host. It is well known that the complex interactions between the gut microbiota and the host’s immune system inevitably affect the function of other organs, creating an “axis” between them. During the past few years, a new technique based mainly on microfluidics and cell biology has been developed to emulate the structure, function, and microenvironment of the human gut, called the “gut-on-chip”. This microfluidic chip provides insight into key aspects of gut function in health and disease, such as the gut–brain axis, gut–liver axis, gut–kidney axis, and gut–lung axis. In this review, we first describe the basic theory of the gut axis and the various composition and parameter monitoring of the gut microarray systems, as well as summarize the development and emerging advances in the gut–organ-on-chip, with a focus on the host-gut flora and nutrient metabolism, and highlight their role in pathophysiological studies. In addition, this paper discusses the challenges and prospects for the current development and further use of the gut–organ-on-chip platform.

Astragali Radix (AR) is one of the well-known traditional Chinese medicines with a long history of medical use and a wide range of clinical applications. AR contains a variety of chemical constituents which can be classified into the following categories: polysaccharides, saponins, flavonoids, amino acids, and trace elements. There are several techniques to extract these constituents, of which microwave-assisted, enzymatic, aqueous, ultrasonic and reflux extraction are the most used. Several methods such as spectroscopy, capillary electrophoresis and various chromatographic methods have been developed to identify and analyze AR. Meanwhile, this paper also summarizes the biological activities of AR, such as anti-inflammatory, antioxidant, antitumor and antiviral activities. It is expected to provide theoretical support for the better development and utilization of AR.

The structural characterization, the in vitro antioxidant activity, and the hypoglycemic activity of a polysaccharide (SGP-1-1) isolated from Siraitia grosvenorii (SG) were studied in this paper. SGP-1-1, whose molecular weight is 19.037 kDa, consisted of Gal:Man:Glc in the molar ratio of 1:2.56:4.90. According to the results of methylation analysis, GC–MS, and NMR, HSQC was interpreted as a glucomannan with a backbone composed of 4)-β-D-Glcp-(1→4)-, α-D-Glcp-(1→4)-, and 4)-Manp-(1 residues. α-1,6 linked an α-D-Galp branch, and α-1,6 linked an α-D-Glcp branch. The study indirectly showed that SGP-1-1 has good in vitro hypoglycemic and antioxidant activities and that these activities may be related to the fact that the SGP-1-1’s monosaccharide composition (a higher proportion of Gal and Man) is the glycosidic-bond type (α- and β-glycosidic bonds). SGP-1-1 could be used as a potential antioxidant and hypoglycemic candidate for functional and nutritional food applications.

The inflammatory and antioxidant effects of a novel Siraitia grosvenorii polysaccharide (SGP-1-1) were investigated in an inflammation-suppressed diabetic nephropathy (DN) mouse model, and the underlying molecular mechanisms of inflammation and oxidative stress in SGP-1-1-treated mouse models were elucidated. The results demonstrated that DN mouse models treated with SGP-1-1 (50, 100, and 200 mg kg⁻¹ d⁻¹) exhibited good inflammation-modulating activity. In addition, histopathological analysis showed that glomerular atrophy, severe glomerular thylakoid hyperplasia, tubular endothelial detachment, basement membrane exposure, cytoplasmic infiltration with inflammatory cells, and interstitial oedema were all alleviated in DN mice after treatment with SGP-1-1. Metabolomics analysis based on UPLC-Q-TOF/MS revealed that a close relationship between the occurrence of DN and the potential 39 biomarkers, especially, leukotriene E3 and arachidonic acid,of which the main invloved metabolic pathways may beglycerophospholipid metabolism, arachidonic acid metabolism and primary bile acid biosynthesis. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis results demonstrated that SGP-1-1 downregulates mRNA and the protein expression of the G protein-coupled cell membrane receptor TLR4 and its downstream protein kinase (NF-κB p65). This, resulted in the inhibition of the TLR4-NF-κB pathway in the peritoneum of DN mice by regulating inflammation, while stimulating the production of superoxide dismutase (SOD) and reducing the production of cytokine (IL-6, TNF-α) and malondialdehyde (MDA).