alpha-Glycosyl Isoquercitrin (AGIQ) and its lack of carcinogenicity in rasH2 mice

Alpha-glycosyl isoquercitrin alleviates subchronic social defeat stress-induced depression symptoms by modulating the microbiota-gut-brain axis in mice

AIMS

Increasing evidence suggests a link between gut microbial dysbiosis and the pathogenesis of depression. Alpha-glycosyl isoquercitrin (AGIQ), consisting of isoquercitrin and its glycosylated quercetin, has beneficial effects on the gut microbiome and brain function. Here, we detected the potential antidepressant impact of a four-week administration of AGIQ and its underlying mechanisms using a mouse model of depression.

MAIN METHODS

Male C57BL/6 mice were orally administered AGIQ (0.05 % or 0.5 % in drinking water) for 28 days; subchronic social defeat stress was performed in the last 10 days. Behavior tests were conducted to assess anxiety and depressive-like behaviors. Additionally, evaluations encompassed 5-hydroxytryptamine (5-HT) levels, the gut microbiota composition, lipopolysaccharide (LPS) concentrations, short-chain fatty acids levels, and intestinal barrier integrity changes.

KEY FINDINGS

AGIQ significantly alleviated depression-like behaviors and increased hippocampal 5-HT levels. Further, AGIQ mitigated stress-induced gut microbial abnormalities and reduced the levels of LPS in the serum, which affected the relative gene expression levels of 5-HT biosynthesis enzymes in vitro. Furthermore, AGIQ reversed the reduced butyrate levels in cecal contents and improved the impaired intestinal barrier by increasing the expression of colonic zonula occluden-1 (ZO-1) and occludin, thereby decreasing LPS leakage.

SIGNIFICANCE

Our results suggest that AGIQ could improve stress-induced depression by regulating the gut microbiome, which inhibits LPS production and maintains the gut barrier. This is the first report on the potential effect of AGIQ on depression via the gut microbiota-brain axis, shedding new light on treatment options.

Isoquercitrin alleviates lipopolysaccharide-induced intestinal mucosal barrier damage in mice by regulating TLR4/MyD88/NF-κB signaling pathway and intestinal flora

Intestinal mucosal barrier damage is closely associated with the development of several intestinal inflammatory diseases. Isoquercitrin (IQ) is a natural flavonoid compound derived from plants, which exhibits high antioxidant and anti-inflammatory activity with minimal side effects in humans. Therefore, it shows great potential for preventing and treating intestinal mucosal barrier damage. This study aims to investigate the ameliorative effect and mechanism of IQ on lipopolysaccharide (LPS)-induced intestinal mucosal barrier damage in mice. The mice were treated with IQ for 7 days and then injected with LPS to induce intestinal mucosal barrier damage. The results revealed that IQ treatment alleviated LPS-induced intestinal mucosal barrier damage in mice, which can be evidenced by the improvements in intestinal morphology and the promotion of expression in intestinal tight junctions (ZO-1, Claudin-1, and Occludin), as well as MUC2 mucin. IQ also attenuated intestinal inflammatory responses by inhibiting the TLR4/MyD88/NF-κB signaling pathway and reducing the expression and plasma levels of IL-6, IL-1β, and TNF-α. Furthermore, IQ significantly increased the relative abundance of beneficial bacteria, including Dubosiella, Akkermansia muciniphila and Faecalibaculum rodentium, while suppressing the growth of harmful bacteria such as Mucispirillum schaedleri in the intestinal flora of mice. Consequently, IQ can alleviate the LPS-induced intestinal mucosal barrier damage in mice by inhibiting the TLR4/MyD88/NF-κB signaling pathway and modulating the intestinal flora.

Oral chronic toxicity and carcinogenicity study of alpha-glycosyl isoquercitrin (AGIQ) in Sprague Dawley rats

alpha-Glycosyl isoquercitrin (AGIQ) is a flavonoid that possesses antioxidant and tumor suppressive capabilities and is marketed as a food additive in Japan. The aim of this study was to assess the potential for oral chronic toxicity and carcinogenicity of AGIQ in male and female Sprague Dawley rats following up to 5.0% dietary exposure. In the chronic toxicity study, rats were exposed to AGIQ or vehicle for one year with a 6-month interim termination point; for the carcinogenicity study, rats were treated for 24 months. No signs of AGIQ-related toxicity clinically or histologically were observed for up to one year except for yellow discoloration of bone. In the carcinogenicity study, a statistically significant increase in the incidence of malignant glioma of the brain or spinal cord was observed in female rats exposed to 5.0% AGIQ compared to those exposed to control feed. A Scientific Advisory Panel of experienced neuropathologists reviewed the gliomas (routine stains and glial cell markers) and concluded that the gliomas were a rare, spontaneous, rat-specific neoplasm: malignant microglial tumor. The lesions could not definitively be attributed to AGIQ exposure and have limited implications with respect to predicting human cancer risk.

Enzymatically Modified Isoquercitrin: Production, Metabolism, Bioavailability, Toxicity, Pharmacology, and Related Molecular Mechanisms

Quercetin and its glycosides, such as isoquercitrin or rutin, are among the most ubiquitous flavonoids present in plants. They possess numerous health-promoting properties, whose applicability is, however, limited by poor water solubility and absorption issues. Enzymatically modified isoquercitrin (EMIQ) is an isoquercitrin derivative obtained from rutin via enzymatic transformations that greatly enhance its bioavailability. Due to advantageous reports on its safety and bioactivity, EMIQ is currently gaining importance as a food additive and a constituent of dietary supplements. This review summarizes the thus-far-conducted investigations into the metabolism, toxicity, biological properties, and molecular mechanisms of EMIQ and presents a comprehensive characterization of this valuable substance, which might represent the future of flavonoid supplementation.