The alleviation effect and its mechanism of Niuhuang Jiedu prescription on realgar-induced genotoxicity in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Realgar (As2S2 or As4S4) is a traditional Chinese medicine (TCM) containing arsenic. Existing studies have shown that it has genotoxicity under long-term use with large doses. Niuhuang Jiedu (NHJD) is a Chinese medicine prescription containing realgar and seven other TCMs. Whether the multiple TCMs combination in NHJD can reduce the genotoxicity induced by realgar in equivalent doses is still unknown. AIM OF THE STUDY: To research the effect of NHJD on realgar's genotoxicity and the possible mechanism involved based on the arsenic methylation metabolic pathway. MATERIAL AND METHODS: Six groups (control, realgar (0.8 g/kg), NHJD (12.48 g/kg), as well as Glycyrrhiza uralensis Fisch (GU), Scutellaria baicalensis Georg (SB), Rheum palmatum L (RP) plus equivalent doses of realgar, respectively) were set up. ICR mice were intragastric administered for 12 weeks. First, genotoxicology tests were conducted to evaluate the effect of NHJD, GU, SB, and RP on reducing realgar's genotoxicity. The inorganic arsenic (iAs), dimethyl arsenic acid (DMA), and monomethyl arsenic acid (MMA) were determined by HPLC-AFS, and the iAs%, MMA%, DMA%, primary methylation index (PMI), etc. Were calculated. Meanwhile, the S-adenosyl methionine (SAM) and arsenate reductase (ARR) levels, the arsenic (+3)methyltransferase (As3MT), purine-nucleoside phosphorylase (PNP), glutathione S-transfer omega1 (GSTO1) gene expression were detected, aimed to explore the possible alleviation mechanisms of NHJD. RESULTS: The combination of multiple TCMs in NHJD decreased the levels of MN‰, SPA%, and DNA damage caused by realgar, with similar effects observed when SB, RP, and GU were used separately with realgar. Notably, the iAs% significantly decreased, while DMA% and PMI notably increased in the NHJD and realgar + SB (or RP) groups compared to the realgar-only group (P < 0.05). Increases in SAM and ARR levels were observed across various groups, but only the ARR increase in the NHJD group was statistically significant. Moreover, significant increases in As3MT mRNA and GSTO1 mRNA were noted in the NHJD group, and PNP mRNA levels significantly rose in the realgar + SB group. CONCLUSIONS: This study revealed that NHJD could attenuate the genotoxic effects of realgar. The botanicals SB, RP, and GU within NHJD may be key contributors to this effect. Enhancements in arsenic methylation capabilities through increased levels of SAM and ARR and elevated gene expressions of As3MT, PNP, and GSTO1 suggest potential mechanisms behind these findings.

Intrauterine arsenic exposure induces glucose metabolism disorders in adult offspring by targeting TET2-mediated DNA hydroxymethylation reprogramming of HNF4α in developing livers, an effect alleviated by ascorbic acid.

Exposure to arsenic during gestation has lasting health-related effects on the developing fetus, including an increase in the risk of metabolic disease later in life. Epigenetics is a potential mechanism involved in this process. Ten-eleven translocation 2 (TET2) has been widely considered as a transferase of 5-hydroxymethylcytosine (5hmC). Here, mice were exposed, via drinking water, to arsenic or arsenic combined with ascorbic acid (AA) during gestation. For adult offspring, intrauterine arsenic exposure exhibited disorders of glucose metabolism, which are associated with DNA hydroxymethylation reprogramming of hepatic nuclear factor 4 alpha (HNF4α). Further molecular structure analysis, by SEC-UV-DAD, SEC-ICP-MS, verified that arsenic binds to the cysteine domain of TET2. Mechanistically, arsenic reduces the stability of TET2 by binding to it, resulting in the decrease of 5hmC levels in Hnf4α and subsequently inhibiting its expression. This leads to the disorders of expression of its downstream key glucose metabolism genes. Supplementation with AA blocked the reduction of TET2 and normalized the 5hmC levels of Hnf4α, thus alleviating the glucose metabolism disorders. Our study provides targets and methods for the prevention of offspring glucose metabolism abnormalities caused by intrauterine arsenic exposure.