Discovery of cysteine-targeting covalent histone methyltransferase inhibitors.

Post-translational methylation of histone lysine or arginine residues by histone methyltransferases (HMTs) plays crucial roles in gene regulation and diverse physiological processes and is implicated in a plethora of human diseases, especially cancer. Therefore, histone methyltransferases have been increasingly recognized as potential therapeutic targets. Consequently, the discovery and development of histone methyltransferase inhibitors have been pursued with steadily increasing interest over the past decade. However, the disadvantages of limited clinical efficacy, moderate selectivity, and propensity for acquired resistance have hindered the development of HMTs inhibitors. Targeted covalent modification represents a proven strategy for kinase drug development and has gained increasing attention in HMTs drug discovery. In this review, we focus on the discovery, characterization, and biological applications of covalent inhibitors for HMTs with emphasis on advancements in the field. In addition, we identify the challenges and future directions in this fast-growing research area of drug discovery.

The Subchronic Toxic Effects of Mosla chinensis Maxim in Normal Rats.

BACKGROUND: The aim of this work was to study the toxic effects and target organs of Mosla chinensis Maxim (MCM) in rats and provide theoretical basis for clinical medication. METHODS: The subchronic toxicity study was conducted on 60 male and female SD rats using the fixed-dose method for the treatment groups and 20 male and female SD rats for the control. At the subchronic toxicity study, the water extract of MCM with fixed doses of 0.2 g/kg/day, 2 g/kg/day, and 20 g/kg/day was administered for 90 days intragastric, and the control group was given the same amount of distilled water. After 90 days, the general conditions of the rats were observed. Assessment on safety of the extract was conducted by a subchronic toxicity test which mainly examined alteration occurrence in gut flora and urine metabolism. RESULTS: There was no significant difference in physical signs, reactivity, and stool characteristics in the four groups. Compared with the control group, the number of red blood cells in the male 2 g/kg/day group and the female 0.2 g/kg/day group was significantly different (P < 0.05). The detection of serum biochemical indicators showed that MCM has an effect on liver and kidney function but has no physiological significance. The level of low-density lipoprotein in male rats was lower than that in the control group (P < 0.05). Compared with the control group, the blood glucose levels of female rats in the 0.2 g/kg/day, 2 g/kg/day, and 20 g/kg/day groups were significantly increased (P < 0.05). As far as the diversity of intestinal flora is concerned, feeding MCM for 90 days has an influence on the distribution of intestinal flora. The content of lactic acid bacteria increased, and the ratio of hard bacteria to Bacteroides (f/b) was also affected, but there was no significant difference. CONCLUSIONS: These findings showed that the long-term intragastric administration of the MCM is safe to use within its dose recommendation. But it could have a slight effect on the metabolism of uric acid by changing the composition of intestinal flora and affecting the metabolism of tryptophan.