Abstract Gut bacterial β-glucuronidase (GUS) can reactivate xenobiotics that exert enterohepatic circulation- triggered gastrointestinal tract toxicity. GUS inhibitors can alleviate drug-induced enteropathy and improve treatment outcomes. We evaluated the inhibitory effect of Polygonum cuspidatum Siebold & Zucc. and its major constituents against Escherichia coli GUS (EcGUS), and characterized the inhibitory mechanism of each of the components. Trans-resveratrol 4’-O-β-D-glucopyranoside (HZ-1) and (-)-epicatechin gallate (HZ-2) isolated from P. cuspidatum were identified as the key components and potent inhibitors. These two components displayed strong to moderate inhibitory effects on EcGUS, with Ki values of 9.95 and 1.95 μM, respectively. Results from molecular docking indicated that HZ-1 and HZ-2 could interact with the key residues Asp163, Ser360, Ile 363, Glu413, Glu504, and Lys 568 of EcGUS via hydrogen bonding. Our findings demonstrate the inhibitory effect of P. cuspidatum and its two components on EcGUS, which supported the further evaluation and development of P. cuspidatum and its two active components as novel candidates for alleviating drug-induced damage in the mammalian gut.

ABSTRACT Herein, a binuclear ruthenium(II) complex modified by calix[4]arene group has been prepared. The complex as potential inducer and stabilizer of c-myc G-quadruplex DNA and antitumor reagent were studied. Observations revealed that the complex could bind to c-myc Pu27 and Pu22 DNA strongly with constants of 1.18 × 107 (Pu27) and 4.13 × 106 M-1 (Pu22) via groove mode as determined from absorption and luminescence titrations, as well as CD spectra. Results of continuous variation analysis confirmed that the complex interacted with c-myc G-quadruplex DNA through a 1:1 binding stoichiometry. As verified by PCR-stop assay, the replication of c-myc DNA was effectively blocked by the complex with the complete inhibition at the complex concentration of 4.0 μM both for Pu27 and Pu22, suggesting that the complex could efficiently induce the formation of c-myc G-quadruplex DNA. The appearance of blue TMB solution in the visual experiment also proved that the sequences of Pu27 and Pu22 could fold into G-quadruplex under the induction of the complex. Nevertheless, the complex was found to exhibit weak stabilization ability on c-myc G-quadruplex DNA according to FRET assay, which increased the melting point of c-myc DNA only 3-3.5 °C. The experiments on Topoisomerase inhibition and cytotoxicity of the complex showed that it acted as an inhibitor of TopoI and exhibited moderate anticancer activity against MCF-7 and Huh-7 tumor cells.

ABSTRACT A dinuclear ruthenium complex [Ru2(bpy)4(bip-phenol)](ClO4)4 {bpy = 2,2′-bipyridine, bip-phenol = 2,4-bis(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenol} has been synthesized and characterized. The calf thymus (ct) DNA binding properties of the complex are investigated by means of DNA viscosity and optical spectroscopic techniques of UV-visible absorption and emission spectral titrations, steady-state emission quenching with ferrocyanide, ethidium bromide competitive binding, DNA thermal denaturation and reverse salt effect, together with molecular simulation technology. The results suggest that the complex is a promising DNA groove binder with a large DNA binding constant on 106 M−1 order of magnitude. The fluorescence of the complex manifests by 6.3-fold upon binding saturately to DNA. The complex is also demonstrated to be an efficient photocleaver of pBR 322 DNA.

This study aimed to investigate how 6-bromoindirubin-3’-oxime (BIO) increases the osteogenic differentiation of canine bone mesenchymal stem cells (BMSCs) and the role of the Wnt/β-catenin signaling pathway in this process. We mimicked the effect of Wnt by adding BIO to the culture medium of BMSCs and examined whether canonical Wnt signaling positively affects the differentiation of these cells into osteoblasts. Canine BMSCs were cultured with 0.5 and 1.0 μM BIO under osteogenic conditions and then differentiation markers were investigated. It was found that BIO significantly increased the activity of alkaline phosphatase (ALP), the number of ALP-positive cells, the mineralization level and calcium deposits. Moreover, cells cultured with 0.5 and 1.0 μM BIO exhibited detectable β-catenin expression in their nuclei, and showed upregulated β-catenin and glycogen synthase kinase 3 beta(GSK3β) phosphorylation compared to untreated cells. In addition, BIO enhanced the mRNA expression of osteoblast differentiation markers such as ALP, runt-related transcription factor 2, collagen I, osteocalcin, and osteonectin. In conclusion, BIO upregulated GSK3β phosphorylation and inhibited its activity, thereby activating the Wnt/β-catenin signaling pathway and promoting the osteogenic differentiation of canine BMSCs. The effect of 1.0 μM BIO on BMSCs differentiation was stronger than that of 0.5 μM BIO.

The effect of bisacodyl on the treatment of rats with slow transit constipation (STC) was studied. Forty-five female Wister rats were divided into control group, STC group, and STC bisacodyl group. The immunohistochemical method was used to determine interstitial cells of Cajal (ICC) and the expression of c-Kit protein. Body mass and the number of defecations were significantly decreased in the STC group compared with the control group on the 100th day after diphenoxylate administration, while dry weight of feces was significantly increased and the intestinal transit time was prolonged. There were significant differences in the number of defecations, dry weight of feces, and intestinal transit time among the three groups. The number of defecations was higher, dry weight of feces was lower, and intestinal transit time was shorter in the STC bisacodyl group compared to the STC group. In addition, ICC basement membrane dissolution occurred in the colon wall of the STC group. The connection between ICC and surrounding cells was destroyed, and the nucleus shrunken to different degrees. Moreover, c-Kit expression in the STC group was significantly lower than the control group. The connection between ICC and surrounding cells in the STC bisacodyl group was significantly stronger than the STC group, and the number of ICC and the expression of c-Kit were increased. Bisacodyl could reduce the severity of STC in rats by increasing the number of ICC and the expression of c-Kit.