Effects of piceatannol on the structure and activities of bovine serum albumin: A multi-spectral and molecular modeling studies.

Piceatannol (PIC) displays a wide spectrum of biological activities, such as antioxidation, antibacterial activity and anti-inflammation, but the biochemical and molecular mechanism is not fully understood. In this study, the interaction of PIC with bovine serum albumin (BSA) was studied by fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, circular dichroism spectroscopy and molecular simulation. The effects of PIC on BSA non-enzymatic glycosylation, fibrillation, thermal stability, and structure information were also studied. The results showed that the formation of PIC-BSA complex by mainly hydrogen-bonding forces resulted in the conformational changes of protein. PIC inhibited the formation of ß-sheets structures of BSA. BSA still maintained the esterase-like good activity in the presence of PIC. In addition, PIC significantly reduced the degree of BSA glycosylation. These results provided a basis for the molecular interaction between PIC and protein, and suggested the potential effect of PIC in preventing the progression of diabetes mellitus.

Peroxisome proliferator-activated receptor gamma (PPARγ) activation and metabolism disturbance induced by bisphenol A and its replacement analog bisphenol S using in vitro macrophages and in vivo mouse models.

Bisphenol A (BPA) and its replacement analog, bisphenol S (BPS), have been proposed as environmental obesogen to disrupt the lipid metabolism through regulating peroxisome proliferator-activated receptor gamma (PPARγ) receptor. However, there is a dearth of information on whether this biological effect can occur in human macrophage, a cell type which closely interacts with adipocytes and hepatocytes to control lipid metabolism. Here, we for the first time investigate the activity of BPA and BPS on PPARγ pathway in human macrophages. The results demonstrated that BPA and BPS served as activators of PPARγ in human macrophage cell line, and significantly induced the expression of lipid metabolism-related genes, including fatty acid binding protein 4 (FABP4), cluster of differentiation 36 (CD36) and nuclear receptor subfamily 1 group H member 3 (NR1H3). In PPARγ knockout cells, expression of these genes was down-regulated, suggesting that these genes are dependent on PPARγ. The underlying mechanisms were further investigated using an in vivo mouse model, and the results confirmed the induction of PPARγ and its respective target genes in mice following exposure to BPA or BPS. Moreover, the observed alteration of PPARγ expression highly correlated with the disturbance of metabolism profiles in liver tissues as detected by 1H Nuclear Magnetic Resonance (NMR)-based metabonomics. Overall, this study provided the first evidence that BPA and BPS activated PPARγ and its target genes in human macrophages, and provided comprehensive information to confirm that BPA and BPS disturb the metabolism through targeting PPARγ via both in vitro assays and in vivo animal models.

RIP1 and RIP3 contribute to Tributyltin-induced toxicity in vitro and in vivo.

Tributyltin (TBT), a widely distributed environmental pollutant, is toxic to animals and human beings. Although its toxicity, especially the immunosuppressive effect, has been reported a lot, the underlying molecular mechanisms are still unclear. In this study, we investigated the mechanisms of TBT-induced cytotoxicity both in vitro and in vivo. TBT induced cell death in both J774A.1 macrophages and mouse bone marrow-derived macrophages (BMDMs) as measured by the LDH and Annexin V-FITC/PI dual staining assays. Pretreatment with RIP1 inhibitor Necrostatin-1 (Nec-1) or transfection with Rip1 siRNA significantly suppressed TBT-induced cytotoxicity in J774A.1 macrophages or human embryonic kidney cell line (HEK293 cells). TBT-induced cell death was also markedly inhibited in RIP3-/- BMDMs. In agreement with in vitro results, TBT-induced in vivo immunotoxic effects including leukocyte depletion and thymus atrophy were significantly attenuated in RIP3-/- mice or WT mice treated with Nec-1. Notably, the mortality rate induced by TBT was remarkably reduced in RIP3-/- mice (100% vs. 12.5% lethality) or Nec-1-treated mice (100% vs. 59.2% lethality) respectively. These results reveal a critical role of RIP1 and RIP3 in TBT-induced toxicity both in vitro and in vivo.

Piceatannol attenuates D-GalN/LPS-induced hepatoxicity in mice: Involvement of ER stress, inflammation and oxidative stress.

Piceatannol, a natural derivative of resveratrol, has been shown to exert similar anti-oxidant and anti-inflammatory effects as resveratrol. However, it remains unknown whether piceatannol has hepatoprotective effect against acute liver injury. In this study, we investigated the in vivo effect of piceatannol on D-GalN/LPS-induced fulminant hepatic failure (FHF), and its in vitro effect on ER stress-inducing drug thapsigargin (TG)-induced proinflammatory cytokines production and ROS release. Our results indicated that piceatannol markedly decreased the mortality rate, reduced the serum levels of alanine transaminase and aspartic aminotransferase, ameliorated the liver damage induced by D-GalN/LPS in mice. In addition, piceatannol reduced the expression of proinflammatory cytokines, including TNF-α, IL-1ß and IL-6, the expression of ER stress markers CHOP and phosphorylated-IRE1α, and the generation of oxidative stress in D-GalN/LPS-treated mouse liver. In vitro results were consistent with in vivo observations, demonstrating that piceatannol suppressed the secretion of proinflammatory cytokines, inflammasome activation and the production of ROS induced by TG with or without LPS priming in J774A.1 macrophages. Our study proposes piceatannol as a promising medication for preventing acute liver failure and the mechanisms may be related to its inhibitory effects on ER stress, inflammation and oxidative stress.