Effect of Propyl Gallate on Activity of Cyclooxygenase 1 and 2 in Mice's Peritoneal Macrophages*

Objective: To investigate the effect of Red Peony 801 (propyl gallate,PrG) on cyclooxygenase (COX) activity in murine peritoneal macrophages. Methods: A screening model for COX inhibitors in vitro based on murine peritoneal macrophages was used. COX-1 activity was reflected by the level of 6-ketoprostaglandin F1α(6-keto-PGF1α) in supernatants of cultured macrophages which were stimulated with calcium ionophore A23187 for a short-term, while COX-2 activity was reflected by the level of prostaglandin E2 (PGE2) in supernatants of cultured macrophages which were stimulated with lipopolysaccharide (LPS) for a long-term. Results: PrG did not affect A23187-induced, COX-1-derived 6-keto-PGF1α synthesis at the concentrations of 1×10-5, 5×10-6 mol/L (P>0.05), but enhanced 6-keto-PGF1α synthesis at the concentrations of 1×10-6, 5×10-7, 1×10-7 mol/L (P<0.01) in vitro, and showed a good dose-dependent manner. It inhibited LPS-induced, COX-2-derived PGE2 synthesis at the concentrations of 1×10-5,1×10-6 mol/L (P< 0. 05). Conclusion: Within the range of 1×10-5 to 1×10-7 mol/L, PrG activated COX-1 at lower concentrations and inhibited COX-2 at higher concentrations in murine peritoneal macrophages.

Thermally Reversible,Self-Healing Polyurethane Based on Propyl Gallate and Polyurethane Prepolymers with Varied Isocyanate Content

Thermosetting polyurethanes are widely used in various fields owing to their excellent elasticity,strength and solvent resistance.Three environmental friendly propyl gallate-based self-healing polyurethanes were prepared from polyurethane prepolymers with varying isocyanate content.The thermal stabilities of the polyurethanes were tested using thermogravimetric analysis.Their self-healing and mechanical properties were analyzed using a universal testing machine and dynamic thermomechanical analysis.The polyurethanes were found with high self-healing ability and excellent mechanical properties due to the absence of phenolic carbamate.These qualities improved with increased isocyanate content and the prolonged selfhealing time.We found,therefore,that the propyl gallate-based polyurethane has potential for use in industrial applications as self-healing materials.

Effects of Propyl Gallate on Adhesion of Polymorphonuclear Leukocytes to Human Endothelial Cells Induced by Tumor Necrosis Factor Alpha

Objective:To investigate the effects of Propyl Gallate(PrG) on cellular adhesion between human umbilical vein endothelial cells(HUVEC) and polymorphonuclear leukocytes(PMN) as well as the expression of intercellular adhesion molecule-1(ICAM-1,CD54) and E-selectin(CD62E) on the VEC surface.Methods: A human VEC inflammation model was induced by tumor necrosis factor alpha(TNF-α).VECs were preincubated with varying concentrations of PrG(0.001-5 mmol/L) or 1‰DMSO(v:v) or 10 mmol/L acetylsalicylic acid(ASA) for ...

Protective Effect of Propyl Gallate Against Oxidized Low-Density Lipoprotein-Induced Injury of Endothelial Cells

Objective： To evaluate the protective effect of propyl gallate （PG）, an alkyl ester of gallic acid which is an active ingredient of Radix Paeoniae, against oxidized low-density lipoprotein （ox-LDL）-induced apoptosis and death in endothelial cells （ECs） and to find out its preliminary mechanism. Methods： The cultured endothelial cells were divided into normal, model （ox-LDL）, control （fetal bovine serum）, PG high dose （20 p,g/mL）, PG middle dose （10 μg/mL）, and PG low dose （5 μg/mL） groups, each derived from three different pools of umbilical cords. The model of injured human umbilical vein endothelial cells （HUVECs） was induced by ox-LDL. The 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl-2H-tetrazolium bromide （MTT） assay, Hoechst 33258 staining, flow cytometry and measurement of nitrogen monoxidum （NO） release were used to evaluate the protective effect of PG against ox-LDL-induced apoptosis and death in HUVECs. To find out the mechanism of this protective effect, the expression of endothelial nitric oxide synthase （eNOS） mRNA, eNOS protein expression, immunofluorescence of intracellular reactive oxygen species （ROS） and activities of malondialdehyde （MDA）, superoxidedismutase （SOD） and glutathione peroxidase （GPx） were observed. Results： PG significantly reduced ox-LDL-induced apoptosis and cell death. The percentage of cells death and apoptosis was significantly higher in the ox-LDL group than that in the control group （P〈0.05）. Compared with the control group, the cells death and apoptosis of PG group was no different （P〉0.05）. As compared with the ox-LDL group, results of the PG high dose group showed that cell viability was significantly increased （P〈0.05）, the level of NO release, expression of eNOS mRNA, densitometric value of eNOS protein expression, as well as the activities of SOD and GPx were all significantly higher （all P〈0.05）. Conclusion： PG could potentially serve as a novel endothelial protective agent against ox-LDL-induced injury of endothelial cell.

Effects of Propyl Gallate on Carotid Artery Thrombosis and Coagulation/Fibrinolysis System in Rats

Objective： To investigate the effects of propyl gallate （PrG） on the thrombus formation time and the coagulation/fibrinolysis system in an experimental carotid artery thrombosis model in rats. Methods： Fifty SD rats were randomly divided into 5 groups （10 animals/group）： the normal group （normal saline 2 mL/kg）, the model group （normal saline, 2 mL/kg）, the heparin control group （1 250 IU/kg）, the low dose PrG group （30 mg/kg）, and the high dose PrG group （60 mg/kg）. Thirty minutes after intravenous injection of saline or the corresponding drugs, a carotid artery thrombus was induced by continuous electric stimulation in all rats except for those in the normal group. The duration from the initiation of the electric stimulation to the sudden drop in carotid temperature was recorded as the thrornbus formation time. Levels of plasma tissue-type plasminogen activator （t-PA） and plasminogen activator inhibitor-1 （PAl-1） were determined by ELISA. Results： PrG （30 and 60 mg/kg） can prolong the thrombus formation time, but the effect was obviously weaker than that of heparin （P〈0.05, P〈0.01）. Compared with the model group, PrG （30 and 60 mg/kg） elevated the plasma activity of t-PA （both P〈0.05） and showed an increasing tendency in elevating the ratio of t-PA/PAI-1 （P〉0.05）, while it had no significant effect on the level of PAI-1. Conclusion： PrG has a certain antithrombotic effect and can slightly regulate the imbalance of the t-PA/PAl-1 ratio.

Insight into synergistic antioxidation mechanisms of butyl hydroxyanisole with common synthetic antioxidants

Butyl hydroxyanisole(BHA) is usually blended with other synthetic antioxidants to improve the antioxidative property due to synergistic antioxidation. However, the synergistic antioxidation mechanisms of BHA with synergists have not been revealed yet. Thus, the antioxidation of BHA with butylated hydroxytoluene(BHT), tert-butylhydroquinone(TBHQ), or propyl gallate(PG) was investigated in the 2,2-azobis(2-amidino-propane) dihydrochloride oxidizing system. The contents of BHA, BHT, TBHQ,PG, and transformation products were measured by high-performance liquid chromatography. Transformation products were identified with liquid chromatography-mass spectrometry and gas chromatography–mass spectrometry. Results showed that synergistic antioxidation occurred between BHA and BHT, TBHQ, or PG. The synergistic antioxidation effect of BHA and BHT was attributed to the regeneration of BHA by BHT. Transformation products of BHA and BHT(compounds 6 and 7, dimers of BHA and BHT) had little contribution due to the relatively low content(<0.6%). The synergistic antioxidation effect of BHA and TBHQ or BHA and PG was attributed to the protective mechanism of TBHQ or PG on BHA. No transformation products were detected of BHA and TBHQ. Transformation products of BHA and PG(compounds 9 and 10, dimers of BHA and PG) had limited contribution due to the relatively low percentage(<7%). Therefore, BHA and BHT performed competitive antioxidation,while BHA and TBHQ or PG performed protective antioxidation.