Propyl gallate reduces the growth of lung cancer cells through caspase­dependent apoptosis and G1 phase arrest of the cell cycle.

Propyl gallate (3,4,5­trihydroxybenzoic acid propyl ester; PG) is a synthetic phenolic antioxidant which exerts many effects on tissue and cell functions. In the present study, Calu­6 and A549 lung cancer cells were used to examine the molecular mechanism of the anti­growth effects of PG in relation to apoptosis and cell cycle arrest. PG inhibited the growth of both lung cancer cell types in a dose­dependent manner with an IC50 of 800 µM at 24 h based on MTT assays. DNA flow cytometry showed that PG induced G1 phase arrest of the cell cycle in Calu­6 and A549 cells. In addition, PG induced apoptosis in both lung cancer cell types, as evidenced by sub­G1 cell population and Annexin V­stained cells. Western blot results demonstrated that PG decreased the Bcl­2 level which was accompanied by an increase in the cleaved form of poly(ADP­ribose) polymerase (PARP). PG also triggered loss of mitochondrial membrane potential (MMP; ∆Ψm) and decreased MMP (∆Ψm) levels in both lung cancer cell types, as assessed by FACS analysis. Furthermore, PG upregulated the activities of caspase­3 and caspase­8 in Calu­6 cells. In conclusion, PG treatment inhibited the growth of lung cancer cells, especially Calu­6 cells via caspase­dependent apoptosis as well as G1 phase arrest of the cell cycle.

In vivo effects of propyl gallate, a novel Ca(2+) sensitizer, in a mouse model of dilated cardiomyopathy caused by cardiac troponin T mutation.

AIMS: We have previously demonstrated that propyl gallate has a Ca(2+) sensitizing effect on the force generation in membrane-permeabilized (skinned) cardiac muscle fibers. However, in vivo beneficial effects of propyl gallate as a novel Ca(2+) sensitizer remain uncertain. In the present study, we aim to explore in vivo effects of propyl gallate. MAIN METHODS: We compared effects of propyl gallate on ex vivo intact cardiac muscle fibers and in vivo hearts in healthy mice with those of pimobendan, a clinically used Ca(2+) sensitizer. The therapeutic effect of propyl gallate was investigated using a mouse model of dilated cardiomyopathy (DCM) with reduced myofilament Ca(2+) sensitivity due to a deletion mutation ΔK210 in cardiac troponin T. KEY FINDINGS: Propyl gallate, as well as pimobendan, showed a positive inotropic effect. Propyl gallate slightly increased the blood pressure without changing the heart rate in healthy mice, whereas pimobendan decreased the blood pressure probably through vasodilation via inhibition of phosphodiesterase and increased the heart rate. Propyl gallate prevented cardiac remodeling and systolic dysfunction and significantly improved the life-expectancy of knock-in mouse model of DCM with reduced myofilament Ca(2+) sensitivity due to a mutation in cardiac troponin T. On the other hand, gallate, a similarly strong antioxidant polyphenol lacking Ca(2+) sensitizing action, had no beneficial effects on the DCM mice. SIGNIFICANCE: These results suggest that propyl gallate might be useful for the treatment of inherited DCM caused by a reduction in the myofilament Ca(2+) sensitivity.

Propyl gallate plays a nephroprotective role in early stage of diabetic nephropathy associated with suppression of glomerular endothelial cell proliferation and angiogenesis.

There is growing evidence suggesting that glomerular endothelial cell proliferation and angiogenesis may be responsible for the pathophysiological events in the early stage of diabetic nephropathy. This study was designed to investigate the factors related to glomerular endothelial cell proliferation and glomerular angiogenesis and assess the effect of propyl gallate on preventing these disorders in diabetic rats. We found that glomerular hypertrophy, glomerular mesangial matrix expansion, and albuminuria were significantly increased in DN rats. CD31+ endothelial cells significantly increased in glomerulus of diabetic rats. Double immunofluorescence staining showed some structurally defective vasculus tubes in glomerulus. Real-time PCR and western blot demonstrated the glomerular eNOS expression remained at the same level, while remarkable decreased NO productions and suppressed eNOS activities were observed in diabetic rats. Treatment with propyl gallate improved glomerular pathological changes, reduced endothelial cell proliferation, decreased albuminuria, and restored eNOS activity, but did not alter eNOS expression. These data suggest that endothelial cell proliferation and immature angiogenesis may be the contributors to progression of DN. Propyl gallate is a potential novel therapeutic agent on prevention of diabetic nephropathy.

Imbalance of glomerular VEGF-NO axis in diabetic rats: prevention by chronic therapy with propyl gallate.

BACKGROUND: The uncoupling of the vascular endothelial growth factor-nitric oxide (VEGF-NO) axis may play a vital role in inducing glomerular endothelial dysfunction. We investigate the factors that contribute to the imbalance of the VEGF-NO axis and evaluate the effect of propyl gallate on preventing endothelial dysfunction. METHODS: Streptozotocin (STZ, 60 mg/kg) was administrated to rats to establish an animal diabetic nephropathy model. The diabetic rats were randomly divided into a diabetic model group and a propyl gallate-treated group. Animals were sacrificed 8 weeks after the model was established. Periodic acid-Schiff staining was conducted to observe pathological changes, and reverse transcriptase polymerase chain reaction and Western blot were employed to analyze endothelial nitric oxide synthase (eNOS) and VEGF expressions. Commercial kits were used to detect glomerular eNOS activity and NO production, as well as oxidative stress. RESULTS: Compared with that in the normal control group, glomerular eNOS activity significantly decreased in diabetic rats, but eNOS expression remained at the same level. The expression of VEGF increased at this stage. Levels of glomerular oxidative stress also increased in diabetic rats and were inversely correlated with eNOS activity. Treatment with propyl gallate restored eNOS activity, ameliorated oxidative stress and improved glomerular pathological changes, but did not alter eNOS and VEGF expressions. CONCLUSION: The imbalance of the VEGF-NO axis in the glomeruli of diabetic rats may have resulted from eNOS inactivation, but not from the decrement in eNOS expressions at the early stage of rat diabetic nephropathy. Propyl gallate improved glomerular pathological changes in diabetic rats, possibly through oxidative stress reduction and VEGF-NO axis recovery.

The antiangiogenic and antinociceptive activities of n-propyl gallate.

n-Propyl gallate dose-dependently displayed an inhibitory effect on chick chorioallantoic membrane (CAM) angiogenesis. It markedly increased the endostatin level in both isolated CAM tissues and human umbilical vein endothelial cells (HUVECs). n-Propyl gallate was also able to enhance the endostatin mRNA level in HUVECs. Antinociceptive activity of n-propyl gallate was assessed using an acetic acid-induced writhing test in mice. In brief, n-propyl gallate possesses antiangiogenic activity via up-regulation of endostatin.

The enhancement of propyl gallate-induced apoptosis in HeLa cells by a proteasome inhibitor MG132.

Propyl gallate (PG) used in processed food and medicinal preparations has been shown to induce cell death in normal and cancer cells. The inhibition of proteasome function has emerged as a useful strategy to maneuver apoptosis. Here, we investigated the combined effects of PG and MG132 (a proteasome inhibitor) on HeLa cells in relation to cell growth, cell death, reactive oxygen species (ROS) and glutathione (GSH). PG induced growth inhibition and apoptosis in HeLa cells, accompanied by the loss of mitochondrial membrane potential (MMP; ΔΨm), activation of caspase 3 and PARP cleavage. The levels of ROS and GSH depletion were increased in PG-treated HeLa cells. MG132 intensified apoptosis and PARP cleavage in PG-treated HeLa cells. MG132 also increased ROS levels including mitochondrial O2•-, MMP (ΔΨm) loss and GSH depletion in PG-treated HeLa cells. PG induced a G1 phase arrest of the cell cycle in HeLa cells, which was significantly prevented by MG132. MG132 alone inhibited HeLa cell growth via inducing the cell cycle arrests and triggering apoptosis. Conclusively, the inhibition of proteasome by MG132 plays a role as an enhancement factor in PG-induced apoptosis of HeLa cells via increasing ROS levels and GSH depletion.

[Treatment of non-ST-elevation acute coronary syndrome with propyl gallate].

OBJECTIVE: To investigate the therapeutic effects of propyl gallate (PrG) in combination with standard medication on patients with non-ST-elevation acute coronary syndrome (NST-ACS), including unstable angina and acute non-ST-elevation myocardial infarction, and its influences on serum inflammatory marker and platelet activation. METHODS: Fifty-five patients with NST-ACS were randomly assigned to two groups. Accessory to the standard Western medicine, the 27 patients in the tested group treated with PrG and the 28 in the control group with salvia composite (SC), all being medicated for 14 days. Effects on angina pectoris and electrocardiogram were observed. The positive rate and mean fluorescence density (MFI) of GP IIb-IIIa and CD62p expression on platelet surface were detected using flow cytometer; the serum concentration of high sensitive C-reactive protein (Hs-CRP) was determined using ELISA before and after treatment respectively. RESULTS: The therapeutic effects on angina and electrocardiogram between the two groups showed no significant difference. Serum level of Hs-CRP, GP IIb-IIIa MFI and CD62p positive rate were significantly lowered after treatment in both groups (P < 0.05), no significant difference was found between groups, though the lowering of Hs-CRP and GP IIb-IIIa MFI in the tested group displayed a further decreasing trend. CONCLUSION: In combination with standard medication of Western medicine, PrG and SC showed no obvious difference in the therapeutic effect and influences on angina pectoris and electrocardiogram in patients with non-ST-elevation acute coronary syndrome.

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 thrombus formation time. Levels of plasma tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-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 /PAI-1 ratio.

Sensibilización por galatos. Revisión de 46 casos / Sensitization to gallates: review of 46 cases

Introducción. Los galatos son antioxidantes empleados en la industria cosmética, farmacéutica y alimentaria desde 1947, con la finalidad de evitar la oxidación de los ácidos grasos insaturados que contienen estos productos. El objetivo de este trabajo es revisar los casos de sensibilización por galatos diagnosticados en nuestro Servicio entre 1985 y 2006. Métodos. Se han extraído de la base de datos de la Sección de Alergia de nuestro Servicio todos los casos investigados por sospecha de dermatitis alérgica de contacto, que presentaron pruebas epicutáneas positivas al propil galato, octil galato y/o dodecil galato. Resultados. Cuarenta y seis pacientes presentaron uno o más parches positivos a los galatos (36 mujeres y 10 varones, con una edad media de 42,8 años). El motivo de consulta más frecuente fue la queilitis (63 % de los casos) seguido de la dermatitis de las manos (28,26 % de los casos). El origen más frecuente de la sensibilización fue el uso de barras labiales (54,3 % de los casos), seguido de la manipulación de productos de panadería (15,2 % de los casos). La relevancia de los resultados se consideró presente en el 73,9 % de los casos y desconocida en el 23,9 % de los pacientes. Conclusiones. En nuestra serie la mayoría de los pacientes sensibilizados a los galatos consultaron por queilitis, el principal alérgeno responsable fue el propil galato, y el mecanismo más frecuente de sensibilización fue el uso de barras labiales. El galato más frecuente en los panaderos fue el octil galato, con relevancia presente en todos los casos estudiados

Background. Since 1947, the cosmetics, pharmaceutical, and food industries have used gallates as antioxidants to prevent the oxidation of unsaturated fats in their products. The aim of this study was to review the cases of sensitization to gallates diagnosed in our department between 1985 and 2006. Methods. All suspected cases of allergic contact dermatitis with patch tests positive for propyl gallate, octyl gallate, and/or dodecyl gallate were retrieved from the database of the allergy section of our dermatology department. Results. Forty-six patients had positive patch tests for 1 or more gallates (36 women and 10 men, with a mean age of 42.8 years). The most common presenting complaint was cheilitis (63 % of the cases) followed by dermatitis of the hands (28.26 %). The most common sensitizing agent was lipstick (54.3 %) followed by bakery products (15.2 %). The test result was considered clinically relevant in 73.9 % of the cases whereas the relevance was unknown in 23.9 %. Conclusions. In our case series, most patients sensitized to gallates attended the clinic due to cheilitis. The main allergen was propyl gallate and the most common mechanism of sensitization was use of lipstick. The most common gallate among bakers was octyl gallate. This agent was considered to be clinically relevant in all cases studied

Advanced hemostatic dressing development program: animal model selection criteria and results of a study of nine hemostatic dressings in a model of severe large venous hemorrhage and hepatic injury in Swine.

BACKGROUND: An advanced hemostatic dressing is needed to augment current methods for the control of life-threatening hemorrhage. A systematic approach to the study of dressings is described. We studied the effects of nine hemostatic dressings on blood loss using a model of severe venous hemorrhage and hepatic injury in swine. METHODS: Swine were treated using one of nine hemostatic dressings. Dressings used the following primary active ingredients: microfibrillar collagen, oxidized cellulose, thrombin, fibrinogen, propyl gallate, aluminum sulfate, and fully acetylated poly-N-acetyl glucosamine. Standardized liver injuries were induced, dressings were applied, and resuscitation was initiated. Blood loss, hemostasis, and 60-minute survival were quantified. RESULTS: The American Red Cross hemostatic dressing (fibrinogen and thrombin) reduced (p < 0.01) posttreatment blood loss (366 mL; 95% confidence interval, 175-762 mL) and increased (p < 0.05) the percentage of animals in which hemostasis was attained (73%), compared with gauze controls (2,973 mL; 95% confidence interval, 1,414-6,102 mL and 0%, respectively). No other dressing was effective. The number of vessels lacerated was positively related to pretreatment blood loss and negatively related to hemostasis. CONCLUSION: The hemorrhage model allowed differentiation among topical hemostatic agents for severe hemorrhage. The American Red Cross hemostatic dressing was effective and warrants further development.

MCI-186: further histochemical and biochemical evidence of neuroprotection.

The bioactivity of 3-methyl-1-phenyl-pyrazolin-5-one (MCI-186) was examined based on histochemical changes in drastic global ischemic rat brains. Rats with mean arterial blood pressure reduction were subjected to 60 min cerebral ischemia/80 min reperfusion. Infusion of MCI-186 at 3.0 mg/Kg reduced brain infarction from 21 +/- 4% (saline control, n= 15) to 11 +/- 3% (n=16, p<0.05). By comparison, infusion of up to 20 mg/Kg propyl galalate (PG)--a well documented antioxidant--produced an infarct percentage of 14 +/- 5% (n=8), close to the saline control. Biochemically, the neuroprotective effect of MCI-186 was demonstrated by diminishing the release of creatine kinase (CK) in serum from 3363 +/- 608 U/L (n=14) in saline control to 1989 +/- 293 U/L (n= 15) in MCI group (p<0.05), while PG did not lower the activity of CK significantly. MCI-186 behaves as a free radical scavenger by suppressing the formation of superoxide anion in xanthine oxidase (XO)-hypoxanthine (HP) system (p<0.05). Our data supported our contention that MCI-186 has potent anti-stroke effect with antioxidant activities.

Attenuation of reperfusion injury by the antioxidant n-propyl gallate.

We studied the effects of n-propyl gallate (n-PG) on Langendorff preparations of isolated rat hearts. Perfusion of the hearts with Krebs-Henseleit (KH) solution containing 20 microM n-PG did not cause a statistically significant change in either left ventricular systolic pressure (LVSP), end-diastolic pressure (LVEDP), developed pressure (LVDP), or heart rate (HR), indicating that n-PG has little acute myocardial toxicity. The effects of n-PG on the reperfused and ischemic myocardium were tested in hearts subjected to 15-min global P4 the ischemic hearts with KH buffer resulted in the recovery of the LVDP to 66 +/- 7% (mean +/- SEM, n = 11) and the recovery of the rate-pressure product (RPP) to 65 +/- 7% of their preischemic values. The LVEDP of the reperfused hearts was 30 +/- 5 mm Hg as compared with the preischemic LVEDP of 5.2 +/- 0.9 mm Hg. The difference between the coronary flow rate of the preischemic hearts (15.4 +/- 0.8 ml/min) and the reperfused hearts (13.9 +/- 0.9 ml/min) was not statistically significant (p > 0.05). Addition of n-PG, at the time of reperfusion, resulted in with KH buffer containing 20 microM n-PG had LVEDP of 6.2 +/- 0.4 mm Hg, and both LVDP and RPP recovered to 92 +/- 4% of the preischemic control.(ABSTRACT TRUNCATED AT 250 WORDS)

The antioxidants as protectors of host stress organ injury in mice infected with Plasmodium berghei.

A study has been made of counteracting the stress organ injury in Plasmodium infection by means of antioxidants on the premise that free radicals are responsible for causing the injury to stress organs. This was evidenced by drastically altered biochemical parameters in liver and spleen of the host in terms of elevated levels of lipid peroxides and xanthine oxidase (XO) activity, and a fall in superoxide dismutase activity coupled with other drastic biochemical changes. The cardinal factor responsible for the above was considered to be XO which engenders free radicals purportedly responsible for the stress organ (biochemical) injury. Results demonstrate a lowering of lipid peroxide levels, xanthine oxidase activity, liver weight and modulation of protein level in liver of the host (mouse) in Plasmodium infection when treated with catechin, glutathione and propylgallate.

Protective actions of propyl gallate, a lipoxygenase inhibitor, on the ischemic myocardium.

Products of the lipoxygenase pathway of arachidonate metabolism, including hydroperoxides, free radicals, and leukotrienes, are thought to mediate ischemic damage during acute myocardial ischemia (MI). Propyl gallate (1 mg/kg/h) was infused in anesthetized cats 0.5 h after coronary artery occlusion. Propyl gallate did not influence mean arterial blood pressure (MABP), heart rate (HR), or the product of these, the pressure-rate index. Treatment of MI with propyl gallate significantly reduced the plasma accumulation of creatine kinase (CK). This was confirmed by reduced CK loss in biopsies from the ischemic region of the heart, indicative of a protective effect. Propyl gallate also reduced the loss of compounds containing amino-nitrogen groups from the ischemic region, although it did not significantly reverse the S-T segment elevation in the electrocardiogram. These results are consistent with the concept that inhibition of formation of lipoxygenase products protects the myocardium from ischemic damage. This study also helps explain the work of others demonstrating that combined cyclooxygenase-lipoxygenase inhibitors or depletion of leukocytes is beneficial in MI.

Depletion of hepatic antioxidants during granulomatous inflammation in the rat and local anti-inflammatory effects of free radical scavengers.

Changes in hepatic oxidative events have been studied during extrahepatic granulomatous inflammation in the rat, together with the local anti-inflammatory effects of scavengers of reactive oxygen species. During remote localized inflammation in the rat, we observed increased hepatic lipid peroxidation and reduced hepatic levels of protecting substances such as ascorbic acid, catalase and reduced glutathione, the specific substrate for the peroxide-metabolizing enzyme, glutathione peroxidase. The levels of superoxide dismutase did not alter significantly during the period of investigation (7 days). The half-life of aminopyrine was longer in rats with a stronger inflammatory response. In addition, catalase and the anti-oxidants, alpha-tocopherol and propyl gallate, inhibited granuloma development on local injection during the acute phase inflammation. Superoxide dismutase alone was devoid of anti-inflammatory effects, but markedly enhanced the effect of catalase. Scavengers of hydroxyl radicals and of singlet oxygen failed to display anti-inflammatory activity. The results indicate that peroxides may act as mediators of inflammation and that increased lipid peroxidation is not limited to the site of inflammation.