Gamma-oryzanol protects human liver cell (L02) from hydrogen peroxide-induced oxidative damage through regulation of the MAPK/Nrf2 signaling pathways.

Gamma-oryzanol (Orz), a mixture of the ferulic acid ester of triterpene alcohols and phytosterols, was found abundantly in rice bran and rice bran oil which could be available and served as an antioxidant. The present study was to explore the potential protective effects of Orz on oxidative stress and cell apoptosis in human hepatic cells (L02 cells) induced by hydrogen peroxide (H2 O2 ). Flow cytometry detection and Hoechst 33258 staining showed that Orz significantly restored cell cycle and ameliorated apoptosis in H2 O2 -challenged L02 cells. Orz pretreatment inhibited H2 O2 -induced cell apoptosis by increasing the scavenging of hydroxyl radicals (OH·), and efficiently decreasing the production of nitric oxide (NO). Moreover, a loss of total antioxidant capacity (T-AOC) and adenosine triphosphatase (ATPase) were enhanced in H2 O2 -mediated L02 cells pretreated with Orz. Furthermore, preincubation with Orz reduced H2 O2 -mediated the proapoptotic protein of Bak expression and the phosphorylation of ASK1, p38, JNK, and ERK, and increased the anti-apoptotic protein of Bcl-xl expression and anti-oxidative stress proteins of Nrf2 and HO-1 expression. The findings suggested that Orz exerts the cytoprotective effects in H2 O2 -induced L02 cells apoptosis by ameliorating oxidative stress via inhibiting MAPK signaling pathway and activating Nrf2 signaling pathway. PRACTICAL APPLICATIONS: Gamma-oryzanol (Orz), a mixture of the ferulic acid ester of triterpene alcohols and phytosterols, was found abundantly in rice bran and rice bran oil which could be availably served as an antioxidant. In this study, it was found that Orz exerts the cytoprotective effects in H2 O2 -induced L02 cell apoptosis by ameliorating oxidative stress via the inhibition of MAPK signaling pathway and the activation of Nrf2 signaling pathway, which provides a theoretical basis for dietary adding natural products to prevent or treat oxidative stress-related diseases.

γ-Oryzanol suppresses cell apoptosis by inhibiting reactive oxygen species-mediated mitochondrial signaling pathway in H2O2-stimulated L02 cells.

γ-Oryzanol, a mixture of ferulic acid esters of plant sterols and triterpene alcohols existed in rice bran oil, can ameliorate lipid metabolism and enhance antioxidant activity. In this study, we used hydrogen peroxide (H2O2)-induced injury in human hepatic L02 cells to investigate the mechanisms involved in the hepatoprotective activity of γ-oryzanol. The injuries produced by H2O2 in L02 cells include increased levels of malondialdehyde (MDA) and intracellular reactive oxygen species (ROS), decreased activities of superoxide dismutase (SOD) and catalase (CAT), loss of mitochondrial membrane potential (MMP), increased protein expressions of caspase-9 and caspase-3, and induced apoptosis. Pretreatment with γ-oryzanol enhanced the ROS scavenging activity of endogenous antioxidant enzymes and decreased lipid peroxidation in H2O2 treated cells. Moreover, pretreatment with γ-oryzanol inhibited H2O2-induced apoptosis by restoring MMP, upregulating the expression ratio of Bcl-2/Bax, and inhibiting the activation of caspase-9 and caspase-3. These findings show that γ-oryzanol can prevent H2O2-induced apoptosis by suppressing intracellular accumulation of ROS and impeding ROS-activated mitochondrial apoptotic pathway.

Protective effects of betulinic acid on intestinal mucosal injury induced by cyclophosphamide in mice.

BACKGROUND: Betulinic acid (BA) is a plant-derived pentacyclic triterpenoid with a variety of biological activities. The purpose of this study was to assess the potential protective role of BA against intestinal mucosal injury induced by cyclophosphamide (CYP) treatment. METHODS: Mice were pretreated with BA daily (0.05, 0.5, and 5.0 mg/kg) for 14 days, then injected intraperitoneally with CYP (50 mg/kg) for 2 days. RESULTS: BA pretreatment reduced the contents of malondialdehyde (MDA) and glutathione (GSH), decreased the activity of superoxide dismutase (SOD) in small intestine, increased villus hight/crypt depth ratio and restored the morphology of intestinal villi in CYP-induced mice. Moreover, BA pretreatment could significantly down-regulate the levels of pro-inflammatory cytokines interleukin-5 (IL-5), IL-17, IL-12 (P70) and tumor necrosis factor α (TNF-α), reduced production of chemokines macrophage inflammatory protein-1α (MIP-1α), macrophage inflammatory protein-1ß (MIP-1ß) and regulated upon activation, normal T-cell expressed and secreted (RANTES), and enhanced the levels of anti-inflammatory such as IL-2 and IL-10 in serum, and decreased the mRNA expressions of IL-1ß and TNF-α in intestine of CYP-induced mice. Furthermore, RT-PCR demonstrated that BA improved intestinal physical and immunological barrier in CYP-stimulated mice by enhancing the mRNA expressions of zonula occluden 1 (ZO-1) and Claudin-1. CONCLUSIONS: BA might be considered as an effective agent in the amelioration of the intestinal mucosal resulting from CYP treatment.

Betulinic acid attenuates dexamethasone-induced oxidative damage through the JNK-P38 MAPK signaling pathway in mice.

Dexamethasone (Dex), a potent anti-inflammatory/immunosuppressive agent, has been shown to induce oxidative stress. Betulinic acid (BA) is a pentacyclic lupane triterpene with a potent antioxidant activity. The aim of this study was to investigate the ameliorative effect and underlying mechanisms of BA on Dex-induced oxidative damage. Mice were pretreated with BA orally (0, 0.25, 0.5, and 1.0 mg/kg) daily for 14 days, and then a single dose of Dex (25 mg/kg body weight) was administered intraperitoneally 8 h after the last administration of BA to induce oxidative stress. BA pretreatment significantly alleviated Dex-induced changes of blood biochemical indices, increased the total antioxidant capacity (T-AOC), the activity of superoxide dismutase (SOD), and the ability of inhibiting hydroxyl radical (AIHR), reduced the level of malondialdehyde (MDA) in serum. Moreover, BA pretreatment enhanced the T-AOC, AIHR and the activity of peroxidase (POD) in liver, spleen and thymus. Concomitant with these biochemical parameters, BA pretreatment significantly reduced gene and protein expressions of apoptosis signal-regulating kinase 1 (ASK1), c-Jun N-terminal kinase (JNK) and P38 mitogen-activated protein kinase (P38 MAPK) in the lymphatic organs of Dex-treated mice. BA was found to effectively attenuate Dex-induced oxidative damage. These protective effects may be mediated in part through the JNK-P38 MAPK signaling transduction pathway and BA may be a potential therapeutic agent due to its anti-oxidative properties.

In vivo protective effect of betulinic acid on dexamethasone induced thymocyte apoptosis by reducing oxidative stress.

BACKGROUND: Dexamethasone (Dex), a synthetic glucocorticoid, is strictly controlled for use due to its serious side effects, including immune suppression. Betulinic acid (BA), an antioxidant prepared from the white birch, exhibits immunomodulation properties. To assess the implications and investigate the mechanisms of BA-elicited immunomodulation, we hypothesized that Dex induced thymocyte apoptosis via oxidative stress could be lessened by BA. METHODS: Mice were given oral doses of BA (0.25, 0.5, and 1.0mg/kg) daily for 14 days, and induced oxidative stress by giving a single dose of Dex intraperitoneal at the dosage of 25mg/kg body weight 8h after the last administration of BA. RESULTS: Dex administration alone significantly decreased antioxidant enzyme activities, while significantly increased reactive oxygen species (ROS) production, lipid peroxidation, mitochondrial dysfunctions, caspase-3 activation and cellular apoptosis. However, pretreatment with BA dose-dependently mitigated Dex-induced oxidative damage after 14 days of feeding. In addition to ROS scavenging activity in Dex-induced thymocyte, BA administration decreased lipid peroxidation, up-regulated antioxidant enzymes, restored mitochondrial function, increased Bcl-2 expression but reduced Bax expression, inhibited caspase-3 activation, and improved cell survival. CONCLUSIONS: These findings reveal a protective capability of BA against Dex-induced cell death by reducing oxidative stress via mitochondrial mediated signal pathway which could be the potential mechanism underlying BA-elicited immunomodulation.

Ameliorative effect of betulinic acid on oxidative damage and apoptosis in the splenocytes of dexamethasone treated mice.

Betulinic acid (BA) is a bioactive pentacyclic triterpene that exhibits a variety of biological activities including antioxidative and immunomodulative properties. The objective of this study was to investigate the potential splenocytes protective effect and underlying mechanism of BA using dexamethasone (Dex)-induced mice as a model system. Pretreatment with BA (0.25, 0.5, and 1.0 mg/kg) dose-dependently ameliorated Dex-induced oxidative damage and apoptosis after 14 days of feeding. In addition to reactive oxygen species scavenging activity in Dex-induced splenocytes, BA administration up-regulated antioxidant enzymes, decreased lipid peroxidation, restored mitochondrial function, decreased the expression of pro-apoptotic protein Bax, prevented the decline of anti-apoptotic protein Bcl-2, inhibited caspase-9 and caspase-3 activation, and improved cell survival. These findings reveal that BA was able to mitigate Dex-induced oxidative stress and might play an important role in repairs of oxidative damage in immunological system.

Betulinic acid prevents alcohol-induced liver damage by improving the antioxidant system in mice.

Betulinic acid (BA), a pentacyclic lupane-type triterpene, has a wide range of bioactivities. The main objective of this work was to evaluate the hepatoprotective activity of BA and the potential mechanism underlying the ability of this compound to prevent liver damage induced by alcohol in vivo. Mice were given oral doses of BA (0.25, 0.5, and 1.0 mg/kg) daily for 14 days, and induced liver injury by feeding 50% alcohol orally at the dosage of 10 ml/kg after 1 h last administration of BA. BA pretreatment significantly reduced the serum levels of alanine transaminase, aspartate transaminase, total cholesterol, and triacylglycerides in a dose-dependent manner in the mice administered alcohol. Hepatic levels of glutathione, superoxide dismutase, glutathione peroxidase, and catalase were remarkably increased, while malondialdehyde contents and microvesicular steatosis in the liver were decreased by BA in a dose-dependent manner after alcohol-induced liver injury. These findings suggest that the mechanism underlying the hepatoprotective effects of BA might be due to increased antioxidant capacity, mainly through improvement of the tissue redox system, maintenance of the antioxidant system, and decreased lipid peroxidation in the liver.

Antioxidant activity of phytosteryl phenolates in different model systems.

As part of a comprehensive study of the physiochemical and biological properties of phytosteryl phenolates, successfully synthesized chemoenzymatically in our lab, their antioxidant activity was evaluated using three different in vitro model systems, namely bulk oil model system, ß-carotene-linoleate model system and low-density lipoprotein cholesterol (LDL-C) oxidation assay. In the bulk oil system, phytosteryl phenolates showed similar or lower antioxidant activity compared with those of phenolic acids. However, in ß-carotene-linoleate assay, an emulsion model system, phytosteryl phenolates showed enhanced antioxidant activity except phytosteryl ferulates. Moderate inhibitory effect of LDL-C oxidation by phytosteryl phenolates was observed. These findings demonstrate that use of multidimensional antioxidant activity determinations with differing reaction mechanisms is necessary to provide an overall understanding of the mechanisms of antioxidant action of phytosteryl phenolates.

Phytosteryl sinapates and vanillates: chemoenzymatic synthesis and antioxidant capacity assessment.

Phytosterols and their derivatives have attracted much attention because of their health benefits to humans and are widely used in food, pharmaceuticals, and cosmetics in the past decades. While most of the research has focused on free phytosterols and phytosteryl esters of fatty acids, few researches reported on phytosteryl phenolates, the esters of phytosterols with phenolic acids. Two novel group phytosteryl phenolates, namely phytosteryl sinapates and vanillates, were successfully chemoenzymatically synthesised in this work and their structures confirmed. Fourier transform infrared (FTIR) and high performance chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) using atmospheric pressure chemical ionisation (APCI) under both positive and negative ion modes were employed for this purpose. High antioxidant capacity of phytosteryl sinapates was observed using both oxygen radical absorbance capacity (ORAC) assay and cooked ground meat model system. Although phytosteryl vanillates showed lower antioxidant capacity than phytosteryl sinapates, they were stronger antioxidants than vanillic acid and vinyl vanillate in both assays employed. Conjugation of phytosterols with sinapic or vanillic acid rendered higher antioxidant capacity. Further studies on health benefits of phytosteryl sinapates and vanillates are necessary.

Enzymatic synthesis of phytosteryl docosahexaneates and evaluation of their anti-atherogenic effects in apo-E deficient mice.

Phytosterols have attracted much attention in recent years due to their health benefits, such as cholesterol lowering, anti-inflammatory, anti-atherogenicity, and anti-cancer potential. Docosahexaenoic acid (DHA) has been demonstrated to possess cardioprotective and immune-enhancing effects. Esterification of phytosterols with DHA may render improved physiochemical properties such as solubility, miscibility, oxidative stability and hence bioactivity and bioavailability. Thus, phytosteryl docosahexaneates (PS-DHA) may offer both the benefits of phytosterols and DHA, possibly in a synergistic manner. Here, we describe a method for enzymatic synthesis of phytosteryl docosahexaneates and evaluation of metabolic and cardiovascular benefits in apo-E deficient (apo E-KO) mice. The structures of phytosteryl docosahexaneates were confirmed by infrared (IR) and high performance liquid chromatography-mass spectrometry (HPLC-MS) using both normal and reverse phase chromatography. Apo E-KO mice were fed with an atherogenic diet containing 2% (w/w) PS-DHA for 7 weeks. Plasma lipid levels and the extent and complexity of atherosclerotic lesions were examined and compared with those in the control group. The PS-DHA-treated mice had significantly lower plasma cholesterol levels and three times smaller atherosclerotic lesions in the aortic roots. This pilot study suggests cardiovascular benefits for PS-DHA. Further experimental and clinical studies are needed to confirm such benefits of PS-DHA.

Chemoenzymatic synthesis of phytosteryl ferulates and evaluation of their antioxidant activity.

The feasibility of a two-step chemoenzymatic synthesis of phytosteryl ferulates was successfully established in this work. An intermediate vinyl ferulate was first chemically produced and subsequently esterified with phytosterols through alcoholysis with Candida rugosa as a catalyst. The structures of phytosteryl ferulates were confirmed by Fourier transform infrared (FTIR) and high-performance chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) using atmospheric pressure chemical ionization (APCI) under both positive and negative ion modes. The antioxidant activity of phytosteryl ferulates was higher than that of the starting material and the intermediate in the assays employed. The results indicated that phytosteryl ferulates had a good potential to be used as food antioxidants and may also serve as cholesterol-lowering agents.