Antioxidative activity of natural products from plants

Cedrelopsis grevei induced hypotension and improved endothelial vasodilatation through an increase of Cu/Zn SOD protein expression

This study was designed to investigate the cardiovascular consequences of oral administration of Cedrelopsis grevei (CG) in normotensive rats. Experiments were designed to investigate hemodynamic parameters in vivo as well as the consequences of CG treatment on the vasoconstriction response to norepinephrine and the vasorelaxant response to ACh ex vivo in isolated aortas and small mesenteric arteries (SMA). Treatment of male Wistar rats with 80 mg/kg CG for 4 wk induced a progressive decrease in systolic blood pressure. In the aorta, CG did not significantly alter the response to norepinephrine despite the participation of extraendothelial nitric oxide (NO)-induced hyporeactivity. In the SMA, contraction to norepinephrine was not modified by CG treatment even though it enhanced the participation of endothelial NO. Endothelium-dependent relaxation to ACh was increased in both the aorta and SMA from CG-treated rats. In the aorta from CG-treated rats, the mechanism involved superoxide dismutase (SOD)- and catalase-sensitive free radical production. The latter was associated with enhanced expression of Cu/Zn SOD and endothelial NO synthase. These results suggest that oral administration of CG produces a decrease in blood pressure in normotensive rats. This hemodynamic effect was associated with enhanced endothelium-dependent relaxation and an induction of Cu/Zn SOD and endothelial NO synthase expressions in the vessel wall. They also show subtle mechanisms that compensate for the increased participation of NO to maintain unchanged agonist-induced contractility. These data provide a pharmacological basis for the empirical use of CG against cardiovascular diseases.

Naringin alters the cholesterol biosynthesis and antioxidant enzyme activities in LDL receptor-knockout mice under cholesterol fed condition

The purpose of the current study was to evaluate the lipid lowering and antioxidant capacity of naringin in LDL receptor knockout (LDLR-KO) mice fed a cholesterol (0.1 g/100 g) diet. As such, naringin or lovastatin (0.02 g/100 g) was supplemented in a cholesterol diet for 6 weeks. The naringin and lovastatin supplementation significantly lowered the plasma total cholesterol level compared to the control group. The plasma and hepatic triglyceride level was only lowered by the lovastatin supplement, while the hepatic cholesterol content was lowered by both the naringin and lovastatin supplements compared to the control group. The hepatic HMG-CoA reductase activity was significantly lower in the naringin and lovastatin supplemented groups than in the control group, whereas the ACAT activity was unaffected. The excretion of total sterol was significantly higher in the naringin and lovastatin groups compared to the control group due to significant changes in the acidic and neutral sterol, respectively. When comparing the hepatic antioxidant enzyme activities, the superoxide dismutase, catalase, and glutathione reductase activities were all significantly higher in the naringin-supplemented group than in the control group, while only the lovastatin supplement increased the glutathione reductase activity. Accordingly, the current results confirmed that naringin lowers the plasma cholesterol level via the inhibition of hepatic HMG-CoA reductase activity and increases the excretion of fecal sterol. Naringin was also found to improve the activities of hepatic antioxidant enzymes against oxidative stress in a hypercholesterolemic animal model, i.e. cholesterol-fed LDLR-KO mice.

A novel and potent biological antioxidant, Kinobeon A, from cell culture of safflower

Kinobeon A was originally isolated from cultured cells of safflower (Carthamus tinctorius L., Compositae). It had never previously been directly isolated from safflower or other plants, animals or microorganisms. In this report, we demonstrate the anti-oxidative effects of kinobeon A and compare the results with those two known natural antioxidants, lignan (nordihydroguaiaretic acid) and quercetin. The NADPH-induced microsomal lipid peroxidation system was employed to assess anti-oxidative effects of kinobeon A. Addition of kinobeon A to the system significantly decreased the formation of thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner with effects similar to those of lignan and quercetin. Formation of TBARS was completely inhibited at 10 microM of kinobeon A. Employing the xanthine/xanthine oxidase/nitroblue tetrazolium system and the KO2/XTT system, the superoxide anion scavenging activity of kinobeon A was greater than that of lignan or quercetin. IC50 values calculated for kinobeon A in these two systems were 1 microM and 0.8 microM, respectively. Kinobeon A exerted cytoprotective effects following oxidative treatments with hydrogen peroxide, cumene hydroperoxide, menadione and xanthine oxidase (XOD). Addition of kinobeon A to the systems markedly enhanced survival ratios of Madin-Darby bovine kidney cells, while their survival significantly decreased with the oxidative treatment alone. Kinobeon A exhibited stronger effect on the cell viability than lignan or quercetin when menadion or XOD were used as inducing reagents of oxidative stress. The present study demonstrates for the first time that kinobeon A prevents oxidative stresses and could be a useful cytoprotective reagent.

Naringin supplementation lowers plasma lipids and enhances erythrocyte antioxidant enzyme activities in hypercholesterolemic subjects

BACKGROUND AND AIMS

Preliminary studies have shown that naringin has a potent lipid-lowering effect and antioxidant capacity in high-cholesterol diet fed animals. Accordingly, the present study was conducted to investigate the effect of naringin on hypercholesterolemic subjects.

METHODS

A hypercholesterolemic group (n=30) and healthy control group (n=30) were established based on the plasma cholesterol levels in the subjects, then all subjects received naringin (400mg/capsule/day) with regular meals for a period of 8 weeks.

RESULTS

In the hypercholesterolemic subjects, naringin supplementation was found to lower the plasma total cholesterol by 14% and low-density lipoprotein cholesterol concentrations by 17%, while the plasma triglyceride and high-density lipoprotein cholesterol concentrations remained unaffected. The apolipoprotein B levels in the hypercholesterolemic subjects were significantly lowered after naringin treatment, yet no change was observed in the apolipoprotein A-1 levels. The erythrocyte superoxide dismutase and catalase activities in the hypercholesterolemic group were significantly increased, whereas the glutathione peroxidase activity and plasma TBARS levels were not different from the baseline measurements. Meanwhile, naringin supplementation had no affect on plasma lipids, apolipoproteins, and TBARS levels or antioxidant enzyme activities in the control group.

CONCLUSIONS

Therefore, these data suggest that naringin may play an important role in lowering plasma cholesterol and regulating the antioxidant capacity in hypercholesterolemic subjects.

Antioxidant and memory enhancing effects of purple sweet potato anthocyanin and cordyceps mushroom extract

The effects of purple sweet potato anthocyanin (SPA) and Cordyceps mushroom extract (CME) on lipid peroxidation, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and cognitive deficits were examined. Both SPA and CME exhibited DPPH radical scavenging activities with similar potency. In contrast, only SPA was shown to effectively inhibit lipid peroxidation initiated by Fe2+ and ascorbic acid in rat brain homogenates. Furthermore, SPA markedly enhanced cognitive performance, assessed by passive avoidance test in ethanol-treated mice. Combined treatments with SPA and CME did not significantly influence the effects of SPA alone. These results demonstrate that anthocyanin prepared from purple sweet potato exhibits memory enhancing effects, which may be associated with its antioxidant properties.

Screening and comparison of antioxidant activity of solvent extracts of herbal medicines used in Korea

The hexane, ethylacetate, n-butanol, and water extracts of 10 Korean herbal medicines were screened and compared for their antioxidant activities in a range of lipid peroxidation system using rat brain homogenates, antihemolysis assay of red blood cells, and other in vitro assays to determine their ability to scavenge superoxide and hydroxyl radicals. All of the 10 Korean herbal medicines have potent antioxidant activities. Among the four solvent extracts, the antioxidant activities of more-polar solvent extracts (BuOH and water extracts) were relatively higher than that of non-polar solvent extracts (hexane and EtOAC extracts). These results will be useful to further analyze those herbal medicines that contain the most antioxidant activity in order to identify the active principles.

Effect of fraxetin and myricetin on rotenone-induced cytotoxicity in SH-SY5Y cells: comparison with N-acetylcysteine

The purpose of this study was to investigate the potential neuroprotective effects of myricetin (flavonoid) and fraxetin (coumarin) on rotenone-induced apoptosis in SH-SY5Y cells, and the possible signal pathway involved in a neuronal cell model of Parkinson's disease. These two compounds were compared to N-acetylcysteine. The viability of cells was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and cytotoxicity was assayed by lactate dehydrogenase (LDH) released into the culture medium. Parameters related to apoptosis, such as caspase-3 activity, the cleavage of poly(ADP-ribose) polymerase and the levels of reactive oxygen species were also determined. Rotenone caused a time- and dose-dependent decrease in cell viability and the degree of LDH release was proportionally to the effects on cell viability. Cells were pretreated with fraxetin, myricetin and N-acetylcysteine at different concentrations for 30 min before exposure to rotenone. Cytotoxicity of rotenone (5 microM) for 16 h was significantly diminished as well as the release of LDH into the medium, by the effect of fraxetin, myricetin and N-acetylcysteine, with fraxetin (100 microM) and N-acetylcysteine (100 microM) being more effective than myricetin (50 microM). Rotenone-induced apoptosis in SH-SY5Y cells was detected by an increase in caspase-3 activity and in the cleavage of poly(ADP-ribose) polymerase. After exposing these cells to rotenone, a significant increase in reactive oxygen species preceded apoptotic events. Fraxetin (100 microM) and N-acetylcysteine (100 microM) not only reduced rotenone-induced reactive oxygen species formation, but also attenuated caspase-3 activity and poly(ADP-ribose) polymerase cleavage at 16 h against rotenone-induced apoptosis. The effect of fraxetin in both experiments was similar to that of N-acetylcysteine. These results demonstrated the protective action of fraxetin and suggest that it can reduce apoptosis, possibly by decreasing free radical generation in SH-SY5Y cells. Myricetin at 100 microM was without any preventive effect.

Role of naringin supplement in regulation of lipid and ethanol metabolism in rats

The current study was performed to investigate the effect of naringin supplements on the alcohol, lipid, and antioxidant metabolism in ethanol-treated rats. Male Sprague-Dawley rats were randomly divided into six groups (n = 10) based on six dietary categories: ethanol and naringin-free, ethanol (50 g/L) plus low-naringin (0.05 g/L), ethanol plus high-naringin (0.125 g/L), and three corresponding pair-fed groups. The pair-fed control rats received an isocaloric diet containing dextrin-maltose instead of ethanol for 5 wks. Among the ethanol treated groups, the naringin supplements significantly lowered the plasma ethanol concentration with a simultaneous increase in the ADH and/or ALDH activities. However, among the ethanol-treated groups, naringin supplementation resulted in a significant decrease in the hepatic triglycerides and plasma and hepatic total cholesterol compared to that in the naringin-free group. Naringin supplementation significantly increased the HDL-cholesterol and HDL-C/total-C ratio, while lowering the AI value among the ethanol-treated groups. Hepatic lipid accumulation was also significantly reduced in the naringin-supplemented groups compared to the naringin-free group among the ethanol-treated groups, while no differences were found among the pair-fed groups. Among the ethanol-treated groups, the low-naringin supplementation resulted in a significant decrease in the levels of plasma and hepatic TBARS, whereas it resulted in higher SOD and GSH-Px activities and gluthathion levels in the liver. Accordingly, naringin would appear to contribute to alleviating the adverse effect of ethanol ingestion by enhancing the ethanol and lipid metabolism as well as the hepatic antioxidant defense system.

Effects of naringin on hydrogen peroxide-induced cytotoxicity and apoptosis in P388 cells

Flavonoids are widely recognized as naturally occurring antioxidants. Naringin (NG) is one of the flavonoid components in citrus fruits such as grapefruit. Hydrogen peroxide (H2O2) causes cytotoxicity through oxidative stress and apoptosis. In this paper, we examined the effects of NG on H2O2-induced cytotoxicity and apoptosis in mouse leukemia P388 cells. Cytotoxicity was determined by mitochondrial activity (MTT assay). Apoptosis and DNA damage were analyzed by measuring chromatin condensation and Comet assay (alkaline single cell gel electrophoresis), respectively. H2O2-induced cytotoxicity was significantly attenuated by NG or the reduced form of glutathione (GSH), a typical intracellular antioxidant. NG suppressed chromatin condensation and DNA damage induced by H2O2. These results indicate that NG from natural products is a useful drug having antioxidant and anti-apoptopic properties.

Evaluation of the redox properties and anti/pro-oxidant effects of selected flavonoids by means of a DNA-based electrochemical biosensor

Quercetin and rutin as well as catechin and epigallocatechin gallate were investigated, as widely distributed representatives of flavonols and flavanols, respectively, regarding their anti/pro-oxidant properties. The flavonoids are irreversibly oxidized at a dsDNA-modified screen-printed electrode within 0.368 to 0.449 V vs. SHE without binding to DNA. Using the DNA biosensor the detection scheme of a DNA prevention/degradation exploits the [Co(phen)(3)](3+) complex as an electrochemical DNA marker. Antioxidant activity of flavonoids was tested in a model cleavage mixture composed of 5 x 10(-7) mol L(-1) [Cu(phen)(2)](2+) as the catalyst, 1 x 10(-3) mol L(-1) ascorbic acid as the chemical reductant and atmospheric oxygen as the natural oxidant where reactive oxygen radicals are generated. The antioxidant activity increases with the concentration of flavonoids reaching a maximum where pro-oxidative behaviour becomes of importance. The pro-oxidant potency of flavonoids depends on the presence of atmospheric oxygen and follows the order quercetin>rutin>epigallocatechin gallate>catechin.

Antioxidative properties of brown algae polyphenolics and their perspectives as chemopreventive agents against vascular risk factors

Several polyphenolic compounds and complex mixtures were isolated from brown algae species. The 1,1-diphenyl-2-picryhydarzyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) of these compounds were evaluated to determine their physiological usefulness as antioxidants for vascular protection. The antioxidative protection of low-density lipoprotein (LDL) was also evaluated and compared with that of catechin, because the generation of oxidized LDL is one of the most active and specific risk factors contributing to atherogenesis. Oral administration to rats of a commercially available sample (VNP) containing 30% of these polyphenolic compounds and 70% dietary fiber revealed that the serum reducing capacity measured in terms of FRAP value was significantly elevated 30 min after the treatment, but declined rather quickly thereafter, indicating the good oral absorption of the compounds and their fast binding to the lumenal surface of the blood vessels. An eight-week, human, clinical trial (n=31) of VNP showed significant improvement in erectile function measured by IIEF (international index of erectile function) score. These results collectively demonstrated the usefulness of these polyphenolic compounds as fundamental chemopreventive agents against vascular risk factors originating from oxidative stress.

Antioxidant Activity of Anthocyanin Extract from Purple Black Rice

Antioxidant activity was studied for anthocyanins extracted from purple black rice (PBR) by a 3% aqueous trifluoroacetic acid solution (TFA), as well as for anthocyanins extracted from blueberry (Bluetta, high bush type). Capillary zone electrophoresis revealed that the PBR extract contained almost exclusively a single anthocyanin, which was identified as cyanidin 3-O-beta-D-glucoside (Cy 3-Glc) after purification by polyvinylpyrrolidone column chromatography. In contrast, 11 anthocyanins were identified in the blueberry extract. PBR extract showed slightly weaker superoxide scavenging and crocin bleaching activities than blueberry extract did. Both PBR and blueberry extracts, however, showed 10 to 25 times stronger activity than the same concentration of Trolox used as a reference antioxidant. It was further noted that the purified Cy 3-Glc from PBR extract retained approximately 74% of the antioxidant activity (both crocin bleaching and superoxide scavenging) observed in the original TFA extract. The hydroxyl radical scavenging activity of both extracts was several times weaker than that of the same concentration of Trolox, although the PBR extract showed approximately two times stronger activity than blueberry extract did. The hydroxyl radical scavenging activity of the purified Cy 3-Glc from PBR, however, decreased to approximately 20% of that of the original PBR extract. These results indicate that the anthocyanin Cy 3-Glc contributes to the antioxidant activity of PBR through its strong superoxide radical but not hydroxyl radical scavenging activity.

Baicalin promoted the repair of DNA single strand breakage caused by H2O2 in cultured NIH3T3 fibroblasts

The protective effect of Baicalin, a flavonoid isolated from the root of Scutellaria baicalensis G., on H2O2-induced DNA single strand break (SSB) was examined in NIH3T3 mouse fibroblasts by Comet assay (single cell gel electrophoresis technique). When the cells were pulse-chased with H2O2 (0.1-0.5 mM) for 15 min in fetal bovine serum (FBS)-free Dulbecco's Modified Eagle's Medium (DMEM), SSB occurred in the DNA as reported elsewhere in dose-dependent manner. Baicalin (50, 100 micro M) which was incubated with the cells for 24 h before the H2O2 chase did not give rise to significant protection against the SSB formation. However, when the time required to cause a change in the DNA damage histogram obtained by the Comet assay was precisely examined after the H2O2 chase, it was found that the H2O2 induced SSB was more promptly repaired in the cells pretreated with Baicalin prior to the H2O2 chase, compared to untreated control cells. At the same time, the cell viability examined by 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide) (MTT) assay after the H2O2 abuse was moderately recovered in the Baicalin increased by the Baicalin treatment. It was thus concluded that Baicalin that was known as an antioxidant flavonoid in vitro also functions as a biological response modifier, improving the cellular repair potential of oxidatively damaged DNA.

Effects of chard (Beta vulgaris L. var. cicla) extract on oxidative injury in the aorta and heart of streptozotocin-diabetic rats

In diabetes mellitus, increased free radical formation raises the incidence of atherosclerosis and cardiovascular diseases. Regardless of the type of diabetes, the objective of the therapy is to achieve normoglycemia and to prevent or delay the complications. Chard (Beta vulgaris L. var. cicla) is used as a hypoglycemic agent by diabetic patients in Turkey. The aim of this study was to investigate the effect of feeding chard on diabetes-induced free radical-mediated injury in rat aorta and heart tissues. Female Swiss albino rats were randomly divided into four groups: control, diabetic, chard, and diabetic + chard. Rats were subjected to intraperitoneal streptozotocin (STZ, 65 mg/kg) to induce diabetes. Chard extract (2 g/kg) was given for 28 days beginning on the 14th day of the study. Aorta and heart tissue lipid peroxidation and glutathione levels as well as blood glucose levels were determined. The results of the present study indicate that lipid peroxidation was increased and glutathione levels were decreased in both aorta and heart tissue of the diabetic rats. However, treatment with chard extract reversed the effects of diabetes on blood glucose and tissue lipid peroxidation and glutathione levels.

Inhibition of LDL oxidation by flavonoids in relation to their structure and calculated enthalpy

Twenty flavonoid compounds of five different subclasses were selected, and the relationship of their structure to the inhibition of low-density lipoprotein (LDL) oxidation in vitro was investigated. The most effective inhibitors, by either copper ion or 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH) induction, were flavonols and/or flavonoids with two adjacent hydroxyl groups at ring B. In the presence of the later catechol group, the contribution of the double bond and the carbonyl group at ring C was negligible. Isoflavonoids were more effective inhibitors than other flavonoid subclasses with similar structure. Substituting ring B with hydroxyl group(s) at 2' position resulted in a significantly higher inhibitory effect than by substituting ring A or ring B at other positions. The type of LDL inducer had no effect in flavonoids with catechol structure. Calculated heat of formation data (deltadeltaH(f)) revealed that the donation of a hydrogen atom from position 3 was the most likely result, followed by that of a hydroxyl from ring B. Position 3 was favored only in the presence of conjugated double bonds between ring A to ring B. This study makes it possible to assign the contribution of different functional groups among the flavonoid subclasses to in vitro inhibition of LDL oxidation.

Flavanones structure-related inhibition on TPA-induced tumor promotion through suppression of extracellular signal-regulated protein kinases: involvement of prostaglandin E2 in anti-promotive process

Biological functions of flavanones have been studied extensively, however, the structure-related activities of flavanones on 12-o-tetradecanoylphorbol 13-acetate (TPA)-induced promotive effects are still unclear. In this study, flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone showed the most significant dose-dependent inhibition on TPA-induced proliferative effects among eight tested flavanones in NIH3T3 cells. TPA-induced mitogen activated protein kinases (MAPK) phosphorylation, ornithine decarboxylase (ODC), c-Jun, and cyclooxygenase 2 (COX-2) protein expressions in a time-dependent manner, and the maximal inductive time point is at 1 h for MAPK phosphorylation and 6 h for others. Flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone showed the dose-dependent inhibition on TPA-stimulated MAPK phosphorylation, COX-2, ODC, c-Jun protein expressions. Induction of, prostaglandin E(2) (PGE(2)) production was detected in TPA-treated NIH3T3 cells, and flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone inhibited significantly PGE(2) production induced by TPA. Addition of PGE(2) reverses the inhibitory activities of flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone on TPA-induced proliferation. And, PD98059, a specific inhibitor of ERKs, inhibited TPA-induced MAPK phosphorylation, accompanied by decreasing COX-2, c-Jun, and ODC protein expression, and showed dose-dependent inhibition on TPA-induced proliferation in cells. These results demonstrated that PGE(2) is an important mediator in TPA-induced proliferation, and MAPK phosphorylation was located at the upstream of COX-2, c-Jun, and ODC gene expressions in TPA-induced responses. Furthermore, flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone (100 microM) suppressed TPA-induced colony formation associated with blocking MAPK phosphorylation, ODC, c-Jun, and COX-2 proteins expression. And, 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay showed that flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone did not perform potent anti-radical activities among these eight tested compounds. In conclusion, this study provided molecular evidences to demonstrate that flavanone, 2'-OH flavanone, 4'-OH flavanone, 6-OH flavanone were potent inhibitors on TPA-induced responses without notable cytotoxicity through suppression of PGE(2) production; and anti-radical activity of flavanones was not correlated with preventing the occurrence of tumor promotion. We proposed that blocking TPA-induced intracellular signaling responses might be involved in the anti-promotive mechanism of flavanones.

Flavonoid antioxidants: chemistry, metabolism and structure-activity relationships

Flavonoids are a class of secondary plant phenolics with significant antioxidant and chelating properties. In the human diet, they are most concentrated in fruits, vegetables, wines, teas and cocoa. Their cardioprotective effects stem from the ability to inhibit lipid peroxidation, chelate redox-active metals, and attenuate other processes involving reactive oxygen species. Flavonoids occur in foods primarily as glycosides and polymers that are degraded to variable extents in the digestive tract. Although metabolism of these compounds remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. The propensity of a flavonoid to inhibit free-radical mediated events is governed by its chemical structure. Since these compounds are based on the flavan nucleus, the number, positions, and types of substitutions influence radical scavenging and chelating activity. The diversity and multiple mechanisms of flavonoid action, together with the numerous methods of initiation, detection and measurement of oxidative processes in vitro and in vivo offer plausible explanations for existing discrepancies in structure-activity relationships. Despite some inconsistent lines of evidence, several structure-activity relationships are well established in vitro. Multiple hydroxyl groups confer upon the molecule substantial antioxidant, chelating and prooxidant activity. Methoxy groups introduce unfavorable steric effects and increase lipophilicity and membrane partitioning. A double bond and carbonyl function in the heterocycle or polymerization of the nuclear structure increases activity by affording a more stable flavonoid radical through conjugation and electron delocalization. Further investigation of the metabolism of these phytochemicals is justified to extend structure-activity relationships (SAR) to preventive and therapeutic nutritional strategies.

Salvia miltiorrhiza inhibits biliary obstruction-induced hepatocyte apoptosis by cytoplasmic sequestration of p53

Cholestatic liver injury is caused by hepatocellular apoptosis induced by toxic bile salts. We have studied the effects of a traditional Chinese herbal medicine, Salvia miltiorrhiza, on apoptotic cell death in bile duct-ligated (BDL) rats. We also attempted to clarify the molecular mechanisms of the hepatoprotective effects of S. miltiorrhiza in this animal model. A water extract of S. miltiorrhiza (Sm-X; 200 mg/kg; po) was administered to BDL rats for 10 days. Rats were euthanized and apoptosis was detected in liver tissue by TUNEL staining. Western blot analysis and immunostaining for alpha-smooth muscle actin (alpha-SMA), Bax, Bcl-2, and p53 were performed. Results show that the treatment of BDL rats with Sm-X significantly improved the liver function parameters, although the expression of alpha-SMA, a marker of hepatic stellate cell activation, was not affected. Treatment with Sm-X significantly reduced the number of apoptotic cells. A time-dependent decrease in Bax protein level and an increase in Bcl-2 protein level were observed in BDL rats treated with Sm-X. Immunohistochemical analysis demonstrated that p53 was strongly positive in hepatocyte nuclei of BDL rats but that treatment with Sm-X induced a cytoplasmic sequestration of p53. Taken together, hepatoprotective effects of Sm-X partially ascribe to the antiapoptotic property in hepatocytes. Treatment of Sm-X-induced cytoplasmic sequestration of p53, downregulation of Bax, and upregulation of Bcl-2 protein. This study identifies and delineates signaling factors involved in the antiapoptotic properties of Sm-X and suggests a potential application of S. miltiorrhiza in the clinical management of hepatic disease induced by toxic bile salts following biliary obstruction.

Effect of lignans isolated from Hernandia nymphaeifolia on estrogenic compounds-induced calcium mobilization in human neutrophils

The effect of five lignans isolated from Hernandia nymphaeifolia on estrogenic compounds (17beta-estradiol, tamoxifen and clomiphene)-induced Ca(2+) mobilization in human neutrophils was investigated. The five lignans were epi-yangambin, epi-magnolin, epi-aschantin, deoxypodophyllotoxin and yatein. In Ca(2+)-containing medium, the lignans (50-100 microM) inhibited 10 microM 17beta-estradiol- and 5 microM tamoxifen-induced increases in intracellular free Ca(2+) levels ([Ca(2+)](i)) without changing 25 microM clomiphene-induced [Ca(2+)](i) increase. 17beta-estradiol and tamoxifen increased [Ca(2+)](i) by causing Ca(2+) influx and Ca(2+) release because their responses were partly reduced by removing extracellular Ca(2+). In contrast, clomiphene solely induced Ca(2+) release. The effect of the lignans on these two Ca(2+) movement pathways underlying 17beta-estradiol- and tamoxifen-induced [Ca(2+)](i) increases was explored. All the lignans (50-100 microM) inhibited 10 microM 17beta-estradiol-and 5 microM tamoxifen-induced Ca(2+) release, and 17beta-estradiol-induced Ca(2+) influx. However, only 100 microM epi-aschantin was able to reduce tamoxifen-induced Ca(2+) influx while the other lignans had no effect. Collectively, this study shows that the lignans altered estrogenic compounds-induced Ca(2+) signaling in human neutrophils in a multiple manner.

Scutellaria baicalensis inhibits liver fibrosis induced by bile duct ligation or carbon tetrachloride in rats

This study was carried out to investigate the antifibrotic effects of methanol extracts from the traditional Chinese medicinal herb, the root of Scutellaria baicalensis Georgi, on liver fibrosis induced by bile duct ligation and scission (BDL) or carbon tetrachloride (CCl4) in rats. Liver fibrosis was assessed by histological observations and by measuring levels of liver hydroxyproline, lipid peroxidation based on malondialdehyde (MDA) production, and serum enzyme activities. The morphological characteristics of livertissuewere examined by Masson'strichrome staining and immunostaining against smooth muscle cell alpha-actin. In both models, the levels of hydroxyproline and MDA in liver were significantly increased. Treatment with a methanol extract of S. baicalensis significantly reduced the levels of liver hydroxyproline and MDA, with improved histological findings. In both models, the liver areas positive for smooth muscle cell alpha-actin were considerably decreased by treatment with oral methanol extract of S. baicalensis (150 mg kg(-1) daily for 28 days). A methanol extract of S. baicalensis root inhibits fibrosis and lipid peroxidation in rat liver induced by BDL or CCl4.

Comparison of antioxidant effects of naringin and probucol in cholesterol-fed rabbits

BACKGROUND

Due to the strong evidence on the involvement of active oxygen species in a variety of disorders, the role of antioxidants against oxidative stress has recently received increased attention.

METHODS

Twenty male rabbits were served a high-cholesterol (HC, 5 g/kg diet) diet or high-cholesterol diet supplemented with naringin (0.5 g/kg diet) or probucol (0.5 g/kg diet) for 8 weeks to compare the antioxidative effects of the citrus bioflavonoid (naringin) and antioxidative cholesterol-lowering drug (probucol).

RESULTS

The plasma thiobarbituric acid-reactive substances (TBARS) concentration was not significantly different between the groups, whereas the hepatic TBARS concentration was significantly lower in the probucol group than in both normal and HC control or naringin group. Probucol and naringin supplementation led to an increase in the hepatic superoxide dismutase (SOD) and catalase (CAT) activities, and a decrease in the hepatic mitochondrial hydrogen peroxide (H(2)O(2)) content compared to the HC-control group. However, there was no difference in the cytosolic H(2)O(2) content or cytosolic glutathion peroxidase (GSH-Px) activity in the liver between the groups. Both naringin and probucol supplements significantly increased the plasma vitamin E concentration compared to the HC-control group. As regards the antioxidant enzyme gene expressions, naringin significantly increased the expression of three antioxidant enzyme mRNAs compared to the HC-control group, whereas probucol significantly increased the only SOD mRNA expression.

CONCLUSIONS

The probucol supplement was very potent in the antioxidative defense system, whereas naringin exhibited a comparable antioxidant capacity based on increasing the gene expressions in the antioxidant enzymes, while also increasing the hepatic SOD and CAT activities, sparing plasma vitamin E, and decreasing the hepatic mitochondrial H(2)O(2) content.

Flavonoids can block PSA production by breast and prostate cancer cell lines

BACKGROUND

Prostatic carcinoma is the most commonly diagnosed cancer and the second leading cause of cancer death of North American men. Combined androgen blockade (CAB) is one treatment option for prostate cancer, using estrogen agonists, luteinizing hormone-releasing hormone (LHRH) agonists and non-steroidal anti-androgens such as nilutamide and cyproterone acetate. Since many of these drugs have serious side effects, many patients are searching for "natural" alternatives or complements to traditional therapy. These include phytoestrogens found in soy and other plant foods. Such compounds have only started to be evaluated for potential androgen-blocking activity. Inhibition of production of androgen-regulated proteins, including prostate-specific antigen (PSA), is one indicator of androgen blocking.

METHODS

The ability of 72 flavonoids and related compounds to inhibit PSA production in a breast cancer cell line, BT-474, and a prostate cancer cell line (PC-3), transfected with the human androgen receptor cDNA, PC-3(AR)(2) was examined.

RESULTS

Twenty-two of the 72 flavonoids tested were found to significantly block PSA production by the BT-474 cell line at the highest tested concentration (10(-5) mol/l), with 17 of these compounds inhibiting production of PSA in the PC-3(AR)(2) cells as well.

CONCLUSIONS

That several flavonoids may significantly block production of this androgen-regulated protein. It will be worthwhile to examine these compounds as possible candidates for prostate cancer prevention or management.

Heteropterys aphrodisiaca (extract BST0298): a Brazilian plant that improves memory in aged rats

Literature report is lacking on pharmacological studies of the plant Heteropterys aphrodisiaca, endemic to the scrublands of Brazil. The present study was carried out to investigate the effects of oral dosing with extract BST0298 from this plant, on learning and on memory, in young (3-6-month-old) and aged (20-28-month-old) rats. The aged animals presented significant memory deficits in both the passive avoidance and T-maze left/right discrimination tests. Treatment for 7 days (50 mg/kg) or 26 days (100 mg/kg) with extract BST0298 restored the memory deficits in the passive avoidance test. However, no improvement in memory was observed after acute administration of extract BST0298 (100 mg/kg) in aged rats. An improvement in learning was also observed in the left/right discrimination test in aged rats treated for 109 days with BST0298 at a dose of 50 mg/kg. These results suggest that treatment for 7 days or more with H. aphrodisiaca improves learning and memory deficits in aged rats.

Effect of natural phenolic acids on DNA oxidation in vitro

We examined the antioxidant activity of the following natural phenolic compounds present in food: 3-OH-benzoic acid (3-OH-BA); 4-OH-benzoic acid (4-OH-BA); 2,3-dihydroxybenzoic acid (2,3-diOH-BA); 3,4-dihydroxybenzoic acid (3,4-diOH-BA or protocatechuic acid); ferulic acid; caffeic acid; and 2-coumaric, 3-coumaric and 4-coumaric acids. We measured the inhibitory effect of these compounds on iron-dependent oxidative DNA damage in vitro [incubating herring sperm DNA with Fe(III)/GSH] or using cumene hydroperoxide (CumOOH) as a free-radical generating system; we also studied the interaction of these phenols with Fe(II) or Fe(III) spectrophotometrically. Among the tested compounds, 2,3-diOH-BA, 3,4-diOH-BA and caffeic acid interacted with Fe(II) and showed a potent inhibitory effect on iron-induced oxidative DNA damage. CumOOH-induced DNA oxidation was not modified by these compounds. On the contrary, 2-coumaric, 3-coumaric and 4-coumaric acids did not interact with iron but protected against oxidative DNA damage induced by Fe(III)/GSH and by CumOOH, indicating a direct free-radical scavenging activity of these compounds in both systems. The IC(50)+/-S.E.M. of the three coumaric acids against CumOOH-induced DNA oxidation was 44.2+/-2.0, 54.7+/-2.0 and 33.1+/-1.0 microM, respectively. On the contrary, 3-OH-BA and 4-OH-BA did not have scavenging activity and 3-OH-BA actually enhanced oxidative DNA damage. In conclusion, some natural phenolic acids, commonly present in food, have interesting protective activity against DNA oxidation in vitro and deserve further consideration as effective antioxidants in vivo.

Examination of pineal indoles and 6-methoxy-2-benzoxazolinone for antioxidant and antimicrobial effects

Oxidative modification of low density lipoprotein (LDL) induced by free radicals is implicated in the development of atherosclerosis. The aim of the present study was to examine the ability of various pineal indoles in inhibiting LDL oxidation which is accompanied by an increase in mobility in agarose gel electrophoresis and by an augmented generation of thiobarbituric acid-reactive substance induced by Cu2+. It was found that the order of potencies in inhibiting malondialdehyde formation was 5-hydroxytryptamine (serotonin)>5-hydroxytryptophol and 5-hydroxyindole-3-acetic acid when tested at 4 mM. 5-methoxytryptamine was as effective as 5-hydroxytryptophol and 5-hydroxyindole-3-acetic acid when tested at 4 mM but was inactive at 1 mM. 5-methoxytryptophol was marginally active at 4 mM. Melatonin, 5-methoxyindole-3-acetic acid and 6-methoxy-2-benzoxazolinone were inactive even at 4 mM. The ranking of antioxidative potencies as reflected in the shift of mobility in agar gel electrophoresis was 5-hydroxytryptamine>5-methoxytryptamine>5-hydroxyindole-3-acetic acid and 5-methoxytryptophol>5-hydroxytryptophol and melatonin. Another aim of this investigation was to ascertain the action of the aforementioned pineal indoles on the enhanced lipid peroxidation brought about in the mouse kidney and liver by intraperitoneal administrations of carbon tetrachloride. It was found that all pineal indoles tested demonstrated an inhibitory effect in the kidney but not in the liver. 6-methox-2-benzoxazolinone and 5-methoxyindole-3-acetic acid exerted antifungal activity against Mycosphaerella arachidicola, Botrytis cinerea and Physalospora piricola. 6-methoxy-2-benzoxazolinone exhibited antibacterial activity against Proteus vulgaris and 5-methoxytryptamine against Staphylocccus aureus and Bacillus subtilis. Other pineal indoles did not possess antifungal or antibacterial action.

Determination of flavone, flavonol, and flavanone aglycones by negative ion liquid chromatography electrospray ion trap mass spectrometry

Eleven naturally occurring flavonoid aglycones, belonging to the representative flavone, flavonol, and flavanone types were separated by high performance liquid chromatography and analyzed on-line with negative ion electrospray ionization tandem mass spectrometry (ESI-MS/MS). In order to resolve the MS/MS spectra obtained, each compound was reinvestigated by direct loop injections using an ion trap mass spectrometer. The MSn spectra obtained allowed us to propose plausible schemes for their fragmentation supported by the analysis of five complementary synthetic flavonoid aglycones. The negative ion ESI-MS/MS behavior of the different aglycones investigated in this study revealed interesting differences when compared with the previously described patterns obtained using various ionization techniques in positive ion. Thus, concerning the retro Diels-Alder (RDA) fragmentation pathways, several structurally informative anions appeared highly specific of the negative ion mode. In addition, a new lactone-type structure, instead of a ketene, was proposed for a classic RDA diagnostic ion. We also observed unusual CO, CO2, and C3O2 losses which appear to be characteristic of the negative ion mode. All these results and these unusual neutral losses show that the negative ion mode was a powerful complementary tool of the positive ion mode for the structural characterization of flavonoid aglycones by ESI-MS/MS.

Estimation of the antioxidant activities of flavonoids from their oxidation potentials

A simple electrochemical method for estimating the antioxidant activity (AA) of flavonoids has been developed. The proposed method is based on a measurement of the half-wave potential (E1/2) of the first oxidation wave of flavonoids by using flow-through column electrolysis. At the same time, the lipid peroxidation (LPO) inhibiting effects of these flavonoids were determined. A quantitative structure-activity relationship was obtained to describe the AA of flavonoids: IC50(microM) = 30.36 + 151.50 E1/2 (V) -12.63 log P (r = 0.852), where IC50 represents the concentration for 50% inhibition of LPO, and P represents the octanol/water partition coefficient. This method is expected to be useful for the quick screening of flavonoid antioxidants, and evaluating the AA of flavonoid-containing foods and medicinal plants.

Differential effects of IH636 grape seed proanthocyanidin extract and a DNA repair modulator 4-aminobenzamide on liver microsomal cytochrome 4502E1-dependent aniline hydroxylation

Previous studies from our laboratories have linked the protective abilities of IH636 grape seed proanthocyanidin extract (GSPE) with inactivation of anti-apoptotic gene bcl-XL, and modification of several other critical molecular targets such as DNA-damage/DNA-repair, lipid peroxidation and intracellular Ca2+ homeostasis. Especially, GSPE provided dramatic protection against acetaminophen (APAP)-induced hepatotoxicity, significantly increased bcl-XL expression in the liver, and antagonized both necrotic and apoptotic deaths of liver cells in vivo. However, it was not clear from this study whether anti-apoptogenic and anti-necrotic effects of GSPE were: (i) due to its interference with endonuclease activity, (ii) due to its antioxidant effect, or, (iii) due to its ability to inhibit microsomal drug metabolizing enzyme(s), such as CYP-4502E1. Since CYP-4502E1 primarily metabolizes acetaminophen in mice and rats, this study specifically focused on CYP-4502E1's catalytic activity in vitro. Overall this investigation compared the in vitro aniline hydroxylation patterns of: (i) in vivo GSPE-exposed and unexposed (control) mouse liver microsomes, (ii) induced (1% acetone in drinking water for 3 days) and uninduced rat liver microsomes in the presence and absence of GSPE in vitro, and (iii) control rat liver microsomes in the presence of an anti-APAP agent 4-aminobenzamide (4-AB) in vitro. For the in vivo assessment, male B6C3F1 mice were fed GSPE diet (ADI 100 mg/kg body wt) for 4 weeks, and liver microsomes were isolated from both control and GSPE-fed mice for aniline hydroxylation, a specific marker of CYP-4502E1 activity. Data show that hydroxylation was 40% less in microsomes from GSPE-exposed livers compared to control microsomes. Similarly, when rat liver microsomes were incubated with various concentrations of GSPE in vitro (100 and 250 microg/ml), aniline hydroxylation was inhibited to various degrees (uninduced: 40 and 60% and induced: 25 and 50%, respectively with 100 and 250 microg/ml). Influence of GSPE on hydroxylation patterns were compared with another hepatoprotective agent 4-aminobenzamide (4-AB), a well-known modulator of nuclear enzyme poly(ADP-ribose) polymerase, and the data shows that 4-AB did not alter aniline hydroxylation at all. Collectively, these results may suggest that GSPE has the ability to inhibit CYP-4502E1, and this is an additional cytoprotective attribute, in conjunction with its novel antioxidant and/or antiendonucleolytic potential.