Ginkgo biloba modulates glutathione redox cycle in vascular endothelial cells

Ginkgo biloba extract (EGb 761) attenuates oxidative stress induction in erythrocytes of sickle cell disease patients

Sickle cell disease promotes hemolytic anemia and occlusion of small blood vessels due to the presence of high concentrations of hemoglobin S, resulting in increased production of reactive oxygen species and decreased antioxidant defense capacity. The aim of this study was to evaluate the protective action of a standardized extract of Ginkgo biloba (EGb 761), selected due to its high content of flavonoids and terpenoids, in erythrocytes of patients with sickle cell anemia (HbSS, SS erythrocytes) subjected to oxidative stress using tert-butylhydroperoxide or 2,2-azobis-(amidinepropane)-dihydrochloride, in vitro. Hemolysis indexes, reduced glutathione, methemoglobin concentrations, lipid peroxidation, and intracellular reactive oxygen species were determined. SS erythrocytes displayed increased rates of oxidation of hemoglobin and membrane lipid peroxidation compared to normal erythrocytes (HbAA, AA erythrocytes), and the concentration of EGb 761 necessary to achieve the same antioxidant effect in SS erythrocytes was at least two times higher than in normal ones, inhibiting the formation of intracellular reactive oxygen species (IC50 of 13.6 µg/mL), partially preventing lipid peroxidation (IC50 of 242.5 µg/mL) and preventing hemolysis (IC50 of 10.5 µg/mL). Thus, EGb 761 has a beneficial effect on the oxidative status of SS erythrocytes. Moreover, EGb 761 failed to prevent oxidation of hemoglobin and reduced glutathione at the concentrations examined.

Antioxidant levels in the pig urinary bladder: distribution within the bladder wall and in the urothelium derived from different bladder regions

This study was designed to determine the antioxidant levels in the urinary bladder wall layers as well as urothelium derived from different bladder regions. Samples of the urothelium, lamina propria, muscularis, and serosa were prepared from the pig's urinary bladder body, while samples used for regional mapping of the urothelium were prepared from trigone, ventral and dorsal middle bladder body, and apex region. Activities of superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase were determined. Concentrations of ascorbic acid and glutathione were also measured. Antioxidant activities, i.e. concentrations of superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione, were shown to be highest in the urothelium and progressively lower towards the serosa. Regional mapping of the urothelium singled out apex as the region with the lowest antioxidant activities, i.e. concentrations of glutathione peroxidase, ascorbic acid, and glutathione. The fact that antioxidants are concentrated in the urothelium implies that urothelium functions as a barrier against reactive species. The urothelium derived from the apex is the region with the lowest antioxidant levels and is therefore probably the region most liable to development of oxidative damage.

The effects of ginkgo biloba extract on tissue adenosine deaminase, xanthine oxidase, myeloperoxidase, malondialdehyde, and nitric oxide in cisplatin-induced nephrotoxicity

This study was carried out to determine if Ginkgo Biloba Extract (GBE or Egb 761) exerts a beneficial effect against cisplatin-induced renal failure in rats. Sprague Dawley rats were divided into four groups. The first group (control) received orally 1 mL/kg/day of 0.9% saline by an oral carrier vehicle on days 1 to 10. The second group was injected with 7 mg/kg cisplatin intraperitoneally (i.p.) on the fourth day, once only. The third group (vit E+cisplatin) was administered 10 mg/kg/day i.p. vit E on 1 to 10 days with one dose of i.p. cisplatin (7 mg/kg) injection on the fourth day. The fourth group (GBE+cisplatin) was given GBE orally at 100 mg/mL/kg started on the first day up to the tenth day with one dose of cisplatin (7 mg/kg) injection on the fourth day. Cisplatin was found to lead a statistically significant increase in plasma BUN and creatinine levels, as well as urine micro total protein (MTP) levels, leading to acute renal failure (ARF) in rats. Renal xanthine oxidase (XO) activities increased in all groups (statistically significant in cisplatin + GBE-treated rats; P < 0.001). Adenosine deaminase (AD) activities were increased in cisplatin-treated rats, and decreased in cisplatin+GBE-treated (P < 0.041) and cisplatin+vit E-treated (P < 0.005) rats, compared to controls. Malondialdehyde (MDA), nitric oxide (NO) levels and myeloperoxidase (MPO) activities were increased in the kidney tissue of cisplatin-treated rats. Vit E improved plasma creatinine and urine MTP levels, together with tissue MDA, NO levels, and MPO activities. But GBE had no statistically significant effect on those parameters. These results indicate that increased XO, AD and MPO activities, as well as MDA and NO levels play a critical role in cisplatin nephrotoxicity. GBE has been shown to protect against cisplatin-induced nephrotoxicity.

Radioprotection by plant products: present status and future prospects

The development of radioprotective agents has been the subject of intense research in view of their potential for use within a radiation environment, such as space exploration, radiotherapy and even nuclear war. However, no ideal, safe synthetic radioprotectors are available to date, so the search for alternative sources, including plants, has been on going for several decades. In Ayurveda, the traditional Indian system of medicine, several plants have been used to treat free radical-mediated ailments and, therefore, it is logical to expect that such plants may also render some protection against radiation damage. A systematic screening approach can provide leads to identifying potential new candidate drugs from plant sources, for mitigation of radiation injury. This article reviews some of the most promising plants, and their bioactive principles, that are widely used in traditional systems of medicine, and which have rendered significant radioprotection in both in vitro and in vivo model systems. Plants and their constituents with pharmacological activities that may be relevant to amelioration of radiation-mediated damage, including antiemetic, antiinflammatory, antioxidant, cell proliferative, wound healing and haemopoietic stimulatories are also discussed.

Ginkgo biloba inhibits hydrogen peroxide-induced activation of nuclear factor kappa B in vascular endothelial cells

The present study determined the effects of Ginkgo biloba extract (GBE) on the activation of nuclear factor kappa B (NF-kappaB) and the level of hydrogen peroxide (H2O2) in bovine pulmonary artery endothelial cells (PAEC). H2O2 showed a concentration-dependent activation of NF-kappaB. GBE demonstrated a concentration-dependent suppression of NF-kappaB activated by H2O2. GBE directly scavenged H2O2 in a cell-free system; it also decreased H2O2 levels in PAEC. These results suggest that the inhibitory effect of GBE on H2O2-induced NF-kappaB activation may be caused by its scavenging and suppression of H2O2. Our experiments demonstrate that GBE can inhibit NF-kappaB activation induced by H2O2 and may thus be effective for the prevention or treatment of atherosclerosis and other disorders related to NF-kappaB activation.

Fructus corni attenuates oxidative stress in macrophages and endothelial cells

The antioxidant effect of a Chinese medicinal herb, Fructus corni extract (FCE), was investigated using models of oxidative stress in macrophages and vascular endothelial cells. Murine macrophages (J774) were incubated with FCE at 37 degrees C and 5% CO2 for 1 hr. Oxidative burst was triggered by zymosan and measured with a fluorescent probe. FCE exhibited a concentration- dependent suppression of oxidative burst. Confluent monolayers of bovine pulmonary artery endothelial cells (PAEC) were preincubated with FCE for 20 hrs, washed, and then exposed to an organic oxidant t-butyl hydroperoxide (tBHP) for 2 hrs. Cell viability was assessed by methylthiazol tetrazolium (MTT) assay, and cell injury by the release of intracellular lactate dehydrogenase (LDH). Lipid peroxidation products of PAEC were determined by measuring thiobarbituric acid-reactive substances (TBARS). Exposure of PAEC to tBHP resulted in decreased cell viability, increased LDH release, and elevated TBARS. Preincubation of PAEC with FCE significantly reversed these changes. Our results demonstrated that FCE can protect vascular endothelial cells from oxidant injury. The data thus suggest that Fructus corni may be useful for the prevention and/or treatment of disorders associated with oxidative damage.

Fructus corni enhances endothelial cell antioxidant defenses

1. The present study determined the effects of Fructus corni extract (FCE) on the levels of hydrogen peroxide (H2O2) and superoxide anion (O2-), on the glutathione (GSH) redox cycle and on the activities of antioxidant enzymes in bovine pulmonary artery endothelial cells (PAECs). 2. Confluent monolayers of PAECs were incubated with FCE, and oxidative stress was triggered by hypoxanthine and xanthine oxidase (to induce H2O2) or H2O2 (to induce O2-). 3. FCE exhibited a concentration-dependent suppression of H2O2 and O2-. 4. It modulated the GSH redox cycle by increasing the intracellular GSH content, the activities of GSH peroxidase and GSH disulfide reductase, and by decreasing the intracellular level of GSH disulfide. 5. It also increased the activities of superoxide dismutase and catalase. 6. These results demonstrate that FCE can promote a protective antioxidant defense state by affecting some important enzymatic and nonenzymatic oxidant-scavenging systems and may thus be useful for the prevention or treatment of disorders associated with oxidative damage.