Protection against radiation oxidative damage in mice by Triphala.

Protection against whole body gamma-irradiation (WBI) of Swiss mice orally fed with Triphala (TPL), an Ayurvedic formulation, in terms of mortality of irradiated animals as well as DNA damage at cellular level has been investigated. It was found that radiation induced mortality was reduced by 60% in mice fed with TPL (1g/kg body weight/day) orally for 7 days prior to WBI at 7.5 Gy followed by post-irradiation feeding for 7 days. An increase in xanthine oxidoreductase activity and decrease in superoxide dismutase activity was observed in the intestine of mice exposed to WBI, which, however, reverted back to those levels of sham-irradiated controls, when animals were fed with TPL for 7 days prior to irradiation. These data have suggested the prevention of oxidative damage caused by whole body radiation exposure after feeding of animals with TPL. To further understand the mechanisms involved, the magnitude of DNA damage was studied by single cell gel electrophoresis (SCGE) in blood leukocytes and splenocytes obtained from either control animals or those fed with TPL for 7 days followed by irradiation. Compared to irradiated animals without administering TPL, the mean tail length was reduced about three-fold in blood leukocytes of animals fed with TPL prior to irradiation. Although, similar protection was observed in splenocytes of TPL fed animals, the magnitude of prevention of DNA damage was significantly higher than that observed in leukocytes. It has been concluded that TPL protected whole body irradiated mice and TPL induced protection was mediated through inhibition of oxidative damage in cells and organs. TPL seems to have potential to develop into a novel herbal radio-protector for practical applications.

Potential of traditional ayurvedic formulation, Triphala, as a novel anticancer drug.

The cytotoxic effects of aqueous extract of Triphala, an ayurvedic formulation, were investigated on human breast cancer cell line (MCF-7) and a transplantable mouse thymic lymphoma (barcl-95). The viability of treated cells was found to decrease with the increasing concentrations of Triphala. On the other hand, treatment of normal breast epithelial cells, MCF-10 F, human peripheral blood mononuclear cells, mouse liver and spleen cells, with similar concentrations of Triphala did not affect their cytotoxicity significantly. The drug treatment was found to induce apoptosis in MCF-7 and barcl-95 cells in vitro as determined by annexin-V fluorescence and proportion of apoptotic cells was found dependent on Triphala concentration. MCF-7 cells treated with Triphala when subjected to single cell gel electrophoresis, revealed a pattern of DNA damage, characteristic of apoptosis. Studies on Triphala treated MCF-7 and barcl-95 cells showed significant increase in intracellular reactive oxygen species (ROS) in a concentration dependent manner. ROS increase was, however, found to be insignificant in MCF-10 F as well as in murine spleen and liver normal cells. In vivo, direct oral feeding of Triphala to mice (40 mg/kg body weight) transplanted with barcl-95 produced significant reduction in tumor growth as evaluated by tumor volume measurement. It was also found that apoptosis was significantly higher in the excised tumor tissue of Triphala fed mice as compared to the control, suggesting the involvement of apoptosis in tumor growth reduction. These results suggest that Triphala possessed ability to induce cytotoxicity in tumor cells but spared the normal cells. The differential effect of Triphala on normal and tumor cells seems to be related to its ability to evoke differential response in intracellular ROS generation. The differential response of normal and tumor cells to Triphala in vitro and the substantial regression of transplanted tumor in mice fed with Triphala points to its potential use as an anticancer drug for clinical treatment.

Investigation with chitosan-oxalate oxidase-catalase conjugate for degrading oxalate from hyperoxaluric rat chyme.

Enteric hyperoxaluria manifests due to hyperabsorption of dietary oxalate, secondary to a variety of chronic gastrointestinal disorders. The potential use of chitosan immobilized oxalate oxidase-catalase conjugate to deplete the oxalate content of food materials, while they are in the digestive tract has been evaluated by treating rat stomach chyme with such an enzyme preparation. Oxalate oxidase, obtained from beet stem, was adsorbed on chitosan along with catalase and then cross linked with glutaraldehyde to stabilize the derivative. This chemical modification of oxalate oxidase brought about a shift in its optimal pH from 4.2 to 3.8 with a marginal increase in its K(m). Compared to native enzyme, the modified oxalate oxidase exhibited increased storage stability, higher thermal stability and enhanced resistance to proteolytic digestion and heavy metal inactivation. These improved properties of the immobilized oxalate oxidase possibly render it suitable for oral administration under hyperoxaluric conditions.

Biogenesis of L-glyceric aciduria, oxalosis and renal injury in rats simulating type II primary hyperoxaluria.

Tracer experiments in rats mimicking type II primary hyperoxaluria, with an expanded intracellular pool of hydroxypyruvate, showed that the excess formation of oxalate did not originate from its immediate precursor glyoxylate. In these animals, the hepatic and kidney activities of oxalate synthesising enzymes such as lactate dehydrogenase and glycolate oxidase were normal, but tissue lipid peroxidation was significantly higher. In vitro experiments established that in a mild alkaline solution, hydroxypyruvate underwent auto-oxidation to form oxalate and H2O2 and also inhibited lactate dehydrogenase and glycolate oxidase from oxidising glyoxylate to oxalate. On the basis of the experimental evidence, we suggest that in type II primary hyperoxaluria, the accumulating hydroxypyruvate could reduce the intracellular pool of glyoxylate and on ageing, give rise to excess oxalate and H2O2, to cause oxalosis in the former and free radical mediated-cell injuries in the latter.

Altered physicochemical characteristics of polyethylene glycol linked beet stem oxalate oxidase.

Oxalate oxidase (EC 1.2.3.4), obtained from the beet stem, was covalently linked to polyethylene glycol (PEG). Compared with native enzyme, the modified oxalate oxidase exhibited decreased electrophoretic mobility, increased storage stability, higher thermal stability, and resistance to heavy metal inactivation and proteolytic digestion. The chemical modification of oxalate oxidase with PEG also brought about a marked shift in its optimal pH, from pH 4.5 to 6.5, without altering its Michaelis constant (K(m)) significantly. These acquired properties of the immobilized oxalate oxidase render it suitable for possible applications in clinical, nutritional, and medical fields. (c) 1995 John Wiley & Sons, Inc.