Antioxidant and antitumor activities of selenium- and zinc-enriched oyster mushroom in mice.

Selenium and zinc are well-known essential trace elements with potent biological functions. However, the possible health benefits of the combined administration of dietary selenium and zinc have not been studied extensively. In this study, we prepared selenium- and zinc-enriched mushrooms (SZMs) containing increased levels of selenium and zinc. The effects of SZMs on antioxidant and antitumor activities were evaluated. Mice were fed with either a control diet or a diet supplemented with SZMs or sodium selenite and zinc sulfate for 6 weeks. Antioxidant capacity was investigated by measuring the activities of antioxidant enzymes and the levels of lipid peroxide products. Results showed that treatment with SZMs significantly increased the activities of glutathione peroxidase (GPx) and superoxide dismutase and decreased the levels of malondialdehyde and lipofuscin. Furthermore, using a mouse model of lung tumors, we found that SZMs significantly decreased the number of tumor nodes with an increase in the activity of GPx. SZMs had a greater effect on the increase in both antioxidant and antitumor activities than did sodium selenite and zinc sulfate. These findings suggest that SZMs may be effective for improving antioxidant capacity and preventing tumors.

The effect of Polbax extract on lipofuscin accumulation in cultured neonatal rat cardiac myocytes.

Polbax, a water-soluble extract of fresh pollen grains and pistils, was tested for its ability to influence the accumulation of lipofuscin (age pigment) in cultured neonatal rat cardiac myocytes. Exposure for 3 weeks to Polbax at concentrations of 0.1, 1.0 or 10 mg/L decreased lipofuscin accumulation morphometrically assayed using laser scanning microscopy images (green excitation light) of formaldehyde-fixed cells, by 24%, 41% or 43%, respectively. Based on the knowledge that oxidative stress and iron-catalysed peroxidation play an important role in lipofuscinogenesis, we suggest that Polbax may slow lipofuscin formation due to antioxidant activities, perhaps involving intralysosomal dismutation of superoxide produced by autophagocytosed mitochondria and/or iron-chelation.

Carnitine as a free radical scavenger in aging.

Carnitine (4-N-trimethylammonium-3-hydroxybutyric acid) plays an important role in the translocation of acetyl moieties from the mitochondria into the cytoplasm for acetylcholine synthesis in the brain. Previous studies in our laboratory have shown that L-carnitine suppresses oxidative damage during aging. This study was carried out to see the effect of L-carnitine on the status of non-enzymatic antioxidants and lipofuscin accumulation in various regions of the aged rat brain. We observed a decrease in the status of ascorbic acid, glutathione and vitamin E in aged rats. Histological work showed that the accumulation of lipofuscin increased as a function of age. The extent of damage varied between the regions we have investigated. Supplementation of L-carnitine to aged rat improved the antioxidant status in a duration dependent manner. The accumulation of lipofuscin was also found to be decreased after L-carnitine administration. The data suggests that decrement of lipofuscin accumulation by L-carnitine may be partially due to its antioxidant promoting action.

Lipofuscin accumulation and its prevention by vitamin E in nervous tissue: quantitative analysis using snail buccal ganglia as a simple model system.

The total numbers and sizes of the lipofuscin granules in buccal ganglia of the pond snail Planorbis corneus were measured by light microscope morphometry of serial sections in different groups of animals. One group, weight range 0.5-5.0 g (age 1-4 years), was maintained on a lettuce diet (low Vitamin E content). Lipofuscin content increased with age by over a 100 times in this group. The lipofuscin deposits accumulate in the glial cells at the periphery of the ganglia. The other group, weight range 0.5-5.0 g was fed a supplemented Vitamin E diet for 4 months before quantitisation of the lipofuscin. This diet prevented lipofuscin appearance in the young animals, and reduced the lipofuscin content by 50% in the old animals. The findings provide direct evidence that Vitamin E reduces lipofuscin accumulation in glial cells in intact nervous tissue. The buccal ganglia of Planorbis provide a useful model system for studying age and dietary related alterations of lipofuscin in nervous tissue.