Effect of propyl gallate feeding on glutathione content in ageing Zaprionus paravittiger (Diptera)

Allocation of cysteine for glutathione production in caterpillars with different antioxidant defense strategies: a comparison of Lymantria dispar and Malacosoma disstria

Sulfur amino acids [cysteine (Cys) and methionine (Met)] play two major roles during animal development: protein synthesis for growth and glutathione synthesis for defense. For caterpillars, the levels of sulfur amino acids found in foliar protein can be especially low relative to their nutritional needs. Previous work has measured concentrations of glutathione (GSH; containing Cys) in specific animal tissues, but has not examined whole-body levels to ascertain the costliness of this defense in terms of Cys allocation. This study examined whether the production of GSH varies between species and within individuals in accordance with an insect's need for antioxidant defense. Secondly, we quantified the allocation of total Cys (peptide-bound plus free Cys) to GSH in caterpillars as an estimate of its cost. Two contrasting species were compared: Lymantria dispar (Lymantriidae), a species that is highly defended, and Malacosoma disstria (Lasiocampidae), a species that is less defended. As expected, GSH levels were significantly higher in L. dispar than in M. disstria. Consistent with the function of the midgut as a first line of defense against ingested toxins, GSH levels were significantly higher in these tissues than in the whole bodies of both species. A major finding in this study was that a large fraction of total Cys is used to produce GSH: GSH in the midguts of L. dispar and M. disstria contained 23 and 21%, respectively, of the total Cys in these tissues, and the GSH in their remaining body tissues contained 19 and 17% of the total Cys in these tissues. Levels of total Cys in caterpillar tissues followed the same pattern of distribution as did GSH, producing a strong association between GSH and total Cys (R(2) = 0.794). We conclude that GSH is a costly defense, especially in generalist tree-feeding species such as L. dispar. These results further suggest that the large allocation of Cys to GSH in highly defended species might produce a tradeoff by limiting the amount of Cys available for rapid growth.

Nutraceutical interventions may delay aging and the age-related diseases

Largely due to better control of infectious diseases and to year-round access to a more nutritious diet, life expectancy in developed countries has increased dramatically in the twentieth century. However, as the average age of the population has risen, the incidence of chronic age-related diseases such as Alzheimer's, Parkinson's, cardiovascular disease, cancer, arthritis, osteoporosis, benign prostatic hyperplasia, late-onset diabetes, and macular degeneration have increased. To obtain further significant improvements in both lifespan and the quality of life in this century, treatments and nutritional changes that address the age-related diseases and the aging process itself need to be examined and validated. There are many reports suggesting that oxidative stress and certain nutritional deficiencies may contribute to the aging process and to many age-related diseases. In this article, we report on two human clinical trials using novel antioxidant supplements in which urinary oxidative stress is significantly reduced. We also discuss the conceptual basis and existing literature for several nutritional supplements that may have beneficial effects on aging and age-related diseases. Based on the available data, we suggest that human life expectancy can be significantly increased in the twenty-first century by optimizing diet and using nutritional supplements.

Neurodegenerative disorders in humans: the role of glutathione in oxidative stress-mediated neuronal death

Oxidative stress has been implicated in both normal aging and in various neurodegenerative disorders and may be a common mechanism underlying various forms of cell death including necrosis, apoptosis, and excitotoxicity. In this review, we develop the hypothesis that oxidative stress-mediated neuronal loss may be initiated by a decline in the antioxidant molecule glutathione (GSH). GSH plays multiple roles in the nervous system including free radical scavenger, redox modulator of ionotropic receptor activity, and possible neurotransmitter. GSH depletion can enhance oxidative stress and may also increase the levels of excitotoxic molecules; both types of action can initiate cell death in distinct neuronal populations. Evidence for a role of oxidative stress and diminished GSH status is presented for Lou Gehrig's disease (ALS), Parkinson's disease, and Alzheimer's disease. Potential links to the Guamanian variant of these diseases (ALS-PD complex) are discussed. In context to the above, we provide a GSH-depletion model of neurodegenerative disorders, suggest experimental verifications of this model, and propose potential therapeutic approaches for preventing or halting these diseases.

Effect of BHA on longevity, antioxygenic enzymes and peroxides in Callosobruchus maculatus

Life span and antioxygenic enzyme activities of insects reared on optimal BHA concentration (1 mM) soaked seeds were higher than their respective controls. However, the reproductive potential, peroxides and the level of free radicals declined. The increased longevity with BHA could be attributed to its free radical quenching effect, thereby leading to the decreased peroxide levels and the increased antioxygenic enzyme activities of the insects.

Effect of ascorbic acid on longevity and biochemical alterations in Callosobruchus maculatus F. (Coleoptera: Bruchidae)

Optimal ascorbic acid concentration (1 mM) increased the median (LT(50)) and maximum (LT(100)) life spans, decreased age-independent susceptibility to death (a(0)), reproductive period, number of eggs laid/female but prolonged the post-reproductive period in Callosobruchus maculatus. The activities of respiratory enzymes and the levels of metabolic end-products declined while the activities of antioxygenic enzymes increased. The increased longevity of insects reared on ascorbic acid soaked seeds may be interpreted in terms of conservation of energy by way of decreased reproductive potentiality and the maintenance of a homeostatic balance between pro-oxidant generation and antioxidant defences.