Is 1,8-Cineole-Rich Extract of Small Cardamom Seeds More Effective in Preventing Alzheimer's Disease than 1,8-Cineole Alone?

The present study demonstrates the efficacies of synthetic 1,8-cineole and an 1,8-cineole-rich supercritical carbon dioxide (SC-CO2) extract of small cardamom seeds in preventing oligomerization of amyloid beta peptide (Aß42) and inhibiting iron-dependent oxyradical production in vitro. The oligomerization of Aß42 was monitored by thioflavin T assay and MALDI-TOF analysis of the oligomers. The iron-dependent production of oxygen free radicals was detected by fluorometric benzoate hydroxylation assay. We observed that both pure 1,8-cineole and 1,8-cineole-rich extract of small cardamom seeds at concentrations of 50 µM and 100 µM prevented the production of reactive hydroxyl radicals from a mixture of Fe2+ and ascorbate. However, the 1,8-cineole-rich extract of small cardamom seeds prevented in vitro Aß42 oligomerization more effectively vis-à-vis the synthetic (99% pure) 1,8-cineole. Additional study on SHSY5Y cells indicated that both pure 1,8-cineole and 1,8-cineole-rich SC-CO2 extract of small cardamom seeds prevented iron-dependent cell death. Since oxidative damage, Aß42 aggregation and loss of cell viability (iron-induced) are characteristics of onset of Alzheimer's disease pathology, our results suggest a putative therapeutic role of 1,8-cineole-rich extract of small cardamom seeds over pure 1,8-cineole in preventing this neurodegenerative disease.

Biochemical deficits and cognitive decline in brain aging: Intervention by dietary supplements.

The aging of brain in the absence of neurodegenerative diseases, usually called non-pathological brain aging or normal cognitive aging, is characterized by an impairment of memory and cognitive functions. The underlying cellular and molecular changes in the aging brain that include oxidative damage, mitochondrial impairment, changes in glucose-energy metabolism and neuroinflammation have been reported widely from animal experiments and human studies. The cognitive deficit of non-pathological brain aging is the resultant of such inter-dependent and reinforcing molecular pathologies which have striking similarities with those operating in Alzheimer's disease which causes progressive, irreversible and a devastating form of dementia and cognitive decline in the elderly people. Further, this article has described elaborately how nutraceuticals present in a wide variety of plants, fruits and seeds, natural vitamins or their analogues, synthetic antioxidants and other compounds taken with the diet can ameliorate the cognitive decline of brain aging by correcting the biochemical alterations at multiple levels. The clinical usefulness of such dietary supplements should be examined both for normal brain aging and Alzheimer's disease through randomized controlled trials.

Multiple mechanisms of age-dependent accumulation of amyloid beta protein in rat brain: Prevention by dietary supplementation with N-acetylcysteine, α-lipoic acid and α-tocopherol.

The aged brain may be used as a tool to investigate altered metabolism of amyloid beta protein (Aß42) that may have implications in the pathogenesis of Alzheimer's disease (AD). In the present study, we have observed a striking increase in the amyloid precursor protein (APP) level in the brain cortex of aged rats (22-24 months) along with a mild but statistically significant increase in the level of APP mRNA. Moreover, the activity of ß secretase is elevated (nearly 55%) and that of neprilysin diminished (48%) in brain cortex of aged rats compared to that in young rats (4-6 months). All these changes lead to a markedly increased accumulation of Aß42 in brain cortical tissue of aged rats. Long-term dietary supplementation of rats with a combination of N-acetylcysteine, α-lipoic and α-tocopherol from 18 months onwards daily till the sacrifice of the animals by 22-24 months, attenuates the age-related alterations in amyloid beta metabolism. In separate experiments, a significant impairment of spatial learning and memory has been observed in aged rats, and the phenomenon is remarkably prevented by the dietary supplementation of the aged animals by the same combination of N-acetylcysteine, α-lipoic acid and α-tocopherol. The results call for further explorations of this combination in suitable animal models in ameliorating AD related brain deficits.

Combination of N-acetylcysteine, α-lipoic acid and α-tocopherol substantially prevents the brain synaptosomal alterations and memory and learning deficits of aged rats.

This study has compared several synaptosomal parameters in three groups of rats: young (46 months), aged (22-24 months) and antioxidant supplemented aged rats (antioxidant supplementation given with the diet as a combination of N-acetylcysteine, α-lipoic acid and α-tocopherol from 18 months onwards till 22-24 months). The synaptosomes from aged rat brain, in comparison to those of young animals, exhibit an increased membrane potential with altered contents of Na(+) and K(+) under basal incubation condition and in the presence of depolarizing agents. The intrasynaptosomal Ca(2+) is also higher in aged than in young rat. These age-dependent changes in synaptosomal parameters are prevented markedly in the antioxidant supplemented group. When examined on T-maze, the aged animals are noticeably impaired in learning and memory functions, but the deficit is remarkably prevented in the antioxidant supplemented aged animals. It is suggested that the synaptosomal alterations partly contribute to the cognitive deficits of aged animals, and both are rescued by long-term antioxidant supplementation.

Dietary supplementation with N-acetyl cysteine, α-tocopherol and α-lipoic acid reduces the extent of oxidative stress and proinflammatory state in aged rat brain.

The present study has attempted to understand how oxidative stress contributes to the development of proinflammatory state in the brain during aging. Three groups of rats have been used in this study: young (4-6 months, Group I), aged (22-24 months, Group II) and aged with dietary antioxidant supplementation (Group III). The antioxidants were given daily from 18 months onwards in the form of a combination of N-acetyl cysteine (50 mg/100 g body weight), α-lipoic acid (3 mg/100 g body weight), and α-tocopherol (1.5 mg/100 g body weight) till the animals were used for the experiments between 22 and 24 months. Several measurements have been made to evaluate the ROS (reactive oxygen species) production rate, the levels of proinflammatory cytokines (IL-1ß, IL-6 and TNF-α) and the activation status of NF-κß (p65 subunit) in brain of the three groups of rats under the study. Our results reveal that brain aging is accompanied with a significant increase in NADPH oxidase activity and mitochondrial ROS production, a distinct elevation of IL-1ß, IL-6 and TNF-α levels along with increased nuclear translocation of NF-κß (p65 subunit) and all these phenomena are partially but significantly prevented by the long-term dietary antioxidant treatment. The results imply that chronic dietary antioxidants by preventing oxidative stress and proinflammatory state may produce beneficial effects against multiple age-related deficits of the brain.

Age-related oxidative decline of mitochondrial functions in rat brain is prevented by long term oral antioxidant supplementation.

A combination of antioxidants (N-acetyl cysteine, α-lipoic acid, and α-tocopherol) was selected for long term oral supplementation study in rats for protective effects on age-related mitochondrial alterations in the brain. Four groups of rats were chosen: young control (6-7 months); aged rats (22-24 months); aged rats (22-24 months) on daily antioxidant supplementation from 18 month onwards and young rats (6-7 months) on daily antioxidant supplementation from 2 month onwards. The brain mitochondrial functional parameters, status of antioxidant enzymes and accumulation of oxidative damage markers were measured in the four groups of rats. A significant decrease in complex IV activity and a loss of transmembrane potential and phosphorylation capacity along with an increased accumulation of oxidative damage markers and compromised antioxidant enzyme status were noticed in aged rat brain mitochondria as compared to that in young controls, but in aged rats supplemented with oral antioxidants the mitochondrial alterations were largely prevented. Antioxidant supplementation in young rats had no effect on mitochondrial parameters investigated in this study. The results have implications in biochemical and functional deficits of brain during aging as well as in neurodegenerative disorders.

Aging and antioxidants modulate rat brain levels of homocysteine and dehydroepiandrosterone sulphate (DHEA-S): implications in the pathogenesis of Alzheimer's disease.

The study has shown that in aged (22-24 months) rat brains an elevation of homocysteine level (42%) and a decrease in dehydroepiandrosterone sulphate (DHEA-S) content (32%) occur compared to those in the brains of young rats (4-6 months). Such changes in the brain levels of homocysteine and DHEA-S in aged rats are prevented, when the diet daily of the rats is supplemented with a combination of antioxidants (N-acetyl cysteine 50 mg, alpha-lipoic acid 3 mg and alpha-tocopherol 1.5 mg - each per 100 g of body weight) starting from 18 months until these are sacrificed between 22 and 24 months. The brain content of reduced glutathione is also decreased in aged rats as compared to that in young ones and the phenomenon can again be prevented completely by the same regimen of antioxidant supplementation. The changes in the levels of homocysteine and DHEA-S in aged rat brain have been related to associated glutathione depletion and oxidative stress and the implications of the results highlighted in the pathogenesis of Alzheimer's disease.

Dietary supplementation with N-acetylcysteine, alpha-tocopherol and alpha-lipoic acid prevents age related decline in Na(+),K (+)-ATPase activity and associated peroxidative damage in rat brain synaptosomes.

This study has shown that in aged rat brain (22-24 months) crude synaptosomes in comparison to that in young animals (4-6 months), a striking decrease in the activity of Na(+),K(+)-ATPase occurs along with decreased K (m) and V (max) but without any change in enzyme content as seen by immunoblotting. This is associated with an accumulation of peroxidative damage products in aged brain. When rats are given antioxidant supplementation in the diet with a combination of N-acetylcysteine, alpha-tocopherol and alpha-lipoic acid daily from 18 months onwards and sacrificed at 22-24 months for experimentation, the age associated decrease of Na(+),K(+)-ATPase activity, alterations of its kinetic parameters and accumulation of peroxidative damage products in brain synaptosomes are prevented nearly completely. Because of the critical importance of Na(+),K(+)-ATPase in neuronal functions, the results of this study may be of potential implications in controlling age-related functional deficits of the brain.