The impact of diet upon mitochondrial physiology (Review)

Mitochondria are considered the 'powerhouses' of cells, generating the essential energy in the form of adenosine triphosphate that they need for their energy demands. Nevertheless, their function is easily adaptable as regards the energy demands and the availability of chemical substrates. This allows cells to buffer sudden changes and reassure cellular metabolism, growth or survival. Currently, humans have different dietary habits, which provide several stimuli to the cell. According to the energy substrate availability due to the diet quality and diet temporality, mitochondrial physiology is greatly affected. The present review article aimed to collect all the available information that has been published to date concerning the impact of five different popular diets (high-fat diet, ketogenic diet, fasting, caloric restriction diet and the Mediterranean diet) on specific mitochondrial physiological aspects, such as function, biogenesis, mitophagy and mitochondrial fission/fusion.

A novel combined bioactivity / chemoactivity holistic approach for the evaluation of dietary supplements

There is increasing evidence that the excessive generation of free radicals in the human body plays a major role in the pathophysiology and development of various diseases, closely associated with oxidative damage. In this frame, the consumption of antioxidant nutrients through food or dietary supplements may prevent from the harmful effects of free radicals on human cells. This work proposes a holistic approach consisting of distinct methodologies, suitable to evaluate the antioxidant and chemoprotective activity of three novel dietary supplements, each one containing active substances with complementary properties. In the first step, this approach includes in vitro studies to evaluate the antioxidant activity of the dietary supplements by measuring the parameters of free radical scavenging capacity, of reducing power activity, as well as, their ability to protect biomolecules from oxidation. Furthermore, the evaluation of their antimutagenic and antigenotoxic effects is also presented. SubsequentlySub, the specific effects of the dietary supplements were examined in three cancer cell lines (HepG2, HeLa, MKN45), by measuring redox biomarkers such as glutathione, reactive oxygen species and thiobarbituric acid reactive substances, using flow cytometry and spectrophotometry. Our results indicate that all the dietary supplements exhibit high antioxidant, antimutagenic, antigenotoxic and lipid protective activity. The most prominent result is their capability to induce oxidative damage on cancer cells via the critical decrease of the levels of their intracellular glutathione, as well as the increase of ROS and lipid peroxidation levels after the administration of non-cytotoxic concentrations. We suggest that the proposed methodology could constitute a valuable tool for the characterization of dietary supplements based on their chemical and functional properties.

Grape Stem Extracts From Three Native Greek Vine Varieties Exhibit Strong Antioxidant and Antimutagenic Properties

BACKGROUND/AIM

The winemaking procedure results in the generation of stems, a by-product that is harmful to the environment. Concomitantly, stems are rich in polyphenols and, hence, they are putatively beneficial for human health.

MATERIALS AND METHODS

In this study, the grape stem extracts derived from three native Greek vine varieties, namely Mavrodaphne, Muscat and Rhoditis were examined for their chemical composition and antioxidant and antimutagenic properties using a battery of in vitro biomarkers.

RESULTS

All extracts are rich in polyphenols. Moreover, they exhibit potent antioxidant and antimutagenic properties with the extract of Mavrodaphne being the strongest in reducing the DPPH^• and O₂ ^-• radicals and the Fe³⁺ and in protecting plasmid DNA from peroxyl radical-induced oxidative modification.

CONCLUSION

Therefore, although they are serious pollutants, grape stems contain phytochemicals with important biological properties and can be used as (ingredients of) bio-functional foods to improve certain aspects of human health.