Beta-estradiol protects against copper-ascorbate induced oxidative damage in goat liver mitochondria in vitro by binding with ascorbic acid.

Aims: β-Estradiol (β-E), one of the chemical forms of female gonad hormone exhibited antioxidant efficacy in biochemical system, in vitro. The aim of the study was to investigate whether any other mechanism of protection by β-E to hepatic mitochondria in presence of stressor agent i.e.,a combination of Cu and ascorbic acid is involved.

Main Methods: Freshly prepared goat liver mitochondria was incubated with stressors and 1 μM β-E and post incubated with the same concentration at 37 °C at pH 7.4. Mitochondrial viability, biomarkers of oxidative stress, activities of Krebs cycle enzymes, mitochondrial membrane potential, Ca permeability were measured. Mitochondrial morphology and binding pattern of β-E with stressors were also studied.

Key Findings: Upon incubation of mitochondria with Cu, ascorbic acid and their combination there is a significant decline in activities of four of Krebs cycle enzymes in an uncompetitive manner with a concomitant increase in Ca permeability and membrane potential of inner mitochondrial membrane, which is withdrawn during co-incubation with β-E, but was not reversed during post incubation with the β-E. The final studies on mitochondrial membrane morphology using scanning electron microscope also exhibited damage. Isothermal titration calorimetry data also showed the negative heat change in the mixture of β-E with ascorbic acid and also its combination with Cu.

Significance: Our results for the first time demonstrated that β-E protects againstCu-ascorbate induced oxidative stress by binding with ascorbic acid. The new mechanism of binding of β-E with stress agents may have a future therapeutic relevance.