Reactive oxygen species (ROS) or oxidants are free radicals or electrons produced in the body due to increased oxidative stress. Oxidative stress is harmful condition that occurs when there is excess of ROS and or decrease in anti oxidant levels, this may cause tissue damage by physical, chemical, psychological factors that lead to tissue injury in humans and causes different diseases e.g. Parkinsonism, Diabetes, Cancer, Hepatitis, Gastritis, Eczemza, COPD, Heart failure, Kidney failure, etc.

An Anti-oxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electron from a sunstance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When the chain reaction occurs in a cell, it can cause damage or death to the cell, Anti-oxidants terminate these chain reactions by removing free radical intermediates and inhibit other oxidation reactions. They do this by oxidized themselves. So anti-oxidants are often reducing agents such as thios, ascorbic acid or polyphenols.

The body produces different anti-oxidants to neutralize free radicals & protect the body from different diseases. Exogenous anti-oxidants are externally supplied to the body through food and they also play important role to protect the body. Endogeneous anti-oxidant defence system developed by the body can be classified into two groups- enzymatic & non-enzymatic. The enzymatic defence system includes different endogeneous enzymes like Superoxide dismutase (SOD), Glutathione reductase (GR). MDA is oxidative stress marker in the body which increases on increase in oxidative stress. Non-enzymatic defence system includes Vit.E , Vit.C  and reduced Glutathione (GSH).

“Rasayana chikitsa” is a specialized section of Ayurveda , which mainly deals with the preservation & promotion of health by revitalizing the metabolism & enhancing immunity. It has been reported that the “Rasayana dravya” are rejuvenators , nutritional supplements & possess strong anti-oxidant activity. They also have antagonistic actions on the oxidative stressors which give rise to the formation of different free radicals. Since free radicals are implicated in a no. of physiological disorders , there is a strong case to believe that “Rasayana dravya” exert their therapeutic actions by their ability to scavenge free radicals or by their anti-oxidant potential.

Written with inputs by Dr. Rekha K. Gaikwad and guidance of Dr. Ashok D. Ramteke.

References:
en.wikipedia.org/wiki/Antioxidant
www.webmd.com/food-recipes/antioxidants-topic-overview