Abstract

Review article base on Free radicals are highly reactive and unstable molecules. Some of the key free radicals include hydroxyl radical, superoxide anion, hydrogen peroxide, singlet oxygen, hypochlorite, nitric oxide, and peroxynitrite. These radicals can damage important biological molecules like DNA, proteins, carbohydrates, and lipids, leading to cell damage. They are also linked to problems like early aging. Both internal and external factors can trigger the production of these reactive species, and oxidative stress plays a major role in many inflammatory diseases. Antioxidants can help neutralize the harmful effects of free radicals. They act by scavenging radicals, donating hydrogen or electrons, breaking down peroxides, quenching singlet oxygen, inhibiting enzymes, working synergistically, and chelating metals. Many natural antioxidants are available, including vitamins (like Vitamin C and E) and enzymes (such as glutathione reductase, glutathione peroxidases, and superoxide dismutase).

Keywords

Introduction

       
           
       
Figure 1:  Generation of reactive oxygen species in the human body.

Free radicals are formed as a result, they are continuously in the cells as a consequence of bothEnzymatically and non-enzymatically

       
           
       
Figure 2: Generation of free radical and ROS.

Some internal sources of free radicals: 

Free Radical Creating Complications:

3. Aging: The primary mechanism of aging involves the accumulation of DNA or cellular and functional damage. Reducing free radicals or slowing their production can slow down aging. Free radicals break down collagen in the skin, resulting in unsightly skin blemishes such as wrinkles, dark spots, fine lines, and loose, saggy skin.

Figure 8: The primary mechanism of aging involves the accumulation of DNA or cellular and functional damage.

       
           
       
Figure 9: Effect of antioxidant on human body.

4. Oxidative Damage to Proteins and DNA:

Oxidative damage to protein products can affect enzyme activity, receptors, and membrane transport. Protein oxidation causes aging by affecting signaling mechanisms, enzyme activity, thermal stability, and changes in susceptibility to protein degradation

5. Signal Transduction Mechanism

1. Signal transduction is a series of steps by which external stimuli are converted into chemical signals and then into cellular responses.
2. Cell signaling ultimately leads to the regulation of one or more cellular activities.
3. Regulation of gene [removed]turning transcription of specific genes on or off) is a common outcome of cell signaling.
4. Signaling pathways can also lead to important cellular events such as cell division or apoptosis (programmed cell death).

Antioxidant Defense System:

1. Antioxidants act as radical scavenger, hydrogen donor, electron donor, peroxide decomposer, singlet oxygen quencher, enzyme inhibitor, synergist, and metal-chelating agents.
2. Both enzymatic and nonenzymatic antioxidants exist in the intracellular and extracellular environment to detoxify ROS

Levels of antioxidant action:

1. The first line of defense is the preventive antioxidants, which suppress the formation of free radicals.

1. To suppress such reactions, some antioxidants reduce hydroperoxides and hydrogen peroxide beforehand to alcohols and water, respectively, without generation of free radicals and some proteins sequester metal ions.

2. The second line of defense: is the antioxidants that scavenge the active radicals to suppress chain initiation and/or break the chain propagation reactions.

1. Vitamin C, uric acid, bilirubin, albumin, and thiols are hydrophilic, radical-scavenging antioxidants, while vitamin E and ubiquinol are lipophilic radical-scavenging antioxidants.
2. Vitamin E is accepted as the most potent radical-scavenging lipophilic antioxidant.

3. The third line of defense: is the repair and de novo (at the beginning) antioxidants.

1. The proteolytic enzymes, proteinases, proteases, and peptidases, present in the cytosol and in the mitochondria of mammalian cells, recognize, degrade, and remove oxidatively modified proteins and prevent the accumulation of oxidized proteins.

4. Adaptation: There is another important function called adaptation where the signal for the production and reactions of free radicals induces formation and transport of the appropriate antioxidant to the right site

Enzymatic:

1. Superoxide dismutase :
2. Catalase :
3. Glutathione systems :
4. glutathione
5. glutathione reductase   
6. glutathione peroxidases
7. glutathione S-transferases

Non-Enzymatic:

1. Ascorbic acid
2. Melatonin
3. Vitamin E
4. Uric acid

Superoxide dismutase:

1. Superoxide dismutases (SODs) are a class of closely related enzymes that catalyze the   breakdown of the superoxide anion into oxygen and hydrogen peroxide

Catalase:

1. Catalase is a common enzyme found in nearly all living organisms, which are exposed to oxygen, where it functions to catalyze the decomposition of hydrogen peroxide to water and oxygen.
2. Hydrogen peroxide is a harmful by-product of many normal metabolic processes: to prevent damage, it must be quickly converted into other, less dangerous substances. 

Glutathione systems:

1. These enzymes are at particularly high levels in the liver and also serve indetoxification metabolism

Nutraceutical:

1. It is defined “as a food or parts of food that provide medical or health benefits, including                  the prevention and treatment of disease.Glucosamine is a natural compound found in cartilage.
2. Strong antioxidants activities have been found in berries, cherries, citrus, prunes, and olives. Green and black teas have been extensively studied in the recent past for antioxidant properties since they contain up to 30% of the dry weight as phenolic compounds.
3. Cocoa, potato, yam, tomato, kale, Brussels sprouts, broccoli and others dark green leafy and brightly-colored vegetables as well as legumes and cereals, in addition to spices and fruits such as cherries and citrus, are particularly rich in phenolic compounds.
4. As is typical for phenolic compounds, they can act as potent antioxidants and metal chelators. They also have long been recognized to possess anti-inflammatory, antiallergic, hepatoprotective, antithrombotic, antiviral, and anticarcinogenic activities.
5. Cocoa, potato, yam, tomato, kale, Brussels sprouts, broccoli and others dark green leafy and brightly-colored vegetables as well as legumes and cereals, in addition to spices and fruits such as cherries and citrus, are particularly rich in phenolic compounds
6. Synthetic and natural food antioxidants are used routinely in foods and medicine especially those containing oils and fats to protect the food against oxidation.
7. Synthetic antioxidants are recently reported to be dangerous to human health. Thus, the search for effective, nontoxic natural compounds with antioxidant activity has been intensified in recent years.

CONCLUSION

As various studies suggest that these free radicles are very harmful for body and they play very vital role in the pathogenesis of various diseases like cancer, cardiovascular diseases, cellular and DNA damage, aging etc. This oxidative damage to the cellsis permanent which cannot be reversed. There are many sources for the generation of these free radicles. The action of these free radicles depends upon their ability to donate electrons to other chemical groups thereby initiating the chain reactions. These chain reactions can be arrest by use of antioxidants and further damage can be prevented. Some naturally occurring antioxidants can prove effective like Vit. C, Vit. E, Catalase, Superoxide dismutase etc. Whereas the synthetic antioxidants can produce harmful side effects on body.  Person should consume the bright colored food which provides a natural antioxidants like vegetables, fruits etc. These substances contain phenolic compounds which are considered as very potent antioxidants.

ACKNOWLEDGMENT

Deepest gratitude is also extended to Professor Ravindra Nikam and the College of Pharmacy in Gondur, Dhule, for kindly providing essential research facilities. Furthermore, I would like to convey my thanks to Dr. A. V. Patil, the Principal of Prof. Ravindra Nikam College of Pharmacy in Gondur and Dhule, for their consistent encouragement and support throughout this make an effort.

Conflict of Interest:

The writer affirms that there are no conflicts of interest to disclose.

Ethical Approval:

Not applicable.

Funding:

Not applicable.

Declarations:

I state that any work of others used in this paper has been appropriately cited and attributed. Any

Assistance received in the research, writing, or editing of this paper has been duly acknowledged.

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