Antioxidants: Functions of Antioxidants, Classification of Antioxidants

• Antioxidants are molecules that can donate an electron to free radicals like reactive oxygen species (ROS) without becoming unstable themselves, thus preventing the free radicals from taking electrons from other vital cellular components and causing damage.

• This property helps in protecting the cells from the harmful effects of oxidative stress, which is implicated in aging and various diseases.

• Antioxidants are categorized based on their source (endogenous or exogenous) and their mechanism of action (enzymatic or non-enzymatic).

Functions of Antioxidants

1. Cell Protection:

• Antioxidants protect cellular components by neutralizing free radicals, thus preventing damage to lipids, proteins, and DNA that can lead to cell dysfunction and death.

2. Anti-inflammatory Effects:

• By reducing oxidative stress, antioxidants can decrease the activation of inflammatory pathways and the production of pro-inflammatory cytokines.

3. Immune Support:

• Some antioxidants, like vitamin C, support the immune system by enhancing the barrier function of skin, stimulating the production and function of leukocytes, and improving antimicrobial and natural killer cell activities.

4. Detoxification:

• Antioxidants like glutathione play a crucial role in detoxifying harmful substances, including drugs and pollutants, by facilitating their removal from the body.

5. Signaling:

• Low levels of ROS play a role in cellular signaling pathways that regulate growth, survival, and adaptation to stress.

• Antioxidants help maintain ROS at levels that are conducive to health and homeostasis.

Classification of Antioxidants

1. Endogenous Antioxidants

• Endogenous antioxidants are produced naturally within the body and play a crucial role in neutralizing free radicals and protecting cells from oxidative damage.

• These can be further subdivided into enzymatic and non-enzymatic antioxidants.

A. Enzymatic Antioxidants

• These are enzymes that catalyze reactions to neutralize free radicals and prevent oxidative damage.

  1. Superoxide Dismutase (SOD)

  2. Catalase

  3. Glutathione Peroxidase

B. Non-enzymatic Antioxidants

• These are molecules that can directly scavenge free radicals or enhance the body’s antioxidant capacity.

  1. Glutathione

  2. Vitamin C (Ascorbic Acid)

  3. Vitamin E (Tocopherol)

  4. α-Lipoic Acid

  5. Melatonin

2. Synthetic Antioxidants

• These are man-made compounds designed to mimic or enhance the actions of natural antioxidants, often used to preserve food and prevent oxidative damage.

A. Butylated Hydroxytoluene (BHT)

B. Butylated Hydroxyanisole (BHA)