Oxidative Stress and Bio-Regulation

Abstract

Reactive oxygen species (ROS) and free radicals work to maintain homeostasis in the body, but their excessive production causes damage to the organism. The human body is composed of a variety of cells totaling over 60 trillion cells. Each cell performs different functions and has a unique lifespan. The lifespan of cells is preprogrammed in their genes, and the death of cells that have reached the end of their lifespan is called apoptosis. This is contrary to necrosis, which is the premature death of cells brought about by physical or scientific forces. Each species has its own unique lifespan, which in humans is estimated to be up to 120 years. Elucidating the mechanism of the death of a single cell will lead to a better understanding of human death, and, conversely, the death of a single cell will lead to exploring the mechanisms of life. In this sense, research on active oxygen and free radicals, which are implicated in biological disorders and homeostasis, requires an understanding of both the physicochemical as well as the biochemical aspects. Based on the discussion above, it is clear to see that active oxygen and free radicals have dual functions of both injuring and facilitating homeostasis in living organisms.

Keywords: anti-oxidant; bio-regulation; biochemistry; free radicals; oxidative stress; reactive oxygen species.

Figure 1

The Earth’s atmosphere and the evolution of living things. Anaerobic bacteria were the first to emerge, but the advent of oxygen caused the extinction of most anaerobic bacteria, and aerobic bacteria adapted to oxygen and cell-based organisms flourished.

Figure 2

Highly pigmented tropical fish. The colorful natural pigments of tropical fish serve to scavenge free radicals and protect the fish from the ultraviolet irradiation (Photo by Shin-ichi Ohama, Diving shop Marine Mate, Ishigaki Island, Okinawa, Japan).

Figure 3

The effect of free radicals on living organisms. Free radicals damage biomolecules, such as lipids, proteins, carbohydrates, oxygen, and DNA, contributing to disease, aging, and cancer in living organisms.

Figure 4

Free radicals: atoms or molecules with unpaired electrons. Electrons normally exist in pairs, with two in each orbital; unpaired electrons, with only one electron in each orbital, are chemically very unstable.

Figure 5

Configuration of oxygen and ROS. Schematic diagrams of the electron configurations of typical molecules are shown.

Figure 6

In vivo and in vitro sources of free radicals. In living organisms, ROS and free radicals are generated by various internal and external stimuli mentioned here.

Figure 7

NO^· regulates blood flow, blood pressure, and tissue damage. NO^· regulates endothelial cell function as an endothelium-derived relaxing factor, in which O^·2− is intimately involved.

Figure 8

The effects of ROS and free radicals. Living organisms utilize the toxicity of ROS and free radicals to protect themselves from cancer, microorganisms, viruses, etc.

Figure 9

The physical and scientific factors involved in activating oxygen. Oxygen can become ROS/free radicals due to various factors, such as chemicals and radiation.