What Are Free Radicals

Free radicals are a group of atoms or molecules that are highly reactive due to having one or more unpaired electrons [7]. As a result of having an incomplete outer valance shell, these molecules attempt to react with other molecules in their vicinity in order to gain one or more electrons. However, once a molecule loses an electron to a free radical, a chain reaction is created, as now the former molecule becomes a free radical itself (Fig. 13.1). The chain reaction created from free radicals can have catastrophic effects for living cells. ROS are a collection of radicals and nonradical derivatives of oxygen. Free radicals derived from nitrogen are called reactive nitrogen species (Table 13.1). The most common ROS that is produced by spermatozoa is the superoxide anion radical; this in turn forms hydrogen peroxide (strong oxidizer) on its own or by the action of superoxide dismutase [8].

Plasma membrane of the spermatozoa is rich in polyunsaturated fatty acids (PUFA). Because their cytoplasm contains low concentrations of scavenging enzymes, they are particularly susceptible to the damage induced by excessive ROS [9, 10]. The seminal plasma, however, contains two different types of antioxidants to minimize free radical-induced damage: enzymatic and nonenzymatic antioxidants. Enzymatic antioxidants are: superoxide dismutase, catalase, glutathione reductase, and peroxidase. Nonenzymatic antioxidants are comprised of vitamins (vitamin C, E), proteins (albumin, transferrin, haptoglobin, and ceruloplasmin), and other molecules (glutathione, pyruvate, and ubiquinol). Both enzymatic and nonen-zymatic antioxidants can help minimize free radical-induced damage. Excessive generation of ROS damages cells, tissues, and organs and is involved in the patho-genesis of a wide range of diseases.

Fig. 13.1 Illustration is showing the oxygen molecule and the generation of a free radical

Fig. 13.1 Illustration is showing the oxygen molecule and the generation of a free radical

Table 13.1 Examples of free radicals

Reactive oxygen species Reactive nitrogen species

Superoxide anion (O^-) Nitric oxide (NOO

Hydrogen peroxide (H2O2) Nitric dioxide (NO20

Hydroxyl radical (OH') Peroxynitrite (ONOO-)

Pregnancy Guide

Pregnancy Guide

A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.

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