What Causes Oxidant Stress

Oxidant stress is caused by the damaging action of ROS. There are two main routes of production of ROS in the body: one is deliberate and useful; the other is accidental but unavoidable (Figure 2). Deliberate production of ROS is seen, for example,

Table 1 Reactive oxygen species found in vivo in general order of reactivity (from lowest to highest)

Name of species

Sign/formula

Radical (R) or

Comment

nonradical (NR)

Molecular oxygen

O2

R

Biradical, with two unpaired electrons; these are in parallel spins,

and this limits reactivity

Nitric oxide

NO'

R

Important to maintain normal vasomotor tone

Superoxide

O2"

R

Single electron reduction product of O2; large amounts produced in \/n//~\

in vivo

Peroxyl

ROO'

R

R is often a carbon of an unsaturated fatty acid

Singlet oxygen

1AgO2

NR

'Energized' nonradical forms of molecular oxygen; one unpaired

1sgO2

electron is transferred to the same orbital as the other

unpaired electron

Hydrogen peroxide

H2O2

NR

Small, uncharged, freely diffusible ROS formed by dismutation of

superoxide

Hydroperoxyl

HOO'

R

Protonated, more reactive form of superoxide; formed at sites of

low pH

Alkoxyl

RO'

R

R is carbon in a carbon-centered radical formed by peroxidation

of unsaturated fatty acid

Hypochlorous

HOCl

NR

Formed in activated phagocytes to aid in microbial killing

Peroxynitrite

HNOO~

NR

Highly reactive product of nitric oxide and superoxide

Hydroxyl

'OH

R

Fiercely, indiscriminately reactive radical

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

Get My Free Ebook


Post a comment