Paracetamol an analgesic
and antipyretic agent is a useful drug in the treatment of mild pain. This
analgesic is one of the silent causes of liver damage due to the constant
abuse. The metabolism of paracetamol is an excellent example of intoxication, because the metabolite
N-acetyl-p-benzo-quinone imine, abbreviated as NAPQI is the primary cause of
toxicity rather than paracetamol itself This metabolite NAPQI reacts with
proteins and nucleic acids to produce toxic free radicals. These unconjugated
free radicals can cause cell damage through mechanisms of covalent binding and
lipid peroxidation with subsequent tissue injury. The mechanism involves a
process where by unsaturated lipids are oxidized to form free radical oxygen
species and other toxic by- products that can be harmful to the host system
(Benzie, 1996).
Polyunsaturated lipids
(in the cell) are especially susceptible to this type of damage. When in an
oxidizing environment, they react to form lipid peroxides. The role of free
radical reactions in disease pathology
is well established. Considerable
attention has recently been focused on the inter- relationships of lipid peroxidation processes, free-
radical- related reactions and the development of a variety
of pathological states (Benzie,1996). It is well established that lipid
peroxidation is the deleterious result of free radical reactions leading to
disruption of biomembranes and subsequent dysfunction of cells and tissues
(Benzie, 1996). Therefore lipid peroxidation is a crucial step in the pathogenesis of free radical related
disease states, including inflammatory injuries, arteriosclerosis, rheumatoid
arthritis, gastrointestinal diseases, cardiovascular, nervous system and other
diseases as well as toxicity of many xenobiotics (Halliwell, 1987).
In recent years, there has been a global trend towards
the use of natural phytochemical present in
herbs and functional foods as antioxidants because polyphenols isolated
from them have potential therapeutic role in the prevention and treatment of
many human disease related to oxidative stress (Halliwell, 1987). Among the species of medicinal plants and
spices, which are being used for various therapeutic purposes, Alliums
sativum and Aloe barbadensis are very prominent.
Allium sativum (garlic) is a powerful natural
antibiotic which has been shown to stimulate cell growth and activity
(Zimmerman, 1996). It reduces blood
pressure in hypertensive patients and is useful in lowering bad cholesterol
while at the same time raising the beneficial cholesterol, HDL. It is excellent
for use in all colds and infections and does not destroy the body’s natural
intestinal flora. Allium sativum
is being considered as a possible cancer prevention agent (Zimmerman, 1996). It
has also been reported to protect the liver, kills worms and parasites,
internally and externally, reduces blood clothing and provides antioxidant
protection to cells (Rev. Waltz 1999).
Aloe barbadensis, often called the miracle plant, the
natural healer or the burn plant (Vutyavanich et al, 2001). Aloe barbadensis has been around for over
4000 years during which its amazing medicinal potentials have benefited mankind
tremendously. Aloe barbadensis
commonly called Aloe is a succulent, thick, fleshy medicinal plant which contains many
nutrient and chemical components like:
vitamins, minerals amino acids, saponins, lignin, alkaloids and antraquinones
(Onuegbu, 2000). The Aloins extracted
from the leaves can be used to treat both
internal and external wounds and
burns like ulcer, cough, gastritis, diabetes, cancer, headaches, arthritis immune
system deficiencies and many other
conditions (Collins et al, 2003).
AIMS OF THE
RESEARCH
1. To determine, in vivo, the effects of ethanol extracts of
A. sativum and A. barbadensis on lipid
peroxidation.
2. To test the possibility of using these medicinal plants as
antidotes for hepatotoxicity.
3. To investigate the antioxidant activity of Allium
sativum and Aloe barbadensis.