INHIBITORY EFFECTS OF EXTRACT OF BLACK PEAR, SOUR SOP, MONKEY SEED DURING LIPID OXIDATION
CHAPTER ONE
INTRODUCTION
Reactive oxygen species (ROS) and reactive nitrogen species (RON) are free radicals, which derived either from normal metabolic processes or from external sources (Magalhaes, 2006). These species are essential to energy supply, detoxification, chemical signalling and immune function (Dimitrios, 2006). However, overproduction of these free radical may lead to damage to valuable biomolecules such as DNA, lipids and proteins.
These free radicals are often associated with the oxidation in food and biological systems which will cause oxidative rancidity in foods and the development of several human diseases such as neurological degeneration, diabetes and certain types of cancer (Magalhaes, 2006).
An antioxidant is any substance which is capable of delaying, preventing the oxidative damage of lipids, protein and nucleic acids by reactive oxygen species, which include reactive free radicals such as superoxide, hydroxyl, peroxyl, alkoxyl and non-radicals such as hydrogen peroxide and hypochlorous (Lim et al., 2007).
Thus, antioxidants have gained numerous attention in the past few years, especially within the food, biological and agrochemical fields. There is increasing evidence that the consumptionof vegetables and fruits is associated with a reduced risk of degenerative disease such as cancer, cardiovascular disease and cataracts (Chinnici et al., 2004). This association is often attributed to the natural antioxidant present in fruits and vegetables, such as vitamin C and E, carotenoids, phenolic acids and flavonoids, which prevent free radical damage (Silva et al., 2004).
Epidemiological studies have established a positive correlation between the intake of fruits and vegetables and prevention of diseases like atherosclerosis, cancer, diabetes, arthritis and also ageing (Kaur and Kapoor, 2001).
Annonamuricata L. (A. muricata) is one of the tropical fruits that demonstrate antioxidant properties. This plant contains annonaceousacetogenins in the twigs, unripe fruit, seeds, roots, and bark tissues, which display antitumor, pesticidal, antimalarial, anthelmintic, piscicidal, antiviral, and antimicrobial effects, thus suggesting many potentially useful applications. Ripe A. muricata pulp extract contains three prominent acetogenins: asimicin, bullatacin, and bullatalicin.
Previous research on A. muricata was focused on the leaves, seeds and roots for pharmaceutical purposes (Gleeve et al., 1997; Jaramillo et al., 2000; Onimawo, 2002). Little attention has been paid to the study of thepulp and peel of A. muricata fruit. This study was therefore conducted to compare the antioxidant properties, phyto-constituents, proximate and mineral compositions of the peel and pulp of A. muricata.
