1.1 Background of Study
The use of medicinal plants as major source of formulated drugs in the industrialized society can be traced back to the traditional use in folk medicine. Scientific utilization of medicinal plants is important as they can be toxic, also, can offer a wide range of therapeutic application. Annona muricata (soursop) belongs to the genus Annona of the custard apple tree family and has age-long traditional use as medicinal plant. Soursop is a tropical plant that is also cultivated in Saharan Africa. They are perennial crops with edible fruits and they are commercially underutilized. The plant has been reported to contain nutrients like vitamins B and C; phosphorus, iron and calcium. These nutrients are thought to be complimentary in the traditional use of the plant. For instance, the iron ameliorates effects of massive haemolysis. All parts of soursop are widely applied in alternative medicine. The bark, leaves and seeds possess diverse biological activities and they are traditionally used in the treatment of infectious and chronic non-communicable diseases such as diabetes, hypertension and inflammation. The leave has been demonstrated to be hepatoprotective, antiplasmodic and anti-diabetic. The fruit has been reported to possess antimicrobial, antitumor and antiviral effects. The juice of ripe fruit is applied as diuretic and the powdered immature fruits can be used as remedy for dysentery. Like other medicinal plants, Annona muricata contains phytochemicals that are responsible for their healing properties. The phytochemical screening of this plant revealed the presence of flavonoids (group of polyphenolic antioxidants), saponins, tannins, glycoside and alkaloids. The leaves and seed of Annona muricata contain 50 mono THF acetogenins which is a key intermediate in acetogenins synthesis. Family Annonaceae family, to which soursop belongs, also contain neurotoxic alkaloids named annonacin. This neurotoxin is suspected to cause atypical Parkinsonism and other neurological effects on large or frequent consumption. Reactive oxygen species are formed in minute quantities during physiological cell metabolism. However, at high concentration, excessive free radical production or decreased capacity of endogenous antioxidant leads to state named oxidative stress.