ANTIOXIDANT ACTIVITY OF METHANOL EXTRACT OF STAR FRUIT LEAVES (Averrhoa carambola L), A RAW MATERIAL FOR BALINESE TRADITIONAL FOOD (LAWAR)

Oxidative stress induced by free radicals has been well known to cause degenerative related diseases, such as cancer, coronary heart attack, and premature aging. These free radicals are form of reactive compounds and known to have unpaired electron on the outermost of their electron orbit, and therefore in such condition, they become very reactive to other compounds in human body and resulting in induction to various diseases to arise. To counter this bad side effect of free radicals, compounds function as antioxidants are needed by our body to neutralize such free radicals, so that damage caused by these free radicals can be reduced. Antioxidants in some levels can be produced naturally by our body, but often in insufficient quantity, and therefore there is a need to regularly consume antioxidant containing food. This background triggered the authors to extract antioxidant compounds from leaves of star fruit plants with a view to develop antioxidant containing products for future use to fight free radicals in human body, so that cases of degenerative-related diseases can be reduced. The antioxidant activity of methanol extract of star fruit leaves (Averrhoa carambola L) was conducted at the laboratory of physiology, Udayana University. These leaves have been used as one of raw materials in a Balinese traditional food (Lawar). The leaves were normally harvested from two types of star fruit plants (plants with sweet fruits and plants with sour fruits or belimbing besi). Leaves from the later type of the plant are preferable for raw material of lawar, because they are more elastic than that the other type. The method of DPPH was applied in the determination of the capacity of antioxidant activity. The results showed that the Activity Antioxidant Index (AAI)of leaves of sweet star fruit plant and sour star fruit plants were 0.17 and 0.63, respectively. This indicated that the leaf methanol extract of sweet star fruit plant had weak antioxidant activity (the value of AAI <0.5), while the leaf methanol extract of sour star fruit plant had moderate antioxidant activity (the value of AAI >0.5 – 1). The IC50 of leaf extract of sweet star fruit plant and sour star fruit plants were 158.3 and 69.2 respectively. This indicated that leaf methanol extract of sour star fruit plants had high active capacity to decrease DPPH radicals, while sweet star fruit plant had moderate capacity. It was also found that the flavonoid and vitamin C contents of sour star fruit leaf extract were higher than that of sweet star fruit leaf extract. Keywords: Star fruit leaves, Antioxidant Activity Index, DPPH