Evaluation to the antioxidant activity of total flavonoids extract from Syzygium jambos seeds and optimization by response surface methodology

The purpose of this work was to assess the antioxidant activity of total flavonoids extract fromSyzygium jambos seeds (TFSJ). Response surface methodology was employed to optimize the main extraction conditions including extraction time, ethanol concentration and solid-liquid ratio. The effect of TFSJ on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2-azino-bis(3-ethyl-benzthiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging and hydroxyl radical (HO•) scavenging were studied. We found that under the conditions of extraction time 32.27 min, solvent concentration 52.01% and solid-liquid ratio to be 27.32:1, TFSJ possesses considerable amounts of flavonoids of 11.4330 mg/g rutin equivalent of extract. The effect of this extract in scavenging activity of ABTS and hydroxyl radical activity was better than that of rutin. However, the effect of TFSJ in free radical scavenging of DPPH was not as good as that of rutin. In conclusion, TFSJ possess potent antioxidant and free radical scavenging activities. These antioxidant activities could contribute, at least in part, to the traditionally claimed therapeutic benefits of S. jambos seeds.   Key words: Total flavonoids, antioxidant activity, response surface methodology.