Antioxidant activity comparison of eight kinds of tropical fruits in Hainan

【Objective】The antioxidant activity and the contents of total phenolics and flavonoids of eight kinds of tropical fruits in Hainan were determined, and the differences of antioxidant activity and antioxidant substances in eight kinds of fruits were compared, so as to provide certain nutritional reference value for people to eat tropical fruits, it also provided reference for the development and utilization of tropical fruit related products with strong antioxidant activity.【Method】Eight tropical fruits including Manilkara zapota, Syzygium samarangense, Garcinia mangostana, Durio zibethinus, Lucuma nervosa, Passiflora edulis, Annona squamosa and Artocarpus heterophyllus were studied in this experiment. The antioxidant activity of the samples was determined by 1, 1-dipheny1-2-picrylhydrazyl(DPPH) free radical method, ferric reducing antioxidant power(FRAP) and diammonium 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) cation free radical scavenging activity method. The total phenolics content was determined by the FolinCiocalteu method, and the total flavonoids content was determined by AlCl₃ chromotest method. The correlation analysis of three different determination methods and two antioxidant substances were carried out, and the results of antioxidant activity were analyzed by technique for order preference by similarity to ideal solution(TOPSIS) method.【Result】The most effective antioxidant activity measured by DPPH method and FRAP method was L. nervosa(178.62 and 140.83μmol Trolox/g), and that of M. zapota was the weakest. The highest antioxidant activity was found in G. mangostana(157.06 μmol Trolox/g) and that of M. zapota was the weakest by ABTS method. At the same time, the content of total phenolics(3.80%) and total flavonoids(7.60%) in L. nervosa was the highest among the eight kinds of fruits, the content of total phenolics in M. zapota was the lowest(0.09%), and the content of total flavonoids in D. zibethinus was the lowest(1.07%). Correlation analysis of three different determination methods and two antioxidant substances was found, the correlation coefficient between DPPH method and total phenolics and total flavonoids contents reached more than 0.81, the correlation between FRAP method and total phenolics and total flavonoids contents was more than 0.90. The results were analyzed by the TOPSIS method, and the antioxidant activity was ranked as:L. nervosa>G. mangostana>S. samarangense>P. edulis>A. squamosa>A. heterophyllus. >D. zibethinus>M. zapota. 【Conclusion】All the eight kinds of tropical fruits have antioxidant activity, the antioxidant activity of L. nervosa is strong, and that of M. zapota is weak.