Screening of the antioxidant and nutritional properties, phenolic contents and proteins of five durian cultivars.

The antioxidant activities of different durian cultivars at the same stage of ripening (Mon Thong, Chani, Kan Yao, Pung Manee and Kradum) were compared in order to choose the best as a supplement in the human diet. Total polyphenols (mg gallic acid equivalent/100 g fresh weight (FW)) and flavonoids (mg catechin equivalent (CE)/100 g FW) in Mon Thong (361.4+/-23.2 and 93.9+/-7.4) were significantly higher (P<0.05) than in Kradum (271.5+/-11.2 and 69.2+/-5.3) and Kan Yao (283.2+/-16.5 and 72.1+/-6.8). The free polyphenols and flavonoids showed lower results than the hydrolyzed ones. Anthocyanins (microg cyanidin-3-glucoside equivalent/100 g FW) and flavanols (microg CE/100 g FW) were significantly higher in Mon Thong (427.3+/-23.8 and 171.4+/-16.3) than in Kradum (320.2+/-12.1 and 128.6+/-9.7) and Kan Yao (335.3+/-14.1 and 134.4+/-11.7). Ultraviolet spectroscopy and high-performance liquid chromatography/diode array detection analyses showed that caffeic acid and quercetin were the dominant bioactive substances in Mon Thong cultivar. The antioxidant activity (microM trolox equivalent/100 g FW) of Mon Thong cultivar (260.8+/-20.2, 1,075.6+/-81.4 and 2,352.7+/-124.2) determined by ferric-reducing/antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) with Trolox equivalent antioxidant capacity (TEAC) assays was significantly higher (P<0.05) than in Kradum (197.4+/-8.9, 806.5+/-31.2 and 1,773.2+/-102.5) and in Kan Yao (204.7+/-9.7, 845.5+/-48.6 and 1,843.6+/-107.5). The correlation coefficients between polyphenols, flavonoids, flavanols and FRAP, CUPRAC and TEAC capacities were between 0.89 and 0.98. In extracted and separated by electrophoresis durian proteins, some differences were found in the sodium dodecyl sulfate-protein bands in the region of 16 and 68 kDa for Kradum, 45 kDa for Mon Thong and three bands for Kan Yao. Antioxidants and proteins can be used for characterization of the quality of durian cultivars. In conclusion, the bioactivity of durian cultivars Mon Thong, Chani and Pung Manee was high and the total polyphenols were the main contributors to the overall antioxidant capacity. The results of our investigation in vitro are comparable with other fruits that widely used in human diets. Therefore, Durian can be used as a supplement for nutritional and healthy purposes, especially Durian Mon Thong, Chani and Pung Manee.