Abstract:

In this study, ultraviolet spectrophotometry and high performance liquid chromatography (HPLC) were used
to determine the contents of phenols and flavonoids in the segment membrane (SM) and juice sac (JS) of 10 popular
cultivars of pomelo (Citrus grandis) in Chongqing. In addition, the antioxidant capacities of these two parts were evaluated
by 1,1-diphenyl-2-picrylhydrazyl radical) (DPPH), ferric reducing antioxidant power (FRAP) and 2,2’-azinobis-(3-
ethylbenzthiazoline-6-sulphonate) (ABTS) methods. Results showed that total flavonoids and the individual contents of
10 measured flavonoid compounds were higher in the SM. The total flavonoid content of ‘Guanxi’ pomelo was the highest
(10.97 mg/g). Among the flavonoids, diosmin was the most abundant with an average of 1 000.72 μg/g. Among 10 cultivars,
‘Wubu’ had the highest diosmin content (2 366.77 μg/g). However, the contents of total phenolic compounds and phenolic
acid were higher in the JS. The highest total phenolic content of 8.84 mg/g was found in ‘Zhenlongyou No. 3’. Gallic acid
was the most predominant phenolic acid with an average of 1 040.16 μg/g and its highest level of 1 325.89 μg/g was noted
in ‘Changshou Shatian’. The JS was found to have stronger DPPH radical scavenging and FRAP capacity, but exhibit
weaker ABTS radical scavenging capacity than the SM. Overall, the segment membrane of ‘Guanxi’ and the juice sac of
‘Liangpingyou 78-8’ possessed the highest antioxidant activity. This study not only reveals the phenolic composition of the
SM and JS of the popular pomelo cultivars in Chongqing, but also offers a theoretical basis for utilizing the phenolics in
citrus and promoting the development of nutritional studies on citrus fruits.

Key words: pomelo, individual flavonoids, total phenolics, total flavonoids, antioxidant capacity