Abstract: Objective: Research on the compositions of phenolic acids and flavanone glycosides and antioxidant capacity in ponkan and satsuma mandarin peels. Methods: The contents of nine phenolic acids and two flavanone glycosides in ponkan and satsuma mandarin peels were determined by RP-HPLC method. Folin-Ciocalteu method, ABTS free radical-scavenging assay and FRAP assay were adopted to evaluate the antioxidant capacity of methanol extract of citrus peels. Results: The soluble esterified portion is the most common form of phenolic acid in citrus peels. Phenolic acids of citrus peels mainly occurr as hydroxycinnamic acid and the contents are in the following order: ferulic acid > p-coumaric acid > sinapic acid > caffeic acid. peels of satsuma mandarin show higher total phenolic acid content than ponkan (p<0.05). Peels of ponkan was abundant in hesperidin, while peels of satsuma mandarin have higher content of narirutin compared with ponkan. Peels of satsuma mandarin contain higher contents of total flavanone glycosides than ponkan (p<0.05). Generally speaking, ponkan extract shows higher antioxidant capacity than satsuma mandarin. Conclusion: Good results are obtained by using HPLC-PDA method to determine the contents of phenolic acids and flavanone glycosides, while citrus peels present certain antioxidant capacity evaluated by several antioxi- dant assays.

Key words: citrus peel, phenolic acid, flavanone glycoside, composition, HPLC, antioxidant capacity