Comparison of the Antioxidant Activities and the Chemical Compositions of the Antioxidants of Different Polarity Crude Extracts from the Fruits of Chaenomeles speciosa (Sweet) Nakai

The aim of this study was to compare the antioxidant activity of crude extracts of differing polarities of the fruits of Chaenomeles speciosa (Sweet) Nakai. The antioxidant compositions of the extracts were analyzed qualitatively and quantitatively, respectively. The 75% ethanol extract of the dried fruits was fractionated by sequential extraction using petroleum ether, ethyl acetate, and n-butyl alcohol. The antioxidant effectiveness of the components of differing polarities was examined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging method and compared with two reference substances: ascorbic acid and butylated hydroxytoluene (BHT). The total phenolic content of the extracts was analyzed using the Folin—Ciocalteu method and expressed as gallic acid equivalents. The active compounds were analyzed by thin-layer chromatography (TLC)—bioautography and ultra-performance liquid chromatography (UPLC). The order of antioxidant capacities of various solvent extracts from the fruit of C. speciosa was found to be ethyl acetate ≥ n-butyl alcohol > petroleum ether. The ethyl acetate extract was more active than the reference substances ascorbic acid and BHT. The radical-scavenging capacity of the extracts decreased as the total phenolic content decreased. TLC—bioautography revealed that the ethyl acetate extract contained many antioxidant spots that can remove DPPH radical, and protocatechuic acid and chlorogenic acid were the major antioxidant components. UPLC analysis confirmed that protocatechuic acid and chlorogenic acid were mainly distributed in the ethyl acetate fraction. The study demonstrated that the ethyl acetate extract had excellent antioxidant capacity. The total phenolic, protocatechuic acid, and chlorogenic acid contents of this extract were higher than those of the other two solvent extracts. These results showed that the ethyl acetate extract from the fruit of C. speciosa could be considered as a potential source of natural antioxidant agent.