Assessment of antioxidant activity of carotenoid-enriched extracts from peach fruits using the new LOX/RNO method

Abstract

Peach (Prunus persica L.) fruits contain several health-promoting phytochemicals. Among these, carotenoids, in addition to being involved in determining flesh color, play a relevant role in cell protection against oxidative stress. Nevertheless, antioxidant activity (AA) of peach carotenoids so far has not been investigated in as much detail as phenols. In the present study, for the first time, AA of peach carotenoid extracts was evaluated using the innovative lipoxygenase/4-nitroso-N,N-dimethylaniline (LOX/RNO) method, able to simultaneously detect different antioxidant mechanisms and synergistic antioxidant interactions, as well as using the well-known ORAC and TEAC assays. In particular, extracts were obtained from fruits collected in S4 development stage from two yellow-fleshed (Armking and Redhaven) and three white-fleshed (Silverking, Caldesi 2000, IFF331) varieties. The LOX/RNO method gave high AA values (10-150 μmol eq. Trolox/g f.w.), about 85-1900-fold higher than ORAC and TEAC methods. Moreover, the ratio between AA values, measured by the LOX/RNO method, of yellow- and white-fleshed peaches resulted equal to 14, but only 2.6 and 3.6 for ORAC and TEAC, respectively. Results of this study indicate that the LOX/RNO method, measuring high AA values and easily discriminating among samples, is an advisable tool to assess the AA of the carotenoid component in peach.