Antioxidant Capacity Determination in Plants and Plant-Derived Products: A Review

Abstract

The present paper aims at reviewing and commenting on the analytical methods applied to antioxidant and antioxidant capacity assessment in plant-derived products. Aspects related to oxidative stress, reactive oxidative species' influence on key biomolecules, and antioxidant benefits and modalities of action are discussed. Also, the oxidant-antioxidant balance is critically discussed. The conventional and nonconventional extraction procedures applied prior to analysis are also presented, as the extraction step is of pivotal importance for isolation and concentration of the compound(s) of interest before analysis. Then, the chromatographic, spectrometric, and electrochemical methods for antioxidant and antioxidant capacity determination in plant-derived products are detailed with respect to their principles, characteristics, and specific applications. Peculiarities related to the matrix characteristics and other factors influencing the method's performances are discussed. Health benefits of plants and derived products are described, as indicated in the original source. Finally, critical and conclusive aspects are given when it comes to the choice of a particular extraction procedure and detection method, which should consider the nature of the sample, prevalent antioxidant/antioxidant class, and the mechanism underlying each technique. Advantages and disadvantages are discussed for each method.

Figure 1

HPLC chromatogram (at 330 nm) of the methanolic extract of Bambusa, with illustration of the antioxidant fractions F1, F2, F9, and F11 [87].

Figure 2

DPPH radical scavenging activity of Sonchus asper extracts in different solvents at various concentrations. Each value stands for the mean ± SD (n = 3) of hexan, ethyl acetate, chloroform, and methanol crude extracts of the whole plant and ascorbic acid [88].

Figure 3

Differential pulse voltammograms at a Pt working electrode for different ascorbic acid concentrations (mM): 20 (1), 15 (2), 10 (3), 5 (4), 2.5 (5), 1.25 (6), 0.625 (7), and 0.31 (8); pulse amplitude, 75 mV, pulse period, 125 ms, and potential scan rate, 50 mV/s [89].