Application of ABTS Radical Cation for Selective On-Line Detection of Radical Scavengers in HPLC Eluates

Abstract

The radical cation 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate), (ABTS*+) was utilized in an on-line HPLC method for the detection of radical scavengers in complex matrixes. The HPLC-separated analytes react postcolumn with the preformed ABTS*+, and the induced bleaching is detected as a negative peak by an absorbance detector at 734 nm. An optimized instrumental and experimental setup is presented. The method is suitable for both isocratic and gradient HPLC runs using mobile phases containing 100% organic solvent or its solution in water, weak acids, or buffers (pH 3-7.4). The method is sensitive, selective, relatively simple, applicable to compounds of different chemical natures; uses common instruments and inexpensive reagents; and has a time-saving, nonlaborious experimental protocol. It can also be used for quantitative analysis. The method was applied to several pure natural antioxidants and plant extracts. The minimum detectable concentration varied from 0.02 to 0.13 microg/mL, depending on the compound tested. The method can be applied to perform kinetic studies, which is illustrated by determination of Trolox equivalent antioxidant capacities (TEAC) of several known antioxidants in flow injection mode.

Clinoptilolite-rich mineral as a novel carrier for the active constituents present in Ginkgo biloba leaf extract

“…The antioxidant activities of standard antioxidants kaempferol, quercetin and propyl gallate (PG) were measured as 0.76 TEAC, 1.25 TEAC and 2.45 TEAC, respectively. These results were consistent with the TEAC values stated for kaempferol, quercetin and PG as 1.45 TEAC, 2.76 TEAC (Koleva et al, 2001) and 2.08 TEAC (Altıok, 2003), respectively. However, in complex mixtures, additive, synergistic, or inhibitory effects among the components have been observed.…”

“…To evaluate the contribution of each single sample component, knowledge of its molecular structure is required. Unfortunately, in the search of novel active compounds in complex matrixes, this is not always possible ( Koleva et al, 2001). Therefore, the total antioxidant activity of plant extracts is rather expressed in terms of μmol of Trolox per 100 g of dry weight ( Cai et al, 2004).…”

Recent developments in the rapid analysis of plants and tracking their bioactive constituents

“…A typical example developed in our group is online radical scavenging detection (Dapkevicius et al 1999;Koleva et al 2000;Koleva et al 2001;Dapkevicius et al 2001;Niederländer et al 2008). Phenolic antioxidants can terminate radical chain processes in lipid rich foods by reacting with reactive oxygen species (ROS) forming more stable resonance-stabilised radicals or quinone-like structures (Fig.…”

Chemical Constituents From Algerian Foeniculum Vulgare Aerial Parts and Evaluation of Antimicrobial Activity

“…These properties are due to many active phytochemicals including flavanoids, terpenoids, carotenoids, coumarins, curcumines, etc. These bioactive principles have also been confirmed using modern analytical techniques [1][2][3][4] . Hence, they are considered to be important in diets or medical therapies for biological tissue deterioration due to free radicals.…”