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Evaluation of Antioxidants in Herbal Tea with a Laccase Biosensor

This paper is available in a repository.
This paper is available in a repository.

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Abstract

In this study, a glassy carbon electrode (GCE) modified with laccase was used as the working electrode for analysis of phenolic compounds. The electrochemical behaviour of rutin and ascorbic acid were used to assess the antioxidant capacities (trolox reagents) for the estimation of total phenolic (TP) content in two herbal tea samples common in South Africa. The result showed a positive linear correlation between the trolox equivalent antioxidant capacities (TEAC) and TP content (R 2 = 0.9812 ± 0.012), which indicated that phenolic compounds could be one of the main components responsible for the antioxidant activities in the tea samples investigated. The experimental results obtained using a Differential Pulse Voltammetry (DPV) suggested that indeed laccase is a suitable biosensor showing good reducing properties. The scavenging ability of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), a diammonium salt assessed using UV-Visible spectrophotometry in the sample extract yielded half maximal effective concentration (EC 50) values of 10.80 μg/ml and 11.62 μg/ml for ascorbic acid and rutin respectively.