Abstract
In this paper, a novel antioxidant analysis is proposed using a simple minimized device based on moving drops as solution handling and a smartphone as a detector. This approach is based on the colorimetric determination of the scavenging activity against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•), expressed as the half-maximal inhibitory concentration (IC50), vitamin C equivalent antioxidant capacity (VCEAC), and Trolox equivalent antioxidant capacity (TEAC). A small drop of the positive control or the samples moves by eluting an ethanol drop down by the force of gravity to react with a DPPH• drop in the detection zone. The color change of DPPH• is monitored by a smartphone camera, and the color signals are processed using Adobe Photoshop software. The magenta-to-yellow ratio was successfully applied to evaluate the percentage of DPPH• inhibition with no significant difference compared with the reference spectrophotometric method at a confidence level of 95%. The total phenolic content (TPC) was measured using the Folin–Ciocalteu assay. An application to Miang (fermented tea leaf extract) showed the consonant relationship between the scavenging activity of DPPH• and TPC.
Highlights
The oxidation of free radicals in humans engenders cell damage, affecting the initiation and augmentation of various diseases such as cancer, gout, and atherosclerosis; cardiovascular and respiratory diseases; and aging
Measuring total antioxidant capacity (TAC) is an important indicator expressed with various methods, especially the scavenging activity of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and total phenolic content (TPC) [5]
From our investigation of the kinetics of DPPH scavenging activity by L-ascorbic acid, Trolox, and gallic acid, we found the highest activities with 3 min of an optimum incubation time, as shown in Figures S1–S3
Summary
The oxidation of free radicals in humans engenders cell damage, affecting the initiation and augmentation of various diseases such as cancer, gout, and atherosclerosis; cardiovascular and respiratory diseases; and aging. Antioxidant compounds have been shown to have the ability to inhibit the emergence and scavenge of free radicals in a variety of ways [1]. They block oxidative enzymes, upregulate antioxidant enzymes, and directly respond to free radicals to minimize oxidative damage [2,3,4]. Green analytical chemistry is intended to encourage long-term sustainable development. This notion encompasses many techniques, including eliminating and reducing the number of chemical substances, avoiding toxic reagents, appropriately managing waste, and lowering energy consumption, all concerned with environmental friendliness, human health, and worker safety [6]. The approach leading to green analytical chemistry includes remote sensing using portable and cost-effective devices without extra power
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