Computational Models for the Determination of Antioxidant Capacity and Phenolics in Dietary Supplements Using Real-Time Proton Transfer Kinetics Data

Abstract

Hydrogen atom transfer (HAT) underlies free-radical chain-breaking by phenolic compounds. Using linear free energy relationship (LFER) analysis, proton transfer kinetics was hypothesized as a surrogate rate process for HAT. Phenol red is a probe that is easily oxidized to highly absorbing specie by hydroxyl ion. Absorbance decay of oxidized phenol red was induced by incremental proton transfer from a model phenolic (resorcinol). Global best-fit kinetics profile of resorcinol approximates a mono-exponential decay model (R 2 = 0.991) as a limiting law. Proton transfer rate constant (K ptt ) versus concentration reveal the utility of the slope (α aoc ) of the linear plot (r 2 = 0.990) as a sensitive predictor of phenolic antioxidant capacity. Superior antioxidant capacity profile of a polyphenol-rich dietary supplement: Garcinia kola seed extract, optimally obeyed a mixed linear/mono-exponential decay equation. Model robustness and selectivity for phenolics was achieved by specifying mathematical constraints as acceptance criteria. The method is more biologically relevant for chain-breaking antioxidants than free-radical-based assays because it captures antioxidant structure-function relationships. Further validation studies, using structurally diverse polyphenols, are warranted to ascertain general utility of the kinetic assay for achieving quality by design (QbD) in phenolic dietary supplement products.

Computational antioxidant capacity simulation assay of Garcinia kola (Heckel) seed extracts

“…The values are generally below 1000/g, although the 650/g obtained for ASE is a significant increase from 300/g obtained for the same extract, when 1000 µL increment was used for the assay in a previous study (Idowu et al, 2009). The sensitivity of the assay was diminished by the fact that the best-fit reaction constant (k ptt ) of 0.80 and 1.00% standard solutions was similar for the three extracts (Tables 1 to 3a).…”

“…Qualityassured ANI is critical to successful commercial manufacturing of dietary supplements. Computational antioxidant capacity simulation (CAOCS) assay is a bespoke assay developed for antioxidant capacity profiling of polyphenols and phenol-like compounds (Idowu et al, 2009;Idowu, 2014). The systematic workflow and associated informatics required to implement the two photometric assays that constitute CAOCS assay is displayed in Figure 2.…”

Camellia sinensis Ameliorates the Efficacy of Last Line Antibiotics Against Carbapenem Resistant Escherichia coli

“…The bioactivity fingerprinting-based standardization of PTRC-31911-A using superoxide ion, site-specific hydroxyl radical and non site-specific hydroxyl radical scavenging exhibited bioactivity ratios as 1.44 ± 0.5, 0.058 ± 0.05 and 0.348 ± 0.05, respectively. These bioactivity ratio values served as standardized indicators for reducing batch-to-batch variations, as reported with other bioactivity parameters like DPPH-free radical scavenging, nitric oxide radical scavenging and lipid peroxidation (Idowu et al, 2009).…”

Computational Antioxidant Capacity Simulation (CAOCS) Assay of Catechol, Resorcinol and Hydroquinone

“…The lack of biorelevance of results and standard quantification procedures means there is yet a gap in the quality assurance of manufactured dietary supplements. In an attempt to bridge this "biorelevance gap", a new assay was recently developed by Idowu & co-workers [4,5]. Computational antioxidant capacity simulation (CAOCS) assay combines experimental data (obtained from proton transfer (PT) kinetics as a surrogate for hydrogen atom (HAT) transfer kinetics), and model fitting to create a systematic workflow that profiles the antioxidant capacity of polyphenol and phenol-like dietary supplements.…”