UV‐irradiation influence on free radical formation and radical scavenging ability of caffeic acid—EPR, UV‐Vis, and colorimetric examination

Abstract

Electron paramagnetic resonance (EPR) spectroscopy, UV-Vis spectrophotometry, and colorimetric analysis, were used to examine nonirradiated and UV-irradiated caffeic acid.In this work free radical formation during UV-irradiation of caffeic acid and the effect of UV-irradiation on its radical scavenging ability, were studied. The influence of time of UV-irradiation on these problems was evaluated. EPR spectra of free radicals in caffeic acid and 1,1-diphenyl-2-picrylo-hydrazyl (DPPH) were measured. DPPH was used as the model free radical reference to test antioxidative properties of caffeic acid. Amplitudes, linewidths, integral intensities, and g-factors were analyzed. Free radical concentrations were determined by comparing of the EPR spectra of caffeic acid and ultramarine-the paramagnetic reference. Free radicals were found (10 18 spin/g) in all the UV-irradiated samples independent on irradiation time. Free radical concentrations in caffeic acid increased with increasing of irradiation time. Analysis of spectral shape for different microwave powers pointed out that free radicals system in UV-irradiated caffeic acid was complex. Nonirradiated and UV-irradiated caffeic acid as antioxidants strongly interacted with free radicals and EPR signals of DPPH were highly quenched. UV-irradiation increased interactions of caffeic acid with free radicals, and this effect increased with increasing of irradiation time. Practical ApplicationThe performed studies indications that caffeic acid should not be storage exposed to UV. UV-irradiation formed free radicals in caffeic acid and changed its antioxidative properties as radical scavenging ability. Free radical concentrations in caffeic acid increased with increased UV irradiation time. UV-irradiation causes a change of color in caffeic acid. The change of color and formation of free radicals in caffeic acid during UV-irradiation can indicate the destruction of the chemical structure of tested samples.

RP-HPLC based analysis of different polyphenols in seven species of Carex L. (Cyperaceae Juss.) from West Bengal, India

“…Among the studied species, catechin was found to present in Carex stramentitia and C. alopecuroides, while absent in other species in our present investigation suggesting the bioactive potentiality of these native species of Carex. Similarly, caffeic acid, one of the potent polyphenolic acids also has many therapeutic potentialities such as antimetastatic, antitumor (Klein et al 2021;Sari et al 2022), anti-hyperglycemic (Oršolić et al 2021), antimutagenic effect and radical scavenging property (Bogacz et al 2021;Temviriyanukul et al 2021). Several lines of evidence showed that this phenolic acid has some physiological effects like antioxidative property (Genaro-Mattos et al 2015;Bajomo et al 2022), antiviral activity (Sinha et al 2022).…”

Free Radical Scavenging Activity of Infusions of Different Medicinal Plants for Use in Obstetrics

“…UVA radiation increases the risk of skin cancer [41]. In this work, it was assumed that the interactions of antioxidants with free radicals not only depend on their type [42][43][44][45], but also the physical factors in the environment, including UV radiation, which affect these interactions [46,47]. We searched for answers to the question of whether the tested plant raw materials can be stored with access to UVA radiation.…”