Kinetics and Mechanism of Epinephrine Autoxidation in the Presence of Plant Superoxide Inhibitors: A New Look at the Methodology of Using a Model System in Biological and Chemical Research

Superoxide is the primary active oxygen form produced in living organisms. Because of superoxide anion radical formation during epinephrine oxidation in alkaline medium, this system is offered in some works for antioxidant activity analysis, however, without enough physicochemical justification. Therefore, the task of developing reliable methods for analyzing the superoxide inhibition activity of various objects is very urgent. In this work, a kinetic model of epinephrine autoxidation in an alkaline medium in the presence of antioxidants of plant origin is proposed. The participation of chain reactions with long oxidation chains in this process is revealed. The limiting stage of the process is a one-electron reduction of oxygen by the anionic forms of the phenolic hydroxyls of epinephrine. The appearance of the absorption maximum at a wavelength of 347 nm during epinephrine autoxidation is associated with adrenolutin formation, which is confirmed by HPLC/UV/MS. No adduct formation between phenolic antioxidants and epinephrine oxidation products was found. The complex U-shaped character of epinephrine autoxidation rate dependence on the content of antioxidants in the reaction system was shown. The study of the kinetics of epinephrine autoxidation in the presence of an individual phenolic plant superoxide inhibitor, chlorogenic acid, was carried out for the first time. The inhibitory effect of yarrow, chamomile, and bur beggar-ticks plant extracts in the adrenaline system was examined.

Polyherbal combination for wound healing: Matricaria chamomilla L. and Punica granatum L

BACKGROUND

Punica granatum L. (pomegranate) with astringent activities and Matricaria chamomilla L. (chamomile) with anti-inflammatory and antioxidant properties are natural remedies used for various skin disorders, including wound healing.

OBJECTIVES

This study was conducted to evaluate the individual and combined wound healing activity of the methanol extracts of pomegranate and chamomile flowers.

METHODS

After preparing the menthol fraction of pomegranate and chamomile flowers, the content of total phenols, total tannins, and total flavonoids of fractions was measured. For standardization of pomegranate and chamomile fractions, Gallic acid and apigenin-7-O-glucoside contents of them were determined using high-performance liquid chromatography (HPLC). Moreover, their antioxidant activities were examined using DPPH and FRAP tests. The antimicrobial assay was performed against Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Three different concentrations of methanol fraction of each plant and one combination dose of fractions were investigated for their wound healing activities in an excision wound model on the rats' dorsum. Finally, histopathological studies were done at the end of the experiment.

RESULTS

Phytochemical examinations showed high amounts of phenolic compounds in pomegranate flowers, while chamomile flower fractions contained a high amount of total flavonoids. Both fractions, especially pomegranate, had potent antioxidant activity. The best results for wound closure were observed 7 days after wound induction. All treated groups exhibited superior wound contraction compared to their placebo at all measurement times. The combined form of pomegranate and chamomile had better wound healing properties compared to a single therapy, especially on time earlier to wound induction.

CONCLUSION

This study represented high antioxidant and wound healing activities for methanol fraction of pomegranate and chamomile flowers, which could be related to their high content of phytochemicals. In comparison with single herb treatment, the combined form of these two fractions in lower concentrations accelerated wound closure.

Degradation and regulation of edible flower pigments under thermal processing: a review

More and more consumers are aware of the potential health benefits of edible flower pigments. With the increased popularity and broader application of edible flower pigments, their degradation under thermal processing has attracted researchers' attention, because this may affect the pigment functionalities. At high temperature of thermal processing, polyene pigments are easy to oxidize, degrade and isomerize due to high unsaturation, and phenolic pigments may hydrolyze and isomerize of glycosides, which will result in the decreased antioxidant activity and eating quality, and discounted potential health benefits. Therefore, it is very important to understand the degradation mechanisms of edible flower pigments under thermal processing, which is important to develop corresponding control methods to minimize such negative impacts. This review paper discussed the recent development in the degradation mechanisms and regulation methods of edible flower pigments under thermal processing.