Aqueous propylene glycol extracts from medicinal plants are commonly used as active ingredients in production of medicine and beauty products for external application. In the scientific literature, however, there are almost no data on the extraction effectiveness of water–propylene glycol mixtures and the chemical composition of aqueous propylene glycol extracts from plant raw material, while in product specifications manufacturers indicate parameters of the product that are absolutely unrelated to its biological activity. By the example of German chamomile (Matricaria chamomilla L. flowers), using high-performance tandem mass spectrometry (HPLC–MS/MS), we show that its aqueous propylene glycol and aqueous ethanol extracts have similar composition in terms of phenolic compounds, with apigenin and its glucosides (apigenin-7-glucoside, apigenin-7-O-6-O-malonyl-D-glycoside, apigenin-7-acetylglycoside, and acetyl-malonyl-apigenin-7-O-glycoside) being the major constituents of the aqueous propylene glycol extracts. The other detected compounds are 5,4'-dioxy-3,6,7,3'-tetramethoxyflavone, cis and trans forms of 2-O-glucopyranoside of 2-hydroxy-4-methoxycinnamic acid, and 7-methoxycumarin. Analytical spectral characteristics of aqueous propylene glycol extracts from a series of medicinal plants that are in high demand in the beauty industry are studied in the UV-visible range. Extracts that display the best protective behavior in the UVA and UVB ranges (Salvia officinalis L. leaves, Matricaria chamomilla L. flowers, and Achillea millefolium L. herb) and antiradical ability (Camellia sinensis L. leaves and Hypericum perforatum L. herb) are identified along with extracts that have the highest flavonoid content (Camellia sinensis L. leaves and Hypericum perforatum L. herb). In extraction from plant raw material of the same batch, the absorbance at 270 nm is related to extraction parameters of flavonoids, antioxidants, and the dry substance by a functional relationship which is very advantageous in rapid analysis for quality control during production processes in order to obtain a product with reproducible characteristics. The formulas for calculation of antioxidant content (as rutin or gallic acid equivalents) from DPPH (2,2-diphenyl-1-picrylhydrazyl) assays are derived, and the data for extracts from different plant raw materials are interpreted in comparison with results of other analytical methods. The spectral profiles for German chamomile flower extracts are highly reproducible, regardless of the source of plant raw material, which, in combination with specific features of the spectra profiles for extracts from raw material of different plant species, can be used as a criterion in identification testing. The UV spectrophotometry method proposed here is used to investigate the dynamics of extraction from German chamomile flowers under different extraction conditions (temperature and the ratio between propylene glycol and water in the extraction agent). Optimal extraction from plant material is achieved using aqueous 50% propylene glycol at a temperature of 50°C and for an extraction duration of 4 h.

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.

Water-soluble forms of fullerene C₆₀ possess unique physicochemical and biological properties, making them promising candidates for the development of various drugs in the fields of medicine and veterinary science. Of particular interest are studies on the synthesis and characterization of C₆₀ fullerene derivatives with biogenic additives such as amino acids and peptides. This review focuses on different approaches to the synthesis of amino acid derivatives of fullerene C₆₀ and their promising biomedical applications.

The kinetic characteristics, mechanisms of activity, and relationship between the antioxidant activity and the molecular and supramolecular structure of fullerene C ₆₀ and some of its N -monosubstituted amino acid derivatives have been studied. The introduction of an amino acid substituent in the C ₆₀ fullerene molecule led to an increase in its antiradical activity in the free radical oxidation of a water-soluble target (fluorescein). The mechanism of the antioxidant activity of amino acid derivatives of fullerene is not associated with the hydrogen atom transfer, electron donation, or catalysis of peroxide decomposition. It was demonstrated that the structure of the amino acid substituent does not affect the antiradical properties, which are thus determined only by the effective total surface area of the nanoparticles of the fullerene C ₆₀ derivatives and increase when their size decreases. This surface can be characterized as nanowalls on which the radical death occurs. A change in the concentration of the compounds in solution does not lead to a change in the relative antiradical activity and hence in the nanoparticle size. The results of this study are important for understanding the biological activity of this group of compounds.

The run of kinetic curves and the changes in the rate of the reaction of the stable radical 2,2-diphenyl-1-picrylhydrazyl with antioxidants present in extracts from some food and medicinal plants and with some individual natural phenolic antioxidants in ethanol have been investigated spectrophotometrically at different hydrogen chloride concentrations. The contributions from different mechanisms to the kinetics of these processes have been evaluated. The choice of optimal hydrogen chloride concentrations facilitating a comparison of the kinetic parameters obtained for various objects (3–10 mmol/L) has been substantiated. Comparative antiradical activity has been measured for complex samples obtained from food and medicinal plants.