Phenolic compounds are frequently present in various natural products, and they can have different beneficial biological potentials. The most widely used method for determination of individual phenolic compounds is high-performance liquid chromatography (HPLC). In this paper, a method for simultaneous determination of 16 phenolic compounds (gallic acid,p-hydroxybenzoic acid, catechin, syringic acid,trans-cinnamic acid, hesperetin, naringenin, vanillic acid, benzoic acid, coumaric acid, resveratrol, chlorogenic acid, caffeic acid, rutin, quercetin, and kaempferol) on a core–shell column was developed. The separation method conducted on a standard ODS (250 mm) column was transferred to Poroshell column and optimized using non-ultra-high-performance liquid chromatography (UHPLC) apparatus. Phenolic compounds were separated fast and efficiently during 30-min analysis, and validation parameters were determined. The developed method was successfully applied on the analysis of phenolic content after direct injection of red wines from three different grape varieties.

Red clover (Trifolium pratense L.) is an important legume that is also known as a rich source of isoflavones, which are compounds with mild estrogenic activity. Therefore, this plant is often used as a raw material in the production of dietary supplements recommended in menopause. Many factors can influence isoflavone content, but those genetically related are considered to be the most important. Therefore, the aim of this study was to evaluate the phytochemical profile of different plant parts of 30 red clover genotypes grouped according to ploidy and country of seed origin by analyzing the content of dominant isoflavones, total phenolic content (TPC) and antioxidant activity. It was found that there are significant differences in the examined traits among plant parts. Red clover leaves had the highest total isoflavone content, with biochanin A as the dominant compound, while flower extracts had the highest TPC and antioxidant activity. Diploid and tetraploid genotypes were significantly different concerning the content of daidzein, genistein, formononetin and TPC with higher quantities in tetraploid samples. On the other hand, seed origin was not a useful separating factor for the analyzed samples. The results of this research indicate that ploidy, as a previously poorly studied factor, could influence isoflavone content in red clover.

Grape pomace is a by-product abundant in phenolic compounds that can be used in the food, cosmetic, and pharmaceutical industries. For the efficient extraction of such compounds, an aqueous solution of non-ionic surfactant Brij S20 was applied as a green extraction medium, and the optimization was performed using surface response methodology. The effects of four independent factors (surfactant concentration, time, pH, and solvent-to-material ratio) were evaluated, and total phenolic content (TPC), DPPH radical inhibition, and selected polyphenol compound concentrations were analyzed as responses. Using response surface methodology (RSM), five regression equations were derived and good adequacy of the models was confirmed. The solvent-to-material (SM) ratio was the most influential factor. Surfactant concentration of 3% (m/V), extraction time of 120 min, pH value of 4.06, and SM ratio of 50 mL/g were determined as optimum conditions to maximize all responses. Under the optimal conditions, the mean validated values obtained for TPC, DPPH, gallic acid, catechin, and quercetin concentrations were 968.50 ± 37.06 mg GAE/L, 61.41 ± 7.13%, 5.10 ± 0.05 mg/L, 10.62 ± 0.79 mg/L, and 6.04 ± 0.10 mg/L, respectively. Furthermore, the established conditions were applied for the extraction of phenolic compounds from grape pomace of four grape varieties. The proposed extraction method proved effective, providing extracts rich in polyphenols suitable for further applications.

Honey is a natural product of complex composition, recognized for its numerous health benefits. It is believed that honey is especially valuable for prevention of diseases associated with oxidative stress. Antioxidative properties of honeys are mainly attributed to phenolic compounds. The aim of this paper was to determine total phenolic content (TPC) and antioxidant capacity (IC50) in 19 Serbian honeys originating from five different floral sources - three monofloral (acacia, lime, sunflower) and two polyfloral types (meadow and forest). Analyses were performed spectrophotometrically using Folin-Ciocalteu method for total phenolic content determination and DPPH• test for antioxidative capacity. Polyfloral honeys on average had up to two times higher total phenolic content as well as antioxidant capacity than monofloral. The highest phenolic content and antioxidative capacity were observed in forest (58.35 mg GAE/100 g) and meadow honeys (0.015 g/mL), respectively. Acacia honeys distinguished with the lowest values obtained in both tests (17.36 mg GAE/100 g; 0.067 g/mL). Additionally, significantly high negative correlation coefficient between TPC and IC50 values was noticed in monofloral honeys (p<0.05).

Antioxidant Effects of Soy Isoflavones, Probiotics and Their Combination on Carbon Tetrachloride-Induced Oxidative Stress in Rats

There is a growing interest in using plant-derived polysaccharides, like tragacanth gum (TG) and gum Arabic (GA), due to their wide availability, relatively low cost, biocompatibility, biodegradability, unique physicochemical properties, and various functional characteristics. Rheological properties are particularly important due to their ability to modify the rheological characteristics of aqueous systems [1, 2]. The aim of this study was to investigate the effect of GA addition on the rheological behavior of TG solutions. Aqueous TG solutions (0.01-1.5%) and mixtures containing fiixed concentrations of TG (0.5% and 1%) with increasing GA concentrations were prepared. Flow curves were determined using a rotational rheometer with coaxial cylinder geometry at 25 °C in the shear rate range of 0.001-100 s-1, and the obtained data were fiitted to the Ostwald-de Waele model. Pure TG solutions exhibited Newtonian behavior at very low concentrations (≤ 0.05%), whereas concentrations ≥ 0.1% showed pseudoplastic character, with increased consistency index (K) and decreased fllow index (n). The addition of GA to TG solutions signifiicantly modifiied their rheological properties. In solutions containing 0.5% and 1% TG, increasing GA concentration led to a decrease in the K index and an increase in the n index, indicating a shift toward more Newtonian behavior. The obtained results demonstrate that the pseudoplastic behavior of TG aqueous solutions is altered by GA addition in a concentration-dependent manner, suggesting intermolecular interactions between these two polysaccharides. Such fiindings provide new opportunities for controlling viscosity and texture in multicomponent pharmaceutical, food, and cosmetic formulations.