Phenolic Antioxidant Activity Research Articles

Accurate & simple open-sourced no-code machine learning and CDFT predictive models for the antioxidant activity of phenols

Phenolic compounds (PC) are important antioxidant biomolecules for medicine and foods industries. The DDPH test is used for testing antioxidant capacity. A fully No-Code methodology is presented for building QSPR models for the anti-DPPH activity of 202 PC. Machine learning (ML) algorithms were used for dimensionality reduction (PCA, InfoGain, GainRatio, CfsSubset) and predictive model training (J48, RandomTree, JCHAID*). Conceptual Density Functional Theory (CDFT) descriptors are calculated at the GFN1-xTB and GFN2-xTB levels of theory and the resulting global reactivity descriptors are used to train the ML models. The obtained Decision Tree (DT) models all present over 85% accuracy and Substantial Agreement with Reality, both for the internal and external validation. All the developed models adhere to the OECD guidelines for regulatory QSPR developments and are discussed in a mechanistic context. This research presents a novel, simple and codeless methodology for developing highly precise predictive models for the anti-DPPH activity of PC, successfully bridging the gap between experimental chemistry, theoretical physical chemistry, and ML.

Assessment and mechanism of antioxidant activity of phenols as asphalt antioxidants

ABSTRACT The interest in the antioxidant properties of phenolic compounds in asphalt has grown significantly. This study primarily focuses on the comprehensive assessment and elucidation of the antioxidant activity mechanisms of various phenolic compounds as asphalt antioxidants. The suitability of different antioxidant indices for evaluating the effectiveness of phenolic anti-aging agents in base and SBS modified asphalt is assessed by experimental outcomes. Through this analysis, the anti-aging mechanism of phenolic antioxidants in asphalt is unveiled. Phenolic antioxidants were observed to diminish the G* value of aged asphalt, elevate the δ values of aged asphalt binder, augment the non-recoverable creep compliance of aged asphalt binder, decrease the percent recovery of aged asphalt binder, enhance the fatigue performance of aged asphalt binder, and lower the Ic = o and Ic = c of aged asphalt binder. This indicates that phenolic antioxidants improve the aging and fatigue resistance of asphalt binders, with antioxidant activities in the following order: p-Coumaric acid < resveratrol < tea polyphenol. Moreover, incorporating phenolic antioxidants into SBS modified asphalt not only restrains asphalt oxidation but also mitigates SBS degradation.

Inhibition of the interactions of myofibrillar proteins with gallic acid by β-cyclodextrin-metal-organic frameworks improves gel quality under oxidative stress

Generally, high levels of natural phenolic antioxidants, which are needed in meat products to exert equivalent antioxidant effects as synthetic antioxidants, can interact with myofibrillar proteins and cause aggregation of the proteins, giving rise to undesirable deterioration of gel quality. In this study, β-cyclodextrin-metal-organic frameworks (K-β-CD-MOFs) were synthesized based on β-CD and K+ ions using methanol vapor diffusion method, and used to inhibit excessive covalent and non-covalent interactions between gallic acid (GA) and myofibrillar proteins under oxidative stress without degrading the phenolic antioxidant activity. Results of zeta potential, scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC) provided evidence for the formation of GA/K-β-CD-MOFs inclusion complexes. From sulfydryl content, surface hydrophobicity, tryptophan fluorescence, turbidity and particle size analyses, the presence of K-β-CD-MOFs dose-dependently prevented the sulfydryl loss, unfolding of the proteins and formation of insoluble aggregates caused by GA (180 μM/g protein). Dynamic rheology, cooking loss, gel strength, water distribution, microstructure and Raman spectrum were further tested to evaluate effects of K-β-CD-MOFs on the qualities of GA-treated myofibrillar protein gel. Results indicated that more proteins were involved in the formation of a more ordered and homogeneous gel structure with higher gel elasticity and strength, more immobilized water and decreased cooking loss. The overall gel properties of myofibrillar proteins were improved. K-β-CD-MOFs ameliorated the instability of protein structure, manifested as increase in β-sheet content and inter-chain hydrogen bonding and decrease in hydrophobic forces (p < 0.05). This paper provides a novel method to increase the loading amount of phenolic antioxidants without jeopardizing the gel quality of meat products.

Review on the Antioxidant Activity of Phenolics in o/w Emulsions along with the Impact of a Few Important Factors on Their Interfacial Behaviour

This review paper focuses on the antioxidant properties of phenolic compounds in oil in water (o/w) emulsion systems. The authors first provide an overview of the most recent studies on the activity of common, naturally occurring phenolic compounds against the oxidative deterioration of o/w emulsions. A screening of the latest literature was subsequently performed with the aim to elucidate how specific parameters (polarity, pH, emulsifiers, and synergistic action) affect the phenolic interfacial distribution, which in turn determines their antioxidant potential in food emulsion systems. An understanding of the interfacial activity of phenolic antioxidants could be of interest to food scientists working on the development of novel food products enriched with functional ingredients. It would also provide further insight to health scientists exploring the potentially beneficial properties of phenolic antioxidants against the oxidative damage of amphiphilic biological membranes (which link to serious pathologic conditions).

Kinetic Analysis of High-Temperature Sunflower Oil Peroxidation Inhibited by the Major Families of Phenolic Antioxidants Unveils the Extraordinary Activity of 1,4-Hydroquinones.

Peroxidation of vegetable oils represents a major problem for the food and biodiesel industries, and it is greatly accelerated by oil degree of unsaturation and by temperature increase. Phenols represent the most common additives used to counteract oil peroxidation, however clear structure-activity relationships at high temperatures are not available. We report, herein, a kinetic study of O2 consumption during spontaneous peroxidation of sunflower oil at 130 °C in the presence of 18 antioxidants belonging to the main families of natural and synthetic phenols, including α-tocopherol, alkylphenols (BHT, BHA), hydroquinones (TBHD), catechols (quercetin, catechin) and gallates. Results show that TBHQ provide the best protection in terms of induction period (IP) duration and O2 consumption rate. EPR spectroscopy demonstrated that the inhibition activity is negatively correlated to the stability of the phenoxyl radical of the antioxidant (A•), suggesting that chain propagation with linoleate (RH) moieties A• + RH → AH + R• decreases the efficacy of those antioxidants forming persistent A• radicals. These results provide important information to optimize the antioxidant activity of phenols and of novel phenol-based materials.

Profile and activity of phenolic antioxidants in chrysanthemum (Huangshan Gongju) as affected by simulated digestions.

The phenolics are the main bioactive substances of Huangshan Gongju, a famous chrysanthemum of China, but their digestive characteristics are still unknown. To explore the digestive properties of Huangshan Gongju phenolics, the flower was extracted and subjected to simulated digestions, and their phenolic profile and activity were analyzed. The results indicated that the total phenolics content and antioxidant activity of the extract varied with the simulated digestion steps, and they generally decreased in the oral and small intestine digestions but increased in the gastric digestion, and high correlations were detected between the total phenolics content and antioxidant activity (0.873 < r < 0.979, p < .01). The change of phenolic profile during the simulated digestions was similar to that of total phenolics content, and six individual phenolics were identified and quantified, and three of them, including chlorogenic acid, apigenin-7-O-rutinoside, and apigenin-7-O-6″-acetylglucoside showed higher recovery (>64.29%), implying they may be the main functional phenolics of Huangshan Gongju. PRACTICAL APPLICATIONS: This study proved that most phenolics in Huangshan Gongju were relatively stable during digestion. The finding may guarantee the application of Huangshan Gongju in the field of functional foods.

The Use of Machine Learning for Comparative Analysis of Amperometric and Chemiluminescent Methods for Determining Antioxidant Activity and Determining the Phenolic Profile of Wines

This paper presents an analysis of modern methods used to determine antioxidant activity. According to research by the World Health Organization, the deficiency of such important nutrients as antioxidants leads to a decrease in body resistance and the development of chronic diseases. When it comes to diet, the inclusion of foods with a high content of antioxidants helps to increase life expectancy. As a result of this research, the mass concentration of phenolic substances and the antioxidant activity of phenolic antioxidants in young white and red table wine materials were determined using amperometric and chemiluminescent methods in order to determine antioxidant activity. Regression equations reflecting the relationship between the indicator of antioxidant activity and the value of the mass concentration of phenolic substances in young table wine materials were derived. The conversion coefficient for determining the mass concentration of phenolic substances when using Trolox-C and gallic acid as standards was established, which was—3.75. Based on a multiple linear regression model, the total antioxidant activity of the samples (F9.5 = 19.10 and p = 0.0023) can be fairly accurately predicted with an R2 of 0.921 for the calibration data set. A neural network regression model (NNRM) was chosen for the machine-learning regression analysis of the antioxidant activity of the wine samples due to its effectiveness in predicting outcomes in various applications. The implementation was performed using the fitrnet function provided in the Statistics and Machine Learning Toolbox in MATLAB R2021b. The MSE of the calibration model was 0.056; however, the MSE for the three validation samples was much higher, at 0.272.

Study on the Stability and Antioxidant Activity of Phenolics in Green Tea, Citrus Peel and Soybean before and after in Vitro Digestion

Study on the Stability and Antioxidant Activity of Phenolics in Green Tea, Citrus Peel and Soybean before and after in Vitro Digestion

LC/MS Profiling and Gold Nanoparticle Formulation of Major Metabolites from Origanum majorana as Antibacterial and Antioxidant Potentialities.

Origanum majoranum L. is a Lamiaceae medicinal plant with culinary and ethnomedical applications. Its biological and phytochemical profiles have been extensively researched. Accordingly, this study aimed to investigate the chemical composition and the antibacterial and antioxidant properties of O. majoranum high features, as well as to search for techniques for activity optimization. A metabolomics study of the crude extract of O. majoranum using liquid chromatography-high-resolution electrospray ionization mass spectrometry (LC ± HR ± ESI ± MS) was conducted. Five fractions (petroleum ether, dichloromethane, ethyl acetate, n-butanol, and aqueous) were derived from the total extract of the aerial parts. Different chromatographic methods and NMR analysis were utilized to purify and identify the isolated phenolics (high features). Moreover, the antimicrobial, antibiofilm, and antioxidant activity of phenolics were performed. Results showed that metabolomic profiling of the crude extract of O. majoranum aerial parts revealed the presence of a variety of phytochemicals, predominantly phenolics, resulting in the isolation and identification of seven high-feature compounds comprising two phenolic acids, rosmarinic and caffeic acids, one phenolic diterpene, 7-methoxyepirosmanol, in addition to four flavonoids, quercetin, hesperitin, hesperidin, and luteolin. On the other hand, 7-methoxyepirosmanol (OM1) displayed the most antimicrobial and antioxidant potential. Such a phenolic principal activity improvement seems to be established after loading on gold nanoparticles.

The effect of different drying methods on total bioactive properties, individual phenolic compounds, rehydration ability, color, and microstructural characteristics of Asian pear

This study aimed to investigate the effects of FD (freeze drying), USVD (ultrasound-assisted vacuum drying), HAD (hot air drying). and IRD (infrared drying) methods on drying behavior, total phenolic antioxidant activity, individual phenolic distribution, rehydration capacity, Scanning Electron Microscopy image, and color quality of Asian pear. HAD showed the longest drying period with 420 min and followed by USVD with 345 and IRD with 240 min. The method difference had a significant effect on the total phenolic and antioxidant activity values of the samples (p < 0.05). The TPC, DPPH, and CUPRAC value were found as 111.59–316.40 mg/100 g GAE, 336.94–559.41 mg/100 g TE, and 161.00–859.73 mg/100 g TE, respectively. Samples dried with FD showed the highest TPC and AA values, followed by USVD, IRD, and HAD. The effect of drying techniques on the distribution of phenolic compounds was found to be significant (p < 0.05). HAD and the IRD process caused a decrease in the amount of all identified phenolic compounds. While USVD caused an increase in the amount of Chlorogenic acid, FD did not cause a significant change. Higher HMF results were found in samples dried via IRD followed by HAD. While the porous structure was preserved in the samples dried with FD and USVD, the porosity structure of the samples dried with HAD and IRD completely disappeared. FD and HAD showed the highest and lowest rehydration capacity, respectively. FD and USVD showed lower color change than IRD and HAD. The results of this study showed that USVD and FD can be used as an alternative method to HAD in drying Asian pear. Practical Application Pear fruit is one of the most consumed fruits worldwide. Pear fruit is very sensitive to microbial and enzymatic degradation due to its high sugar, bioactive component, and moisture content. To increase the shelf life of the pear fruit and to ensure consumption throughout the year, it must be subjected to a preservation technique. Drying is one of the main methods used to extend the long shelf life of fruits and vegetables. Undesirable changes may occur in the quality characteristics of fruits during drying. Therefore, determining the appropriate drying method is vital for the quality of the final product. In this study, the effects of different drying methods on many quality characteristics of pear fruit were investigated. This study has the potential to provide a new perspective on the drying of pear fruit.

Ultrasound‐assisted vacuum drying as alternative drying method to increase drying rate and bioactive compounds retention of raspberry

This study aimed to determine the effect of different drying methods, namely hot air drying (HAD), vacuum drying (VD), ultrasound-assisted vacuum drying (USVD), and freeze drying (FD) on drying kinetic, total phenolic antioxidant activity, anthocyanin profile, in vitro-bioaccessibility of phenolic and color quality of raspberry samples. The drying time of the raspberry was 540, 720, and 1,140 min for USVD, VD, and HAD, respectively, indicating that USVD showed a significantly lower drying time than VD and HAD. The results of anthocyanin profile, TPC, CUPRAC, and DPPH analysis showed that FD had higher bioactive compound retention than other methods, followed by USVD. Cyanidin 3-O-sophoroside and Cyanidin 3-O-glucoside were found as the most abundant anthocyanin in raspberry samples. In the content of cyanidin 3-O-sophoroside, a loss of 78.33%, 15.41%, and 4.63% was observed in HAD, VD, and USVD, respectively. In vitro bioaccessibility of the VD and USVD were higher than FD and HAD. While the recovery value of TPC (%) was found for fresh raspberry as 3.09%, it was found as 6.79, 9.42, 8.46, and 5.58% for HAD, VD, USVD, and FD, respectively. Color quality was significantly affected by drying methods (p < .05), and USVD showed the lowest ∆E value. SEM analysis showed that less shrinkage and cell damage were observed in FD- and USVD-dried samples. This study suggested that USVD could be used as an alternative drying method since it showed lower drying time and shrinkage, higher bioactive compounds, and color retention than VD and HAD. Practical application Raspberry is a popularly consumed fruit rich in bioactive compounds such as anthocyanin and vitamin C. Raspberry is a fruit with a low shelf life, sensitive to microorganisms and enzyme activities due to its high nutritional content and water activity. Drying is one of the most widely used methods to increase the shelf life of raspberries. It is crucial to find a suitable drying method because the bioactive components, color, and physical structure may change during drying. In this study, the effects of four drying methods on the total bioactive components, anthocyanin profile, microstructural structure, color, and phenolic antioxidant in vitro bioaccessibility of raspberry fruit were investigated. The study contains original data.

Standardized method to extract phenolic compounds from Lagerstroemia speciosa L. (Jarul) for enhanced antioxidant activity

Phenolic compounds contribute to the antioxidant property of plants and the efficient extraction of plant phenolics could enhance its antioxidant potential. Lagerstroemia speciosa (L.) Pers. has been investigated for its pharmacological activities, but comparing its antioxidant activities of phenolics derived from its various parts has a key role in developing natural antioxidants. This study was conducted to standardize the extraction of phenolics from leaves, pods and branches of L. speciosa plant, followed by determination of antioxidant activities of their solvent fractions. Phenolic compounds were extracted from the leaves, pods and branches under different parameters such as temperature, pH, type of solvent and volume of the solvent. The extracted phenolic compounds were subjected to solvent fractions and antioxidant assays were performed. Among the various extraction methods tested, the best method was 50% ethanol +1% HCl, refluxing temperature, 100 ml of solvent and 1 hour extraction time. The best solvent fractions were determined as NaHCO3 + ethyl acetate for pods and ethyl acetate alone for leaves and branches with extracted phenolics content of 150.2 mg/g, 136.2 mg/g and 82.9 mg/g, respectively. The chloroform fraction was best among the fractions with maximum ascorbic acid equivalent (ASE) in all the parts of L. speciosa tested. Ferrous ion chelating capacity indicated that butanol fraction had the highest chelation and the same was recorded in ferric ion chelating assay with an EC50 value of 28.2. Hydroxyl radical scavenging activity of the fractions indicated that NaHCO3 + EtOAc fraction of pods had potential activity. Thus, the phenolic compounds from L. speciosa are excellent sources for future investigation on potent natural antioxidant compounds.

Optimization of Extraction Process and the Antioxidant Activity of Phenolics from Sanghuangporus baumii.

Sanghuangporus baumii, is a widely used medicinal fungus. The polyphenols extracted from this fungus exert antioxidant, anti-inflammatory, and hypoglycemic effects. In this study, polyphenols from the fruiting bodies of S. baumii were obtained using the deep eutectic solvent (DES) extraction method. The factors affecting the extraction yield were investigated at different conditions. Based on the results from single-factor experiments, response surface methodology was used to optimize the extraction conditions. The scavenging ability of the polyphenols on •OH, DPPH, and ABTS+ was determined. The results showed that the DES system composed of choline chloride and malic acid had the best extraction yield (6.37 mg/g). The optimal extraction parameters for response surface methodology were as follows: 42 min, 58 ℃, 1:34 solid–liquid (mg/mL), and water content of 39%. Under these conditions, the yield of polyphenols was the highest (12.58 mg/g). At 0.30 mg/mL, the scavenging ability of the polyphenols on •OH, DPPH, and ABTS+ was 95.71%, 91.08%, and 85.52%, respectively. Thus, the method using DES was more effective than the conventional method of extracting phenolic compounds from the fruiting bodies of S. baumii. Moreover, the extracted polyphenols exhibited potent antioxidant activity.

LC-ESI-QTOF-MS/MS Profiling and Antioxidant Activity of Phenolics from Custard Apple Fruit and By-Products

Custard apple is an edible fruit grown in tropical and subtropical regions. Due to its abundant nutrient content and perceived health benefits, it is a popular food for consumption and is utilized as a medicinal aid. Although some published research had provided the phenolic compound of custard apple, the comprehensive phenolic profiling of Australian grown custard apple is limited. Hence, this research aimed to evaluate the phenolic content and antioxidant potential by various phenolic content and antioxidant assays, followed by characterization and quantification of the phenolic profile using LC-ESI-QTOF-MS/MS and HPLC-PDA. African Pride peel had the highest value in TPC (61.69 ± 1.48 mg GAE/g), TFC (0.42 ± 0.01 mg QE/g) and TTC (43.25 ± 6.70 mg CE/g), followed by Pink’s Mammoth peel (19.37 ± 1.48 mg GAE/g for TPC, 0.27 ± 0.03 mg QE/g for TFC and 10.25 ± 1.13 mg CE/g for TTC). African Pride peel also exhibited the highest antioxidant potential for TAC (43.41 ± 1.66 mg AAE/g), FRAP (3.60 ± 0.14 mg AAE/g) and ABTS (127.67 ± 4.60 mg AAE/g), whereas Pink’s Mammoth peel had the highest DPPH (16.09 ± 0.34 mg AAE/g), RPA (5.32 ± 0.14 mg AAE/g), •OH-RSA (1.23 ± 0.25 mg AAE/g) and FICA (3.17 ± 0.18 mg EDTA/g). LC-ESI-QTOF-MS/MS experiment successfully characterized 85 phenolic compounds in total, encompassing phenolic acids (20), flavonoids (42), stilbenes (4), lignans (6) and other polyphenols (13) in all three parts (pulp, peel and seeds) of custard apple. The phenolic compounds in different portions of custard apples were quantified by HPLC-PDA, and it was shown that African Pride peel had higher concentrations of the most abundant phenolics. This is the first study to provide the comprehensive phenolic profile of Australian grown custard apples, and the results highlight that each part of custard apple can be a rich source of phenolics for the utilization of custard apple fruit and waste in the food, animal feeding and nutraceutical industries.

Molecular interaction between pectin and catechin/procyanidin in simulative juice model: Insights from spectroscopic, morphology, and antioxidant activity.

The interactions between polysaccharides and phenolics in foods affect their physicochemical properties and bioactivity. Pectin and catechin/procyanidin present in plants ubiquitously and attracting more attentions for the potential health benefits. This work investigates the interactions between high methoxyl pectin and catechin/procyanidin in a simulative juice model using multiple microscopic and spectroscopic approaches and their influences on the antioxidant activity of phenolics were evaluated in the Caco-2 cells model. The results showed that pectin with either of phenolic compunds exhibited lower transmittance, zeta potential, viscosity, and larger particle size than it alone. The morphology of pectin complexes with either of phenolics under experimental conditions (pH=3.5) was observed. The ΔH° (-6.821kJ mol-1 ) and ΔS° (6.357×10-2 kJ mol-1 ) indicated that pectin interacts with procyanidin via electrostatic interaction, whereas hydrophobic interaction was the dominant drive force between pectin and catechin (ΔH°=1.422kJ mol-1 ; ΔS°=13.048 × 10-2 kJ mol-1 ). The antioxidant activities of catechin/procyanidin decreased while binding with pectin based on indexes of glutathione peroxidase, total superoxide dismutase, total antioxidant capacity, and malondialdehyde. PRACTICAL APPLICATION: The findings of this work indicated that the physicochemicalproperty of pectin and the antioxidant activity of catechin/procyanidin were influenced by the interactions between pectin and catechin/procyanidin in a simulative food system. This study provides insights into the molecular interactions between pectin and phenolics in a simulative food system.

Phenolic profiles and antioxidant activities of free, esterified and bound phenolic compounds in walnut kernel

The free, esterified and bound forms of 37 phenolic compounds (including hydroxybenzoic acid, hydroxycinnamic acids, flavanols, flavonols and flavones) from walnut kernel (Juglans regia L.) were investigated in this study. Results showed that the majority of walnut phenolics were presented in the free form (51.1%–68.1%), followed by bound (21.0%–38.0%) and esterified forms (9.7%–18.7%). Ellagic acid, gallic acid, ferulic acid, sinapic acid and caffeic acid were widely distributed in three forms. Differently, jeuglone, kaempferol, quercetin-7-o-β-d-glucoside and dihydroquercetin were only found in free phenolics. Among the three forms, free phenolics had the highest radical scavenging activity (IC50: DPPH, 15.5 µg/ml; ABTS, 13.6 µg/ml). The correlation coefficients between the antioxidant activities of phenolics and their corresponding contents were 0.82–0.92. More soluble phenolics (free and esterified forms) could be extracted by acetone, while methanol was better at extracting insoluble bound phenolics.

Effects of in vitro simulated digestion on the free and bound phenolic content and antioxidant activity of seven species of seaweeds

SummaryThe effects of simulated gastrointestinal digestion on the content and antioxidant activity of phenolics of seven seaweeds were investigated: Two methods of digestion were used – simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) to mimic the stomach and upper intestinal environment. Results showed that SIF can significantly increase the free phenolic content of all tested seaweeds. The total phenolic content of the seaweeds increased in range from 4.16 to 17.24 mg GAE/g before simulated digestion to 4.08 to 40.37 mg GAE/g after digestion. The antioxidant activity of seaweed‐bound phenolics was superior to that of free phenolics. Among the seven varieties of seaweeds, Sargassum thunbergii and Sargassum kjellmanianum contained the highest content of bound phenolics after SGF digestion. Bound phenolics of Undaria pinnatifida and Sargassum thunbergii showed the highest in vitro ABTS+ free radical scavenging ability, while Sargassum thunbergii and Sargassum fusiforme showed the highest in vitro FRAP antioxidant activity.

Вплив наночастинок СеО2 на проростання насіння та синтез фенолів у проростках ялини європейської

Modern technologies make it possible to obtain nanoparticles of biogenic metals for use as an additional source of micronutrient for plants. However, the complexity of mass application of nanosized metal particles and their oxides is due to the significant differences in physicochemical properties of nanocrystalline structures which are dependent on production technology, nanoparticle size, surface charge (-potential), and stabilization methods. The biocompatibility and nature of nanoparticles has an impact on living organisms. Regarding the effectiveness and feasibility of using cerium dioxide nanoparticles in crop practice, there is no definitive conclusion. Due to difficulty in the preparation of planting material for seedlings of conifers, the study of the effect of nanocrystalline cerium dioxide on plants is not well researched. The aim of our research was to study the effect of nanocrystalline cerium dioxide solution on the germination of spruce seeds and then to evaluate its effect on the synthesis of phenols as components of the antioxidant system within seedlings. The research used methods for determining the germination energy and seed similarities. Other methods used in this research were determining the content of phenolic compounds, flavonoids, and phenolic antioxidants. The results showed that nanocrystalline cerium dioxide in a concentration of solution from 0.1 to 1.0 mg/mL stimulates the germination of spruce seeds. Under the influence of nanoparticles at a concentration of 0.1 mg/L in the tissues of spruce seedlings increases the content of phenolic compounds. The increase in antioxidant activity of phenols in seedling tissues while decreasing their total amount at a concentration of nanocrystalline cerium dioxide from 0.5 to 1.0 mg/L occurs when increasing the total pool of flavonoids, which are determined by high antioxidant activity. Nanocrystalline cerium dioxide is a promising material for stimulating germination energy and on the overall germination of spruce seeds.

In vitro human digestion simulation of the bioavailability and antioxidant activity of phenolics from Sambucus ebulus L. fruit extracts

Bioavailability is an important concept when evaluating natural products for their bioactivities. The present study measured the bioavailability of phenolics of Sambucus ebulus (dwarfelder) fruit extracts, along with its antioxidant activity after simulated digestion. Total phenolics, phenolic acid, proanthocyanidin and flavonoid content assays were used along with different antioxidant assays such as metal reducing and free radical scavenging activities. High performance thin layer chromatography was used to measure bioactive metabolite of the plant sample, chlorogenic acid. Results indicated that aqueous and methanolic extracts of S. ebulus fruits were affected by simulated human digestion, alterations in antioxidant activity were consistent with the changes in the phenolics. Chlorogenic acid bioavailability rates were calculated as 45.8 and 51.9% for methanolic and aqueous extracts, respectively. Total antioxidant capacity was reduced to 37 ± 0.5 from 82 ± 4 (AAE)/g DE for methanolic extracts after the digestion process.

PHYTOCHEMICAL STUDY OF TRIFOLIUM PANNONICUM JACQ. IN THE FOREST-STEPPE OF WESTERN SIBERIA

The article presents data on the content of biologically active compounds and the total activity of phenolic antioxidants in the leaves and inflorescences of the valuable forage plant Trifolium pannonicum Premier cultivar grown in different agroclimatic subareas of the Novosibirsk region – moderately warm, moist and moderately warm, not sufficiently moist. It is shown that, depending on the plant growth, biologically active substances are synthesized in differently: the content of flavonols, catechins, carotenoids and pectin substances is 1.1–1.6 times higher in plants from a more humid area. Tannins maximally (up to 17.43%) accumulate in the leaves of T. pannonicum, grown in an area with insufficient moisture. All samples of T. pannonicum variety Premier are characterized by high antioxidant activity of ethanol extracts from leaves and inflorescences (1.50–2.20 mg/g). The maximum of the total activity of antioxidants was found in the inflorescences of T. pannonicum from an area with insufficient moisture. Plant material T. pannonicum variety Premier is characterized by a fairly high content of biologically active substances.