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Anthocyanins, typical polyphenol compounds in grape skin, have attracted increasing interest due to their health-promoting properties. In this body of work, five representative anthocyanins (Cy-3-O-glc, Dp-3-O-glc, Pn-3-O-glc, Mv-3-O-glc, and Pt-3-O-glc) were studied using the density functional theory (DFT) to elucidate structure–radical scavenging activity in the relationship and the reaction path underlying the radical-trapping process. Based on thermodynamic parameters involved in HAT, SET-PT, and SPLET mechanisms, along with the structural attributes, it was found that the C4′ hydroxyl group mainly contributes to the radical scavenging activities of the investigated compounds. Pt-3-O-glc exhibits a good antioxidant capacity among the five compounds. The preferred radical scavenging mechanisms vary in different phases. For the Pt-3-O-glc compound, the calculations indicate the thermodynamically favoured product is benzodioxole, rather than o-quinone, displaying considerably reduced energy in double HAT mechanisms. Additionally, the thermodynamic and kinetic calculations indicate that the reaction of •OH into the 4′-OH site of Pt-3-O-glc has a lower energy barrier (7.6 kcal/mol), a higher rate constant (5.72 × 109 M−1 s−1), and exhibits potent •OH radical scavenging properties. Molecular docking results have shown the strong affinity of the studied anthocyanins with the pro-oxidant enzyme xanthine oxidase, displaying their significant role in inhibiting ROS formation. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of platinum(II) complex bearing 3′-aminothiocyclohexanespiro-5′-hydantoin as ligand. The complex was characterized by IR, NMR spectral analyses, elemental analyses and density functional theory (DFT) calculations. Cytotoxicity and inhibitory potential on xanthine oxidase (XO) were evaluated by performed docking calculations. The cytotoxic activities of the 3′-aminothiocyclohexanespiro-5′-hydantoin (1), its Pt(II) complex (2), thiocyclohexanespiro-5′-hydantoin (3), and its platinum complex (4) were assessed against HL-60 and MDA-MB-231 cells in comparison with the antiproliferative activity of cisplatin as a referent. The ligands (1 and 3) did not exhibit in vitro antitumor efficacy on either of the human tumor cell lines. Complex 2 showed higher antitumor activity (IC50 = 42.1 ± 2.8 μM on HL-60 and 97.8 ± 7.5 μM against MDA-MB-231 cells) than complex 4 (IC50 = 89.6 ± 2.8 μM on HL-60 and 112.5 ± 4.2 μM in MDA-MB-231 cells). IC50 values of cisplatin as referent were 8.7 ± 2.4 μM on HL-60 and 31.6 ± 5.4 μM on MDA-MB-231 cell lines. The inhibitory activity of ligands and complexes against XO, evaluated in vitro, were compared with allopurinol (IC50 = 1.70 ± 0.51 μM) as standard inhibitor. The platinum(II) complexes (2 and 4) inhibited the activity of XO, with IC50 values 110.33 ± 26.38 μM and 115.45 ± 42.43 μM, respectively, while the ligands 1 and 3 did not show higher degrees of inhibition at concentrations lower than 150 μM. The inhibitory potential against XO might be a possible precedent resulting in improved profile and anticancer properties. [ABSTRACT FROM AUTHOR]

The enzyme-mediated polymerization of bioactive phenolic compounds, such as the flavonoid rutin, has gained interest due to the enhanced physico-chemical and biological properties of the products, which increases their potential application as a nutraceutical. In this work, the influence of enzyme activity on rutin oligomerization was evaluated in reactions with low (1000 U/L) and high (10,000 U/L) initial laccase activities. For both reactions, high molecular weight oligomer fractions showed better properties compared to lower weight oligomers. Products of the reaction with low laccase activity exhibited thermal stability and antioxidant potential similar to control reaction, but led to higher inhibitory activity of xanthine oxidase and apparent aqueous solubility. Oligomers obtained in the reaction with high laccase activity showed better apparent aqueous solubility but decreased biological activities and stability. Their low antioxidant activity was correlated with a decreased phenolic content, which could be attributed to the formation of several bonds between rutin molecules. [ABSTRACT FROM AUTHOR]

Evaluation of abundantly available agro-industrial by-products for their bioactive compounds and biological activities is beneficial in particular for the food and pharmaceutical industries. In this study, rapeseed meal, cottonseed meal and soybean meal were investigated for the presence of bioactive compounds and antioxidant, anti-inflammatory, xanthine oxidase and tyrosinase inhibitory activities. Methanolic extracts of rapeseed meal showed significantly (P < 0.01) higher phenolics and flavonoids contents; and significantly (P < 0.01) higher DPPH and nitric oxide free radical scavenging activities when compared to that of cottonseed meal and soybean meal extracts. Ferric thiocyanate and thiobarbituric acid tests results showed rapeseed meal with the highest antioxidant activity (P < 0.01) followed by BHT, cotton seed meal and soybean meal. Rapeseed meal extract in xanthine oxidase and tyrosinase inhibitory assays showed the lowest IC50 values followed by cottonseed and soybean meals. Anti-inflammatory assay using IFN-γ/LPS stimulated RAW 264.7 cells indicated rapeseed meal is a potent source of anti-inflammatory agent. Correlation analysis showed that phenolics and flavonoids were highly correlated to both antioxidant and anti-inflammatory activities. Rapeseed meal was found to be promising as a natural source of bioactive compounds with high antioxidant, anti-inflammatory, xanthine oxidase and tyrosinase inhibitory activities in contrast to cotton and soybean meals. [ABSTRACT FROM AUTHOR]

Propolis is a resinous natural product collected by honeybees (Apis mellifera and others) from tree exudates that has been widely used in folk medicine. The present study was carried out to investigate the fatty acid composition, chemical constituents, antioxidant, and xanthine oxidase (XO) inhibitory activity of Jordanian propolis, collected from Al-Ghour, Jordan. The hexane extract of Jordanian propolis contained different fatty acids, which are reported for the first time by using GC-FID. The HPLC was carried out to identify important chemical constituents such as fatty acids, polyphenols and α-tocopherol. The antioxidant and xanthine oxidase inhibitory activities were also monitored. The major fatty acid identified were palmitic acid (44.6%), oleic acid (18:1∆9cis, 24.6%), arachidic acid (7.4%), stearic acid (5.4%), linoleic acid (18:2∆9–12cis, 3.1%), caprylic acid (2.9%), lignoceric acid (2.6%), cis-11,14-eicosaldienoic acid (20:2∆11–14cis, 2.4%), palmitoleic acid (1.5%), cis-11-eicosenoic acid (1.2%), α–linolenic acid (18:3∆9–12–15cis, 1.1%), cis-13,16-docosadienoic acid (22:2∆13–16cis, 1.0%), along with other fatty acids. The major chemical constituents identified using gradient HPLC-PDA analysis were pinocembrin (2.82%), chrysin (1.83%), luteolin-7-O-glucoside (1.23%), caffeic acid (1.12%), caffeic acid phenethyl ester (CAPE, 0.79%), apigenin (0.54%), galangin (0.46%), and luteolin (0.30%); while the minor constituents were hesperidin, quercetin, rutin, and vanillic acid. The percentage of α-tocopherol was 2.01 µg/g of the lipid fraction of propolis. Antioxidant properties of the extracts were determined via DPPH radical scavenging. The DPPH radical scavenging activities (IC50) of different extracts ranged from 6.13 to 60.5 µg/mL compared to ascorbic acid (1.21 µg/mL). The xanthine oxidase inhibition (IC50) ranged from 75.11 to 250.74 µg/mL compared to allopurinol (0.38 µg/mL). The results indicate that the various flavonoids, phenolic compounds, α-tocopherol, and other constituents which are present in propolis are responsible for the antioxidant and xanthine oxidation inhibition activity. To evaluate the safety studies of propolis, the pesticide residues were also monitored by LC-MS-MS 4500 Q-Trap. Trace amounts of pesticide residue (ng/mL) were detected in the samples, which are far below the permissible limit as per international guidelines. [ABSTRACT FROM AUTHOR]

The white beetroot cv. Śnieżna Kula is the first betanin-free beetroot registered in the European Union. The aim of this study was to compare the phenolic acids profile and antioxidant capacity of leaves of white (SK) and red (CC) beetroots and red (LC) and white (BL) Swiss chard growing in Poland. LC leaves were the richest source of total phenolics (16.55 mg GAE/g FW) and phenolic acids (1.81 mg/g FW), while the highest content of flavonoids was determined in CC leaves (1.6 mg QE/g FW). The highest antiradical activity was observed for LC, whereas CC extract exhibited the highest chelating power. BL and CC leaf extracts demonstrated high LOX inhibitory potential (EC50 = 53.23 and 56.97 mg FW/mL, respectively). An uncompetitive type of LOX inhibition was obtained for all extracts. SK extracts demonstrated the highest XO inhibitory activity (EC50 = 81.04 mg FW/mL). A noncompetitive type of XO inhibition was obtained in both extracts from red leaves (CC and LC), whereas an uncompetitive mode of inhibition was observed in the case of white leaf (SK and LC) extracts. Thus, it can be assumed that the presence of betanin influences the XO inhibition mechanism. [ABSTRACT FROM AUTHOR]

Xanthine oxidase is a frontier enzyme to produce oxidants, which leads to inflammation in the blood. Prenylated isoflavones from Flemingia philippinensis were found to display potent inhibition against xanthine oxidase (XO). All isolates (1–9) inhibited XO enzyme with IC50 ranging 7.8~36.4 μM. The most active isoflavones (2–5, IC50 = 7.8~14.8 μM) have the structural feature of a catechol motif in B-ring. Inhibitory behaviors were disclosed as a mixed type I mode of inhibition with KI < KIS. Binding affinities to XO enzyme were evaluated. Fluorescence quenching effects agreed with inhibitory potencies (IC50s). The compounds (2–5) also showed potent anti-LDL oxidation effects in the thiobarbituric acid-reactive substances (TBARS) assay, the lag time of conjugated diene formation, relative electrophoretic mobility (REM), and fragmentation of apoB-100 on copper-mediated LDL oxidation. The compound 4 protected LDL oxidation with 0.7 μM in TBARS assay, which was 40-fold more active than genistein (IC50 = 30.4 μM). [ABSTRACT FROM AUTHOR]