Structure-activity relationships of polymethoxyflavones and other flavonoids as inhibitors of non-enzymic lipid peroxidation

Interactions between phenolic constituents of Scutellaria salviifolia and key targets associated with inflammation: network pharmacology, molecular docking analysis and in vitro assays

Scutellaria salviifolia Benth. (SS), an endemic plant for Turkey, is used for gastric ailments as folk medicine. In this study, we aimed to uncover the underlying molecular mechanisms with the help of network pharmacology and molecular docking analysis in the inflammation processes of gastric ailments. Gene enrichment analysis and target screening were carried out. Experimental validation was performed via cytokines of nitric oxide (NO) and interleukin-6 (IL-6) in LPS stimulated RAW 264.7 cells. Furthermore, antioxidant activity studies were performed by radical scavenging effects on different radicals. A total of 144 targets were listed for the isolated compounds where 26 of them were related to selected inflammation targets. According to the gene enrichment analysis, HIF1 signaling pathway and TNF signaling pathway were found to be involved in inflammation. We also defined AKT1, TNF, EGFR, and COX2 as key targets due to the protein-protein interactions of 26 common targets. The extract inhibited NO and IL-6 production at 100 and 200 µg/mL, while flavonoid-rich fraction possessed significant anti-inflammatory activity at the concentration of 50 and 100 µg/mL via NO and IL-6 production, respectively. It is thought that the anti-inflammatory effects of extracts, fractions and pure compounds were achieved by reducing NO and IL-6 levels via regulating the NF-κB pathway or reducing NO production by suppressing iNOS through the HIF-1 pathway when evaluated together with the results of network analysis and literature. Anti-inflammatory activities of the extract and fractions were promising and comparably with S. baicalensis, commonly used for its anti-inflammatory activity.

Untargeted Metabolomics Analysis of the Orchid Species Oncidium sotoanum Reveals the Presence of Rare Bioactive C-Diglycosylated Chrysin Derivatives

Plants are valuable sources of secondary metabolites with pharmaceutical properties, but only a small proportion of plant life has been actively exploited for medicinal purposes to date. Underexplored plant species are therefore likely to contain novel bioactive compounds. In this study, we investigated the content of secondary metabolites in the flowers, leaves and pseudobulbs of the orchid Oncidium sotoanum using an untargeted metabolomics approach. We observed the strong accumulation of C-diglycosylated chrysin derivatives, which are rarely found in nature. Further characterization revealed evidence of antioxidant activity (FRAP and DPPH assays) and potential activity against neurodegenerative disorders (MAO-B inhibition assay) depending on the specific molecular structure of the metabolites. Natural product bioprospecting in underexplored plant species based on untargeted metabolomics can therefore help to identify novel chemical structures with diverse pharmaceutical properties.

Anti-Inflammatory Property of 5-Demethylnobiletin (5-Hydroxy-6, 7, 8, 3', 4'-pentamethoxyflavone) and Its Metabolites in Lipopolysaccharide (LPS)-Induced RAW 264.7 Cells

Hydroxylated polymethoxyflavones (PMFs) are a unique class of flavonoid compounds mainly found in citrus plants. We investigated the anti-inflammatory effects of one major 5-hydroxy PMF, namely 5-demethylnobiletin (5DN) and its metabolites 5, 3'-didemethylnobiletin (M1), 5, 4'-didemethylnobiletin (M2), and 5, 3', 4'-tridemethylnobiletin (M3) in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. The results showed that M2 and M3 produced stronger inhibitory effects on the production of nitric oxide (NO) than their parent compound at non-cytotoxic concentrations. Western blotting and real-time PCR analyses demonstrated that M2 and M3 significantly decreased iNOS and COX-2 gene expression. The results also showed that M1 and M3 induced heme oxygenase-1(HO-1) gene expression. Overall, our results demonstrated that metabolites of 5DN significantly inhibited LPS-induced inflammation in RAW 264.7 macrophage cells and generally possessed more potent anti-inflammatory activity than the parent compound, 5DN.

Effect of honey on cardiometabolic risk factors: a systematic review and meta-analysis

Context

Excess calories from free sugars are implicated in the epidemics of obesity and type 2 diabetes. Honey is a free sugar but is generally regarded as healthy.

Objective

The effect of honey on cardiometabolic risk factors was assessed via a systematic review and meta-analysis of controlled trials using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.

Data Sources

MEDLINE, Embase, and the Cochrane Library databases were searched up to January 4, 2021, for controlled trials ≥1 week in duration that assessed the effect of oral honey intake on adiposity, glycemic control, lipids, blood pressure, uric acid, inflammatory markers, and markers of nonalcoholic fatty liver disease.

Data Extraction

Independent reviewers extracted data and assessed risk of bias. Data were pooled using the inverse variance method and expressed as mean differences (MDs) with 95%CIs. Certainty of evidence was assessed using GRADE.

Data Analysis

A total of 18 controlled trials (33 trial comparisons, N = 1105 participants) were included. Overall, honey reduced fasting glucose (MD = −0.20 mmol/L, 95%CI, −0.37 to −0.04 mmol/L; low certainty of evidence), total cholesterol (MD = −0.18 mmol/L, 95%CI, −0.33 to −0.04 mmol/L; low certainty), low-density lipoprotein cholesterol (MD = −0.16 mmol/L, 95%CI, −0.30 to −0.02 mmol/L; low certainty), fasting triglycerides (MD = −0.13 mmol/L, 95%CI, −0.20 to −0.07 mmol/L; low certainty), and alanine aminotransferase (MD = −9.75 U/L, 95%CI, −18.29 to −1.21 U/L; low certainty) and increased high-density lipoprotein cholesterol (MD = 0.07 mmol/L, 95%CI, 0.04–0.10 mmol/L; high certainty). There were significant subgroup differences by floral source and by honey processing, with robinia honey, clover honey, and raw honey showing beneficial effects on fasting glucose and total cholesterol.

Conclusion

Honey, especially robinia, clover, and unprocessed raw honey, may improve glycemic control and lipid levels when consumed within a healthy dietary pattern. More studies focusing on the floral source and the processing of honey are required to increase certainty of the evidence.

Systematic Review Registration

PROSPERO registration number CRD42015023580.

Structure-antiradical activity relationships of 25 natural antioxidant phenolic compounds from different classes

In this study, 11 hydroxybenzoic acids, 6 hydroxycinnamic acids, 6 flavonoids, and 2 synthetic phenolic antioxidants were evaluated according to their scavenging capacity and structure relationships. The IC50 was calculated for all compounds and the effects of the concentration of antioxidant and the length of the reaction on antioxidant capacity were taken into consideration. Based on the data of tested phenolics some structure-activity relationships were suggested and discussed in detail. Poor correspondence of the results between ABTS+• and DPPH• assays was attained, indicating that the antioxidant properties of each compound differ with regards to the applied method. Nevertheless, it can be argued that the number of electron-donating substituents (-OH and -OCH3) and their configuration has a significant impact on the antioxidant capacity. Undoubtedly, concerns about the reliability of these assays demand further in-depth investigations to give detailed insight into the structure and antioxidant activity relationships.

Castor Oil Plant (Ricinus communis L.) Leaves Improve Dexamethasone-Induced Muscle Atrophy via Nrf2 Activation

Skeletal muscle atrophy is characterized by reduced muscle function and size. Oxidative stress contributes to muscle atrophy but can be treated with antioxidants. This study investigated the antioxidant activity of a castor oil plant leaf (Ricinus communis L.) extract (RC) and its effects on muscle atrophy. Rutin was identified as the major compound among the thirty compounds identified in RC via LC-MS/MS and was found to inhibit dexamethasone (DEX)-induced muscle atrophy and mitochondrial oxidative stress. Rutin-rich RC showed DPPH and ABTS radical scavenging activities and efficiently reduced the DEX-induced myotube atrophy and mitochondrial oxidative damage in C2C12 cells. RC supplementation prevented the loss of muscle function and muscle mass in DEX-administered mice and ameliorated DEX-induced oxidative stress via Nrf2 signaling. Taken together, both RC and rutin ameliorated muscle atrophy and helped in maintaining redox homeostasis; hence, rutin-rich RC could be a promising functional food that is beneficial for muscle health.

Creating diverse glycosides of 2'-hydroxyflavone through microbial glycosylation

Four new 2'-hydroxyflavone glycosides, namely hydroxyflavone-2'-O-β-D-glucuronide (1), hydroxyflavone-2'-O-α-L-rhamnoside (2), hydroxyflavone-2'-O-β-D-glucoside (3), and hydroxyflavone-2'-O-4"-O-methyl-β-D-glucoside (4), were biosynthesized through microbial glycosylation using Streptomyces coeruleorubidus NRRL B-2569, Streptomyces toxytricini NRRL 15443, Escherichia coli BL21(DE3)/pWZ8, and Beauveria bassiana ATCC 7159, respectively. Compounds 1-4 were structurally characterized through extensive analysis of 1D and 2D NMR spectroscopic data. The water solubility of glycosylated products 1-4 were enhanced by 7 to 15 times compared to the substrate 2'-hydroxyflavone. Moreover, antioxidant assays revealed that compounds 1 and 2 exhibited stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity than the substrate, decreasing the logIC₅₀ by 68.7% and 80.7%, respectively. Therefore, this research provides several effective biocatalysts that can be used for structural modification of flavonoids for enhanced water solubility and biological activities.

Effect of Ethanol Solvents on Total Phenolic Content and Antioxidant Properties of Seed Extracts of Fenugreek (Trigonella foenum-graecum L.) Varieties and Determination of Phenolic Composition by HPLC-ESI-MS

Fenugreek (Trigonella foenum-graecum L.) is one of the oldest cultivated plants grown for its leaves and seeds that are used for both culinary and medicinal purpose. This study aims to evaluate the effect of ethanol concentration (30, 50, 70 and 96% (v/v) of ethanol in water) as a solvent for the extraction of total phenolic content (TPC) and antioxidant properties (antiradical activity (ARA), transition metal reducing power (TMRP), iron chelating ability (ICA)) of seed extracts of spring variety Ovari 4 (FSV) and winter variety PSZ.G.SZ (FWV) fenugreek, and separate and identify the major phenolics of the extracts by HPLC-ESI-MS. The results indicated that 70% ethanol solution resulted in the maximum amount of TPC for both FSV and FWV seeds. The TPC decreased in the treatments in the following order: 70% ethanol > 96% ethanol > 50% ethanol > 30% ethanol, whereas extraction yield changed in a different manner: 30% ethanol > 50% ethanol > 70% ethanol > 96% ethanol. The extracts from seeds of both fenugreek varieties obtained with 70% and 96% ethanol showed equal high RSA while superior TMRP and ICA were observed in 70% ethanol extracts. The TMRP and ICA were strongly correlated with TPC for both varieties. The correlation between RSA and TPC was high, but not significant. Thus, the obtained data indicate the 70% ethanol solvent suitability for efficient extraction of phenolic compounds from seeds of the FWV and FSV. According to an HPLC-ESI-MS analysis, the polyphenolic profiles of fenugreek are presumably formed by flavone C-glycosides with apigenin or luteolin as aglycone linked with different glycones. High antioxidant activity of FWV seeds can be an adaptation to cold stress of the winter variety aimed at strengthening the antioxidant defense of the germinating seeds.

New insights in drug development for Alzheimer's disease based on microglia function

One of the biggest challenges in drug development for Alzheimer's disease (AD) is how to effectively remove deposits of amyloid-beta (Aβ). Recently, the relationship between microglia and Aβ has become a research hotspot. Emerging evidence suggests that Aβ-induced microglia-mediated neuroinflammation further aggravates the decline of cognitive function, while microglia are also involved in the process of Aβ clearance. Hence, microglia have become a potential therapeutic target for the treatment or prevention of AD. An in-depth understanding of the role played by microglia in the development of AD will help us to broaden therapeutic strategies for AD. In this review, we provide an overview of the dual roles of microglia in AD progression: the positive effect of phagocytosis of Aβ and its negative effect on neuroinflammation after over-activation. With the advantages of novel structure, high efficiency, and low toxicity, small-molecule compounds as modulators of microglial function have attracted considerable attention in the therapeutic areas of AD. In this review, we also summarize the therapeutic potential of small molecule compounds (SMCs) and their structure-activity relationship for AD treatment through modulating microglial phagocytosis and inhibiting neuroinflammation. For example, the position and number of phenolic hydroxyl groups on the B ring are the key to the activity of flavonoids, and the substitution of hydroxyl groups on the benzene ring enhances the anti-inflammatory activity of phenolic acids. This review is expected to be useful for developing effective modulators of microglial function from SMCs for the amelioration and treatment of AD.

Molecular complexes of calf thymus DNA with various bioactive compounds: Formation and characterization

The interaction between biomacromolecules and ligands has attracted great interest because of their biological properties. Calf thymus DNA (ctDNA) can interact with bioactive compounds to form complexes. Here, ctDNA-ligand complexes were studied using fluorescence, absorption, and infrared spectroscopy, circular dichroism, ABTS assay and competitive displacement. The binding constants of bioactive compounds at the intercalative site of ctDNA ranked in order kaempferol > apigenin > quercetin > curcumin > riboflavin, while the binding constants at minor groove sites ranked quercetin > kaempferol > naringenin ~ apigenin > hesperetin > curcumin ~ resveratrol ~ riboflavin > caffeic acid. CtDNA maintained stable B-form with an enhancement of base stacking and a decrease of right-handed helicity in the presence of these bioactive compounds, except for hesperetin and caffeic acid. Bioactive compounds preferentially bound to guanine bases and tended to transfer into a more hydrophobic environment upon complexation with ctDNA. The DNA complexation did not affect the ABTS·⁺ scavenging capacity of quercetin, kaempferol, resveratrol and apigenin but increased the ones of naringenin, caffeic acid, curcumin, hesperetin and riboflavin. The data gathered here should be useful to understand the binding modes of DNA with ligands for their potential application in pharmaceutical and food industries.

The antioxidant activity and active sites of delphinidin and petunidin measured by DFT, in vitro chemical-based and cell-based assays

A computational DFT B3LYP method with 6-311G (d,p) basis set, the in vitro chemical-based and cellular antioxidant activity (CAA) assays were applied in this study to explain the structure-antioxidant activity relationships of delphinidin and petunidin. The compound molecular structures, spectral properties, frontier orbital energy, and transition state of delphinidin and petunidin were compared. In transition state, the result of the active site (O21-H32 and O22-H33) was consistent with the result of bond length. The frontier orbital theory results indicated that the probable antioxidant activity order was petunidin (0.09126 a.u.) > delphinidin (0.09175 a.u.), which agreed well with the cell-based antioxidant activity determined by CAA. However, the order of ABTS^•+ and DPPH radical scavenging activity was delphinidin > petunidin. Our study could help to provide a rational approach for the investigation of antioxidant activity of phytochemicals. PRACTICAL APPLICATIONS: As anthocyanins, delphinidin and petunidin with great antioxidant activity are widely found in various fruits and vegetables. However, there are many kinds of methods used to measure their antioxidant activity and the antioxidant mechanism which are not concrete and clear. Therefore, it is crucial to study the antioxidant actvity of anthocyanins utilizing the DFT method combined with in vitro chemical-based and cell-based assays. Our study could contribute not only to the elucidation of chemical mechanism of antioxidants and exploration the structural features in essence, but also to promote the further development of phytochemicals in the field of food chemistry and pharmacy.

Antioxidant activity evaluation of rosemary ethanol extract and their cellular antioxidant activity toward HeLa cells

Rosemary ethanol extract (REE) from Rosmarinus officinalis was identified by LC-ESI-MS/MS and 12 compounds were found. Among them, rosmarinic acid (389.78 μg/mg in REE), luteolin-3'-O-glucuronide (325.58 μg/mg), luteolin-5-O-glucuronide (120.92 μg/mg), and geniposide (120.83 μg/mg) are the major components. The antioxidant activity evaluation of REE by off-line HPLC methods indicated that among the 12 compounds, rosmarinic acid had the strongest scavenging activities in both DPPH· and ·OH. The cytotoxicity experiment showed that REE with the concentration ranges from 1 to 100 µg/ml did not significantly affect the cell viability of HeLa, while inhibitory rate reduced to 62.3% when the concentration was increased to 1,000 µg/ml. The results of intracellular antioxidation assay showed that the ability of REE in reducing the reactive oxygen species (ROS) in HeLa cells was higher than rosmanol, and lower than rosmarinic acid without cell toxicity. PRACTICAL APPLICATIONS: Plant polyphenols are essential components of functional foods, due to their antioxidant and enzyme inhibition activities. This paper is the first study about the quantification of antioxidant compounds, antioxidant activity evaluation, and their cellular antioxidant activity of polyphenols extract from R. officinalis toward HeLa cells. We aimed to elucidate the chemical composition and recognition of antioxidant components with DPPH and OH free radicals scavenging activity. In addition, the polyphenols dose-response correlations with cellular antioxidant activity were also determined. These results indicated that off-line HPLC method with DPPH and OH free radicals as markers is available for screening antioxidant activity of polyphenols from the mixture.

Antioxidative and Protective Actions of Apigenin in a Paracetamol-Induced Hepatotoxicity Rat Model

BACKGROUND AND OBJECTIVES

Apigenin is known to have various pharmacological properties without causing significant toxicity; however, hepatoprotective effect of apigenin is not often reported. The aim of our study was to investigate if the alterations in lipid peroxidation and antioxidant status are in favor to prove the efficacy of apigenin against paracetamol-induced hepatotoxicity.

METHODS

The effect of apigenin on paracetamol-induced hepatotoxicity in rats was examined by determining biochemical parameters, histological assessment and oxidative status in liver homogenates.

RESULTS

The treatment of animals with both apigenin and paracetamol attenuates the parameters of hepatotoxicity, especially for ALT and ALP activity which was significantly lower compared to groups of animals treated with saline and paracetamol. Hepatotoxicity induced by toxic dose of paracetamol was revealed also by notable histopathological alterations, which were not observed in the group treated with paracetamol together with apigenin. Apigenin also prevented paracetamol-induced increase in malondialdehyde (MDA) level. The activities of both CAT (catalase) and GR (glutathione reductase) enzymes after the toxic dose of paracetamol were significantly increased in the liver homogenates, compared to control group. Apigenin reversed these parameters near to values of control group.

CONCLUSIONS

The result of our study indicates that apigenin inhibits the level of lipid peroxidation and significantly increases the enzyme antioxidant defense mechanisms in paracetamol-induced hepatotoxicity in rats.

Neuroprotective effects of orientin on oxygen-glucose deprivation/reperfusion-induced cell injury in primary culture of rat cortical neurons

Orientin (luteolin-8-C-glucoside) is a phenolic compound found abundantly in millet, juice, and peel of passion fruit and has been shown to have antioxidant properties. In the present study, we explored the effects of orientin on oxygen-glucose deprivation/reperfusion (OGD/RP)-induced cell injury in primary culture of rat cortical neurons using an in vitro model of neonatal ischemic brain injury. The reduced cell viability and elevated lactate dehydrogenase leakage were observed after OGD/RP exposure, which were then reversed by orientin (10, 20, and 30 µM) pretreatment in a dose-dependent manner. Additionally, OGD/RP treatment resulted in significant oxidative stress, accompanied by enhanced intracellular reactive oxygen species (ROS) generation, and obvious depletion in the activities of intracellular Mn-superoxide dismutase, catalase, and glutathione peroxidase antioxidases. However, these effects were dose dependently restored by orientin pretreatment. We also found that orientin pretreatment dose dependently suppressed [Ca²⁺]_i increase and mitochondrial membrane potential dissipation caused by OGD/RP in primary culture of rat cortical neurons. Western blot analysis showed that OGD/RP exposure induced a distinct decrease of Bcl-2 protein and a marked elevation of Bax, caspase-3, and cleaved caspase-3 proteins; whereas these effects were dose dependently reversed by orientin incubation. Both the caspase-3 activity and the apoptosis rate were increased under OGD/RP treatment, but was then dose dependently down-regulated by orientin (10, 20, and 30 µM) incubation. Moreover, orientin pretreatment dose dependently inhibited OGD/RP-induced phosphorylation of JNK and ERK1/2. Notably, JNK inhibitor SP600125 and ERK1/2 inhibitor PD98059 also dramatically attenuated OGD/RP-induced cell viability loss and ROS generation, and further, orientin failed to protect cortical neurons with the interference of JNK activator anisomycin or ERK1/2 activator FGF-2. Taken together, these results demonstrated that orientin has significant neuroprotective effects against OGD/RP-induced cell injury via JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons. Impact statement Orientin has been used in traditional eastern medicine and reported to possess antioxidant properties. However, the effects of orientin on neonatal ischemic brain injury and the underlying mechanisms involved have not been studied. Our results showed that orientin exerts significant neuroprotective effects on cell injury caused by oxygen-glucose deprivation/reperfusion via the JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons, implying the potential therapeutic application of orientin via the suppression of oxidative stress and cell apoptosis. This research suggested that orientin may be used as a therapeutic and preventive option for newborn cerebral ischemia/reperfusion injury.

Effects of light sources on major flavonoids and antioxidant activity in common buckwheat sprouts

It is known that flavonoids in sprouts were accumulated more under light irradiation than under dark. Light source affecting flavonoid accumulation in sprouts is still investigating. We evaluated the effects of light sources, including red, blue and fluorescent lights, on the flavonoid accumulation and antioxidant activity in common buckwheat sprouts. Experimental results showed that blue light significantly enhanced the contents of C-glycosylflavones, including orientin, vitexin and their isomers, and rutin and a rutin isomer. Sprouts grown under blue light exhibit also the highest total phenolics and total flavonoids as well as the highest antioxidant activities. It was found that isoorientin is the highest antioxidant flavonoid whereas numerous former studies suggested that rutin is a typical antioxidant compound in common buckwheat. These results indicated that blue light could be applied for enhancing not only the content of flavonoids but also antioxidant activity in common buckwheat sprouts.

Metabolism variation and better storability of dark- versus light-coloured soybean (Glycine max L. Merr.) seeds

The effects of storage duration on the seed germination and metabolite profiling of soybean seeds with five different coloured coats were studied. Their germination, constituents and transcript expressions of isoflavones and free fatty acids (FFAs) were compared using chromatographic metabolomic profiling and transcriptome sequencing. The seed water content was characterized using nuclear magnetic resonance (NMR) relaxometry. Results showed that dark-coloured seeds were less inactivated than light-coloured seeds. The aglycone and β-glucoside concentrations of upstream constituents increased significantly, whereas the acetylglucosides and malonylglucosides of downstream constituents decreased with an increase in the storage period. FFAs increased considerably in the soybean seeds as a result of storage. These results indicate that dark-coloured soybean seeds have better storability than light-coloured seeds, and seed water content plays a role in seed inactivation. It was concluded that there are certain metabolic regularities that are associated with different coloured seed coats of soybeans under storage conditions.

Metabolomic tool to identify soybean [Glycine max (L.) Merrill] germplasms with a high level of shade tolerance at the seedling stage

The isoflavone profiles of seeds of various soybean genotypes with different levels of shade tolerance at the seedling stage were investigated. High-performance liquid chromatography (HPLC) was used to quantify 12 isoflavones, and the data were analyzed using a multivariate statistical analysis. Combined with field experimental data and an orthogonal partial least-squares discriminant analysis (OPLS-DA), several aglycones (genistein (GE), daidzein (DE), and glycitein (GLE)) were selected and identified as key compounds involved in the shade tolerance of soybean seedlings. Additional correlation analysis and laboratory shading stress experiments with soybean seedlings also confirmed the function of these selected isoflavones, especially GE, in the discrimination of soybean seedlings with different levels of shade tolerance. Furthermore, the structure-antioxidant activity relationships between a range of isoflavones and the plant shade-tolerance mechanism are discussed. Targeted metabolomic analyses of isoflavones could reveal the diversity of shade tolerance in soybean seedlings, thus contributing to the breeding of excellent soybean varieties.

Cellular Metabolomics Revealed the Cytoprotection of Amentoflavone, a Natural Compound, in Lipopolysaccharide-Induced Injury of Human Umbilical Vein Endothelial Cells

Amentoflavone is one of the important bioactive flavonoids in the ethylacetate extract of “Cebaiye”, which is a blood cooling and hematostatic herb in traditional Chinese medicine. The previous work in our group has demonstrated that the ethylacetate extract of Cebaiye has a notable antagonistic effect on the injury induced by lipopolysaccharide (LPS) to human umbilical vein endothelial cells (HUVECs). The present investigation was designed to assess the effects and possible mechanism of cytoprotection of amentoflavone via metabolomics. Ultra-performance liquid chromatography/quadrupole time of flight-mass spectrometry (UPLC/QTOF-MS) coupled with multivariate data analysis was used to characterize the variations in the metabolites of HUVECs in response to exposure to LPS and amentoflavone treatment. Seven putative metabolites (glycine, argininosuccinic acid, putrescine, ornithine, spermidine, 5-oxoproline and dihydrouracil) were discovered in cells incubated with LPS and/or amentoflavone. Functional pathway analysis uncovered that the changes of these metabolites related to various significant metabolic pathways (glutathione metabolism, arginine and proline metabolism, β-alanine metabolism and glycine, serine and threonine metabolism), which may explain the potential cytoprotection function of amentoflavone. These findings also demonstrate that cellular metabolomics through UPLC/QTOF-MS is a powerful tool for detecting variations in a range of intracellular compounds upon toxin and/or drug exposure.

Syntheses of new 3-thiazolyl coumarin derivatives, in vitro α-glucosidase inhibitory activity, and molecular modeling studies

3-Thiazolylcoumarin derivatives 1-14 were synthesized via one-pot two step reactions, and screened for in vitro α-glucosidase inhibitory activity. All compounds showed inhibitory activity in the range of IC50 = 0.12 ± 0.01-16.20 ± 0.23 μM as compared to standard acarbose (IC50 = 38.25 ± 0.12 μM), and also found to be nontoxic. Molecular docking study was carried out in order to establish the structure-activity relationship (SAR) which demonstrated that electron rich centers at one and electron withdrawing centers at the other end of the molecules showed strong inhibitory activity. All the synthesized compounds were characterized by spectroscopic techniques such as EI-MS, HREI-MS, (1)H NMR and (13)C NMR. CHN analysis was also performed.

Human Sperm Quality and Metal Toxicants: Protective Effects of some Flavonoids on Male Reproductive Function

Background

Metals can cause male infertility through affection of spermatogenesis and sperm quality. Strong evidences confirm that male infertility in metal-exposed humans is mediated via various mechanisms such as production of reactive oxygen species (ROS). Flavonoids have antioxidant and metal chelating properties which make them suitable candidates for neutralizing adverse effects of metals on semen quality. In the current study, we have evaluated the effects of five types of flavonoids (rutin, naringin, kaempferol, quercetin, and catechin) on recovery of sperm motility and prevention of membrane oxidative damage from aluminum chloride (AlCl₃), cadmium chloride (CdCl₂), and lead chloride (PbCl₄).

Materials and Methods

In this experimental study, motility and lipid peroxidation of metalexposed sperm was investigated in the presence of different concentrations of five kinds of flavonoids. Malondialdehyde (MDA) production was assessed as a lipid peroxidation marker.

Results

Aluminum chloride (AlCl₃), cadmium chloride (CdCl₂), and lead chloride (PbCl₄) diminished sperm motility. Treatment of metal-exposed sperm with rutin, naringin, and kaempferol attenuated the negative effects of the metals on sperm motility. Quercetin and catechin decreased the motility of metal-exposed sperm.

Conclusion

Based on the MDA production results, only AlCl₃ significantly induced lipid peroxidation. Treatment with rutin, naringin, and kaempferol significantly decreased MDA production.

Trolox equivalent antioxidant capacities and fatty acids profile of 18 alpine plants available as forage for yaks on the Qinghai-Tibetan Plateau

Traditionally, yaks (Poephagus grunniens) raised on the Qinghai-Tibetan plateau graze only natural pasture and much of their diet consists of sedges, in particular Kobresia spp. These ruminants are subjected to an extremely harsh environment of strong UV radiation, hypoxia and severe cold, which can lead to high oxidative stress. Consequently, it was predicted that sedges would contain high concentrations of functional antioxidants when compared with other alpine plants, and that this would help them survive the harsh conditions. To test the prediction, 18 alpine plants on the Qinghai-Tibetan plateau, which are available to yaks as forage, were examined. These plants, including four sedges, five grasses, five forbs and four shrubs, were analysed for gross constituents, Trolox equivalent antioxidant capacity, phenol content, and fatty acids composition. Based on their Trolox equivalent antioxidant capacity, the 18 plants were divided into three groups: low, medium and high. Three of the four sedges were ranked in the medium group and one in the low group, whereas three of four shrubs were ranked in the high group. The total phenol content of the plants ranged between 1.1 and 12.4 g gallic acid equivalents per 100 g DM, with the shrubs containing the highest concentrations. The prediction that sedges would contain higher antioxidant capacity than other alpine plants was not supported. It was concluded that other factors such as anti-nutritional contents and biomass availability are also important in determining dietary selection in yaks.

Amentoflavone acts as a radioprotector for irradiated v79 cells by regulating reactive oxygen species (ROS), cell cycle and mitochondrial mass

Radioprotective effects of amentoflavone were investigated by examining cell viability, apoptosis, cell cycling concentrations of intracellular ROS (reactive oxygen species), and relative mitochondrial mass by flow cytometry after 60Co irradiation. Pretreatment with amentoflavone 24 hours prior to 8 Gy 60Co γ-ray irradiation significantly inhibited apoptosis, promoted the G2 phase, decreased the concentration of ROS and mitochondrial mass. These results collectively indicate that amentoflavone is an effective radioprotective agent.

The role of antioxidants in the chemistry of oxidative stress: A review

This Review Article is focused on the action of the reactive oxygenated species in inducing oxidative injury of the lipid membrane components, as well as on the ability of antioxidants (of different structures and sources, and following different mechanisms of action) in fighting against oxidative stress. Oxidative stress is defined as an excessive production of reactive oxygenated species that cannot be counteracted by the action of antioxidants, but also as a perturbation of cell redox balance. Reactive oxygenated/nitrogenated species are represented by superoxide anion radical, hydroxyl, alkoxyl and lipid peroxyl radicals, nitric oxide and peroxynitrite. Oxidative stress determines structure modifications and function modulation in nucleic acids, lipids and proteins. Oxidative degradation of lipids yields malondialdehyde and 4-hydroxynonenal, but also isoprostanes, from unsaturated fatty acids. Protein damage may occur with thiol oxidation, carbonylation, side-chain oxidation, fragmentation, unfolding and misfolding, resulting activity loss. 8-hydroxydeoxyguanosine is an index of DNA damage. The involvement of the reactive oxygenated/nitrogenated species in disease occurrence is described. The unbalance between the oxidant species and the antioxidant defense system may trigger specific factors responsible for oxidative damage in the cell: over-expression of oncogene genes, generation of mutagen compounds, promotion of atherogenic activity, senile plaque occurrence or inflammation. This leads to cancer, neurodegeneration, cardiovascular diseases, diabetes, kidney diseases. The concept of antioxidant is defined, along with a discussion of the existent classification criteria: enzymatic and non-enzymatic, preventative or repair-systems, endogenous and exogenous, primary and secondary, hydrosoluble and liposoluble, natural or synthetic. Primary antioxidants are mainly chain breakers, able to scavenge radical species by hydrogen donation. Secondary antioxidants are singlet oxygen quenchers, peroxide decomposers, metal chelators, oxidative enzyme inhibitors or UV radiation absorbers. The specific mechanism of action of the most important representatives of each antioxidant class (endogenous and exogenous) in preventing or inhibiting particular factors leading to oxidative injury in the cell, is then reviewed. Mutual influences, including synergistic effects are presented and discussed. Prooxidative influences likely to occur, as for instance in the presence of transition metal ions, are also reminded.

Highly efficient and regioselective synthesis of dihydromyricetin esters by immobilized lipase

Dihydromyricetin is the principle component of the Chinese herbal tea Teng-cha and a promising ingredient for functional food and nutraceuticals, but its low solubility limits its application potentials. This study explored enzymatic acylation of dihydromyricetin to improve its solubility in lipid systems. Acylation was achieved with several lipases with the synthesis of a major (>86%) product and a minor product. Isolation and purification of the products by preparative HPLC followed by LC-MS, (13)C NMR, (1)H NMR and 2 D-HSQC NMR analyses showed that the major product was a dihydromyricetin monoester with the acylation site at the 3-OH group of C ring. Quantum chemical calculations revealed that the 3-OH had the lowest antioxidant activity, and therefore acylation at this site was expected to have minimum impact on the antioxidant activity. Several factors, including solvent, acyl donor, enzyme origin, molar ratio of substrates and reaction temperature and time, exhibited significant effects on the initial rate, conversion yield and regioselectivity of the reaction. Acylation occurred only with vinyl acetate as the acyl donor, and highest conversion yields were achieved with immobilized Penicillium expansum lipase and Novozyme 435 with DMSO and acetonitrile being the best solvents. In general, the acylation results were found to be superior to previous reports on acylation of aglycone flavonoids with respects to conversion yield and regioselectivity.

WITHDRAWN: The paradox of natural flavonoid C-glycosides and health benefits: When more occurrence is less research

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Substituent effects on in vitro antioxidizing properties, stability, and solubility in flavonoids

Antioxidants are widely used by humans, both as dietary supplements and as additives to different types of products. The desired properties of an antioxidant often include a balance between the antioxidizing capacity, stability, and solubility. This review focuses on flavonoids, which are naturally occurring antioxidants, and different common substituent groups on flavonoids and how these affect the properties of the molecules in vitro. Hydroxyl groups on flavonoids are both important for the antioxidizing capacity and key points for further modification resulting in O-methylation, -glycosylation, -sulfation, or -acylation. The effects of O-glycosylation and acylation are discussed as these types of substitutions have been most explored in vitro concerning antioxidizing properties as well as stability and solubility. Possibilities to control the properties by enzymatic acylation and glycosylation are also reviewed, showing that depending on the choice of enzyme and substrate, regioselective results can be obtained, introducing possibilities for more targeted production of antioxidants with predesigned properties.

One-pot synthesis of coumarin-3-carboxamides containing a triazole ring via an isocyanide-based six-component reaction

A facile, efficient, and environmentally friendly approach has been developed for the diversity oriented synthesis of trifunctional coumarin-amide-triazole containing compounds. A wide variety of pharmacologically significant and structurally interesting compounds were synthesized via a one-pot, six-component, tandem Knoevenagel/Ugi/click reaction sequence from readily available starting materials in ethanol at room temperature in excellent overall yields. Substituents could be independently varied at five different positions.

Targeting FASN in Breast Cancer and the Discovery of Promising Inhibitors from Natural Products Derived from Traditional Chinese Medicine

Molecular targeted therapy has been developed for cancer chemoprevention and treatment. Cancer cells process a fundamental change in its bioenergetic metabolism from normal cells on an altered lipid metabolism, also known as the de novo fatty acid synthesis, for sustaining their high proliferation rates. Fatty acid synthesis is now associated with clinically aggressive tumor behavior and tumor cell growth and has become a novel target pathway for chemotherapy development. Although the underlying mechanisms of the altered de novo fatty acid synthesis still remains unclear, recent progress has shown that by targeting Fatty acid synthase (FASN), a key enzyme that catalyzes the synthesis of endogenous long chain fatty acid could be a critical target for drug discovery. However, relatively few FASN inhibitors have been discovered. With the long history of clinical practices and numerous histological case study reports, traditional Chinese medicine enjoys an important role in seeking bioactive anticancer natural compounds. Herein, we will give an overall picture of the current progress of molecular targeted therapy in cancer fatty acid synthesis, describe the advances in the research on natural products-derived FASN inhibitors and their potential for enhancing our understanding of fatty acids in tumor biology, and may provide new therapeutic moieties for breast cancer patient care.

Protective effects of silymarin against acetaminophen-induced hepatotoxicity and nephrotoxicity in mice

This study was designed to estimate protective effects of silymarin on acetaminophen ( N-acetyl- p-aminophenol, paracetamol; APAP)-induced hepatotoxicity and nephrotoxicity in mice. Treatment of mice with overdose of APAP resulted in the elevation of aspartate aminotransferase (AST), alanine transaminase (ALT), blood urea nitrogen (BUN), and serum creatinine (SCr) levels in serum, liver, and kidney nitric oxide (NO) levels and significant histological changes including decreased body weight, swelling of hepatocytes, cell infiltration, dilatation and congestion, necrosis and apoptosis in liver, and dilatation of Bowman’s capsular space and glomerular capillaries, pale-stained tubules epithelium, cell infiltration, and apoptosis in kidney. Posttreatment with silymarin 1 h after APAP injectionfor 7 days, however, significantly normalized the body weight, histological damage, serum ALT, AST, BUN, SCr, and tissue NO levels. Our observation suggested that silymarin ameliorated the toxic effects of APAP-induced hepatotoxicity and nephrotoxicity in mice. The protective role of silymarin against APAP-induced damages might result from its antioxidative and anti-inflammatory effects.

Amentoflavone inhibits iNOS, COX-2 expression and modulates cytokine profile, NF-κB signal transduction pathways in rats with ulcerative colitis

Ulcerative colitis is a chronic inflammatory disorder characterized by oxidative stress, leucocyte infiltration and upregulation of pro-inflammatory cytokines. The aim of the present study was to examine the effect of amentoflavone on a murine model of ulcerative colitis (UC). UC was induced by intracolonic injection of 3% acetic acid in male Wistar rats. amentoflavone (10 mg/kg·b.wt) or reference drug sulfasalazine (100 mg/kg·b.wt) was administrated intra-peritoneally for 5 consecutive days before induction of colitis with acetic acid. Administration of amentoflavone was found to reduce the extent of inflammatory colonic injury. This was manifested by a decrease in the score of mucosal injury, by lowered colonic wet weight as well as vascular permeability and diminished lactate dehydrogenase (LDH) and myeloperoxidase (MPO) activity reflecting reduced leukocyte infiltration. Furthermore, the mucosal content of lipid peroxidation (LPO), glutathione (GSH), superoxide dismutase (SOD), nitric oxide (NO) activity confirms that amentoflavone could significantly inhibit colitis. The treatment also reduced significantly the colonic tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and IL-6 levels as well as the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) compared to colitis control group. The histopathological studies also confirm the foregoing findings. amentoflavone was also able to inhibit the activation and translocation of transcription factors, nuclear factor (NF)-κB subunits (p65/p50). These results suggest that amentoflavone exhibits protective effect in acetic acid-induced ulcerative colitis which might be due to its modulation of oxidant/anti-oxidant balance, down-regulation of productions and expressions of pro-inflammatory cytokines, inflammatory mediators and inhibition of NF-κB signal transduction pathways.