Prevention of cellular ROS damage by isovitexin and related flavonoids

Dietary flavonoids in health and diseases: A concise review of their role in homeostasis and therapeutics

Over the past few decades, extensive research has delved into the health advantages of flavonoids, exploring their physiological effects through cell-based assays, epidemiological studies, and human intervention trials. The regular intake of plant-derived flavonoids has shown therapeutic potential against noncommunicable pathophysiological conditions, including carcinoma and various inflammatory disorders. Among the myriads of flavonoids, many have been shown to inhibit the aggregation of amyloid-beta peptides in Alzheimer's disease, while anthocyanins exhibit cardioprotective effects by improving endothelial function and lowering blood pressure. In addition, their efficacy is known to manage infectious communicable diseases caused by various bacteria and viruses, such as S. pneumoniae and SARS-CoV-2. Currently, flavonoids are being used to develop new drugs for both communicable and noncommunicable diseases because of their intricate metabolism and bioavailability, leveraging their anti-inflammatory and antioxidant properties. This concise review provides insights into the potential of flavonoids for therapeutics and disease management, particularly with respect to cardiovascular health, neuroprotection, and antimicrobial action. The implications of these findings underscore the necessity for further exploration of flavonoid-rich diets and their incorporation into therapeutic practices to harness their full health benefits.

Silicon dioxide nanoparticles as a protective agent against As(III) toxicity in Vigna mungo L. Hepper

The toxicity of As(III) significantly disrupts the growth and development of plants. In this study, black gram plants were exposed to 75 μM NaAsO2 and 10 mg/L SiO2 NPs, and various physiological, biochemical, and molecular changes were observed. Arsenic toxicity led to a notable reduction in plant development, accompanied by an accumulation of ROS and disturbances in proline levels due to electrolyte production. Treating As(III) contaminated black gram with SiO2 NPs resulted in increased root length and chlorophyll content, while decreasing ROS levels. The application of SiO2 NPs effectively mitigated As(III) toxicity by enhancing the activity of antioxidant enzymes such as peroxidase, catalase, glutathione, and superoxide dismutase, consequently reducing lipid peroxidation attributed to lower ROS production. RNA-seq analysis revealed several differentially expressed genes. Additionally, Fourier Transform Infrared (FTIR) Spectroscopy was utilized to explore the plant's capability to remove arsenic, identifying ligands such as O-H, C-O, C-C, and C-H that aid in the accumulation of heavy metals in plant tissues. An investigation using HR-LC/MS unveiled about 199 potential phytochemical components. A SwissADME analysis of these compounds showed that 136 out of 199 compounds followed Lipinski's rule. The bioavailability radar determined that 71 of these phytoconstituents had good oral bioavailability. Overall, the study indicates that the phytoconstituents that were found to have a shedload of pharmacological potential. The overall study showed that identified potential phytochemical compounds with pharmaceutical values, showing promise for drug development.

Antihyperuricemia and chemical composition of Boehmeria virgata, in vitro and in silico approach with ADME prediction

Boehmeria virgata, a traditional South Sulawesi herb, was investigated for its potential to inhibit xanthine oxidase (XO), a key enzyme involved in uric acid production. Extracts from B. virgata demonstrated potent XO inhibition in vitro. Through bioassay-guided fractionation, flavonoids were identified as the primary inhibitory compounds. Molecular docking simulations revealed that these flavonoids, particularly 3-hydroxyflavon and luteolin, bind to XO with high affinity, forming hydrogen bonds and hydrophobic interactions. Their binding affinities were superior to allopurinol, a commonly used XO inhibitor. These findings suggest that B. virgata could be a promising natural source for developing novel treatments for hyperuricaemia.

Efficacy and Safety of Natural Apigenin Treatment for Alzheimer's Disease: Focus on In vivo Research Advancements

BACKGROUND

Alzheimer's Disease (AD) is the most common dementia in clinics. Despite decades of progress in the study of the pathogenesis of AD, clinical treatment strategies for AD remain lacking. Apigenin, a natural flavonoid compound, is present in a variety of food and Chinese herbs and has been proposed to have a wide range of therapeutic effects on dementia.

OBJECTIVE

To clarify the relevant pharmacological mechanism and therapeutic effect of apigenin on animal models of AD.

METHODS

Computer-based searches of the PubMed, Cochrane Library, Embase, and Web of Science databases were used to identify preclinical literature on the use of apigenin for treating AD. All databases were searched from their respective inception dates until June 2023. The meta-analysis was performed with Review manager 5.4.1 and STATA 17.0.

RESULTS

Thirteen studies were eventually enrolled, which included 736 animals in total. Meta-analysis showed that apigenin had a positive effect on AD. Compared to controls, apigenin treatment reduced escape latency, increased the percentage of time spent in the target quadrant and the number of plateaus traversed; apigenin was effective in reducing nuclear factor kappa-B (NF-κB) p65 levels; apigenin effectively increased antioxidant molecules SOD and GSH-px and decreased oxidative index MDA; for ERK/CREB/BDNF pathway, apigenin effectively increased BDNF and pCREB molecules; additionally, apigenin effectively decreased caspase3 levels and the number of apoptotic cells in the hippocampus.

CONCLUSION

The results show some efficacy of apigenin in the treatment of AD models. However, further clinical studies are needed to confirm the clinical efficacy of apigenin.

Phytochemical profile and antimicrobial activity of Jatropha curcas extracts against oral microorganisms

Introduction

The growing problem of antimicrobial resistance on a global scale has highlighted the need to investigate alternative antimicrobial agents with reduced side effects. Plant-derived secondary metabolites have emerged as potential contenders in tackling this challenge. Jatropha curcas, a perennial plant, has traditionally been utilized for the treatment of gum boils, toothaches, and infections. This plant exhibits a wide range of pharmacological properties. However, its potential as an antimicrobial agent against oral microorganisms has yet to be investigated. Hence, the objective of this study was to investigate the antimicrobial properties of Jatropha curcas extracts against selected bacteria and fungi commonly present in the oral cavity.

Methodology

Jatropha curcas samples were collected from Bagan Datuk, Perak, Malaysia, and subsequently identified at Universiti Malaya. The ethanolic extract of the leaves (ELJC) and the stem bark latex (LJC) of Jatropha curcas were tested against six species of oral microorganism: Streptococcus sanguinis , Streptococcus mutans, Streptococcus mitis, Lactobacillus helveticus, Candida albicans , Candida tropicalis, and a mixture of these microorganisms. The methods employed in this study were well diffusion assay, minimum inhibitory concentration, minimum bacterial concentration, live-dead assay, field emission scanning electron microscopy, and liquid chromatography with tandem mass spectrometry.

Results

ELJC and LJC demonstrated significant antimicrobial effects (p < 0.05). Treatment with ELJC and LJC resulted in morphological changes and increased death rates in the targeted microorganisms. ELJC was found to contain more than 300 bioactive compounds, with isovitexin, being the most abundant. In contrast, LJC exhibited over 1000 bioactive compounds with 2-hexyl-decanoic acid and 2,4,6-trihydroxybenzoic acid being the predominant constituents.

Conclusion

These findings suggest that the antimicrobial effects observed in ELJC and LJC against S. sanguinis and S. mutans can be primarily attributed to isovitexin, 2-hexyl-decanoic acid, and trihydroxybenzoic acid. However, further research and investigation are necessary to elucidate the mechanisms by which these constituents exert their antimicrobial effects on the microorganisms.

A comprehensive review of the botany, ethnopharmacology, phytochemistry, and pharmacological activities of two Iranian Rydingia species (Lamiaceae)

Rydingia michauxii and R. persica, respectively, known as Kase Gol and Goldar in Persian, belong to the family Lamiaceae and they are well known herbal medicine in Iran for the treatment of various diseases, particularly diabetes. This review aims to appraise the phytochemistry, ethnopharmacology, and pharmacological activities of Rydingia species growing in Iran and assess their potential in clinical applications. Besides, it critically evaluates existing literature and looks into the perspective for further research and utilization. All available scientific literature was consulted using the database searches involving Google Scholar, PubMed, and Web of Science applying the keyword Rydingia and its Syn; Otostegia. Only the search results that are associated with the Iranian species R. michauxii and R. persica are included in this review. α-pinene, carvacrol, caryophyllene oxide, diisooctyl phthalate, dillapiole, eugenol, hexadecanoic acid, and pentacosane are the major constituents of the essential oils of the Rydingia species. Additionally, these species produce bioactive flavonoids, phenolic acids, steroids, and terpenoids. Extracts and active compounds from Rydingia species have been reported to possess various pharmacological activities including antidiabetic, anti-inflammatory, antimalarial, antimicrobial, antioxidant, cytotoxic, and lipid-lowering properties. Based on the information available to date on the Iranian Rydingia species, it will be worth subjecting these species to further developmental work involving preclinical and clinical trials.

Integrated ultrastructural, physiological, transcriptomic, and metabolomic analysis uncovers the mechanisms by which nicotinamide alleviates cadmium toxicity in Pistia stratiotes L

Exogenous nicotinamide (NIC) is a promising solution to relieve heavy metal (HM) toxicity in plants. Nonetheless, the underlying mechanisms involved remain poorly understood. As NIC addition (200 μM) can increase the tolerance of Pistia stratiotes L. to Cd stress (10 mg L-1), this strategy was subjected to integrated ultrastructural, physiological, transcriptomic, and metabolomic analysis to reveal the mechanisms involved. Exogenous NIC initiated a series of physiological, transcriptional, and metabolic responses that alleviated Cd damage. NIC addition improved Cd transfer from roots to leaves and reduced Cd damage in roots. The transported Cd to leaves did not induce further toxicity because it was abundantly compartmentalised in cell walls, which might be mediated by lignin synthesis. Moreover, NIC addition improved the repair of photosystem II in leaves under Cd stress by inducing key genes (e.g., chlorophyll A-B binding protein and PSII repair protein encoding genes), resulting in the restoration of Fv/Fm. In addition, antioxidant enzyme activities (e.g., peroxidase and catalase) and synthesis of antioxidants (e.g., stachydrine and curculigoside) were triggered to overcome oxidative stress. Our work paves the way for a deeper understanding of the mechanisms by which NIC alleviates HM toxicity in plants, providing a basis for improving phytoremediation.

A New Glucosyl Flavone with Inhibitory Activity of Cancer Cell Viability and Other Bioactive Constituents from the Traditional Kurdish Plant Plantago loeflingii L

A new glucosyl flavone, 5,7,2',5'-tetrahydroxyflavone 7-O-β-d-glucopyranoside, named loeflingiin, together with apigenin 6-C-glucoside (isovitexin), coumarins citropten and isompinellin, triterpenoids betulin and betulinic acid, and a mixture of phytosterols β-sitosterol, stigmasterol and campesterol were isolated for the first time from the leaves of wild Plantago loeflingii L. (Plantaginaceae) collected in the Iraqi Kurdistan region. The plant is used by local people to treat wounds and as a vulnerary remedy. The structures of isolated compounds were determined by spectroscopic analysis. The activities of isovitexin and loeflingiinon the viability of breast (MCF7), ovarian (BG-1), endometrial (Ishikawa), and mesothelioma (IST-MES1) human cancer cells and two normal cell lines were determined with an MTT assay. Notably, the new 7-O-glucosyl flavone showed effects higher than cisplatin against the Ishikawa and IST-MESI cell lines. The significant biological activities exhibited by all the compounds isolated from P. loeflingii provided scientific evidence to support the use of the plant in the Kurdish traditional medicine.

Apigenin attenuates tetrabromobisphenol A-induced cytotoxicity in neuronal SK-N-MC cells

Tetrabromobisphenol A (TBBPA) is a reactive brominated flame retardant widely used in various industrial and household products. This compound is persistent in the environment and accumulates in living organisms through the food chain, and is toxic to animals and human beings. Studies have shown that TBBPA is toxic to various human cell lines, including neuronal cells. Apigenin is a dietary flavonoid that exhibits various beneficial health effects on biological activities, including antioxidant, anti-inflammatory, and neuroprotective effects. This study investigated the cytoprotective effects of apigenin against TBBPA-mediated cytotoxicity in SK-N-MC cells. Our results demonstrated that treatment of SK-N-MC cells with apigenin increased the cell viability, which was decreased by TBBPA, and reduced apoptosis and autophagy induced by TBBPA. Although we did not observe any change in the levels of IL-1β and nitrite in cultured cells after TBBPA treatment, apigenin was found to decrease the production of these pro-inflammatory mediators. Apigenin decreased the intracellular Ca²⁺ concentration, NOX4 level, oxidative stress, and mitochondrial membrane potential loss and increased the mitochondrial biogenesis and nuclear Nrf2 levels that were reduced by TBBPA. Finally, apigenin treatment decreased Akt and ERK induction in cells exposed to TBBPA. Based on these results, apigenin could be a promising candidate for designing natural drugs to treat or prevent TBBPA-related neurological disorders.

Leaf Functional Traits in Relation to Species Composition in an Arctic-Alpine Tundra Grassland

The relict arctic-alpine tundra provides a natural laboratory to study the potential impacts of climate change and anthropogenic disturbance on tundra vegetation. The Nardus stricta-dominated relict tundra grasslands in the Krkonoše Mountains have experienced shifting species dynamics over the past few decades. Changes in species cover of the four competing grasses-Nardus stricta, Calamagrostis villosa, Molinia caerulea, and Deschampsia cespitosa-were successfully detected using orthophotos. Leaf functional traits (anatomy/morphology, element accumulation, leaf pigments, and phenolic compound profiles), were examined in combination with in situ chlorophyll fluorescence in order to shed light on their respective spatial expansions and retreats. Our results suggest a diverse phenolic profile in combination with early leaf expansion and pigment accumulation has aided the expansion of C. villosa, while microhabitats may drive the expansion and decline of D. cespitosa in different areas of the grassland. N. stricta-the dominant species-is retreating, while M. caerulea did not demonstrate significant changes in territory between 2012 and 2018. We propose that the seasonal dynamics of pigment accumulation and canopy formation are important factors when assessing potential "spreader" species and recommend that phenology be taken into account when monitoring grass species using remote sensing.

Identifying conserved genes involved in crop tolerance to cold stress

Low temperature is a limiting factor for crop productivity in tropical and subtropical climates. Cold stress response in plants involves perceiving and relaying the signal through a transcriptional cascade composed of different transduction components, resulting in altered gene activity. We performed a meta-analysis of four previously published datasets of cold-tolerant and cold-sensitive crops to better understand the gene regulatory networks and identify key genes involved in cold stress tolerance conserved across phylogenetically distant species. Re-analysing the raw data with the same bioinformatics pipeline, we identified common cold tolerance-related genes. We found 236 and 242 commonly regulated genes in sensitive and tolerant genotypes, respectively. Gene enrichment analysis showed that protein modifications, hormone metabolism, cell wall, and secondary metabolism are the most conserved pathways involved in cold tolerance. Upregulation of the abiotic stress (heat and drought/salt) related genes [heat shock N -terminal domain-containing protein, 15.7kDa class I-related small heat shock protein-like, DNAJ heat shock N -terminal domain-containing protein, and HYP1 (HYPOTHETICAL PROTEIN 1)] in sensitive genotypes and downregulation of the abiotic stress (heat and drought/salt) related genes (zinc ion binding and pollen Ole e 1 allergen and extensin family protein) in tolerant genotypes was observed across the species. Almost all development-related genes were upregulated in tolerant and downregulated in sensitive genotypes. Moreover, protein-protein network analysis identified highly interacting proteins linked to cold tolerance. Mapping of abiotic stress-related genes on analysed species genomes provided information that could be essential to developing molecular markers for breeding and building up genetic improvement strategies using CRISPR/Cas9 technologies.

Bioactives and their metabolites from Tetrastigma hemsleyanum leaves ameliorate DSS-induced colitis via protecting the intestinal barrier, mitigating oxidative stress and regulating the gut microbiota

Tetrastigma hemsleyanum, a precious edible and medicinal plant in China, has attracted extensive research attention in recent years due to its high traditional value for the treatment of various diseases. In vitro digestion and colonic fermentation models were established to evaluate the stability of Tetrastigma hemsleyanum leaves (THL) phenolics by the HPLC-QqQ-MS/MS method. The total phenolic and flavonoid contents were degraded during digestion and fermentation. 3-caffeoylquinic acid, 5-caffeoylquinic acid, orientin and (iso)vitexin were metabolized by digestive enzymes and the gut microbiota, and absorbed in the form of glycosides and smaller phenolic acids for hepatic metabolism. The protective effects of THL on dextran sodium sulfate (DSS)-induced colitis in mice and potential mechanisms were explored. The results showed that THL supplementation increased the body weight and colon length, and the expression levels of tight junction proteins including occludin, claudin-1 and ZO-1 were up-regulated by THL. The secretions of pro-inflammatory cytokines containing IL-1β, IL-6 and TNF-α were significantly suppressed, whereas the content of anti-inflammatory cytokine IL-10 was promoted in the THL treated group. In addition, THL treatment activated the nuclear transfer of Nrf2, improved the expression of SOD, CAT, HO-1, NQO1 and GCLC, and decreased the content of MPO and MDA. It is worth noting that THL treatment significantly increased the content of short-chain fatty acids (SCFAs), increased the abundance of Ruminococcaceae, and decreased the abundance of Verrucomicrobia which is positively correlated with pro-inflammatory cytokines. These results indicated that THL effectively inhibited DSS-induced colitis by maintaining the intestinal epithelial barrier, mitigated oxidative stress through regulating the Keap1/Nrf2 signaling pathway and regulated the imbalance of the intestinal flora structure.

Comparative transcriptomics analysis reveals differential Cd response processes in roots of two turnip landraces with different Cd accumulation capacities

Understanding the molecular mechanisms of cadmium (Cd) tolerance and accumulation in plants is important to address Cd pollution. In the present study, we performed comparative transcriptome analysis to identify the Cd response processes in the roots of two turnip landraces, KTRG-B14 (high-Cd accumulation) and KTRG-B36 (low-Cd accumulation). Two common enhanced processes, glutathione metabolism and antioxidant system, were identified in both landraces. However, some differential antioxidant processes are likely employed by two landraces, namely, several genes encoding peptide methionine sulfoxide reductases and thioredoxins were up-regulated in B14, whereas flavonoid synthesis was potentially induced to fight against oxidative stress in B36. In addition to the commonly upregulated ZINC INDUCED FACILITATOR 1-like gene in two landraces, different metal transporter-encoding genes identified in B14 (DETOXIFICATION 1) and B36 (PLANT CADMIUM RESISTANCE 2-like, probable zinc transporter 10, and ABC transporter C family member 3) were responsible for Cd accumulation and distribution in cells. Several genes that encode extensins were specifically upregulated in B14, which may improve Cd accumulation in cell walls or regulate root development to absorb more Cd. Meanwhile, the induced high-affinity nitrate transporter 2.1-like gene was also likely to contribute to the higher Cd accumulation in B14. However, Cd also caused some toxic symptoms in both landraces. Cd stress might inhibit iron uptake in both landraces whereas many apoenzyme-encoding genes were influenced in B36, which may be attributed to the interaction between Cd and other metal ions. This study provides novel insights into the molecular mechanism of plant root response to Cd at an early stage. The transporters and key enzymes identified in this study are helpful for the molecular-assisted breeding of low- or high-Cd-accumulating plant resources.

EkFLS overexpression promotes flavonoid accumulation and abiotic stress tolerance in plant

Flavonoids with great medicinal value play an important role in plant individual growth and stress resistance. Flavonol synthetase (FLS) is one of the key enzymes to synthesize flavonoids. However, the role of the FLS gene in flavonoid accumulation and tolerance to abiotic stresses, as well as its mechanism has not yet been investigated systematically in plants. The aim of this research is to evaluate the effect of FLS overexpression on the accumulation of active ingredients and stress resistance in Euphorbia kansui Liou. The results showed that when the EkFLS gene was overexpressed in Arabidopsis thaliana, the accumulation of flavonoids was improved. In addition, when the wild-type and EkFLS overexpressed Arabidopsis plants were treated with ABA and MeJA, compared with WT Arabidopsis, EkFLS overexpressed Arabidopsis promoted stomatal aperture to influence photosynthesis of the plants, which in turn can promote stress resistance. Meanwhile, under MeJA, NaCl, and PEG treatment, EkFLS overexpressed in Arabidopsis induced higher accumulation of flavonoids, which significantly enhanced peroxidase (POD) and superoxide dismutase (SOD) activities that can scavenge reactive oxygen species in cells to protect the plant. These results indicated that EkFLS overexpression is strongly correlated to the increase of flavonoid synthesis and therefore the tolerance to abiotic stresses in plants, providing a theoretical basis for further improving the quality of medicinal plants and their resistance to abiotic stresses simultaneously.

Combined transcriptomic, proteomic and biochemical approaches to identify the cadmium hyper-tolerance mechanism of turnip seedling leaves

Cadmium (Cd) pollution is a prominent environment problem, and great interests have been developed towards the molecular mechanism of Cd accumulation in plants. In this study, we conducted combined transcriptomic, proteomic and biochemical approaches to explore the detoxification of a Cd-hyperaccumulating turnip landrace exposed to 5 μM (T5) and 25 μM (T25) Cd treatments. A total of 1090 and 2111 differentially expressed genes (DEGs) and 161 and 303 differentially expressed proteins (DEPs) were identified in turnips under T5 and T25, respectively. However, poor correlations were observed in expression changes between mRNA and protein levels. The enriched KEGG pathways of DEGs with a high proportion (> 80%) of upregulated genes were focused on the flavonoid biosynthesis, sulphur metabolism and glucosinolate biosynthesis pathways, whereas those of DEPs were enriched on the glutathione metabolism pathway. This result suggests that these pathways contribute to Cd detoxification in turnips. Furthermore, induced antioxidant enzymes, heat stock proteins and stimulated protein acetylation modification seemed to play important roles in Cd tolerance in turnips. In addition, several metal transporters were found responsible for the Cd accumulation capacity of turnips. This study may serve as a basis for breeding low-Cd-accumulating vegetables for foodstuff or high-Cd-abstracting plants for phytoremediation.

Multitargeted Effects of Vitexin and Isovitexin on Diabetes Mellitus and Its Complications

BACKGROUND

Till date, there is no known antidote to cure diabetes mellitus despite the discovery and development of diverse pharmacotherapeutic agents many years ago. Technological advancement in natural product chemistry has led to the isolation of analogs of vitexin and isovitexin found in diverse bioresources. These compounds have been extensively studied to explore their pharmacological relevance in diabetes mellitus. Aim of the Study. The present review was to compile results from in vitro and in vivo studies performed with vitexin and isovitexin derivatives relating to diabetes mellitus and its complications. A systematic online literature query was executed to collect all relevant articles published up to March 2020.

RESULTS

In this piece, we have collected data and presented it in a one-stop document to support the multitargeted mechanistic actions of vitexin and isovitexin in controlling diabetes mellitus and its complications.

CONCLUSION

Data collected hint that vitexin and isovitexin work by targeting diverse pathophysiological and metabolic pathways and molecular drug points involved in the clinical manifestations of diabetes mellitus. This is expected to provide a deeper understanding of its actions and also serve as a catapult for clinical trials and application research.

Isovitexin modulates autophagy in Alzheimer's disease via miR-107 signalling

Background:

Alzheimer’s disease (AD) is an ultimately fatal, degenerative brain disease in the elderly people. In the current work, we assessed the defensive capability of isovitexin (IVX) through an intracerebroventricular injection of streptozotocin (STZ)-induced AD mouse model.

Methods:

Mice were separated into four cohorts: sham-operated control mice; STZ-intoxicated Alzheimer’s mice; IVX cohort, IVX + STZ; and Ant-107 cohort, antagomiR-107 + IVX/STZ as in the IVX cohort.

Results:

The outcomes indicated that IVX administration ameliorated spatial memory loss and blunted a cascade of neuro-noxious episodes – including increased amyloid-beta (Aβ) and degraded myelin basic protein burden, neuroinflammation (represented by elevated caspase-1, TNF-α and IL-6 levels) and autophagic dysfunction (represented by altered LC3-II, Atg7 and beclin-1 expressions) – via the inhibition of PI3K/Akt/mTOR signalling axis. We considered the question of whether the epigenetic role of microRNA-107 (miR-107) has any impact on these events, by using antagomiR-107.

Conclusion:

This probing underscored that miR-107 could be a pivotal regulatory button in the activation of molecular signals linked with the beneficial autophagic process and anti-inflammatory activities in relation to IVX treatment. Hence, this report exemplifies that IVX could guard against Aβ toxicity and serve as an effectual treatment for patients afflicted with AD.

In vitro and in silico Xanthine Oxidase Inhibitory Activity of Selected Phytochemicals Widely Present in Various Edible Plants

AIM AND OBJECTIVE

The present study was designed to evaluate the xanthine oxidase (XO) inhibitory and antioxidant activities of 30 bioactive compounds present in edible food plants for the possible treatment of hyperuricemia.

MATERIALS AND METHODS

The XO inhibitory, SO and DPPH radical scavenging activities of selected dietary polyphenols were determined by using colorimetric assays. The molecular docking analysis was performed to evaluate the insight into inhibitory mode of action of bioactive compounds against XO.

RESULTS

The results show that apigenin, galangin, kaempferol, quercetin, genistein and resveratrol potently inhibit XO enzyme among all tested compounds. Flavonoids exhibit higher, anthocyanins and hydroxycinnamic acids moderate, maslinic acid, ellagic acid, salicylic acid, [6]-gingerol and flavan-3-ols showed weak XO inhibitory activity. The results of molecular docking study revealed that these bioactive compounds bind with the active site of XO and occupy the active site which further prevents the entrance of substrate and results in the inhibition of XO.

CONCLUSION

Inhibition of XO gives a robust biochemical basis for management of hyperuricemia, gout and other associated diseases via controlling uric acid synthesis.

Prosopis alba seed flour improves vascular function in a rabbit model of high fat diet-induced metabolic syndrome

AIMS

Prosopis alba flour is a natural source of nutrient and phytochemicals with potential effects on cardiovascular risk factors. The aim of this work was to examine the effects of dietary supplementation with Prosopis alba seed flour (Pr-Feed) on a high fat diet (FD)-induced rabbit model of metabolic syndrome.

MAIN METHODS

Rabbits were separated in four groups: fed regular diet (CD); CD supplemented with Pr-Feed; fed on 18 % FD; FD supplemented with Pr-Feed. All diets were administrated for 6 weeks. After the feeding period body weights, mean blood pressure, heart rate and visceral abdominal fat (VAF) were determined; glucose tolerance test (GTT) was performed; total cholesterol (TC), HDL-cholesterol, LDL-cholesterol, triglycerides (TG), fasting glucose (FG), aspartate amino transferase, alanine amino transferase, bilirubin and creatinine were measured in serum. Abdominal aorta was excised and vascular function was assessed by acetylcholine relaxation and contractile response to KCl, norepinephrine and angiotensin II.

KEY FINDINGS

Phytochemical analyses showed that the main compounds of Pr-Feed were apigenin C-glycosides. FD increased VAF, FG, TG, reduced HDL-cholesterol and induced abnormal GTT. Pr-Feed addition to FD did not modify these alterations. Aortic rings from rabbits fed on FD exhibited an impaired relaxation-response to acetylcholine and increased agonist vasoconstrictor responses. Pr Feed-supplemented FD improved the response to acetylcholine, and prevented the increase of the contractile response to KCl, norepinephrine and angiotensin II.

SIGNIFICANCE

Results suggest that dietary supplementation with Pr-Feed, rich in apigenin C-glycosides, has vascular protector properties and could be used to prevent vascular alterations characterizing the metabolic syndrome.

Anti-Inflammatory Effect of an Apigenin-Maillard Reaction Product in Macrophages and Macrophage-Endothelial Cocultures

Chronic inflammation is involved in the progression of various diseases, while dietary flavonoids are reported to possess antioxidative and anti-inflammatory properties against age-related diseases. Previously, an apigenin-Maillard reaction product, dimethylglyoxal apigenin (DMA), was identified by us and demonstrated to be antioxidative. In this study, we investigated the inhibitory effect of DMA on advanced glycation end product- (AGE-) induced inflammation in macrophages and macrophage-endothelial cocultures. Results showed that DMA remarkably inhibited the mRNA and protein expression of receptor for AGEs (RAGE), thereby inhibiting the production of ROS and proinflammatory cytokines, including tumor necrosis factor- (TNF-) α, interleukin (IL) 1, IL 6, and monocyte chemoattractant protein- (MCP-) 1 in RAW 264.7 cells. In the coculture system which was performed in the Boyden chamber, macrophage infiltration and adhesion to endothelial cells were significantly suppressed by DMA. Further study indicated that DMA decreased AGE-evoked IL 6 and MCP-1 secretion, which might be achieved through RAGE and its downstream-regulated transforming growth factor- (TGF-) β1 and intercellular adhesion molecule (ICAM) 1 expression in the coculture system. In conclusion, our study demonstrates that DMA, a thermally induced compound, has anti-inflammatory activity in both macrophages and macrophage-endothelial cocultures, offering a promising approach for slowing down the development of chronic diseases.

Cecropia obtusa extract and chlorogenic acid exhibit anti aging effect in human fibroblasts and keratinocytes cells exposed to UV radiation

Cecropia obtusa is popularly used in the Amazonian region and exhibits antioxidant activity. Cosmetic formulations containing C. obtusa extract are commercially available for purchase; however, the chemical composition and the effects of the topical application of the extract are not described in the literature. Therefore, this study aimed to identify the main components of C. obtusa for the first time and to assess the anti aging effect in human fibroblasts and keratinocytes exposed to UVR. The main components in C. obtusa extract were identified by LC-DAD-MS/MS as chlorogenic acid (CGA), luteolin-C-hexoside, luteolin-C-hexose-O-deoxy-hexose, and apigenin-C-hexose-O-deoxy-hexose. C. obtusa extract and CGA decreased the metalloproteinase-1 and protein carbonyl levels and increased the collagen and hyaluronic acid contents. Overall, the extract exhibited better activity than CGA, and we demonstrated the ability of the extract to protect against the UV-induced increase in the pro inflammatory cytokines IL-1β and IL-6, which are potential pathways of the antioxidant and anti aging effect. The chemical characterization added important data to broaden the knowledge related to C. obtusa, and the results suggest that the extract is a promising candidate to be incorporated in topical photochemoprotective formulations.

Comparative study on amylosucrases derived from Deinococcus species and catalytic characterization and use of amylosucrase derived from Deinococcus wulumuqiensis

Amylosucrase (ASase; EC 2.4.1.4), a versatile enzyme, exhibits three characteristic activities: hydrolysis, isomerization, and transglycosylation. In this study, a novel ASase derived from Deinococcus wulumuquiensis (DWAS) was identified and expressed in Escherichia coli. The optimal reaction temperature and pH for the sucrose hydrolysis activity of DWAS were determined to be 45 °C and 9.0, respectively. DWAS displays relatively high thermostability compared with other ASases, as demonstrated by half-life of 96.7 and 4.7 min at 50 °C and 55 °C, respectively. DWAS fused with 6×His was successfully purified to apparent homogeneity with a molecular mass of approximately 72 kDa by Ni-NTA affinity chromatography and confirmed by SDS-PAGE. DWAS transglycosylation activity can be used to modify isovitexin, a representative flavone C-glucoside contained in buckwheat sprouts to increase its limited bioavailability, which is due to its low absorption rate and unstable structure in the human body. Using isovitexin as a substrate, the major transglycosylation product of DWAS was found to be isovitexin monoglucoside. The comparison of transglycosylation reaction products of DWAS with those of other ASases derived from Deinococcus species revealed that the low sequence homology of loop 8 in ASases may affect the acceptor specificity of ASases and result in a distinctive acceptor specificity of DWAS.

Catalytic and stoichiometric flavanone oxidation mediated by nonheme oxoiron(iv) complexes as flavone synthase mimics: kinetic, mechanistic and computational studies

The present study describes the first example of the stoichiometric and catalytic oxidation of flavanone by synthetic nonheme oxoiron(iv) complexes and their precursor iron(ii) complexes with m-CPBA as the terminal oxidant. These models, including detailed kinetic, mechanistic and computational studies, may serve as the biomimics of flavone synthase (FS) enzymes.

High-performance reoxygenation from PLGA-PEG/PFOB emulsions: a feedback relationship between ROS and HIF-1α

Background

Hypoxemia is one of the most common pathological processes in various clinical diseases.

Methods

A novel emulsion of poly(lactide-co-glycolide)-poly(ethylene glycol)/perfluorooctyl bromide has been developed to improve arterial hypoxemia through pulmonary drug delivery. Hypoxia-reoxygenation experiment was used to investigate the ability of the emulsion to supply oxygen and the saline lavage acute lung injury model was established to evaluate oxygen supply of the emulsion.

Results

It has been demonstrated that an apparent increase has been detected in the cytotoxicity test of the emulsion, indicating its lower cell toxicity. A hypoxia-reoxygenation experiment uncovered the fact that notable cell growth was observed after reoxygenation with poly(lactide-co-glycolide)-poly(ethylene glycol)/perfluorooctyl bromide emulsion because of the ability of the emulsion to supply oxygen adequately and reasonably. Moreover, the level of intracellular reactive oxygen species was significantly enhanced during hypoxia, which further influenced the concentration and activity of hypoxia-inducible factor-1α (HIF-1α). Furthermore, the upregulated expression of HIF-1α during hypoxia has verified that certain emulsions can increase HIF-1α content and relieve hypoxia, which further indicates HIF-1α plays an essential role in improving cell viability. Afterwards, the saline lavage acute lung injury model was established to evaluate oxygen supply of the emulsion and the result shows considerable improvement of lung ventilation of rabbits.

Conclusion

We recommend that the feedback relationship between reactive oxygen species and HIF-1 plays an essential role in improving cell viability. It is anticipated that the emulsion will be applied in the field of alleviating hypoxemia.

Dietary Flavonoids in the Prevention of T2D: An Overview

Type 2 diabetes (T2D) is a progressive metabolic disease that is increasing in prevalence globally. It is well established that insulin resistance (IR) and a progressive decline in functional β-cell mass are hallmarks of developing T2D. Obesity is a leading pathogenic factor for developing IR. Constant IR will progress to T2D when β-cells are unable to secret adequate amounts of insulin to compensate for decreased insulin sensitivity. Recently, a considerable amount of research has been devoted to identifying naturally occurring anti-diabetic compounds that are abundant in certain types of foods. Flavonoids are a group of polyphenols that have drawn great interest for their various health benefits. Results from many clinical and animal studies demonstrate that dietary intake of flavonoids might be helpful in preventing T2D, although cellular and molecular mechanisms underlying these effects are still not completely understood. This review discusses our current understanding of the pathophysiology of T2D and highlights the potential anti-diabetic effects of flavonoids and mechanisms of their actions.

Hepatoprotective Effect of Polyphenol-Enriched Fraction from Folium Microcos on Oxidative Stress and Apoptosis in Acetaminophen-Induced Liver Injury in Mice

Folium Microcos (FM), the leaves of Microcos paniculata L., shows various biological functions including antioxidant activity and α-glucosidase inhibitory effect. However, its therapeutic potential in acute liver injury is still unknown. This study investigated the hepatoprotective effect and underlying mechanisms of the polyphenol-enriched fraction (FMF) from Folium Microcos. FMF exhibited strong free radical scavenging activities and prevented HepG2/Hepa1-6 cells from hydrogen peroxide- (H₂O₂-) induced ROS production and apoptosis in vitro. Antioxidant activity and cytoprotective effects were further verified by alleviating APAP-induced hepatotoxicity in mice. Western blot analysis revealed that FMF pretreatment significantly abrogated APAP-mediated phosphorylation of MAPKs, activation of proapoptotic protein caspase-3/9 and Bax, and restored expression of antiapoptotic protein Bcl2. APAP-intoxicated mice pretreated with FMF showed increased nuclear accumulation of nuclear factor erythroid 2-related factor (Nrf2) and elevated hepatic expression of its target genes, NAD(P)H:quinine oxidoreductase 1 (NQO1) and hemeoxygenase-1(HO-1). HPLC analysis revealed the four predominantly phenolic compounds present in FMF: narcissin, isorhamnetin-3-O-β-D-glucoside, isovitexin, and vitexin. Consequently, these findings indicate that FMF possesses a hepatoprotective effect against APAP-induced hepatotoxicity mainly through dual modification of ROS/MAPKs/apoptosis axis and Nrf2-mediated antioxidant response, which may be attributed to the strong antioxidant activity of phenolic components.

Echinodorus grandiflorus: Ethnobotanical, phytochemical and pharmacological overview of a medicinal plant used in Brazil

Echinodorus grandiflorus (Cham. & Schltdl.) Micheli is a native Brazilian species used in traditional practices for the treatment of several conditions such as inflammatory diseases, arthritis and hypertension. Through a systematic review of the accumulated knowledge about the species E. grandiflorus, the botanical, phytochemistry, ethnobotanical and pharmacological properties of this medicinal plant demonstrates its potential to naturally provide anti-inflammatory and anti-oxidant with a special emphasis on anti-hypertensive and cardioprotective effects. The body of literature reports that the chemical composition of crude E. grandiflorus extracts are notably composed of diterpenoids and flavonoids metabolites. Pharmacological studies have shown that oral treatments using the hydroalcoholic extracts of leaves from this plant has a significant anti-inflammatory, anti-hypertensive, diuretic and cardioprotective effects in rats with no toxicity. The holistic activities of complex extracts are corroborated by the individuals mechanisms of action, as well as, synergistic benefits attributed to the isolated chemical major constituents in this species. In light of the serious health concerns ascribed, it is important to investigate medicinal plant species with histories of traditional use for circulatory problems to meet the growing demands by scientifically validating their use and safety.

Inhibition of Epstein-Barr virus reactivation by the flavonoid apigenin

Background

Lytic reactivation of EBV has been reported to play an important role in human diseases, including NPC carcinogenesis. Inhibition of EBV reactivation is considered to be of great benefit in the treatment of virus-associated diseases. For this purpose, we screened for inhibitory compounds and found that apigenin, a flavonoid, seemed to have the ability to inhibit EBV reactivation.

Methods

We performed western blotting, immunofluorescence and luciferase analyses to determine whether apigenin has anti-EBV activity.

Results

Apigenin inhibited expression of the EBV lytic proteins, Zta, Rta, EAD and DNase in epithelial and B cells. It also reduced the number of EBV-reactivating cells detectable by immunofluorescence analysis. In addition, apigenin has been found to reduce dramatically the production of EBV virions. Luciferase reporter analysis was performed to determine the mechanism by which apigenin inhibits EBV reactivation: apigenin suppressed the activity of the immediate-early (IE) gene Zta and Rta promoters, suggesting it can block initiation of the EBV lytic cycle.

Conclusion

Taken together, apigenin inhibits EBV reactivation by suppressing the promoter activities of two viral IE genes, suggesting apigenin is a potential dietary compound for prevention of EBV reactivation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-016-0313-9) contains supplementary material, which is available to authorized users.

Review: Health Effects of Cocoa Flavonoids

Flavonoids are phenolic substances widely found in fruits and vegetables. Many epidemiological studies associate the ingestion of flavonoids with a reduced risk of cardiovascular disease and certain types of cancer. These effects are due to the physiological activity of flavonoids in the reduction of oxidative stress, inhibiting low-density lipoproteins (LDL) oxidation and platelet aggregation, acting as vasodilators in blood vessels, inhibiting the adherence of monocytes to the vascular endothelium, promoting fibrinolysis, acting as immunomodulators and anti-inflammatory agents and as inhibitors in the different phases of tumour process. Cocoa is an important source of polyphenols, which comprise 12-18% of its total weight on dry basis; the major phenolic compounds are epicatechin, proanthocyanidins and cate-chin. The levels of flavonoids contained are higher than the ones founds in apples, onions or wine, foods known for their high amount of phenolic compounds. Cocoa and cocoa products are important sources of flavonoids in our diet. In the Dutch population chocolate contributes up to 20% of the total flavonoid intake in adults, and in children the percentage is even higher. The bioavailability of these compounds depends on other food constituents, and their interaction with the food matrix. This article reviews current evidence on the health effects of cocoa flavonoids in our diet. The compiled data supports the premise that the consumption of cocoa flavonoids is beneficial to human health.

Flavonoid C-glucosides Derived from Flax Straw Extracts Reduce Human Breast Cancer Cell Growth In vitro and Induce Apoptosis

Flax straw of flax varieties that are grown for oil production is a by product which represents a considerable biomass source. Therefore, its potential application for human use is of high interest. Our research has revealed that flax straw is rich in flavonoid C-glucosides, including vitexin, orientin, and isoorientin. The objective of this study was to evaluate the cytotoxicity and possible proapoptotic effect of flax straw derived C-glucosides of flavonoids in the human breast adenocarcinoma cell line (MCF-7). The effects of flax straw derived flavonoid C-glucosides on cell proliferation of MCF-7 cells were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) and sulforhodamine B assays. The expression of apoptosis-related genes was assessed by real-time PCR. Our data revealed that flax C-glucosides as well as pure compounds are cytotoxic toward MCF-7 cells and inhibit their proliferation. Moreover, the induction of apoptosis was correlated with the changes in the mRNA level of pro-apoptotic genes. Increased expression of bax and caspase-7, -8, and -9 and decreased mRNA expression of bcl-2 was observed, whereas the mRNA levels of p53 and mdm2 were not altered. These results clearly demonstrated that flax straw metabolites effectively induced growth inhibition and apoptosis in human breast adenocarcinoma cells.

Polyphenol protection and treatment of hypertension

INTRODUCTION

High blood pressure is the major risk factor for cardiovascular diseases and the rising prevalence of human hypertension precedes the trend toward a global epidemic of unhealthy ageing. A focus on lifestyle and dietary interventions minimizes dependency on pharmacological antihypertensive therapies.

REVIEW

Observational studies indicate that the intake of dietary flavonoids is associated with a decreased risk of cardiovascular disease (CVD). The evidence suggests that the dietary intakes of polyphenol-rich foods, herbs and beverages including flavonols, anthocyanidins, proanthocyanidins, flavones, flavanones, isoflavones and flavan-3-ols, improves vascular health, thereby significantly reducing the risk of hypertension and CVD. Consumption is associated with an improvement in endothelial function via vascular eNOS and Akt activation. Increased NO bioavailability improves vasodilation and blood circulation, effects protein kinases, ion channels and phosphodiesterases, counteracting vascular inflammation and LDL oxidative stress. Importantly, some polyphenols also inhibit the activity of matrix metalloproteinases, inhibit angiotensin converting enzyme activity and thereby improving SBP and DSB. We review the improvement of polyphenol intake on blood pressure and endothelial function for the treatment of hypertension, including not only observational but also RCTs and pre-clinical studies.

CONCLUSION

The antihypertensive phytotherapy of polyphenol-rich foods for protection and improving endothelial function with vascular relaxation occurs via the NO-cGMP pathway and ACE inhibition. OPCs stimulate endothelium-dependent vasodilation, suppress vasoconstrictor ET-1 synthesis, activate a laminar shear stress response in endothelial cells and also inhibit the activity of metalloproteinases including ACE lowering blood pressure.

Passiflora actinia hydroalcoholic extract and its major constituent, isovitexin, are neuroprotective against glutamate-induced cell damage in mice hippocampal slices

OBJECTIVES

To investigate whether Passiflora actinia hydroalcoholic extract and its major constituent, isovitexin, protect mice hippocampal brain slices from glutamate-induced neurotoxicity.

METHODS

Neuroprotective effect of the extract against glutamate-induced excitotoxicity (10 mm) was evaluated through cell viability of hippocampal slices. The extract or its flavonoids were directly applied to hippocampal slices and then subjected to glutamate-induced toxicity. Alternatively, hippocampal slices from extract-treated mice were also subjected to the same toxicity protocol.

KEY FINDINGS

Mice supplementation with the extract protected hippocampal slices from in-vitro neurotoxicity. When directly applied to hippocampal slices, the extract showed a higher neuroprotective potential than a commercial dry extract of Passiflora incarnata, which was related to P. actinia extract which had higher isovitexin and total flavonoid content expressed as isovitexin. Isovitexin, but not apigenin, induced a similar neuroprotective response when applied alone, at a concentration equivalent to that found in the extract.

CONCLUSIONS

This study highlights new neuropharmacological activity of the Passiflora genus, suggesting that it can act as modulator of the glutamatergic system. The search for improved pharmacotherapies with novel mechanisms of action has been shown of great importance for the treatment of resistant neurological and psychiatric disorders.

Isovitexin Exerts Anti-Inflammatory and Anti-Oxidant Activities on Lipopolysaccharide-Induced Acute Lung Injury by Inhibiting MAPK and NF-κB and Activating HO-1/Nrf2 Pathways

Oxidative damage and inflammation are closely associated with the pathogenesis of acute lung injury (ALI). Thus, we explored the protective effect of isovitexin (IV), a glycosylflavonoid, in the context of ALI. To accomplish this, we created in vitro and in vivo models by respectively exposing macrophages to lipopolysaccharide (LPS) and using LPS to induce ALI in mice. In vitro, our results showed that IV treatment reduced LPS-induced pro-inflammatory cytokine secretion, iNOS and COX-2 expression and decreased the generation of ROS. Consistent findings were obtained in vivo. Additionally, IV inhibited H₂O₂-induced cytotoxicity and apoptosis. However, these effects were partially reversed following the use of an HO-1 inhibitor in vitro. Further studies revealed that IV significantly inhibited MAPK phosphorylation, reduced NF-κB nuclear translocation, and upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) expression in RAW 264.7 cells. In vivo, pretreatment with IV attenuated histopathological changes, infiltration of polymorphonuclear granulocytes and endothelial activation, decreased the expression of ICAM-1 and VCAM-1, reduced the levels of MPO and MDA, and increased the content of GSH and SOD in ALI. Furthermore, IV treatment effectively increased Nrf2 and HO-1 expression in lung tissues. Therefore, IV may offer a protective role against LPS-induced ALI by inhibiting MAPK and NF-κB and activating HO-1/Nrf2 pathways.

Effect of ganglioside GT1b on the in vitro maturation of porcine oocytes and embryonic development

Ganglioside is an acidic glycosphingolipid with sialic acids residues. This study was performed to investigate the effect and mechanism of ganglioside GT1b in porcine oocytes in the process of in vitro maturation (IVM) and preimplantation development. Metaphase II (MII) rates were significantly (P < 0.05) different between the control group and the 5 nM GT1b treatment group. Intracellular glutathione (GSH) levels in oocytes matured with 5 nM and 20 nM and GT1b decreased significantly (P < 0.05). The 10 nM group showed a significant (P < 0.05) decrease in intracellular reactive oxygen species (ROS) levels compared with the control group. Subsequently, the level of intracellular Ca(2+) in oocytes treated with different concentrations of GT1b was measured. Intracellular Ca(2+) was significantly (P < 0.05) increased with a higher concentration of GT1b in a dose-dependent manner. Real-time PCR was performed and showed that the expression of bradykinin 2 receptor (B2R) and calcium/calmodulin-dependent protein kinase II delta (CaMKIIδ) in cumulus cells was significantly (P < 0.05) decreased in the 20 nM GT1b treatment group. Treatment with 5 nM GT1b significantly (P < 0.05) decreased the expression of CaMKIIδ. In oocytes, treatment with 5 nM GT1b significantly (P < 0.05) decreased CaMKIIγ and POU5F1 (POU domain, class 5, transcription factor 1). However, treatment with 20 nM GT1b significantly (P < 0.05) increased the expression of POU5F1. Finally, embryonic developmental data showed no significant differences in the two experiments (parthenogenesis and in vitro fertilization). In conclusion, the results of the present study indicated that GT1b plays an important role in increasing the nuclear maturation rate and decreasing the intracellular ROS levels during IVM. However, GT1b inhibited maturation of the cytoplasm by maintaining intracellular Ca(2+) in the process of oocyte maturation regardless of the cell cycle stage. Therefore, GT1b is thought to act on another mechanism that controls intracellular Ca(2+).

Dietary Flavonoids as Xanthine Oxidase Inhibitors: Structure-Affinity and Structure-Activity Relationships

The flavonoid family has been reported to possess a high potential for inhibition of xanthine oxidase (XO). This study concerned the structural aspects of inhibitory activities and binding affinities of flavonoids as XO inhibitors. The result indicated that the hydrophobic interaction was important in the binding of flavonoids to XO, and the XO inhibitory ability increased generally with increasing affinities within the class of flavones and flavonols. The planar structure and the C2═C3 double bonds of flavonoids were advantageous for binding to XO and for XO inhibition. Both the hydroxylation on ring B and the substitution at C3 were unfavorable for XO inhibition more profoundly than their XO affinity. The methylation greatly reduced the inhibition (0.75-3.07 times) but hardly affected the affinity. The bulky sugar substitutions of flavonoids decreased the inhibition (1.69-1.99 times) and lowered the affinities (4.20-9.22 times) to different degrees depending on the conjunction site.

Apigenin modulates the expression levels of pro-inflammatory mediators to reduce the human insulin amyloid-induced oxidant damages in SK-N-MC cells

Amyloid depositions of proteins play crucial roles in a wide variety of degenerative disorders called amyloidosis. Although the exact mechanisms involved in amyloid-mediated cytotoxicity remain unknown, increased formation of reactive oxygen species (ROS) and nitrogen species and overproduction of pro-inflammatory cytokines are believed to play key roles in the process. In that regard, we investigated the effect of apigenin, a common dietary flavonoid with high antioxidant and anti-inflammatory properties on potential factors involved in cytotoxicity of human insulin amyloids. Pretreatment of SK-N-MC neuroblastoma cells with apigenin increased cell viability and reduced the apoptosis induced by insulin fibrils. In addition, apigenin attenuated insulin fibril-induced ROS production and lipid peroxidation. Our result also demonstrated that pretreatment of the fibril-affected cells with apigenin caused an increase in catalase activity and the intracellular glutathione content along with reduction in nitric oxide production and nuclear factor κB, tumor necrosis factor α, and interleukin 6 gene expression based on real-time polymerase chain reaction evaluation. In accordance with these results, apigenin could be a promising candidate in the design of natural-based drugs for treatment or prevention of amyloid-related disorders.

Cytotoxicity of dietary flavonoids on different human cancer types

Flavonoids are ubiquitous in nature. They are also in food, providing an essential link between diet and prevention of chronic diseases including cancer. Anticancer effects of these polyphenols depend on several factors: Their chemical structure and concentration, and also on the type of cancer. Malignant cells from different tissues reveal somewhat different sensitivity toward flavonoids and, therefore, the preferences of the most common dietary flavonoids to various human cancer types are analyzed in this review. While luteolin and kaempferol can be considered as promising candidate agents for treatment of gastric and ovarian cancers, respectively, apigenin, chrysin, and luteolin have good perspectives as potent antitumor agents for cervical cancer; cells from main sites of flavonoid metabolism (colon and liver) reveal rather large fluctuations in anticancer activity probably due to exposure to various metabolites with different activities. Anticancer effect of flavonoids toward blood cancer cells depend on their myeloid, lymphoid, or erythroid origin; cytotoxic effects of flavonoids on breast and prostate cancer cells are highly related to the expression of hormone receptors. Different flavonoids are often preferentially present in certain food items, and knowledge about the malignant tissue-specific anticancer effects of flavonoids could be purposely applied both in chemoprevention as well as in cancer treatment.

Characterization and determination of antioxidant components in the leaves of Camellia chrysantha (Hu) Tuyama based on composition-activity relationship approach

Camellia chrysantha (Hu) Tuyama (CCT), an ornamental plant possessing antioxidant activity, has been infused as tea and drank for its health benefits. The antioxidant components in CCT, however, had not been clearly characterized. To quickly identify the antioxidant constituents of CCT, a composition–activity relationship strategy based on ultra high-pressure liquid chromatography coupled with linear ion trap hybrid orbitrap mass spectrometry and orthogonal partial least-squares method has been applied. As a result, 16 variables were found to make significant contributions to the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. Six of them were identified as catechin (1), epicatechin (5), vitexin (8), isovitexin (10), quercetin-7-O-β-D-glucopyranoside (12) and kaempferol (16). The strength of 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity was found to be 12 > 1 > 5 > 16 > 8 > 10 by validation test. Meanwhile, a liquid chromatography-electrospray ionization-mass spectrometry method was established for quantitative determination of six marker compounds in CCT samples from different preparations. The validation of the method, including linearity, sensitivity (limitation of detection and limitation of quantification), repeatability, precision, stability, and recoveries, was carried out and demonstrated to meet the requirements of quantitative analysis. This is the first report on the comprehensive characterization and determination of chemical constituents in CCT by ultra high-pressure liquid chromatography coupled with linear ion trap hybrid orbitrap mass spectrometry. The results indicate that the composition–activity relationship approach may be a useful method for the discovery of active constituents in natural plants and the quality control of medicinal herbs.

Site-specific anticancer effects of dietary flavonoid quercetin

Food-derived flavonoid quercetin, widely distributed in onions, apples, and tea, is able to inhibit growth of various cancer cells indicating that this compound can be considered as a good candidate for anticancer therapy. Although the exact mechanism of this action is not thoroughly understood, behaving as antioxidant and/or prooxidant as well as modulating different intracellular signalling cascades may all play a certain role. Such inhibitory activity of quercetin has been shown to depend first of all on cell lines and cancer types; however, no comprehensive site-specific analysis of this effect has been published. In this review article, cytotoxicity constants of quercetin measured in various human malignant cell lines of different origin were compiled from literature and a clear cancer selective action was demonstrated. The most sensitive malignant sites for quercetin revealed to be cancers of blood, brain, lung, uterine, and salivary gland as well as melanoma whereas cytotoxic activity was higher in more aggressive cells compared to the slowly growing cells showing that the most harmful cells for the organism are probably targeted. More research is needed to overcome the issues of poor water solubility and relatively low bioavailability of quercetin as the major obstacles limiting its clinical use.