Effect of O-glycosilation on the antioxidant activity and free radical reactions of a plant flavonoid, chrysoeriol

Changes in biochemical composition of Ethiopian Coffee arabica with growing region and traditional roasting

Updating the biochemical composition of coffee beans across the years is necessary. This is important to understand the vulnerability of coffee toward climate adaptation longitudinally. Accordingly, in this study the influence of growing area and traditional roasting on the biochemical composition of five common Ethiopian Arabica coffee beans collected in the harvest year of 2021/22 were investigated. With an average of 11.34 g/100 g, the Hararge and Jimma coffee beans had the highest crude fat content (p < 0.05). The crude protein content of the five varieties was in the range of 13-15 g/100 g, with respective highest and lowest contents in the (Hararge and Nekemte) and (Sidama and Yirgachefe) coffee beans (p < 0.05). The total phenolic content (TPC) of the coffee beans was in the order of Jimma (46.52) > Nekemte (44.55) > Sidama (44.31) > Hararge (39.02) > Yirgachefe (34.25) mg GAE/100 g. The 50% inhibitory concentration (IC50) of ascorbic acid, coffee bean extract from Jimma and Hararge against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical was 19.86, 20.22 and 20.02 μg/mL, respectively. The respective highest and lowest caffeine concentration was obtained in the Yirgachefe (10.38) and Hararge (7.55 g/100 g) coffee beans (p < 0.05). The Jimma, Sidama, and Nekemte coffee varieties had the highest chlorogenic acid content of 45 g/100 g (p > 0.05); whereas the lowest content was in Hararge coffee (36.78 g/100 g). While the caffeine concentration did not show significant (p > 0.05) difference, with all the coffee beans the roasting has reduced significantly the TPC, trigonelline and mainly the chlorogenic acid (p < 0.05). These data can update the existing facts on biochemical diversity of coffee beans in the country which can be used for evidence based innovations of climate adaptation in predicting the quality of coffee. Further recommendation of optimizing the traditional coffee processing method is supported from this study.

Physicochemical Characterization, Antioxidant, and Proliferative Activity of Colombian Propolis Extracts: A Comparative Study

Propolis extracts have been widely studied due to their popularity in traditional medicine, presenting incredible biodiversity. This study aimed to analyze propolis extracts' phytochemical, physicochemical, and biological activities from four different biogeographic zones of the Huila region (Colombia). The raw material samples were collected by the scraping method and the ethanolic extracts (EEPs) were obtained by cold maceration with ethanol (96%). The physicochemical and sensory characterization was carried out according to the protocols recommended by the Brazilian Ministry of Agriculture and the main components of the EEPs were identified by LC-HRMS analysis. The determination of total phenols and flavonoids was carried out using colorimetric techniques. The antioxidant activity, cytotoxicity, and cell cycle regulation analyses in L929 and HGnF cells were evaluated using DPPH, Alamar Blue, and 7-amino actinomycin D (7-AAD) assays. The propolis samples presented an average yield of 33.1%, humidity between 1.6 and 2.8%, melting point between 54 and 62 °C, ashes between 1.40 and 2.19%, and waxes of 6.6-17.9%, respectively. The sensory characteristics of all samples were heterogeneous, complying with the quality specifications established by international standards. The polyphenolic and total flavonoid content was representative in the samples from Quebradon (255.9 ± 9.2 mg GAE/g, 543.1 ± 8.4 mg QE/g) and Arcadia (543.1 ± 8.4 mg GAE/g, 32.5 ± 1.18 g QE/g) (p < 0.05) that correlated with high antioxidant activity (Quebradon: 37.2 ± 1.2 µmol/g, Arcadia: 38.19 ± 0.7 µmol/g). In the chemical composition analysis, 19 compounds were characterized as phenolic acids and flavonoids, the most representative being chrysoeriol-O-methyl-ether, ellagic acid, and 3,4-O-dimethylcaffeic acid. Regarding biological activity, Quebradon and Arcadia propolis presented low toxicity with IC50 of 2.83 ± 2.3 mg/mL and 4.28 ± 1.4 mg/mL in HGnF cells, respectively, and an arrest of the cell cycle in the G2/M phase of 71.6% and 50.8% compared to the control (11.9%) (p < 0.05). In general, the results of this study contribute to the identification of valid quality criteria to evaluate Colombian propolis, contributing to its study and chemical and biological characterization as a source of raw material for industrial and pharmaceutical use. In addition, Quebradon and Arcadia propolis can be important sources of bioactive molecules for the development of new drugs.

Preparation of low molecular weight chondroitin sulfate from different sources by H2O2/ascorbic acid degradation and its degradation mechanism

Low molecular weight chondroitin sulfate (LMCS) has attention for enhanced bioavailability and bioactivity compared to native CS. We optimized H2O2/ ascorbic acid (Vc) degradation conditions to prepare LMCS from chicken, bovine, and shark cartilages. Degradation kinetics models and chemical composition data of LMCS showed the GlcA residues of chondroitin-4-sulfate (CSA) may be preferentially attacked. Nuclear magnetic resonance (NMR) spectroscopy and high-performance liquid chromatography-electrospray mass spectrometry (HPLC-MS) indicated that the CH of GlcA in CS was broken through a hydrogen abstraction reaction to break the β-(1 → 3) bond and form the hexendioic acid product. Standard density functional theory (DFT) calculations indicated that the energy required for the hydrogen abstraction from the C1-H bond in GlcA was lower than that of GalNAc. Molecular dynamics (MD) showed that CSA was more likely to interact with hydroxyl radicals (·OH) than non-sulfated chondroitin (CSO) and chondroitin-6-sulfate (CSC). These results provide guidance for producing LMCS.

Phenolic Compound, Antioxidant, Antibacterial, and In Silico Studies of Extracts from the Aerial Parts of Lactuca saligna L

Medicinal plants are considered a major source for discovering novel effective drugs. To our knowledge, no studies have reported the chemical composition and biological activities of Moroccan Lactuca saligna extracts. In this context, this study aims to characterize the polyphenolic compounds distributed in hydro-methanolic extracts of L. saligna and evaluate their antioxidant and antibacterial activities; in addition, in silico analysis based on molecular docking and ADMET was performed to predict the antibacterial activity of the identified phenolic compounds. Our results showed the identification of 29 among 30 detected phenolic compounds with an abundance of dicaffeoyltartaric acid, luteolin 7-glucoronide, 3,5-di-O-caffeoylquinic acid, and 5-caffeoylquinic acid with 472.77, 224.30, 196.79, and 171.74 mg/kg of dried extract, respectively. Additionally, antioxidant activity assessed by DPPH scavenging activity, ferric reducing antioxidant power (FRAP) assay, and ferrous ion-chelating (FIC) assay showed interesting antioxidant activity. Moreover, the results showed remarkable antibacterial activity against Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, and Listeria monocytogenes with minimum inhibitory concentrations between 1.30 ± 0.31 and 10.41 ± 0.23 mg/mL. Furthermore, in silico analysis identified three compounds, including Apigenin 7-O-glucuronide, Quercetin-3-O-glucuronide, and 3-p-Coumaroylquinic acid as potent candidates for developing new antibacterial agents with acceptable pharmacokinetic properties. Hence, L. saligna can be considered a source of phytochemical compounds with remarkable activities, while further in vitro and in vivo studies are required to explore the main biological activities of this plant.

Chrysoeriol Improves In Vitro Porcine Embryo Development by Reducing Oxidative Stress and Autophagy

Chrysoeriol (CHE) is a flavonoid substance that exists in many plants. It has various physiological and pharmacological effects, including anti-inflammatory, antioxidant, anti-tumor, and protective activity, especially for the cardiovascular system and liver. Among common livestock embryos, porcine embryos are often considered high-quality objects for studying the antioxidant mechanisms of oocytes. Because porcine embryos contain high levels of lipids, they are more vulnerable to external stimuli, which affect development. Our study explored the influence of CHE supplementation on oxidative stress in porcine oocytes and its possible mechanisms. Different concentrations of CHE (0, 0.1, 1, and 3 µM) were supplemented in the in vitro culture medium of the porcine oocytes. The results showed that supplementation with 1 µM CHE significantly increased the blastocyst rate and total cell number of embryos in vitro. After finding the beneficial effects of CHE, we measured reactive oxygen species (ROS), glutathione (GSH), and mitochondrial membrane potential (MMP) when the oocytes reached the 4-cell stage of development and determined the levels of apoptosis, cell proliferation, and autophagy at the blastocyst stage of development. The expression levels of some related genes were preliminarily detected by qRT-PCR. The results showed that the apoptosis of blastocysts in the CHE-treated culture also decreased compared with the untreated culture. Furthermore, CHE downregulated intracellular ROS and increased GSH in the embryos. CHE was also shown to improve the activity of mitochondria and inhibit the occurrence of autophagy. In addition, antioxidant-related genes (SOD1, SOD2, and CAT) and cell pluripotency-related genes (SOX2, OCT4, and NANOG) were upregulated. At the same time, apoptosis-related (Caspase 3) and autophagy-related (LC3B) genes showed a downward trend after supplementation with CHE. These results indicate that CHE improved the development of porcine embryos in vitro by reducing oxidative stress and autophagy levels.

Chryseriol attenuates the progression of OVA-induced asthma in mice through NF-κB/HIF-1α and MAPK/STAT1 pathways

BACKGROUND

Asthma is a hackneyed chronic inflammatory disease of the airway. Chryseriol (CSR) is a kind of flavonoid, and has the effect of bronchiectasis, indicating its potential application for treating respiratory diseases. However, the functions of CSR in asthma have not been reported till now.

MATERIALS AND METHODS

The histopathologic changes of the lung tissues were assessed by hematoxylin and eosin staining. The cell apoptosis was identified through terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay. Total numbers of eosinophils, neutrophils, and macrophages were assessed under microscope. The levels of interleukin (IL)-1β, IL-4, IL-5, and IL-13 were detected by enzyme-linked-immunosorbent serologic assay. The airway hyper-responsiveness (AHR) was evaluated by the whole body plethysmography. The levels of methane dicarboxylic aldehyde, superoxide dismutase, glutathione S-transferase, and glutathione in lung homogenates were confirmed by using corresponding commercial kits. The protein expressions were examined by Western blot analysis.

RESULTS

The ovalbumin (OVA) was utilized to establish asthma mouse model. At first, it was revealed that CSR treatment reduced lung injury in OVA-stimulated mice. Moreover, cell apoptosis was enhanced after OVA stimulation but was attenuated by CSR treatment. In addition, CSR treatment decreased the infiltration of inflammatory cells and the production of inflammatory factors in OVA-treated mice. Further investigations demonstrated that CSR treatment relieved AHR in OVA-stimulated mice. The oxidative stress was strengthened in OVA-treated mice, but these effects were relieved by CSR treatment. Lastly, it was discovered that CSR treatment retarded nuclear factor kappa B (NF-κB)/hypoxia-inducible factor 1 alpha (HIF-1α) and p38 mitogen-activated protein kinase (MAPK)/signal transducer and activator of transcription 1 (STAT1) pathways in OVA-triggered asthma mice.

CONCLUSION

Our findings proved that CSR attenuated the progression of OVA-induced asthma in mice through inhibiting NF-κB/HIF-1α and MAPK/STAT1 pathways. This work might highlight the functions of CSR in the treatment of asthma.

Health Benefits and Pharmacological Aspects of Chrysoeriol

A flavone, chrysoeriol is synthetized in several plant species. It comes from several natural sources, especially medicinal plants. The identification and isolation of this compound has been carried out and verified by several research teams using different spectral methods. It seems that the concentration of this molecule is variable and fluctuating depending on the source, the part extracted, the region, and the methods of extraction and characterization. The aim of this paper is to highlight the in vitro and in vivo pharmacological properties of chrysoeriol and to provide insight into its pharmacokinetics. Anticancer, anti-inflammatory, antibacterial, antifungal, anti-osteoporosis, anti-insecticide, and neuroprotective actions have been shown in a number of studies on this chemical. Different mechanisms in theses pharmacological effects include subcellular, cellular, and molecular targets. In vivo pharmacokinetic analysis has proved the good stability of this molecule, showing its promising potential to prevent or treat diseases including cancer, diabetes, inflammation, osteoporosis, Parkinson’s disease, and cardiovascular diseases.

A Preliminary Assessment of the Nutraceutical Potential of Acai Berry (Euterpe sp.) as a Potential Natural Treatment for Alzheimer's Disease

Alzheimer's disease (AD) is characterised by progressive neuronal atrophy and the loss of neuronal function as a consequence of multiple pathomechanisms. Current AD treatments primarily operate at a symptomatic level to treat a cholinergic deficiency and can cause side effects. Hence, there is an unmet need for healthier lifestyles to reduce the likelihood of AD as well as improved treatments with fewer adverse reactions. Diets rich in phytochemicals may reduce neurodegenerative risk and limit disease progression. The native South American palm acai berry (Euterpe oleraceae) is a potential source of dietary phytochemicals beneficial to health. This study aimed to screen the nutraceutical potential of the acai berry, in the form of aqueous and ethanolic extracts, for the ability to inhibit acetyl- and butyryl-cholinesterase (ChE) enzymes and scavenge free radicals via 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) or 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assays. In addition, this study aimed to quantify the acai berry's antioxidant potential via hydrogen peroxide or hydroxyl scavenging, nitric oxide scavenging, lipid peroxidation inhibition, and the ability to reduce ferric ions. Total polyphenol and flavonoid contents were also determined. Acai aqueous extract displayed a concentration-dependent inhibition of acetyl- and butyryl-cholinesterase enzymes. Both acai extracts displayed useful concentration-dependent free radical scavenging and antioxidant abilities, with the acai ethanolic extract being the most potent antioxidant and displaying the highest phenolic and flavonoid contents. In summary, extracts of the acai berry contain nutraceutical components with anti-cholinesterase and antioxidant capabilities and may therefore provide a beneficial dietary component that limits the pathological deficits evidenced in AD.

Role of Mitochondria in Retinal Pigment Epithelial Aging and Degeneration

Retinal pigment epithelial (RPE) cells form a monolayer between the neuroretina and choroid. It has multiple important functions, including acting as outer blood-retina barrier, maintaining the function of neuroretina and photoreceptors, participating in the visual cycle and regulating retinal immune response. Due to high oxidative stress environment, RPE cells are vulnerable to dysfunction, cellular senescence, and cell death, which underlies RPE aging and age-related diseases, including age-related macular degeneration (AMD). Mitochondria are the powerhouse of cells and a major source of cellular reactive oxygen species (ROS) that contribute to mitochondrial DNA damage, cell death, senescence, and age-related diseases. Mitochondria also undergo dynamic changes including fission/fusion, biogenesis and mitophagy for quality control in response to stresses. The role of mitochondria, especially mitochondrial dynamics, in RPE aging and age-related diseases, is still unclear. In this review, we summarize the current understanding of mitochondrial function, biogenesis and especially dynamics such as morphological changes and mitophagy in RPE aging and age-related RPE diseases, as well as in the biological processes of RPE cellular senescence and cell death. We also discuss the current preclinical and clinical research efforts to prevent or treat RPE degeneration by restoring mitochondrial function and dynamics.

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.

The Cross-Talk between Polyphenols and the Target Enzymes Related to Oxidative Stress-Induced Thyroid Cancer

The most serious hallmark step of carcinogenesis is oxidative stress, which induces cell DNA damage. Although in normal conditions ROS are important second messengers, in pathological conditions such as cancer, due to imbalanced redox enzyme expression, oxidative stress can occur. Recent studies with firmly established evidence suggest an interdependence between oxidative stress and thyroid cancer based on thyroid hormone synthesis. Indeed, a reduced antioxidant defense system might play a part in several steps of progression in thyroid cancer. Based on studies that have been conducted previously, future drug designs for targeting enzymatic ROS sources, as a single agent or in combination, have to be tested. Polyphenols represent the potential for modulating biological events in thyroid cancer, including antioxidative activity. Targeting enzymatic ROS sources, without affecting the physiological redox state, might be an important purpose. As regards the underlying chemopreventive mechanisms of natural compounds that have been discussed in other cancer models, the confirmation of the influence of polyphenols on thyroid cancer is inconclusive and rarely available. Therefore, there is a need for further scientific investigations into the features of the antioxidative effects of polyphenols on thyroid cancer. The current review illustrates the association between some polyphenols and the key enzymes that take place in oxidation reactions in developing thyroid cancer cells. This review gives the main points of the enzymatic ROS sources act and redox signaling in normal physiological or pathological contexts and supplies a survey of the currently available modulators of TPO, LOX, NOX, DUOX, Nrf2, and LPO derived from polyphenols.

The Genus Alternanthera: Phytochemical and Ethnopharmacological Perspectives

Ethnopharmacological relevance: The genus Alternanthera (Amaranthaceae) comprises 139 species including 14 species used traditionally for the treatment of various ailments such as hypertension, pain, inflammation, diabetes, cancer, microbial and mental disorders.

Aim of the review: To search research gaps through critical assessment of pharmacological activities not performed to validate traditional claims of various species of Alternanthera. This review will aid natural product researchers in identifying Alternanthera species with therapeutic potential for future investigation.

Materials and methods: Scattered raw data on ethnopharmacological, morphological, phytochemical, pharmacological, toxicological, and clinical studies of various species of the genus Alternanthera have been compiled utilizing search engines like SciFinder, Google Scholar, PubMed, Science Direct, and Open J-Gate for 100 years up to April 2021.

Results: Few species of Alternanthera genus have been exhaustively investigated phytochemically, and about 129 chemical constituents related to different classes such as flavonoids, steroids, saponins, alkaloids, triterpenoids, glycosides, and phenolic compounds have been isolated from 9 species. Anticancer, antioxidant, antibacterial, CNS depressive, antidiabetic, analgesic, anti-inflammatory, and immunomodulator effects have been explored in the twelve species of the genus. A toxicity study has been conducted on 3 species and a clinical study on 2 species.

Conclusions: The available literature on pharmacological studies of Alternanthera species reveals that few species have been selected based on ethnobotanical surveys for scientific validation of their traditional claims. But most of these studies have been conducted on uncharacterized and non-standardized crude extracts. A roadmap of research needs to be developed for the isolation of new bioactive compounds from Alternanthera species, which can emerge out as clinically potential medicines.

Bio-Efficacy of Chrysoeriol7, a Natural Chemical and Repellent, against Brown Planthopper in Rice

Brown planthopper (BPH, Nilaparvata lugens Stal.) is the most damaging rice pest affecting stable rice yields worldwide. Currently, methods for controlling BPH include breeding a BPH-resistant cultivar and using synthetic pesticides. Nevertheless, the continuous cultivation of resistant cultivars allows for the emergence of various resistant races, and the use of synthetic pesticides can induce environmental pollution as well as the emergence of unpredictable new pest species. As plants cannot migrate to other locations on their own to combat various stresses, the production of secondary metabolites allows plants to protect themselves from stress and tolerate their reproduction. Pesticides using natural products are currently being developed to prevent environmental pollution and ecosystem disturbance caused by synthetic pesticides. In this study, after BPH infection in rice, chrysoeriol7 (C7), a secondary metabolite that induces resistance against BPH, was assessed. After C7 treatment and BPH infection, relative expression levels of the flavonoid-related genes were elevated, suggesting that in plants subjected to BPH, compounds related to flavonoids, among the secondary metabolites, play an important role in inducing resistance. The plant-derived natural compound chrysoeriol7 can potentially thus be used to develop environmentally friendly pesticides. The suggested control of BPH can be effectively used to alleviate concerns regarding environmental pollution and to construct a relatively safe rice breeding environment.

Suppression of PI3K/Akt/mTOR pathway in chrysoeriol-induced apoptosis of rat C6 glioma cells

Chrysoeriol, a dietary methoxyflavonoid which is found in tropical medicinal plants, has been shown to have antioxidant, anti-inflammatory, and antineoplastic properties. The present study aimed to investigate the effects of chrysoeriol and its related mechanisms in rat C6 glioma cells. Cell viability in rat C6 glioma cells were measured by MTT assay. The protein expression levels of cleaved caspase-3, caspase-3, pro-apoptotic (Bax), anti-apoptotic protein (Bcl-2), and Annexin V were detected by Western blot analysis and immunocytochemical staining. Results showed that chrysoeriol significantly decreased cell viability and induced apoptosis in rat C6 glioma cells. Chrysoeriol significantly increased the levels of Bax/Bcl-2 ratio and cleaved caspase-3/caspase-3 ratio. Moreover, treatment with chrysoeriol significantly reduced the phosphorylation of PI3K, Akt, and mTOR expression in ratios. These results suggest that chrysoeriol promote apoptosis in rat C6 glioma cells via suppression of the PI3K/Akt/mTOR signaling pathway, thereby demonstrating the potential antineoplastic effects of chrysoeriol on glioma cells.

Investigation of the interaction between Chrysoeriol and xanthine oxidase using computational and in vitro approaches

Xanthine oxidase (XO) plays a vital role in inducing hyperuricemia and increasing the level of superoxide free radicals in blood, and is proved as an important target for gout. Chrysoeriol (CHE) is a natural flavone with potent XO inhibitory activity (IC₅₀ = 2.487 ± 0.213 μM), however, the mechanism of interaction is still unclear. Therefore, a comprehensive analysis of the interaction between CHE and XO was accomplished by enzyme kinetics, isothermal titration calorimetry (ITC), multi-spectroscopic methods, molecular simulation and ADMET. The results showed that CHE acted as a rapid reversible and competitive-type XO inhibitor and its binding to XO was driven by hydrogen bonding and hydrophobic interaction. Moreover, CHE exhibited a strong fluorescence quenching effect through a static quenching procedure and induced conformational changes of XO. Its binding pattern with XO was revealed by docking study and the binding affinity to XO was enhanced by the interactions with key amino acid residues in the active pocket of XO. Further, CHE showed good stability and pharmacokinetic behavior properties in molecule dynamic simulation and ADMET prediction. Overall, this study shed some light on the mechanism of interaction between CHE and XO, also provided some valuable information concerning the future therapeutic application of CHE as natural XO inhibitor.

Rutin: A Flavonoid as an Effective Sensitizer for Anticancer Therapy; Insights into Multifaceted Mechanisms and Applicability for Combination Therapy

Rutin is a unique antioxidant flavonoid that is mainly found in fruit, vegetables, cereals, and many other plant-based human diets. This review aims to highlight the in vitro anticancer properties of rutin including combination therapeutic strategies. Literature resources were gathered through PubMed, Scopus, Web of Science, and Google Scholar databases that cover the period of 1995–2021. Rutin is demonstrated to inhibit the proliferation of breast, colon, lung, and prostate cancers and other tumors. Furthermore, rutin alone or in combination with other therapeutic agents has been shown to regulate several signalling pathways involving the Ras/Raf and PI3K/Akt, MAPK, and TGF-β2/Smad2/3Akt/PTEN, etc., which are related to the processes of carcinogenesis and induction of apoptosis. The combination of rutin with other chemotherapy drugs may benefit on prevention of tumor cells by decreasing drug resistance and chemotherapy side effects. Moreover, rutin induces apoptosis synergistically with the therapeutic agent. More in vivo and clinical data are however needed to evaluate the true potential of rutin as an anticancer agent as an adjuvant. The present review highlights the effects of rutin which can be a promising candidate in combination with other antitumor drugs or alone for cancer treatment in vitro. Also, rutin can lead to decrease in drug resistance and chemotherapeutic side effects.

The role of quercetin in plants

Flavonoids are a special category of hydroxylated phenolic compounds having an aromatic ring structure. Quercetin is aspecial subclass of flavonoid. It is a bioactive natural compound built upon the flavon structure nC6(ring A)-C3(ring C)-C6(ring B). Quercetin facilitates several plant physiological processes, such as seed germination, pollen growth, antioxidant machinery, and photosynthesis, as well as induces proper plant growth and development. Quercetin is a powerful antioxidant, so it potently provides plant tolerance against several biotic and abiotic stresses. This review highlights quercetin's role in increasing several physiological and biochemical processes under stress and non-stress environments. Additionally, this review briefly assesses quercetin's role in mitigating biotic and abiotic stresses (e.g., salt, heavy metal, and UV stress). The biosynthesis of flavonoids, their signaling pathways, and quercetin's role in plant signaling are also discussed.

Ethanolic Extracts of Adlay Testa and Hull and Their Active Biomolecules Exert Relaxing Effect on Uterine Muscle Contraction through Blocking Extracellular Calcium Influx in Ex Vivo and In Vivo Studies

Dysmenorrhea is one of the most prevalent disorders in gynecology. Historically, adlay (Coix lachryma-jobi L. var. Ma-yuen Stapf.) has been explored for its anti-tumor, pain relief, anti-inflammatory, and analgesic effects. The aim of this study was to evaluate the effects of adlay seeds on the inhibition of uterine contraction and thus dysmenorrhea relief, in vitro and in vivo. HPLC-MS and GC were used to elucidate the ethyl acetate fraction of adlay testa ethanolic extract (ATE-EA) and ethyl acetate fraction of adlay hull ethanolic extract (AHE-EA). Elucidation yielded flavonoids, phytosterols, and fatty acids. Uterine leiomyomas and normal adjacent myometrial tissue were evaluated by oxytocin- and PG-induced uterine contractility. ATE-EA and AHE-EA suppressed uterine contraction induced by prostaglandin F2 alpha (PGF_2α), oxytocin, carbachol, and high-KCl solution ex vivo. In addition, the external calcium (Ca²⁺) influx induced contraction, and increased Ca²⁺ concentration was inhibited by ATE-EA and AHE-EA on the uterine smooth muscle of rats. Furthermore, ATE-EA and AHE-EA effectively attenuated the contraction of normal human myometrium tissues more than adjacent uterine leiomyoma in response to PGF_2α. 3,5,6,7,8,3′,4′-Heptamethoxyflavone and chrysoeriol produced a remarkable inhibition with values of IC₅₀ = 24.91 and 25.59 µM, respectively. The experimental results showed that treatment with ATE-EA at 30 mg/day effectively decreased the writhing frequency both on the oxytocin-induced writhing test and acetic acid writhing test of the ICR mouse.

Chrysoeriol ameliorates COX-2 expression through NF-κB, AP-1 and MAPK regulation via the TLR4/MyD88 signaling pathway in LPS-stimulated murine macrophages

Chrysoeriol is a flavonoid that has diverse biological properties, including antioxidation, anti-inflammation, chemoprevention and immunomodulation. Despite its reported anti-inflammatory activity, the exact underlying molecular mechanism has not yet been elucidated. In the current study, the anti-inflammatory mechanism of chrysoeriol involving lipopolysaccharide (LPS)-induced cyclooxygenase-2 (COX-2) and its upstream signaling molecules was investigated in RAW 264.7 cells. The mechanism was evaluated via ELISA and western blotting assays. Chrysoeriol significantly inhibited LPS-induced prostaglandin E₂ (PGE₂) production and COX-2 expression without cytotoxicity. Activated transcription factors that further induced the inflammation response, including nuclear factor (NF)-κB and activator protein-1 (AP-1), were significantly attenuated by chrysoeriol treatment. Furthermore, LPS-induced phosphorylation levels of phosphoinositide-3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK) were abolished by chrysoeriol treatment, which was confirmed by selective inhibitors. Additionally, chrysoeriol significantly inhibited the LPS-induced activation of adaptor molecules in RAW 264.7 cells, including toll-like receptor 4 (TLR4) and myeloid differentiation primary response 88. Therefore, the results suggested that chrysoeriol ameliorates TLR4-mediated inflammatory responses by inhibiting NF-κB and AP-1 activation as well as suppressing PI3K/Akt and MAPK phosphorylation in LPS-stimulated RAW 264.7 cells.

Flavonoids from the Genus Euphorbia: Isolation, Structure, Pharmacological Activities and Structure-Activity Relationships

Plants of the genus Euphorbia are widely distributed across temperate, tropical and subtropical regions of South America, Asia and Africa with established Ayurvedic, Chinese and Malay ethnomedical records. The present review reports the isolation, occurrence, phytochemistry, biological properties, therapeutic potential and structure-activity relationship of Euphorbia flavonoids for the period covering 2000-2020, while identifying potential areas for future studies aimed at development of new therapeutic agents from these plants. The findings suggest that the extracts and isolated flavonoids possess anticancer, antiproliferative, antimalarial, antibacterial, anti-venom, anti-inflammatory, anti-hepatitis and antioxidant properties and have different mechanisms of action against cancer cells. Of the investigated species, over 80 different types of flavonoids have been isolated to date. Most of the isolated flavonoids were flavonols and comprised simple O-substitution patterns, C-methylation and prenylation. Others had a glycoside, glycosidic linkages and a carbohydrate attached at either C-3 or C-7, and were designated as d-glucose, l-rhamnose or glucorhamnose. The structure-activity relationship studies showed that methylation of the hydroxyl groups on C-3 or C-7 reduces the activities while glycosylation loses the activity and that the parent skeletal structure is essential in retaining the activity. These constituents can therefore offer potential alternative scaffolds towards development of new Euphorbia-based therapeutic agents.

Antioxidative Effects of Chrysoeriol via Activation of the Nrf2 Signaling Pathway and Modulation of Mitochondrial Function

Retinal pigment epithelium (RPE) cell dysfunction caused by excessive oxidative damage is partly involved in age-related macular degeneration, which is among the leading causes of visual impairment in elderly people. Here, we investigated the protective role of chrysoeriol against hydrogen peroxide (H₂O₂)-induced oxidative stress in RPE cells. The cellular viability, reactive oxygen species (ROS) generation, and mitochondrial function of retinal ARPE-19 cells were monitored under oxidative stress or pre-treatment with chrysoeriol. The expression levels of mitochondrial-related genes and associated transcription factors were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Moreover, the protein expression of antioxidant signal molecules was characterized by Western blot analysis. Chrysoeriol significantly increased cell viability, reduced ROS generation, and increased the occurrence of antioxidant molecules in H₂O₂-treated ARPE-19 cells. Additionally, mitochondrial dysfunction caused by H₂O₂-induced oxidative stress was also considerably diminished by chrysoeriol treatment, which reduced the mitochondrial membrane potential (MMP) and upregulated mitochondrial-associated genes and proteins. Chrysoeriol also markedly enhanced key transcription factors (Nrf2) and antioxidant-associated genes (particularly HO-1 and NQO-1). Therefore, our study confirms the protective effect of chrysoeriol against H₂O₂-induced oxidative stress in RPE cells, thus confirming that it may prevent mitochondrial dysfunction by upregulating antioxidant-related molecules.

A Novel Chinese Honey from Amorpha fruticosa L.: Nutritional Composition and Antioxidant Capacity In Vitro

False indigo (Amorpha fruticosa L., A. fruticosa) is the preferred tree indigenous for windbreak and sand control in Northwest China, while information on nutritional and bioactive characteristics of its honey is rare. Herein, 12 honey of Amorpha fruticosa L. (AFH) were sampled in Northwest China and the nutritional composition was determined. Sixteen mineral element and ten dominant polyphenols content were identified and quantified by ICP-MS (Inductively coupled plasma mass spectrometry) and HPLC-QTOF-MS (High performance liquid chromatography-Quadrupole time-of-flight mass spectrometry), respectively. Moreover, AFH demonstrated high levels of DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical scavenging activity (IC50 100.41 ± 15.35 mg/mL), ferric reducing antioxidant power (2.04 ± 0.29 µmol FeSO4·7H2O/g), and ferrous ion-chelating activity (82.56 ± 16.01 mg Na2EDTA/kg), which were significantly associated with total phenolic contents (270.07 ± 27.15 mg GA/kg) and ascorbic acid contents (213.69 ± 27.87 mg/kg). The cell model verified that AFH exhibited dose-dependent preventive effects on pBR322 plasmid DNA and mouse lymphocyte DNA damage in response to oxidative stress. Taken together, our findings provide evidence for the future application of AFH as a potential antioxidant dietary in food industry.

Antimicrobial Activity of Chrysoeriol 7 and Chochlioquinone 9, White-Backed Planthopper-Resistant Compounds, Against Rice Pathogenic Strains

As environmental damage caused by chemical pesticides appears worldwide, eco-friendly agriculture is increasing, and finding eco-friendly pesticide materials has become very important. Chrysoeriol and cochlioquinone, two flavonoids, act as an antibacterial and antioxidant, and increase the resistance of rice to the white-backed planthopper (WBPH). In this experiment, chrysoeriol 7 (C7) and cochlioquinone 9 (C9) were extracted from rice inoculated with the WBPH using MeOH, and cultivars with high extraction efficiency were selected. In addition, the antimicrobial activity of C7 and C9 against various pathogens causing disease in rice was tested. The results show that C7 has antifungal activity against Fusarium graminearum and Pythium graminicola, and C9 show antifungal activity against Cladosporium herbarum, Cladosporium cladosporioides, Gibberella zeae, Fusarium graminearum and Pythium graminicola. When both substances were treated at a concentration of 1000 ppm, they showed high inhibition rates of 62.3% and 36.2% against P.graminicola, respectively. After that, a phylogenetic tree was created to clarify the relationship between the microorganisms whose growth was inhibited and divided into three groups. This result can contribute to the study of biopesticide materials that can control pests and pathogens.

Water Soldier Stratiotes aloides L.-Forgotten Famine Plant With Unique Composition and Antioxidant Properties

Stratiotes aloides L. is common water plant in central Poland. Due to its expansive character, S. aloides L. can strongly affect the functioning of aquatic ecosystems. S. aloides L. was an important famine plant in central Poland. This plant was commonly collected and cooked until the turn of the 20th century. It has also been used to heal wounds, especially when these are made by an iron implement. The objective of the present work was to study the phenolic profile in the leaves and roots of S. aloides as well as their antioxidant potential and ability to inhibit lipoxygenase (LOX) in the light of their potential bioaccessibility. The dominant compound in its leaves was luteolin-7-O-hexoside-glucuronide (5.84 mg/g DW), whereas the dominant root component was chrysoeriol-7-O-hexoside-glucuronide (0.83 mg/g DW). Infusions from leaves, roots, and their 1:1 (v/v) mixture contained potentially bioaccessible antiradical compounds. S. aloides is a good source of water-extractable reductive compounds. Especially valuable are the leaves of this plant. The roots of S. aloides contained very active hydrophilic compounds able to chelate metal ions. However, their potential bioaccessibility was relatively low. The hydrophilic compounds from the leaves were the most effective XO inhibitors (EC₅₀ = 9.91 mg DW/mL). The water-extractable compounds derived from the leaves and roots acted as uncompetitive LOX inhibitors.

Investigating the Impact of Various Parameters On the Activity of Acid Phosphatases from Seedlings of Coronopus didymus

The thermal stability of purified acid phosphatase from the germinating seedlings of Coronopus didymus (Jangli halon) was investigated by studying the impact of various thermodynamic parameters [t_1/2, E_d, ΔH° (enthalpy change), ΔG° (free energy change), and ΔS° (entropy change)] of heat treatment in the temperature range of 55-75 °C. The thermal denaturation of acid phosphatase, assessed by loss in activity, was evidently followed by first-order kinetics, which varies with time and yield during the process of denaturation. The half-life of the enzyme was 693 min at 55 °C. The E_d (activation energy of denaturation) was calculated by the Arrhenius plot (30 kcal mol^-1), and the Z-value was 17.3 °C. The various thermodynamic parameters studied were as follows: ΔH°, the change in enthalpy of inactivation, was 121.93 kJ mol^-1 at 55 °C; ΔG°, the change in free energy of inactivation, was 110.65 kJ mol^-1 at 55 °C; and ΔS°, the change in entropy of inactivation, was 34.39 J mol^-1 k^-1 at 55 °C. This suggests that acid phosphatase activity is thermostable to long heat treatment up to 60 °C.

Multitargeting Antibacterial Activity of a Synthesized Mn2+ Complex of Curcumin on Gram-Positive and Gram-Negative Bacterial Strains

Curcumin is an important molecule with a plethora of pharmacological activities and therapeutic potentials. Despite its efficacy, it remained a potential drug candidate owing to hydrolytic instability and poor aqueous solubility. To overcome the limitations related to low solubility, low bioavailability, and the fact that curcumin is never present in solution as a "single unit", its complex was prepared with MnII with the idea that binding to a metal ion might help to resolve these issues. The complex was characterized by elemental and spectral analysis. The structure of the complex was determined by density functional theory calculations. The complex was stable at physiological buffer conditions, unlike curcumin. It did not have any detrimental effect on mammalian cells. There was a significant enhancement in the antibacterial activity of the complex compared to curcumin against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. It showed a strong affinity for deoxyribonucleic acid (DNA) evident from a high binding constant value with calf thymus DNA and also from the retarded electrophoretic mobility of bacterial plasmid DNA. The complex showed "superoxide dismutase-like" activity leading to the generation of reactive oxygen species (ROS). The complex caused bacterial membrane perturbation evident from calcein leakage assay, which was further corroborated by scanning and transmission electron microscopic experiments. Overall, the present study shows improved stability and antibacterial potency of a nontoxic complex over curcumin. Its multitargeting mode of action such as ROS-production, effective binding with DNA, and permeabilization of bacterial membrane together allows it to be an effective antibacterial agent that could be taken further for therapeutic use against bacterial infections.

Antioxidant, Anti-Inflammatory and Cytotoxic Properties of Centaurea africana Lamk var. [Bonnet] M]

BACKGROUND

In Algerian traditional medicine, Centaurea species are well known in traditherapy. Centaurea africana has been used in folk medicine for the treatment of several inflammatory disorders.

OBJECTIVE

This study aims to examine the antioxidant, anti-inflammatory and anti-proliferative potential of both n-Butanol (BECA) and ethyl acetate (EAECA) extracts of Centaurea africana.

METHODS

The phytochemical analysis of both BECA and EAECA were explored and the antioxidant activities were investigated by measuring the DPPH° scavenging effect, the reducing power and the inhibition of lipid peroxidation (LPO) induced by by Fe²⁺/ ascorbic acid system. The antiinflammatory properties were determined by measuring the NO° scavenging effect and by using carrageenan-induced rat paw oedema. The antiproliferative activity was studied on HT29 (human colorectal adenocarcinoma), OV2008 (human ovarian cancer) and C6 (Rattus norvegicus brain glioma) cell lines using the Sulforhodamine B assay.

RESULTS

The total polyphenol contents (TPC) of EAECA and BECA are recorded at 125.24±10.14 and 53.03±2.50 mgGAE/g extract, respectively. Both extracts revealed the antioxidant activity in a concentration-dependent manner; this effect is more pronounced with EAECA. The BECA exhibited a higher anti-inflammatory activity. This anti-inflammatory activity was reflected in a reduction of swelling of carrageenan-evoked edemas (48.45 %), inhibition of nitric oxide (84.7 %), effective decrease in myeloperoxidase activity (58.82 %) and malondialdehyde level (65.58 %). The cytotoxic effect of BECA was found to be more pronounced against C6 cell lines (IC₅₀ value: 131.93 μg/mL) while the cytotoxic activity of EAECA was more effective against HT29 and OV2008 cell lines.

CONCLUSION

The obtained results indicated that EAECA exhibited a high antioxidant activity, while BECA has significant anti-inflammatory activity. Both extracts showed cytotoxic effects against cancer cell lines at certain concentrations in a cell-specific manner.

A combined experimental and DFT approach on free radical induced oxidations of kynurenic acid

Using in vitro methods, the one electron oxidations of kynurenic acid and its efficacy in scavenging lipid peroxidation have been demonstrated.

Effects of Helichrysum bracteatum flower extracts on UVB irradiation-induced inflammatory biomarker expression

Background

The present study aimed to investigate the anti-inflammatory activity of Helichrysum bracteatum (H. bracteatum) flower extracts in vitro.

Methods

H. bracteatum flowers were extracted with water, ethanol and 1,3-butylene glycol, and the anti-oxidative activities of the extracts were measured using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The inhibition of the expression of inflammation-related genes, including tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2), was evaluated in vitro using reverse transcription-PCR in ultraviolet B (UVB)-irradiated human epidermal keratinocytes (HEKa cells). To investigate the inhibitory effects of H. bracteatum flower extracts on UVB-induced inflammatory responses in HEKa cells, the production of nitric oxide (NO) and TNF-α was measured using enzyme-linked immunosorbent assays. Results were expressed as the mean ± standard deviation; statistical significance was calculated using the Student’s t-test.

Results

The DPPH assay results showed that H. bracteatum flower extracts have good anti-oxidative effects and inhibited the expression of inflammation-related genes IL-6, COX-2 and TNF-α. Moreover, the production of NO and TNF-α was inhibited by H. bracteatum flower extracts.

Conclusions

These findings indicate that H. bracteatum flower extracts have efficacy against UVB-induced inflammation-related gene expression.

Chrysoeriol mediates mitochondrial protection via PI3K/Akt pathway in MPP+ treated SH-SY5Y cells

Chrysoeriol is a plant flavone extracted from the roots and leaves of the genus Phyllanthus. Although many biological properties of chrysoeriol have been reported, such as its antioxidant and anti-inflammatory activities, the effects of chrysoeriol on the cellular models of Parkinson's disease (PD) have not yet been elucidated. In the present study, we aimed to investigate whether chrysoeriol prevents neurotoxicity induced by 1-methyl-4-phenylpyridinium iodide (MPP⁺) in SH-SY5Y cells, a typical in vitro PD model. The cell viability was measured by MTT assay. The morphological changes of apoptotic cell nuclei were observed by Hoechst 33,342 staining. The expression of Bax, Bcl-2 and Caspase-3 were detected by western blot analysis. The mitochondria location in the cells was observed by Mitotracker staining. Mitochondrial membrane potential was evaluated by the JC-10 assay. Treatment with MPP⁺ significantly caused a decrease in the viability of cells and an increase in apoptosis, as evidenced by the upregulation of apoptotic cells, caspase-3 activity and antiapoptotic ratio. These effects were all reversed by pretreatment with chrysoeriol in SH-SY5Y cells. Moreover, pretreatment with chrysoeriol markedly mitigated the MPP⁺-caused increases in the levels of the prosurvial signaling proteins, phosphorylated Akt and phosphorylated mTOR. The presence of a specific PI3K inhibitor, wortmannin, particularly abolished the chrysoeriol-induced activation of Akt phosphorylation and prevented the chrysoeriol-induced survival effect. These results indicate that the neuroprotective effect of chrysoeriol against MPP⁺ treatment requires the activation of PI3K/Akt pathway. Ultimately, chrysoeriol could be a promising therapeutic agent for the further experiment on the treatment of PD.

Metabolite profiling in two contrasting Tibetan hulless barley cultivars revealed the core salt-responsive metabolome and key salt-tolerance biomarkers

Salinity stress represents one of the most harmful abiotic stresses for agricultural productivity. Tibetan hulless barley is an important economic crop widely grown in highly stressful conditions in the Qinghai-Tibet Plateau and is often challenged by salinity stress. To investigate the temporal metabolic responses to salinity stress in hulless barley, we performed a widely targeted metabolomic analysis of 72 leaf samples from two contrasting cultivars. We identified 642 compounds 57 % of which were affected by salt stress in the two cultivars, principally amino acids and derivatives, organic acids, nucleotides, and derivatives and flavonoids. A total of 13 stress-related metabolites including piperidine, L-tryptophan, L-glutamic acid, L-saccharopine, L-phenylalanine, 6-methylcoumarin, cinnamic acid, inosine 5'-monophosphate, aminomalonic acid, 6-aminocaproic acid, putrescine, tyramine and abscisic acid (ABA) represent the core metabolome responsive to salinity stress in hulless barley regardless of the tolerance level. In particular, we found that the ABA signalling pathway is essential to salt stress response in hulless barley. The high tolerance of the cultivar 0119 is due to a metabolic reprogramming at key stress times. During the early salt stress stages (0-24 h), 0119 tended to save energy through reduced glycolysis, nucleotide metabolism and amino acid synthesis, while increased antioxidant compounds such as flavonoids. Under prolonged stress (48-72 h), 0119 significantly enhanced energy production and amino acid synthesis. In addition, some important compatible solutes were strongly accumulated. By comparing the two cultivars, nine salt-tolerance biomarkers, mostly unreported salt-tolerance compounds in plants, were uncovered. Our study indicated that the salt tolerant hulless barley cultivar invokes a tolerance strategy which is conserved in other plant species. Overall, we provide for the first time some extensive metabolic data and some important salt-tolerance biomarkers which may assist in efforts to improve hulless barley tolerance to salinity stress.

Bread Enriched With Legume Microgreens and Leaves-Ontogenetic and Baking-Driven Changes in the Profile of Secondary Plant Metabolites

Flavonoids, carotenoids, and chlorophylls were characterized in microgreens and leaves of pea (Pisum sativum) and lupin (Lupinus angustifolius) as these metabolites change during ontogeny. All metabolites were higher in the leaves for both species. Acylated quercetin and kaempferol sophorotrioses were predominant in pea. Genistein and malonylated chrysoeriol were predominant in lupin. Further, the impact of breadmaking on these metabolites using pea and lupin material of two ontogenetic stages as an added ingredient in wheat-based bread was assessed. In "pea microgreen bread" no decrease of quercetin was found with regard to the non-processed plant material. However kaempferol glycosides showed slight decreases induced by the breadmaking process in "pea microgreen bread" and "pea leaf bread." In "lupin microgreen bread" no decrease of genistein compared to the non-processed plant material was found. Chrysoeriol glycosides showed slight decreases induced by the breadmaking process in "lupin microgreen bread" and "lupin leaf bread." In all breads, carotenoids and chlorophylls were depleted however pheophytin formation was caused. Thus, pea and lupin microgreens and leaves are suitable, natural ingredients for enhancing health-promoting secondary plant metabolites in bread and may even be used to tailor bread for specific consumer health needs.

Rice Bran Metabolome Contains Amino Acids, Vitamins & Cofactors, and Phytochemicals with Medicinal and Nutritional Properties

BACKGROUND

Rice bran is a functional food that has shown protection against major chronic diseases (e.g. obesity, diabetes, cardiovascular disease and cancer) in animals and humans, and these health effects have been associated with the presence of bioactive phytochemicals. Food metabolomics uses multiple chromatography and mass spectrometry platforms to detect and identify a diverse range of small molecules with high sensitivity and precision, and has not been completed for rice bran.

RESULTS

This study utilized global, non-targeted metabolomics to identify small molecules in rice bran, and conducted a comprehensive search of peer-reviewed literature to determine bioactive compounds. Three U.S. rice varieties (Calrose, Dixiebelle, and Neptune), that have been used for human dietary intervention trials, were assessed herein for bioactive compounds that have disease control and prevention properties. The profiling of rice bran by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) identified 453 distinct phytochemicals, 209 of which were classified as amino acids, cofactors & vitamins, and secondary metabolites, and were further assessed for bioactivity. A scientific literature search revealed 65 compounds with health properties, 16 of which had not been previously identified in rice bran. This suite of amino acids, cofactors & vitamins, and secondary metabolites comprised 46% of the identified rice bran metabolome, which substantially enhanced our knowledge of health-promoting rice bran compounds provided during dietary supplementation.

CONCLUSION

Rice bran metabolite profiling revealed a suite of biochemical molecules that can be further investigated and exploited for multiple nutritional therapies and medical food applications. These bioactive compounds may also be biomarkers of dietary rice bran intake. The medicinal compounds associated with rice bran can function as a network across metabolic pathways and this metabolite network may occur via additive and synergistic effects between compounds in the food matrix.

Hyperglycemia-induced oxidative stress and heart disease-cardioprotective effects of rooibos flavonoids and phenylpyruvic acid-2-O-β-D-glucoside

Diabetic patients are at an increased risk of developing heart failure when compared to their non-diabetic counter parts. Accumulative evidence suggests chronic hyperglycemia to be central in the development of myocardial infarction in these patients. At present, there are limited therapies aimed at specifically protecting the diabetic heart at risk from hyperglycemia-induced injury. Oxidative stress, through over production of free radical species, has been hypothesized to alter mitochondrial function and abnormally augment the activity of the NADPH oxidase enzyme system resulting in accelerated myocardial injury within a diabetic state. This has led to a dramatic increase in the exploration of plant-derived materials known to possess antioxidative properties. Several edible plants contain various natural constituents, including polyphenols that may counteract oxidative-induced tissue damage through their modulatory effects of intracellular signaling pathways. Rooibos, an indigenous South African plant, well-known for its use as herbal tea, is increasingly studied for its metabolic benefits. Prospective studies linking diet rich in polyphenols from rooibos to reduced diabetes associated cardiovascular complications have not been extensively assessed. Aspalathin, a flavonoid, and phenylpyruvic acid-2-O-β-D-glucoside, a phenolic precursor, are some of the major compounds found in rooibos that can ameliorate hyperglycemia-induced cardiomyocyte damage in vitro. While the latter has demonstrated potential to protect against cell apoptosis, the proposed mechanism of action of aspalathin is linked to its capacity to enhance the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression, an intracellular antioxidant response element. Thus, here we review literature on the potential cardioprotective properties of flavonoids and a phenylpropenoic acid found in rooibos against diabetes-induced oxidative injury.

Dietary flavonoid aglycones and their glycosides: Which show better biological significance?

The dietary flavonoids, especially their glycosides, are the most vital phytochemicals in diets and are of great general interest due to their diverse bioactivity. The natural flavonoids almost all exist as their O-glycoside or C-glycoside forms in plants. In this review, we summarized the existing knowledge on the different biological benefits and pharmacokinetic behaviors between flavonoid aglycones and their glycosides. Due to various conclusions from different flavonoid types and health/disease conditions, it is very difficult to draw general or universally applicable comments regarding the impact of glycosylation on the biological benefits of flavonoids. It seems as though O-glycosylation generally reduces the bioactivity of these compounds - this has been observed for diverse properties including antioxidant activity, antidiabetes activity, anti-inflammation activity, antibacterial, antifungal activity, antitumor activity, anticoagulant activity, antiplatelet activity, antidegranulating activity, antitrypanosomal activity, influenza virus neuraminidase inhibition, aldehyde oxidase inhibition, immunomodulatory, and antitubercular activity. However, O-glycosylation can enhance certain types of biological benefits including anti-HIV activity, tyrosinase inhibition, antirotavirus activity, antistress activity, antiobesity activity, anticholinesterase potential, antiadipogenic activity, and antiallergic activity. However, there is a lack of data for most flavonoids, and their structures vary widely. There is also a profound lack of data on the impact of C-glycosylation on flavonoid biological benefits, although it has been demonstrated that in at least some cases C-glycosylation has positive effects on properties that may be useful in human healthcare such as antioxidant and antidiabetes activity. Furthermore, there is a lack of in vivo data that would make it possible to make broad generalizations concerning the influence of glycosylation on the benefits of flavonoids for human health. It is possible that the effects of glycosylation on flavonoid bioactivity in vitro may differ from that seen in vivo. With in vivo (oral) treatment, flavonoid glycosides showed similar or even higher antidiabetes, anti-inflammatory, antidegranulating, antistress, and antiallergic activity than their flavonoid aglycones. Flavonoid glycosides keep higher plasma levels and have a longer mean residence time than those of aglycones. We should pay more attention to in vivo benefits of flavonoid glycosides, especially C-glycosides.

Metabolic Disposition of Luteolin Is Mediated by the Interplay of UDP-Glucuronosyltransferases and Catechol-O-Methyltransferases in Rats

Luteolin partially exerts its biologic effects via its metabolites catalyzed by UDP-glucuronosyltransferases (UGTs) and catechol-O-methyltransferases (COMTs). However, the interplay of UGTs and COMTs in mediating luteolin disposition has not been well clarified. In this study, we investigated the glucuronidation and methylation pathways of luteolin mediated by the interplay of UGTs and COMTs in vivo and in vitro. A total of nine luteolin metabolites was detected in rat plasma and bile by liquid chromatography-tandem mass spectrometry, namely, three glucuronides, two methylated metabolites, and four methylated glucuronides. Luteolin-3'-glucuronide (Lut-3'-G) exhibited the highest systemic exposure among these metabolites. Kinetics studies in rat liver S9 fractions suggested two pathways, as follows: 1) Luteolin was glucuronidated to luteolin-7-glucuronide, luteolin-4'-glucuronide, and Lut-3'-G by UGTs, and then Lut-7-G was methylated to chrysoeriol-7-glucuronide and diosmetin-7-glucuronide by COMTs. 2) Alternatively, luteolin was methylated to chrysoeriol and diosmetin by COMTs, and then chrysoeriol and diosmetin were glucuronidated by UGTs to their respective glucuronides. The methylation rate of luteolin was significantly increased by the absence of glucuronidation, whereas the glucuronidation rate was increased by the absence of methylation, but to a lesser extent. In conclusion, two pathways mediated by the interplay of UGTs and COMTs are probably involved in the metabolic disposition of luteolin. The glucuronidation and methylation of luteolin compensate for each other, although glucuronidation is the predominant pathway.

Bioassay-guided isolation of cytotoxic flavonoids from aerial parts of Coronopus didymus

ETHNOPHARMACOLOGICAL RELEVANCE

Coronopus didymus Linn. (Brassicaceae) is a medicinal plant used traditionally as antipyretic, expectorant, to purify blood and for alleviating symptoms of pain, inflammations, malaria, wounds and cancer.

AIM OF THE STUDY

The present study was designed to isolate and identify the cytotoxic compounds responsible for anticancer activity from this traditionally useful medicinal plant.

MATERIALS AND METHODS

Bioassay-guided fractionation of the ethanolic extract of aerial parts of C. didymus allowed the isolation of compounds responsible for anticancer activity. Their structures were elucidated by UV Spectroscopy (with shift reagents), ESI-MS and NMR spectral data. Preliminary anticancer activity of ethanolic extract, different fractions and isolated compounds was assessed through MTT in vitro cytotoxicity assay in a dose dependent manner against human cancer cell lines (HeLa and LN18) and normal 293T cells.

RESULTS

Three flavonoids namely 5,7,4'-trihydroxy-3'-methoxyflavone-4'-O-β-D-glucoside (1), 5,7,4'-trihydroxy-3'-methoxyflavone-4'-O-(6''-acetyl)-β-D-glucoside (2) and 5,7,4'-trihydroxy-3'-methoxy flavone (3), were isolated from aerial parts. Compound 1 was identified for the first time from the genus Coronopus. All the compounds 1-3 showed promising activity against HeLa cells with IC50 values of 43.50, 0.63 and 3.67 µM, respectively. Significant result was also obtained with compound 3 against LN18 cells with IC50 value of 46.63 µM.

CONCLUSION

The cytotoxic activity of the crude extract and fractions which may largely be due to its major isolated constituents, flavonoids 1-3, against both HeLa and LN18 cells provides a scientific basis for the ethnopharmacological use of C. didymus as anticancer agent.

Regioselective Glucuronidation of Diosmetin and Chrysoeriol by the Interplay of Glucuronidation and Transport in UGT1A9-Overexpressing HeLa Cells

This study aimed to determine the reaction kinetics of the regioselective glucuronidation of diosmetin and chrysoeriol, two important methylated metabolites of luteolin, by human liver microsomes (HLMs) and uridine-5′-diphosphate glucuronosyltransferase (UGTs) enzymes. This study also investigated the effects of breast cancer resistance protein (BCRP) on the efflux of diosmetin and chrysoeriol glucuronides in HeLa cells overexpressing UGT1A9 (HeLa—UGT1A9). After incubation with HLMs in the presence of UDP-glucuronic acid, diosmetin and chrysoeriol gained two glucuronides each, and the OH—in each B ring of diosmetin and chrysoeriol was the preferable site for glucuronidation. Screening assays with 12 human expressed UGT enzymes and chemical-inhibition assays demonstrated that glucuronide formation was almost exclusively catalyzed by UGT1A1, UGT1A6, and UGT1A9. Importantly, in HeLa—UGT1A9, Ko143 significantly inhibited the efflux of diosmetin and chrysoeriol glucuronides and increased their intracellular levels in a dose-dependent manner. This observation suggested that BCRP-mediated excretion was the predominant pathway for diosmetin and chrysoeriol disposition. In conclusion, UGT1A1, UGT1A6, and UGT1A9 were the chief contributors to the regioselective glucuronidation of diosmetin and chrysoeriol in the liver. Moreover, cellular glucuronidation was significantly altered by inhibiting BCRP, revealing a notable interplay between glucuronidation and efflux transport. Diosmetin and chrysoeriol possibly have different effects on anti-cancer due to the difference of UGT isoforms in different cancer cells.

The influence of the carbohydrate anomeric linkage on the free radical scavenging activity of enzymatically-synthesized phenolic glycosides

Phenolic glycosides, widely recognized for their nutraceutical properties exist in nature as α- and β-glycosides.

Anticancer activities of citrus peel polymethoxyflavones related to angiogenesis and others

Citrus is a kind of common fruit and contains multiple beneficial nutrients for human beings. Flavonoids, as a class of plant secondary metabolites, exist in citrus fruits abundantly. Due to their broad range of pharmacological properties, citrus flavonoids have gained increased attention. Accumulative in vitro and in vivo studies indicate protective effects of polymethoxyflavones (PMFs) against the occurrence of cancer. PMFs inhibit carcinogenesis by mechanisms like blocking the metastasis cascade, inhibition of cancer cell mobility in circulatory systems, proapoptosis, and antiangiogenesis. This review systematically summarized anticarcinogenic effect of citrus flavonoids in cancer therapy, together with the underlying important molecular mechanisms, in purpose of further exploring more effective use of citrus peel flavonoids.

Effective antidiabetic and antioxidant fractions of Otostegia persica extract and their constituents

CONTEXT

Otostegia persica (Burm.) Boiss. (Lamiaceae), "Goldar" in Persian, is widely used in the folk medicine of south Iran for control of diabetes mellitus.

OBJECTIVE

In the present study, hypoglycemic and antioxidant effects of different fractions of the O. persica extract were investigated and constituents of effective fractions were elucidated.

MATERIALS AND METHOD

Different concentrations (100-400 mg/kg) of aqueous infusion (AI) of flowering aerial parts of the plant (traditional preparation) and all fractions of the O. persica extract (i.p. injection) were tested for antidiabetic activity in streptozocin-induced diabetic NMRI mice. Blood glucose level was measured at time 0 and intervals of 1, 2, 4, and 6 h later. Antioxidant activities of different fractions of the plant extract and pure compounds (0.1, 0.5, and 1 mg/ml) were determined with the DPPH method. Four compounds were isolated and identified from potent fractions.

RESULTS AND DISCUSSION

Antidiabetic activity demonstrated that the effect of the methanol fraction at a dose of 300 mg/kg was equivalent with glibenclamide, and at a dose of 400 mg/kg was comparable with glibenclamide and insulin (p > 0.05). The EC50 of the methanol fraction was 307.12 mg. Methanol and ethyl acetate fractions showed antioxidant activities (both IC50 equal to 0.49 mg/ml), so these fractions were selected for the purification of compounds. Chrysoeriol from ethyl acetate and three apigenin derivatives (6-methylapigenin, apigenin-7-O-glucoside, and echinaticin) from the methanol fraction were isolated and identified (new for the species). Chrysoeriol exhibited potent antioxidant activity comparable with vitamin E and BHT (p > 0.05).

CONCLUSION

The present study confirmed the folklore usage of O. persica for antidiabetic properties.

Flavones: an important scaffold for medicinal chemistry

Flavones have antioxidant, anti-proliferative, anti-tumor, anti-microbial, estrogenic, acetyl cholinesterase, anti-inflammatory activities and are also used in cancer, cardiovascular disease, neurodegenerative disorders, etc. Also, flavonoids are found to have an effect on several mammalian enzymes like protein kinases that regulate multiple cell signaling pathways and alterations in multiple cellular signaling pathways are frequently found in many diseases. Flavones have been an indispensable anchor for the development of new therapeutic agents. The majority of metabolic diseases are speculated to originate from oxidative stress, and it is therefore significant that recent studies have shown the positive effect of flavones on diseases related to oxidative stress. Due to the wide range of biological activities of flavones, their structure-activity relationships have generated interest among medicinal chemists. The outstanding development of flavones derivatives in diverse diseases in very short span of time proves its magnitude for medicinal chemistry research. The present review gives detail about the structural requirement of flavone derivatives for various pharmacological activities. This information may provide an opportunity to scientists of medicinal chemistry discipline to design selective, optimize as well as poly-functional flavone derivatives for the treatment of multi-factorial diseases.

WITHDRAWN: Flavonoid glycosylation and biological benefits

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Total flavonoids from Plumula Nelumbinis suppress angiotensin II-induced fractalkine production by inhibiting the ROS/NF-κB pathway in human umbilical vein endothelial cells

Angiotensin II (Ang II) is a neuroendocrine factor that promotes hypertension and has been implicated in vascular inflammation through the induction of reactive oxygen species (ROS) and proinflammatory genes in endothelial cells. However, relatively little attention has been paid to the effect of Ang II on fractalkine (FKN), an important chemokine involved in endothelial dysfunction. In the study, we aimed to investigate the protective role of total flavonoids from Plumula Nelumbinis (TFPN), the main component extracted from Semen Nelumbinis, in Ang II-induced oxidative stress injury in human umbilical vein endothelial cells (HUVECs). Furthermore, we studied whether TFPN could attenuate the Ang II-induced generation of ROS and the activation of nuclear factor-κB (NF-κB); whether these Ang II-induced effects were inhibited by apocynin (a nicotinamide adenine dinucleotide phosphate oxidase inhibitor) and pyrrolidine dithiocarbamate (an NF-κB inhibitor). In the present study, it was observed that total flavonoids from Plumula Nelumbinis (TFPN), the main component extracted from Semen Nelumbinis, concentration-dependently inhibited the FKN production induced by Ang II in human umbilical vein endothelial cells (HUVECs). Furthermore, TFPN attenuated the Ang II-induced generation of ROS and the activation of nuclear factor-κB (NF-κB); these Ang II-induced effects were also inhibited by apocynin (a nicotinamide adenine dinucleotide phosphate oxidase inhibitor) and pyrrolidine dithiocarbamate (an NF-κB inhibitor). In conclusion, the findings of the present study indicate that TFPN attenuate Ang II-induced upregulation of FKN by inhibiting the ROS/NF-κB pathway in HUVECs and thus have a suppressive effect on vascular inflammation.