Inhibitory effect of Erigeron breviscapus extract and its flavonoid components on GABA shunt enzymes

Is hepatic GABA transaminase a promising target for obesity and epilepsy treatments?

γ-Aminobutyric acid (GABA) transaminase (GABA-T) is a GABA-degrading enzyme that plays an essential role in regulating GABA levels and maintaining supplies of GABA. Although GABA in the mammalian brain was discovered 70 years ago, research on GABA and GABA-T has predominantly focused on the brain. Notwithstanding the high activity and expression of GABA-T in the liver, the exact functions of GABA-T in the liver remain unknown. This article reviews the up-to-date information on GABA-T in the liver. It presents recent findings on the role of liver GABA-T in food intake suppression and appetite regulation. Finally, the potential functions of liver GABA-T in other neurological diseases, natural GABA-T inhibitors, and future perspectives in this research area are discussed.

Baicalein exerts anxiolytic and antinociceptive effects in a mouse model of posttraumatic stress disorder: Involvement of the serotonergic system and spinal delta-opioid receptors

Post-traumatic stress disorder (PTSD) is a serious mental disease featured by a stress dysfunction that occurs after an individual has faced intense mental stress, often accompanied by anxiety and chronic pain. Currently, the mainstream drug for PTSD is serotonin reuptake inhibitors (SSRIs), however, their pain management for patients is limited. Baicalein, a Chinese traditional herbal medicine, has shown promising results in treating anxiety, depression, and pain. In this study, we found that baicalein may alleviate single prolonged stress (SPS)-induced PTSD-like behaviors in mice without altering baseline nociceptive sensitivity or activity. Meanwhile, baicalein increased the noradrenaline (NE) and serotonin (5-HT) content and decreased the ratio of 5-hydroxyindoleacetic acid (5-HIAA)/5-HT by inhibiting the activity of monoamine oxidase A (MAO-A) in SPS-induce mice. The anxiolytic and antinociceptive effects induced by baicalein were totally abolished by 5-HT depleting agents. Moreover, the anxiolytic effects of baicalein could be abolished by the 5-HT_1A receptor antagonist WAY-100635, and the analgesic effects could be abolished by delta-opioid receptor antagonists in the spinal. Taken together, our study provides compelling evidence that baicalein reversed anxiety-like behaviors and neuropathic pain in PTSD through serotonergic system and spinal delta-opioid receptors.

Structure-guided discovery of food-derived GABA-T inhibitors as hunters for anti-anxiety compounds

With the acceleration of the pace of life, people may face all kinds of pressure, and anxiety has become a common mental issue that is seriously affecting human life. Safe and effective food-derived compounds may be used as anti-anxiety compounds. In this study, anti-anxiety compounds were collected and curated for database construction. Quantitative structure-activity relationship (QSAR) models were developed using a combination of various machine-learning approaches and chemical descriptors to predict natural compounds in food with anti-anxiety effects. High-throughput molecular docking was used to screen out compounds that could function as anti-anxiety molecules by inhibiting γ-aminobutyrate transaminase (GABA-T) enzyme, and 7 compounds were screened for in vitro activity verification. Pharmacokinetic analysis revealed three compounds (quercetin, lithocholic acid, and ferulic acid) that met Lipinski's Rule of Five and inhibited the GABA-T enzyme to alleviate anxiety in vitro. The established QSAR model combined with molecular docking and molecular dynamics was proved by the synthesis and discovery of novel food-derived anti-anxiety compounds.

Erigeron breviscapus (Vant.) Hand-Mazz.: A Promising Natural Neuroprotective Agent for Alzheimer's Disease

Alzheimer’s disease (AD) is the most common neurodegenerative disease and is characterized by progressive cognitive dysfunction and memory loss in the elderly, which seriously affects the quality of their lives. Currently, the pathogenesis of AD remains unclear. Molecular biologists have proposed a variety of hypotheses, including the amyloid-β hypothesis, tau hyperphosphorylation hypothesis, cholinergic neuron injury, inflammation caused by an abnormal immune response, and gene mutation. Drugs based on these pathological studies, including cholinesterase inhibitors and N-methyl-D-aspartate receptor antagonists, have achieved a certain level of efficacy but are far from meeting clinical needs. In the recent years, some important advances have been made in the traditional Chinese medicine treatment of AD. Erigeron breviscapus (Vant.) Hand-Mazz. (EBHM) is an important medicinal plant distributed in Yunnan Province, China. Studies have shown that EBHM and its active ingredients have a variety of pharmacological effects with good therapeutic effects and wide application prospects for cognitive disability-related diseases. However, to our best knowledge, only few review articles have been published on the anti-AD effects of EBHM. Through a literature review, we identified the possible pathogenesis of AD, discussed the cultivation and phytochemistry of EBHM, and summarized the pharmacological mechanism of EBHM and its active ingredients in the treatment of AD to provide suggestions regarding anti-AD therapy as well as a broader insight into the therapeutic potential of EBHM.

Role of medicinal plants in inhibiting SARS-CoV-2 and in the management of post-COVID-19 complications

BACKGROUND

The worldwide corona virus disease outbreak, generally known as COVID-19 pandemic outbreak resulted in a major health crisis globally. The morbidity and transmission modality of COVID-19 appear more severe and uncontrollable. The respiratory failure and following cardiovascular complications are the main pathophysiology of this deadly disease. Several therapeutic strategies are put forward for the development of safe and effective treatment against SARS-CoV-2 virus from the pharmacological view point but till date there are no specific treatment regimen developed for this viral infection.

PURPOSE

The present review emphasizes the role of herbs and herbs-derived secondary metabolites in inhibiting SARS-CoV-2 virus and also for the management of post-COVID-19 related complications. This approach will foster and ensure the safeguards of using medicinal plant resources to support the healthcare system. Plant-derived phytochemicals have already been reported to prevent the viral infection and to overcome the post-COVID complications like parkinsonism, kidney and heart failure, liver and lungs injury and mental problems. In this review, we explored mechanistic approaches of herbal medicines and their phytocomponenets as antiviral and post-COVID complications by modulating the immunological and inflammatory states.

STUDY DESIGN

Studies related to diagnosis and treatment guidelines issued for COVID-19 by different traditional system of medicine were included. The information was gathered from pharmacological or non-pharmacological interventions approaches. The gathered information sorted based on therapeutic application of herbs and their components against SARSCoV-2 and COVID-19 related complications.

METHODS

A systemic search of published literature was conducted from 2003 to 2021 using different literature database like Google Scholar, PubMed, Science Direct, Scopus and Web of Science to emphasize relevant articles on medicinal plants against SARS-CoV-2 viral infection and Post-COVID related complications.

RESULTS

Collected published literature from 2003 onwards yielded with total 625 articles, from more than 18 countries. Among these 625 articles, more than 95 medicinal plants and 25 active phytomolecules belong to 48 plant families. Reports on the therapeutic activity of the medicinal plants belong to the Lamiaceae family (11 reports), which was found to be maximum reported from 4 different countries including India, China, Australia, and Morocco. Other reports on the medicinal plant of Asteraceae (7 reports), Fabaceae (8 reports), Piperaceae (3 reports), Zingiberaceae (3 reports), Ranunculaceae (3 reports), Meliaceae (4 reports) were found, which can be explored for the development of safe and efficacious products targeting COVID-19.

CONCLUSION

Keeping in mind that the natural alternatives are in the priority for the management and prevention of the COVID-19, the present review may help to develop an alternative approach for the management of COVID-19 viral infection and post-COVID complications from a mechanistic point of view.

Metabolism and Pharmacological Mechanisms of Active Ingredients in Erigeron breviscapus

BACKGROUND

Erigeron breviscapus (Vant.) Hand-Mazz. is a plant species in the Compositae family. More than ten types of compounds-such as flavonoids, caffeinate esters, and volatile oils-have been identified in Erigeron breviscapus; however, it remains unknown as to which compounds are associated with clinical efficacy. In recent years, flavonoids and phenolic acids have been considered as the main effective components of Erigeron breviscapus. The metabolism and mechanisms of these compounds in vivo have been extensively studied to improve our understanding of the drug.

METHODS

In the present review, we summarize the relationships among these compounds, their metabolites, and their pharmacodynamics. Many methods have been implemented to improve the separation and bioavailability of these compounds from Erigeron breviscapus.

RESULTS

In China, Erigeron breviscapus has been used for many years. In recent years, through the study of its metabolism and the mechanisms of its effective components, the effects of Erigeron breviscapus in the treatment of various diseases have been extensively studied. Findings have indicated that Erigeron breviscapus improves cardiovascular and cerebrovascular function and that one of its ingredients, scutellarin, has potential value in the treatment of Alzheimer's disease, cancer, diabetic vascular complications, and other conditions. In addition, phenolic acid compounds and their metabolites also play an important role in anti-oxidation, anti-inflammation, and improving blood lipids.

CONCLUSION

Erigeron breviscapus plays an important role in the prevention and treatment of cardiovascular/ cerebrovascular diseases, neuroprotection, and cancer through many different mechanisms of action. Further investigation of its efficacious components and metabolites may provide more possibilities for the clinical application of traditional Chinese medicine and the development of novel drugs.

Flavonoids as an Intervention for Alzheimer's Disease: Progress and Hurdles Towards Defining a Mechanism of Action

Attempts to develop a disease modifying intervention for Alzheimer's disease (AD) through targeting amyloid β (Aβ) have so far been unsuccessful. There is, therefore, a need for novel therapeutics against alternative targets coupled with approaches which may be suitable for early and sustained use likely required for AD prevention. Numerous in vitro and in vivo studies have shown that flavonoids can act within processes and pathways relevant to AD, such as Aβ and tau pathology, increases in BDNF, inflammation, oxidative stress and neurogenesis. However, the therapeutic development of flavonoids has been hindered by an ongoing lack of clear mechanistic data that fully takes into consideration metabolism and bioavailability of flavonoids in vivo. With a focus on studies that incorporate these considerations into their experimental design, this review will evaluate the evidence for developing specific flavonoids as therapeutics for AD. Given the current lack of success of anti-Aβ targeting therapeutics, particular attention will be given to flavonoid-mediated regulation of tau phosphorylation and aggregation, where there is a comparable lack of study. Reflecting on this evidence, the obstacles that prevent therapeutic development of flavonoids will be examined. Finally, the significance of recent advances in flavonoid metabolomics, modifications and influence of the microbiome on the therapeutic capacity of flavonoids in AD are explored. By highlighting the potential of flavonoids to target multiple aspects of AD pathology, as well as considering the hurdles, this review aims to promote the efficient and effective identification of flavonoid-based approaches that have potential as therapeutic interventions for AD.

Ruta graveolens and rutin, as its major compound: investigating their effect on spatial memory and passive avoidance memory in rats

Context: There are numerous pharmacological activities for Ruta graveolens and its bioactive constituent, rutin, on learning and memory.Objective: This study aimed to examine the effect of R. graveolens and rutin on memory in rats.Materials and methods: In this study animals were treated with the hydroalcholic extract of R. graveolens and rutin by IP injection for 10 days. Behavioural and biochemical tests as well as HPLC analysis and antioxidant activity of extract have been evaluated.Results: R. graveolens extract and rutin significantly increased learning and improved spatial memory, as well as secondary latency; moreover, there were significant increases in the serum and brain antioxidant capacity as well as the level of TBARS in serum and brain tissues. Results also showed that R. graveolens has significant DPPH radical scavenging effect (IC50: 159.17 ± 1.56 μg/mL). The HPLC analysis of extract showed that caffeic acid (19.92 ± 0.01), rutin (40.15 ± 0.01), and apigenin (0.84 ± 0.01) mg/g of dry extract are the main components of the extract.Discussion and conclusion: Regarding the effects of R. graveolens extract and rutin on animal brain cells, memory function, and learning, additional studies, including clinical trials, might be beneficial in producing natural supplementary drugs from this herb.

Genome-wide identification and expression profile of the MADS-box gene family in Erigeron breviscapus

The MADS-box gene family encodes transcription factors with many biological functions that extensively regulate plant growth, development and reproduction. Erigeron breviscapus is a medicinal herb used widely in traditional Chinese medicine, and is believed to improve blood circulation and ameliorate platelet coagulation. In order to gain a detailed understanding of how transcription factor expression may regulate the growth of this potentially important medicinal plant, a genome-wide analysis of the MADS-box gene family of E. breviscapus is needed. In the present study, 44 MADS-box genes were identified in E. breviscapus and categorized into five subgroups (MIKC, Mα, Mβ, Mγ and Mδ) according to their phylogenetic relationships with the Arabidopsis MADS-box genes. Additionally, the functional domain, subcellular location and motif compositions of the E. breviscapus MADS-box gene products were characterized. The expression levels for each of the E. breviscapus MADS-box (EbMADS) genes were analyzed in flower, leaf, stem and root organs, and showed that the majority of EbMADS genes were expressed in flowers. Meanwhile, some MADS genes were found to express high levels in leaf, stem and root, indicating that the MADS-box genes are involved in various aspects of the physiological and developmental processes of the E. breviscapus. The results from gene expression analysis under different pollination treatments revealed that the MADS-box genes were highly expressed after non-pollinated treatment. To the best of our knowledge, this study describes the first genome-wide analysis of the E. breviscapus MADS-box gene family, and the results provide valuable information for understanding of the classification, cloning and putative functions of the MADS-box family.

Systematic investigation of the Erigeron breviscapus mechanism for treating cerebrovascular disease

ETHNOPHARMACOLOGICAL RELEVANCE

Cerebrovascular diseases (CBVDs), characterized by striking morbidity and mortality, have become the most common life-threatening diseases. The existing drugs of CBVDs target one or a few of pathogenic factors, the efficacy of which is limited because of the complexity of CBVDs. Traditional Chinese medicine (TCM), featured by multi-component and multi-target endows the great effectiveness in CBVDs treatment. For instance, Erigeron breviscapus (vant.) Hand. Mazz. （Erigeron breviscapus) has been used to treat CBVDs for a long time and the efficacy has been verified through years' of practice. Nevertheless, the mechanisms of Erigeron breviscapus for treating CBVDs are still unclear.

THE AIM OF THE STUDY

Systematically decipher the mechanisms of Erigeron breviscapus for treating CBVDs.

MATERIALS AND METHODS

The systems pharmacology approach is utilized by integrating ADME pharmacokinetic screening, target fishing, protein-protein interaction (PPI), network analysis and in vitro experiments verification.

RESULTS

First, 14 potentially active molecules were screened out through in silico ADME pharmacokinetic evaluation, most of which have been reported with excellent biological activities. Then 169 targets of active molecules were read out using our in-house softwares, systems drug targeting (sysDT) and Weighted Ensemble Similarity(WES). We found that the targets of the active compounds were significantly enriched to the CBVDs therapeutic targets by analyzing their biological processes and protein-protein interactions (PPIs). A multi-layer network analysis including compound-target network, target-pathway network and "CBVDs pathway" indicated that the Erigeron breviscapus exerts a protective effect on CBVDs via regulating multiple pathways and hitting on multiple targets. Meanwhile in vitro experiments confirmed that the stigmasterol, scutellarein, and daucosterol from Erigeron breviscapus increased the MEK and PLCγ proteins levels, and decreased the expression of Bax, PI3K, and eNOS, which led to the cell survival, proliferation and contraction.

CONCLUSION

The approach used in this work offers a new exemplification for systematically understanding the mechanisms of herbal medicines, which will give an impulse to the CBVDs drug development.

The Effect of 4-hydroxybenzaldehyde on the γ-aminobutyric Acid Type A Receptor

The α₁β₂γ₂ subtype of GABA_A receptors is the most commonly found GABA_A receptor subtype in the mammalian cortex and hippocampus. It is expressed heterologously in the Xenopus laevis oocyte as a α₁β₂γ₂S/L subtype for application as an in vitro model for the screening of compounds that modulate receptor activities. In fact, 4-hydroxybenzaldehyde (4-HB) has been identified as one of the major components in Dendrocalamus asper bamboo shoots in our previous study, and the current study showed that at 101.7 μM, 4-HB significantly reduced the GABA-induced chloride current of GABA_A receptors expressed on Xenopus oocytes, indicating a possible GABAergic antagonistic effect at high concentrations.

Synthesis and Bioactivity Characterization of Scutellarein Sulfonated Derivative

Scutellarin (1) has been widely used to treat acute cerebral infarction in clinic, but poor aqueous solubility decreases its bioavailability. Interestingly, scutellarin (1) could be metabolized into scutellarein (2) in vivo. In this study, a sulfonic group was introduced at position C-8 of scutellarein (2) to enhance the aqueous solubility of the obtained derivative (3). DPPH (1,1-diphenyl-2-picrylhydrazyl)-radical scavenging ability and antithrombic activity were also conducted to determine its bioactivity. The result showed that scutellarein derivate (3) could be a better agent for ischemic cerebrovascular disease treatment.

Transcriptomic comparison of the self-pollinated and cross-pollinated flowers of Erigeron breviscapus to analyze candidate self-incompatibility-associated genes

BACKGROUND

Self-incompatibility (SI) is a widespread and important mating system that promotes outcrossing in plants. Erigeron breviscapus, a medicinal herb used widely in traditional Chinese medicine, is a self-incompatible species of Asteraceae. However, the genetic characteristics of SI responses in E. breviscapus remain largely unknown. To understand the possible mechanisms of E. breviscapus in response to SI, we performed a comparative transcriptomic analysis with capitulum of E. breviscapus after self- and cross-pollination, which may provide valuable information for analyzing the candidate SI-associated genes of E. breviscapus.

METHODS

Using a high-throughput next-generation sequencing (Illumina) approach, the transcriptionexpression profiling of the different genes of E. breviscapus were obtained, some results were verified by quantitative real time PCR (qRT-PCR).

RESULTS

After assembly, 63,485 gene models were obtained (average gene size 882 bp; N50 = 1485 bp), among which 38,540 unigenes (60.70% of total gene models) were annotated by comparisons with four public databases (Nr, Swiss-Prot, KEGG and COG): 38,338 unigenes (60.38% of total gene models) showed high homology with sequences in the Nr database. Differentially expressed genes were identified among the three cDNA libraries (non-, self- and cross-pollinated capitulum of E. breviscapus), and approximately 230 genes might be associated with SI responses. Several these genes were upregulated in self-pollinated capitulum but downregulated in cross-pollinated capitulum, such as SRLK (SRK-like) and its downstream signal factor, MLPK. qRT-PCR confirmed that the expression patterns of EbSRLK1 and EbSRLK3 genes were not closely related to SI of E. breviscapus.

CONCLUSIONS

This work represents the first large-scale analysis of gene expression in the self-pollinated and cross-pollinated flowers of E. breviscapus. A larger number of notable genes potentially involved in SI responses showed differential expression, including genes playing crucial roles in cell-cell communication, signal transduction and the pollination process. We thus hypothesized that those genes showing differential expression and encoding critical regulators of SI responses, such as MLPK, ARC1, CaM, Exo70A1, MAP, SF21 and Nod, might affect SI responses in E. breviscapus. Taken together, our study provides a pool of SI-related genes in E. breviscapus and offers a valuable resource for elucidating the mechanisms of SI in Asteraceae.

Comparative Metabolomic Analysis of the Neuroprotective Effects of Scutellarin and Scutellarein against Ischemic Insult

For more than thirty years, scutellarin (Scu) has been used in China to clinically treat acute cerebral infarction and paralysis. Scutellarein (Scue), the major Scu metabolite in vivo, exhibits heightened neuroprotective effects when compared to Scu. To explore the neuroprotective role of these compounds, we performed ultra-high-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UHPLC-QTOF/MS) coupled with a pattern recognition approach to investigate metabolomic differences in a rat model of ischemia after treatment with each compound. We examined metabolites in urine, hippocampal tissue, and plasma, and we tentatively identified 23 endogenous metabolites whose levels differed significantly between sham-operated and model groups. Upon pathway analysis, we found an additional 11 metabolic pathways in urine, 14 metabolic pathways in the hippocampal tissue, and 3 metabolic pathways in plasma. These endogenous metabolites were mainly involved in sphingolipid metabolism, lysine biosynthesis, and alanine, aspartate, and glutamate metabolism. We found that metabolic changes after ischemic injury returned to near-normal levels after Scue intervention, unlike Scu treatment, further validating the heightened protective effects exerted by Scue compared to Scu. These results demonstrate that Scue is a potential drug for treatment of ischemic insult.

Biological evaluation and molecular docking of baicalin and scutellarin as Helicobacter pylori urease inhibitors

ETHNOPHARMACOLOGICAL RELEVANCE

Baicalin and scutellarin are the principal bioactive components of Scutellaria baicalensis Georgi which has extensively been incorporated into heat-clearing and detoxification formulas for the treatment of Helicobacter pylori-related gastrointestinal disorders in traditional Chinese medicine. However, the mechanism of action remained to be defined.

AIM OF THE STUDY

To explore the inhibitory effect, kinetics and mechanism of Helicobacter pylori urease (the vital pathogenetic factor for Helicobacter pylori infection) inhibition by baicalin and scutellarin, for their therapeutic potential.

MATERIALS AND METHODS

The ammonia formations, indicator of urease activity, were examined using modified spectrophotometric Berthelot (phenol-hypochlorite) method. The inhibitory effect of baicalin and scutellarin was characterized with IC50 values, compared to acetohydroxamic acid (AHA), a well known Helicobacter pylori urease inhibitor. Lineweaver-Burk and Dixon plots for the Helicobacter pylori urease inhibition of baicalin and scutellarin was constructed from the kinetic data. SH-blocking reagents and competitive active site Ni(2+) binding inhibitors were employed for mechanism study. Molecular docking technique was used to provide some information on binding conformations as well as confirm the inhibition mode. Moreover, cytotoxicity experiment using Gastric Epithelial Cells (GES-1) was evaluated.

RESULTS

Baicalin and scutellarin effectively suppressed Helicobacter pylori urease in dose-dependent and time-independent manner with IC50 of 0.82±0.07 mM and 0.47±0.04 mM, respectively, compared to AHA (IC50=0.14±0.05 mM). Structure-activity relationship disclosed 4'-hydroxyl gave flavones an advantage to binding with Helicobacter pylori urease. Kinetic analysis revealed that the types of inhibition were non-competitive and reversible with inhibition constant Ki of 0.14±0.01 mM and 0.18±0.02 mM for baicalin and scutellarin, respectively. The mechanism of urease inhibition was considered to be blockage of the SH groups of Helicobacter pylori urease, since thiol reagents (L,D-dithiothreitol, L-cysteine and glutathione) abolished the inhibitory action and competitive active site Ni(2+) binding inhibitors (boric acid and sodium fluoride) carried invalid effect. Molecular docking study further supported the structure-activity analysis and indicated that baicalin and scutellarin interacted with the key residues Cys321 located on the mobile flap through S-H·π interaction, but did not interact with active site Ni(2+). Moreover, Baicalin (at 0.59-1.05 mM concentrations) and scutellarin (at 0.23-0.71 mM concentrations) did not exhibit significant cytotoxicity to GES-1.

CONCLUSIONS

Baicalin and scutellarin were non-competitive inhibitors targeting sulfhydryl groups especially Cys321 around the active site of Helicobacter pylori urease, representing potential to be good candidate for future research as urease inhibitor for treatment of Helicobacter pylori infection. Furthermore, our work gave additional scientific support to the use of Scutellaria baicalensis in traditional Chinese medicine (TCM) to treat gastrointestinal disorders.

Studies on the Protective Effects of Scutellarein against Neuronal Injury by Ischemia through the Analysis of Endogenous Amino Acids and Ca2+Concentration Together with Ca2+-ATPase Activity

Scutellarin, which is extracted from the dried plant ofErigeron breviscapus, has been reported to protect the neural injury against excitotoxicity induced by ischemia. However, there are a few studies on the protective effects of scutellarein, which is the main metabolite of scutellarin in vivo. Thus, this study investigated the neuroprotective effects of scutellarein on cerebral ischemia/reperfusion in rats by bilateral common carotid artery occlusion (BCCAO) model, through the analysis of endogenous amino acids using HILIC-MS/MS, and evaluation of Ca2+concentration together with Ca2+-ATPase activity. The results showed that scutellarein having good protective effects on cerebral ischemia/reperfusion might by decreasing the excitatory amino acids, increasing the inhibitory amino acids, lowing intracellular Ca2+level, and improving Ca2+-ATPase activity, which suggested that scutellarein might be a promising potent agent for the therapy of ischemic cerebrovascular disease.

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.

The relationships between chemical and genetic differentiation and environmental factors across the distribution of Erigeron breviscapus (Asteraceae)

Aims

Erigeron breviscapus (Vant.) Hand.-Mazz. is an important, widely used Chinese herb with scutellarin, 1,5-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and erigoster B being its major active compounds. We aimed to resolve the influence of biotic and abiotic factors on the concentrations of these compounds and to determine appropriate cultivation methods to improve the yields of the four compounds in this herb.

Methods

In order to detect the major genetic and natural environmental factors affecting the yields of these four compounds, we applied AFLP markers to investigate the population genetic differentiation and HPLC to measure the concentrations of four major active compounds among 23 wild populations which were located across almost the entire distribution of this species in China. The meteorological data including annual average temperature, annual average precipitation and annual average hours of sunshine were collected. The relationships among the concentrations of four compounds and environmental factors and genetic differentiation were studied.

Important Findings

Low intraspecific genetic differentiation is detected, and there is no obvious correlation between the genetic differentiation and the contents of the chemical compounds. We investigated the correlation between the concentrationsof four compounds (scutellarin, 1,5-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and erigoster B) and environmental factors. Concentrations of two compounds (1,5-dicaffeoylquinic acid and 3,5-dicaffeoylquinic acid) were correlated with environmental factors. The concentration of 1,5-dicaffeoylquinic acid is positively correlated with latitude, and is negatively correlated with the annual average temperature. The concentration of 3,5-dicaffeoylquinic acid is positively correlated with annual average precipitation. Therefore, changing cultivation conditions may significantly improve the yields of these two compounds. We found the concentration of scutellarin positively correlated with that of erigoster B and 3,5-dicaffeoylquinic acid, respectively. We inferred that the synthesis of these two pairs of compounds may share similar triggering mechanism as they synthesized in a common pathway.

Baicalein reduces β-amyloid and promotes nonamyloidogenic amyloid precursor protein processing in an Alzheimer's disease transgenic mouse model

Baicalein, a flavonoid isolated from the roots of Scutellaria baicalensis, is known to modulate γ-aminobutyric acid (GABA) type A receptors. Given prior reports demonstrating benefits of GABA_A modulation for Alzheimer’s disease (AD) treatment, we wished to determine whether this agent might be beneficial for AD. CHO cells engineered to overexpress wild-type amyloid precursor protein (APP), primary culture neuronal cells from AD mice (Tg2576) and AD mice were treated with baicalein. In the cell cultures, baicalein significantly reduced the production of β-amyloid (Aβ) by increasing APP α-processing. These effects were blocked by the GABA_A antagonist bicuculline. Likewise, AD mice treated daily with i.p. baicalein for 8 weeks showed enhanced APP α-secretase processing, reduced Aβ production, and reduced AD-like pathology together with improved cognitive performance. Our findings suggest that baicalein promotes nonamyloidogenic processing of APP, thereby reducing Aβ production and improving cognitive performance, by activating GABA_A receptors. © 2013 Wiley Periodicals, Inc.

Isolation and characterization of 11 new microsatellite loci in Erigeron breviscapus (Asteraceae), an important Chinese traditional herb

Erigeron breviscapus (Vant.) Hand.-Mazz. (Asteraceae) is a species endemic to southwestern China and an important traditional Chinese herb for cardiovascular and cerebral vessel diseases. Applying a modified biotin-streptavidin capture method, 11 microsatellite loci were discovered. Polymorphism of each locus was assessed in 24 individuals collected from five wild populations. The number of alleles per locus ranged from 2 to 7, with an average of 4.273. The observed (HO) and expected (HE) heterozygosities varied from 0.250 to 0.958 and from 0.337 to 0.786, respectively. Over half of these loci were successfully amplified in two congeneric species. The developed microsatellite markers will be useful for future population genetics and conservation studies, as well as accurate identification of different varieties.

Mismatch between changes in baicalein-induced memory-related biochemical parameters and behavioral consequences in mouse

Baicalein is one of the major flavonoids originally isolated from the roots of Scutellaria baicalensis Georgi (Labiatae). Reports on baicalein-induced changes in memory-related biochemical parameters including extracellular signal-regulated kinases (ERK), Akt, cAMP response element-binding protein (CREB), and brain-derived neurotrophic factor (BDNF) have been scarce, and the action of baicalein is controversial. Baicalein promotes phosphorylation of ERK under normal conditions; on the other hand, it inhibits phosphorylation of ERK extracellularly under oxidative conditions. In the present study, we observed that baicalein (20mg/kg, p.o.) as compared to vehicle significantly increased the expression of phosphorylated ERK (pERK), phosphorylated CREB (pCREB), and BDNF but did not increase phosphorylated Akt expression in the hippocampus of naive mice. Baicalein also significantly increased the expression of pERK and BDNF in the cortex of naive mice. However, baicalein had no effect on memory acquisition in the step-through passive avoidance task. On the contrary, baicalein (20mg/kg, p.o.) co-injected with flumazenil (10mg/kg, i.p.) significantly increased the retention latency in the passive avoidance task in comparison to the flumazenil-treated group, baicalein-treated group, and vehicle-treated control group. In addition, the number of platform crossings in the Morris water maze test during the probe trial session was significantly increased by co-administration of baicalein with flumazenil. Furthermore, the expressions level of BDNF was significantly increased in the baicalein with flumazenil-treated group compared to the baicalein- or flumazenil-treated groups in the hippocampus after an acquisition trial. These results suggest that the reasons why baicalein does not exert cognitive enhancement although it enhances the expression levels of pERK, pCREB, and BDNF are, in part, derived from its GABA(A) receptor agonistic property which is antagonized by flumazenil.

Anticonvulsive effects of intracerebroventricular administration of rutin in rats

Various synthetic derivatives of natural flavonoids are known to have neuroactive properties. The aim of the present study was to investigate the anticonvulsant effects of rutin (3, 3', 4', 5, 7-pentahydrohyflavone-3-rhamnoglucoside), a flavonoid which is an important dietary constituent of food and plant-based beverages. To this end, we assessed the anticonvulsant effects of rutin in rats treated with pentylenetetrazole (PTZ) (90 mg/kg, i.p.) and sought to clarify this mechanism. Intracerebroventricular (i.c.v.) injection of rutin dose-dependently affected minimal clonic seizures (MCS) and generalized tonic-clonic seizures (GTCS) induced by PTZ, through increments in seizure onset. Additionally, pretreatment with flumazenil (5 nM, i.c.v.) abolished the anticonvulsant effects of rutin during the onset of both seizures. These results indicate that rutin has anticonvulsant effects in the brain, possibly through positive allosteric modulation of the GABA(A) receptor complex via interaction at the benzodiazepine site.