Protections of pinocembrin on brain mitochondria contribute to cognitive improvement in chronic cerebral hypoperfused rats

Natural herbal extract roles and mechanisms in treating cerebral ischemia: A systematic review

Background

Stroke has been the focus of medical research due to its serious consequences and sequelae. Among the tens of millions of new stroke patients every year, cerebral ischemia patients account for the vast majority. While cerebral ischemia drug research and development is still ongoing, most drugs are terminated at preclinical stages due to their unacceptable toxic side effects. In recent years, natural herbs have received considerable attention in the pharmaceutical research and development field due to their low toxicity levels. Numerous studies have shown that natural herbs exert actions that cannot be ignored when treating cerebral ischemia.

Methods

We reviewed and summarized the therapeutic effects and mechanisms of different natural herbal extracts on cerebral ischemia to promote their application in this field. We used keywords such as "natural herbal extract," "herbal medicine," "Chinese herbal medicine" and "cerebral ischemia" to comprehensively search PubMed, ScienceDirect, ScienceNet, CNKI, and Wanfang databases, after which we conducted a detailed screening and review strategy.

Results

We included 120 high-quality studies up to 10 January 2024. Natural herbal extracts had significant roles in cerebral ischemia treatments via several molecular mechanisms, such as improving regional blood flow disorders, protecting the blood-brain barrier, and inhibiting neuronal apoptosis, oxidative stress and inflammatory responses.

Conclusion

Natural herbal extracts are represented by low toxicity and high curative effects, and will become indispensable therapeutic options in the cerebral ischemia treatment field.

A High-Throughput Screening of a Natural Products Library for Mitochondria Modulators

Mitochondria, the energy hubs of the cell, are progressively becoming attractive targets in the search for potent therapeutics against neurodegenerative diseases. The pivotal role of mitochondrial dysfunction in the pathogenesis of various diseases, including Parkinson's disease (PD), underscores the urgency of discovering novel therapeutic strategies. Given the limitations associated with available treatments for mitochondrial dysfunction-associated diseases, the search for new potent alternatives has become imperative. In this report, we embarked on an extensive screening of 4224 fractions from 384 Australian marine organisms and plant samples to identify natural products with protective effects on mitochondria. Our initial screening using PD patient-sourced olfactory neurosphere-derived (hONS) cells with rotenone as a mitochondria stressor resulted in 108 promising fractions from 11 different biota. To further assess the potency and efficacy of these hits, the 11 biotas were subjected to a subsequent round of screening on human neuroblastoma (SH-SY5Y) cells, using 6-hydroxydopamine to induce mitochondrial stress, complemented by a mitochondrial membrane potential assay. This rigorous process yielded 35 active fractions from eight biotas. Advanced analysis using an orbit trap mass spectrophotometer facilitated the identification of the molecular constituents of the most active fraction from each of the eight biotas. This meticulous approach led to the discovery of 57 unique compounds, among which 12 were previously recognized for their mitoprotective effects. Our findings highlight the vast potential of natural products derived from Australian marine organisms and plants in the quest for innovative treatments targeting mitochondrial dysfunction in neurodegenerative diseases.

Exploring the Prospective Role of Propolis in Modifying Aging Hallmarks

Aging populations worldwide are placing age-related diseases at the forefront of the research agenda. The therapeutic potential of natural substances, especially propolis and its components, has led to these products being promising agents for alleviating several cellular and molecular-level changes associated with age-related diseases. With this in mind, scientists have introduced a contextual framework to guide future aging research, called the hallmarks of aging. This framework encompasses various mechanisms including genomic instability, epigenetic changes, mitochondrial dysfunction, inflammation, impaired nutrient sensing, and altered intercellular communication. Propolis, with its rich array of bioactive compounds, functions as a potent functional food, modulating metabolism, gut microbiota, inflammation, and immune response, offering significant health benefits. Studies emphasize propolis' properties, such as antitumor, cardioprotective, and neuroprotective effects, as well as its ability to mitigate inflammation, oxidative stress, DNA damage, and pathogenic gut bacteria growth. This article underscores current scientific evidence supporting propolis' role in controlling molecular and cellular characteristics linked to aging and its hallmarks, hypothesizing its potential in geroscience research. The aim is to discover novel therapeutic strategies to improve health and quality of life in older individuals, addressing existing deficits and perspectives in this research area.

Research progress of mitophagy in chronic cerebral ischemia

Chronic cerebral ischemia (CCI), a condition that can result in headaches, dizziness, cognitive decline, and stroke, is caused by a sustained decrease in cerebral blood flow. Statistics show that 70% of patients with CCI are aged > 80 years and approximately 30% are 45-50 years. The incidence of CCI tends to be lower, and treatment for CCI is urgent. Studies have confirmed that CCI can activate the corresponding mechanisms that lead to mitochondrial dysfunction, which, in turn, can induce mitophagy to maintain mitochondrial homeostasis. Simultaneously, mitochondrial dysfunction can aggravate the insufficient energy supply to cells and various diseases caused by CCI. Regulation of mitophagy has become a promising therapeutic target for the treatment of CCI. This article reviews the latest progress in the important role of mitophagy in CCI and discusses the induction pathways of mitophagy in CCI, including ATP synthesis disorder, oxidative stress injury, induction of reactive oxygen species, and Ca2+ homeostasis disorder, as well as the role of drugs in CCI by regulating mitophagy.

Target specific inhibition of West Nile virus envelope glycoprotein and methyltransferase using phytocompounds: an in silico strategy leveraging molecular docking and dynamics simulation

Mosquitoes are the primary vector for West Nile virus, a flavivirus. The virus's ability to infiltrate and establish itself in increasing numbers of nations has made it a persistent threat to public health worldwide. Despite the widespread occurrence of this potentially fatal disease, no effective treatment options are currently on the market. As a result, there is an immediate need for the research and development of novel pharmaceuticals. To begin, molecular docking was performed on two possible West Nile virus target proteins using a panel of twelve natural chemicals, including Apigenin, Resveratrol, Hesperetin, Fungisterol, Lucidone, Ganoderic acid, Curcumin, Kaempferol, Cholic acid, Chlorogenic acid, Pinocembrin, and Sanguinarine. West Nile virus methyltransferase (PDB ID: 2OY0) binding affinities varied from -7.4 to -8.3 kcal/mol, whereas West Nile virus envelope glycoprotein affinities ranged from -6.2 to -8.1 kcal/mol (PDB ID: 2I69). Second, substances with larger molecular weights are less likely to be unhappy with the Lipinski rule. Hence, additional research was carried out without regard to molecular weight. In addition, compounds 01, 02, 03, 05, 06, 07, 08, 09, 10 and 11 are more soluble in water than compound 04 is. Besides, based on maximum binding affinity, best three compounds (Apigenin, Curcumin, and Ganoderic Acid) has been carried out molecular dynamic simulation (MDs) at 100 ns to determine their stability. The MDs data is also reported that these mentioned molecules are highly stable. Finally, advanced principal component analysis (PCA), dynamics cross-correlation matrices (DCCM) analysis, binding free energy and dynamic cross correlation matrix (DCCM) theoretical study is also included to established mentioned phytochemical as a potential drug candidate. Research has indicated that the aforementioned natural substances may be an effective tool in the battle against the dangerous West Nile virus. This study aims to locate a bioactive natural component that might be used as a pharmaceutical.

Kaempferol Mediated AMPK/mTOR Signal Pathway Has a Protective Effect on Cerebral Ischemic-Reperfusion Injury in Rats by Inducing Autophagy

Ischemia/reperfusion (I/R) caused by ischemic stroke treatments leads to brain injury and its pathological mechanism is related to autophagy. The underlying mechanism of kaempferol on cerebral I/R injury needs to be explored. To establish I/R injury, we used a middle cerebral artery occlusion-reperfusion (MCAO) model in rats. MCAO rats were treated with the same amount of saline (I/R group); Treatment group rats were treated orally with kaempferol (50, 100, 200 mg/kg) for 7 days before surgery. After reperfusion for 24 h, the scores of neurological deficits and infarct volume in each group were evaluated. LC3, Beclin-1 p62, AMPK and mTOR protein expression levels were examined by TTC staining, immunofluorescence staining, qRT-PCR and western blotting assay. H&E and TTC staining showed that compared with model group, the infarction size of rats in kaempferol group was markedly reduced. Meanwhile, the results showed that kaempferol had a dose-dependent nerve function repairability. Nissl and TUNEL staining showed that kaempferol could reduce neuronal apoptosis and ameliorate neuronal impairment after I/R. Western blotting and qRT-PCR results showed that kaempferol could protect the brain from ischemia reperfusion by activating autophagy. In addition, add AMPK inhibitor, western blotting and immumohistochemical staining showed that kaempferol mediated AMPK/mTOR signal pathway in MCAO rats. Kaempferol could mediate the AMPK signal pathway to regulate autophagy and inhibit apoptosis to protect brain against I/R injury.

Flavonoids as Molecules With Anti-Zika virus Activity

Zika virus (ZIKV) is an arthropod-born virus that is mainly transmitted to humans by mosquitoes of the genus Aedes spp. Since its first isolation in 1947, only a few human cases had been described until large outbreaks occurred on Yap Island (2007), French Polynesia (2013), and Brazil (2015). Most ZIKV-infected individuals are asymptomatic or present with a self-limiting disease and nonspecific symptoms such as fever, myalgia, and headache. However, in French Polynesia and Brazil, ZIKV outbreaks led to the diagnosis of congenital malformations and microcephaly in newborns and Guillain-Barré syndrome (GBS) in adults. These new clinical presentations raised concern from public health authorities and highlighted the need for anti-Zika treatments and vaccines to control the neurological damage caused by the virus. Despite many efforts in the search for an effective treatment, neither vaccines nor antiviral drugs have become available to control ZIKV infection and/or replication. Flavonoids, a class of natural compounds that are well-known for possessing several biological properties, have shown activity against different viruses. Additionally, the use of flavonoids in some countries as food supplements indicates that these molecules are nontoxic to humans. Thus, here, we summarize knowledge on the use of flavonoids as a source of anti-ZIKV molecules and discuss the gaps and challenges in this area before these compounds can be considered for further preclinical and clinical trials.

Flavonoids with Potential Anti-Amyloidogenic Effects as Therapeutic Drugs for Treating Alzheimer's Disease

Alzheimer's disease (AD) is a central neurodegenerative disease generally among the elderly; it accounts for approximately 50-75%of total cases of dementia patients and poses a serious threat to physical and mental health. Currently available treatments for AD mainly relieves its symptoms, and effective therapy is urgently needed. Deposition of amyloid-β protein in the brain is an early and invariant neuropathological feature of AD. Currently the main efforts in developing anti-AD drugs focus on anti-amyloidogenic therapeutics that prevent amyloid-β production or aggregation and decrease the occurrence of neurotoxic events. The results of an increasing number of studies suggest that natural extracts and phytochemicals have a positive impact on brain aging. Flavonoids belong to the broad group of polyphenols and recent data indicate a favorable effect of flavonoids on brain aging. In this review, we collect relevant discoveries from 1999 to 2021, discuss 75 flavonoids that effectively influence AD pathogenesis, and summarize their functional mechanisms in detail. The data we have reviewed show that, these flavonoids belong to various subclasses, including flavone, flavanone, biflavone, etc. Our results provide a reference for further study of the effects of flavonoids on AD and the progress of anti-AD therapy.

Pharmacological Potentiality of Bioactive Flavonoid against Ketamine Induced Cell Death of PC 12 Cell Lines: An In Vitro Study

During the past few years, there has been exponential growth in the field of ethnopharmacology in the treatment of different human ailments, including neurological disorders. In our previous study, we isolated, characterized, and reported a novel bioactive compound with therapeutic efficacy in vivo, which was used in the current study. This study was designed to investigate the pharmacological effect and therapeutic mechanism of the natural plant compound 3-(3,4-dimethoxy phenyl)-1-(4-methoxy phenyl)prop-2-en-1-one against ketamine-induced toxicity in PC 12 cell lines. Cell death was induced in PC 12 cell lines by incubating with ketamine, and the protection offered by the compound at different concentrations was studied during pretreatment. The therapeutic efficacy was screened through MTT assay, LDH assay, DCF-DA assay, clonogenic assay, RT-PCR, and densitometric analysis. The bioactive compound caused a significant elevation in cell viability up to approximately 80%, down-regulation of cell damage, reduction in free radical damage caused by intracellular reactive oxygen species, and up-regulation of cell survival ability, which was dysregulated during ketamine induction. In addition, RT-PCR analysis of DOPA-related genes suggests that the compound exerted significant inhibition in the expression of these genes, which were overexpressed during ketamine induction. The current findings provide new insight into the neuroprotective mediation of bioactive factors as a prospective therapy for neurological disorders.

Pinocembrin inhibited cardiomyocyte pyroptosis against doxorubicin-induced cardiac dysfunction via regulating Nrf2/Sirt3 signaling pathway

Doxorubicin (DOX) is a potent chemotherapeutic drug but the clinical use was limited by its dose-dependent cardiotoxicity. Pinocembrin (PCB), a flavonoid originally isolated from honeybee propolis and rhizomes of Boesenbergia pandurate displays diverse biological activities. However, the role of PCB in DOX-induced cardiac injury and its underlying molecular mechanism are not fully elucidated. The present study was designed to evaluate the protective role of PCB in a DOX-induced cardiotoxicity in vivo and in vitro. Our results revealed that PCB administration greatly improved cardiac function and reduced cardiac fibrosis manifested by LVEF, LVFS, LVIDd, LVIDs, and myocardial fibrotic area which were impaired by DOX treatment. The cardiac injury evidenced by LDH and CK-MB activities were reduced while the levels of IL-1β and IL-18 were decreased following PCB treatment compared to DOX-treated mice. Mechanically, our present results showed that PCB significantly inhibited DOX-induced cardiomyocyte pyroptosis via activating Nrf2/Sirt3 signal pathway. Furthermore, the inhibition of Nrf2 in H9c2 cells abolished the protective role of PCB against DOX-induced cell toxicity, which was at least partly via upregulation of NLRP3-mediated pyroptosis. In conclusion, our study clearly demonstrated that PCB reduced cardiomyocyte pyroptosis to protect hearts from DOX-induced cardiotoxicity through activation of Nrf2/Sirt3 signal pathway.

Propolis Extract and Its Bioactive Compounds-From Traditional to Modern Extraction Technologies

Propolis is a honeybee product known for its antioxidant, anti-inflammatory, anticancer, and antimicrobial effects. It is rich in bioactive molecules whose content varies depending on the botanical and geographical origin of propolis. These bioactive molecules have been studied individually and as a part of propolis extracts, as they can be used as representative markers for propolis standardization. Here, we compare the pharmacological effects of representative polyphenols and whole propolis extracts. Based on the literature data, polyphenols and extracts act by suppressing similar targets, from pro-inflammatory TNF/NF-κB to the pro-proliferative MAPK/ERK pathway. In addition, they activate similar antioxidant mechanisms of action, like Nrf2-ARE intracellular antioxidant pathway, and they all have antimicrobial activity. These similarities do not imply that we should attribute the action of propolis solely to the most representative compounds. Moreover, its pharmacological effects will depend on the efficacy of these compounds’ extraction. Thus, we also give an overview of different propolis extraction technologies, from traditional to modern ones, which are environmentally friendlier. These technologies belong to an open research area that needs further effective solutions in terms of well-standardized liquid and solid extracts, which would be reliable in their pharmacological effects, environmentally friendly, and sustainable for production.

Propolis: A useful agent on psychiatric and neurological disorders? A focus on CAPE and pinocembrin components

Propolis consists of a honeybee product, with a complex mix of substances that have been widely used in traditional medicine. Among several compounds present in propolis, caffeic acid phenethyl ester (CAPE), and pinocembrin emerge as two principal bioactive compounds, with benefits in a variety of body systems. In addition to its well-explored pharmacological properties, neuropharmacological activities have been poorly discussed. In an unprecedented way, the present review addresses the current finding on the promising therapeutic purposes of propolis, focusing on CAPE and pinocembrin, highlighting its use on neurological disturbance, as cerebral ischemia, neuroinflammation, convulsion, and cognitive impairment, as well as psychiatric disorders, such as anxiety and depression. In addition, we provide a critical analysis, discussion, and systematization of the molecular mechanisms which underlie these central nervous system effects. We hypothesize that the pleiotropic action of CAPE and pinocembrin, per se or associated with other substances present in propolis may result in the therapeutic activities reported. Inhibition of the pro-inflammatory cascade, antioxidant activity, and positive neurotrophic modulatory effects consist of the main molecular targets attributed to CAPE and pinocembrin in health benefits.

Pinocembrin Ameliorates Cognitive Impairment Induced by Vascular Dementia: Contribution of Reelin-dab1 Signaling Pathway

Background

As a substrate of apoER2, Reelin has been verified to exert neuroprotection by preventing memory impairment. Pinocembrin is the most abundant natural flavonoid found in propolis, and it has been used to exert neuroprotection, blood–brain barrier protection, anti-oxidation, and inflammation diminishing, both in vitro and in vivo. However, the roles and molecular mechanisms of pinocembrin in neurobehavioral outcomes and neuronal repair after vascular dementia are still under investigation.

Purpose

To explore the role of pinocembrin in the involvement of the Reelin-dab1 signaling pathway in improving memory impairment, both in cell culture and animals experiments.

Material and Methods

Behavioral tests were conducted on day 48 to confirm the protection of pinocembrin against cognitive impairment. Cell and molecular biology experiments demonstrated that the Reelin-dab1 pathway mediates the underlying mechanism of cognitive improvement by pinocembrin.

Results

It was showed that pinocembrin alleviated learning and memory deficits induced by vascular dementia, by inducing the expression of Reelin, apoER2, and p-dab1 in the hippocampus. The expression of Reelin and p-dab1 was both inhibited following Reelin RNA interference in SH-SY5Y prior to oxygen glucose deprivation (OGD) injury, suggesting that Reelin played a core role in pinocembrin’s effect on OGD in vitro.

Conclusion

Pinocembrin improves the cognition via the Reelin-dab1 signaling pathway.

The Nrf2/HO-1 Axis as Targets for Flavanones: Neuroprotection by Pinocembrin, Naringenin, and Eriodictyol

Flavanones are a group of flavonoids that derive from their immediate chalcone precursors through the action of chalcone isomerase enzymes. The Aromatic A and B rings, C4-keto group, and the 15-carbon flavonoid skeleton are all evident in flavanones, but a notable absence of C2-C3 double bond and a lack of oxygenation at C-3 position of the C-ring makes them distinctively different from other groups such as flavonols (e.g., quercetin). On the basis of oxygenation level in the B ring, flavanones can vary from each other as exemplified by pinocembrin (no oxygenation), naringenin (4′-hydroxyl), or eriodictyol (3′,4′-dihydroxyl substitution). These groups are generally weaker free radical scavengers as compared to quercetin and derivatives though eriodictyol has a better free radical scavenging profile within the group due to the presence of the catechol functional moiety. In this communication, their antioxidant potential through the induction of antioxidant defenses is scrutinized. These compounds as exemplified by pinocembrin could induce the nuclear factor erythroid 2-related factor 2- (Nrf2-) heme oxygenase-1 (HO-1) axis leading to amelioration of oxidative stress in cellular and animal models. Their neuroprotective effect through such mechanism is discussed.

Advances in Biosynthesis, Pharmacology, and Pharmacokinetics of Pinocembrin, a Promising Natural Small-Molecule Drug

Pinocembrin is one of the most abundant flavonoids in propolis, and it may also be widely found in a variety of plants. In addition to natural extraction, pinocembrin can be obtained by biosynthesis. Biosynthesis efficiency can be improved by a metabolic engineering strategy and a two-phase pH fermentation strategy. Pinocembrin poses an interest for its remarkable pharmacological activities, such as neuroprotection, anti-oxidation, and anti-inflammation. Studies have shown that pinocembrin works excellently in treating ischemic stroke. Pinocembrin can reduce nerve damage in the ischemic area and reduce mitochondrial dysfunction and the degree of oxidative stress. Given its significant efficacy in cerebral ischemia, pinocembrin has been approved by China Food and Drug Administration (CFDA) as a new treatment drug for ischemic stroke and is currently in progress in phase II clinical trials. Research has shown that pinocembrin can be absorbed rapidly in the body and easily cross the blood-brain barrier. In addition, the absorption/elimination process of pinocembrin occurs rapidly and shows no serious accumulation in the body. Pinocembrin has also been found to play a role in Parkinson's disease, Alzheimer's disease, and specific solid tumors, but its mechanisms of action require in-depth studies. In this review, we summarized the latest 10 years of studies on the biosynthesis, pharmacological activities, and pharmacokinetics of pinocembrin, focusing on its effects on certain diseases, aiming to explore its targets, explaining possible mechanisms of action, and finding potential therapeutic applications.

Ulmosides A: Flavonoid 6-C-glycosides from Ulmus wallichiana attenuates lipopolysacchride induced oxidative stress, apoptosis and neuronal death

Extract of Ulmus wallichiana is being used as traditional medicine used for the treatment of fractured bones however the effect of its individual flavonols is not known. The present study was conducted to investigate the effect of its novel flavonol, (2S, 3S)-(+)-30, 40, 5, 7-tetrahydroxydihydroflavonol-6-C-b-d-glucopyranoside named as Ulmoside A (UA), on lipopolysaccharides (LPS) treated neurons. LPS treatment to neuronal cells caused significant cytotoxicity, reactive oxygen species generation, depletion in glutathione and mitochondrial impairment which were significantly inhibited with UA treatment. LPS treatment also caused significant translocation of cytochrome-c, decreased level of Bcl2, increased level of Bax and cleaved caspase-3 in neuronal cells reflecting the involvement of intrinsic apoptotic pathway in neuronal death which was attenuated with UA treatment. Since LPS is a well known pro-inflammatory agent it also offered the significant increase in proinflammatory cytokines (tumor necrosis factors-α & interleukin 1-beta) however, UA treatment did not exhibit significant inhibition against LPS induced inflammatory response. LPS also caused the augmented level of inducible nitric oxide synthase (iNOS) which was also not inhibited with co treatment of UA. We have also observed the significant DNA fragmentation and augmented level of cleaved Poly (ADP-Ribose) polymerase 1 after LPS treatment which was significantly reverted with UA treatment. Findings suggested that UA acts through mitochondria and exhibited its anti-oxidative and anti-apoptotic activities in neuronal cells while no significant anti-inflammatory activity and effect on iNOS were observed.

Neuroprotective effects of pinocembrin on ischemia/reperfusion-induced brain injury by inhibiting autophagy

BACKGROUND

Cerebral ischemia/reperfusion (I/R) injury is a common pathological process after cardiac arrest, shock and acute cerebral infarction recanalization, which causes serious injury in brain function. Pinocembrin (Pino), a natural flavonoid at the highest concentration in propolis, exhibited a variety of biological effects, including antitumor, antimicrobial and anti-inflammatory activities. However, the effects of Pino on brain injured after I/R and the mechanisms of its neuroprotective effects remain elusive.

METHODS

In the present study, we used I/R model rats underwent transient cerebral ischemia inducing by four-vessel occlusion and reperfusion. Pino alone or in combination with autophagy inducer rapamycin (RAPA) was administered to I/R rats. The behavior and cognitive function were evaluated by open field test and Morris water maze test. HE staining was used to determine the survival of hippocampus CA1 pyramidal cells. Three key proteins of autophagy, LC3, Beclin1 and p62, were detected by Western blot.

RESULTS

Our results showed that Pino could significantly reduce the damage of hippocampus CA1 pyramidal neurons and alleviate the impairments of behavior and cognitive function in I/R rats. Pino also decreased the expression of LC3II and Beclin1 and increased the level of p62 in hippocampus CA1 of I/R rats. In addition, Pino also decreased RAPA-induced neuronal damage and excessive activation of autophagy in I/R rats.

CONCLUSIONS

Taken together, these results suggested that Pino could protect the brain injury induced by I/R and the potential mechanisms might attribute to inhibition of autophagy activity.

Phytochemical Composition of the Decoctions of Greek Edible Greens (Chórta) and Evaluation of Antioxidant and Cytotoxic Properties

Wild or semi-wild edible greens (chórta) are an integral part of the traditional Greek Mediterranean diet due to their nutritional value, containing various phytonutrients beneficial to human health. Water-based decoctions of chórta are widely consumed in Greek alternative medicine as health promoting agents. This study examined the chemical profile of the decoctions of eight edible plants, Cichorium intybus, C. endivia, C. spinosum, Crepis sancta, Sonchus asper, Carthamus lanatus, Centaurea raphanina, and Amaranthus blitum, by UPLC-ESI-HRMS and HRMS/MS analysis, to determine possibly bioactive constituents. The profiles of the plants from the Asteraceae family are dominated by the presence of phenolic acids and flavonoid derivatives, whereas the A. blitum decoction is rich in triterpene saponins. Interestingly, the Centaurea raphanina decoction was found to be extremely rich in flavanones, particularly in the aglycone pinocembrin. Further phytochemical investigation and fractionation of this extract resulted in the isolation and identification of five compounds: phlorin (1), syringin (2), pinocembrin (3), pinocembroside (4), and pinocembrin-7-O-neohesperidoside (5). The extracts were also tested for their antioxidant and differential cytotoxic activity against tumor cells. C. raphanina was found to be differentially toxic against metastatic tumor cells. In conclusion, we found that Greek edible greens are a rich source of bioactive secondary metabolites and their consumption could contribute to the maintenance of overall health.

Pinocembrin⁻Lecithin Complex: Characterization, Solubilization, and Antioxidant Activities

Pinocembrin is a natural flavonoid compound which is capable of antioxidant, antibacterial, anti-inflammatory, and antineoplastic activities. The present study aimed to enhance the solubility and antioxidant activities of pinocembrin by complex formation with lecithin. The physicochemical characteristics of pinocembrin–lecithin complex were analyzed by ultraviolet (UV), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and solubility assay, and the antioxidant activities of pinocembrin–lecithin complex were evaluated via radical scavenging capacities for 2,2′-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), hydroxyl, and superoxide-anion. The results indicated that pinocembrin complex with lecithin could significantly improve the solubility of pinocembrin in water and n-octane, the pinocembrin–lecithin complex displayed no characteristic endothermic peak and the appearance of amorphous state, compared to the pinocembrin, and no new covalent bond was produced in the pinocembrin and lecithin compound. It was demonstrated that the antioxidant activities of pinocembrin were obviously enhanced by the complex with lecithin, and the scavenging capacities for hydroxyl radical, DPPH, superoxide-anion radical, and ABTS radical of pinocembrin–lecithin complex were 82.44 ± 2.21%, 40.07 ± 1.32%, 59.15 ± 0.86%, and 24.73 ± 1.04% at 1.0 mg/mL, respectively. It suggested that the pinocembrin–lecithin complex had a great potential application prospect in the healthcare industry and in clinical practice.

Pinocembrin alleviates cognition deficits by inhibiting inflammation in diabetic mice

Diabetic encephalopathy (DE) is one of the most common diabetic complications in diabetes mellitus and is characterized by cognitive impairment and neuroinflammation. It has been reported that hyperglycemia can induce hippocampal and cortical neuronal damage, which can result in severe spatial learning and memory impairment. Pinocembrin (Pino) has been widely used in the therapy of cancer and other diseases due to its anti-inflammatory, anti-allergic, anti-oxidant, anti-carcinogenic, and anti-viral activities. However, the effects of Pino on DE-induced cognition deficits and its precise mechanisms remain largely unknown. Therefore, the aim of this study was to investigate the neuroprotective effects of Pino on cognition and its potential mechanisms in a DE mouse model induced by streptozotocin (STZ, 150mg/kg). Here, we demonstrated that Pino significantly improved the behavior and cognitive deficits of DE mice in open field tasks and the Morris water maze. Pino also markedly increased neuronal survival in the frontal cortex and hippocampal CA3 region. Furthermore, western blotting was performed to measure nuclear translocation of nuclear factor-kappaB (NF-κB) and the expression of tumor necrosis factor-α (TNF-α) in the frontal cortex and hippocampus. The results demonstrated that Pino could suppress the nuclear translocation of NF-κB and decrease TNF-α expression in the cerebral cortex and the hippocampus of DE mice. Taken together, the results suggest that Pino alleviates cognition deficits by protecting neurons from inflammation injury in diabetic mice.

Plants-Derived Neuroprotective Agents: Cutting the Cycle of Cell Death through Multiple Mechanisms

Neuroprotection is the preservation of the structure and function of neurons from insults arising from cellular injuries induced by a variety of agents or neurodegenerative diseases (NDs). The various NDs including Alzheimer's, Parkinson's, and Huntington's diseases as well as amyotropic lateral sclerosis affect millions of people around the world with the main risk factor being advancing age. Each of these diseases affects specific neurons and/or regions in the brain and involves characteristic pathological and molecular features. Hence, several in vitro and in vivo study models specific to each disease have been employed to study NDs with the aim of understanding their underlying mechanisms and identifying new therapeutic strategies. Of the most prevalent drug development efforts employed in the past few decades, mechanisms implicated in the accumulation of protein-based deposits, oxidative stress, neuroinflammation, and certain neurotransmitter deficits such as acetylcholine and dopamine have been scrutinized in great detail. In this review, we presented classical examples of plant-derived neuroprotective agents by highlighting their structural class and specific mechanisms of action. Many of these natural products that have shown therapeutic efficacies appear to be working through the above-mentioned key multiple mechanisms of action.

Using functional and molecular MRI techniques to detect neuroinflammation and neuroprotection after traumatic brain injury

This study was designed to investigate whether functional and molecular MRI techniques are sensitive biomarkers for assessment of neuroinflammation and drug efficacy after traumatic brain injury (TBI) in rats. We subjected rats to a controlled cortical impact model and used behavioral tests, histology, and immunofluorescence to assess whether flavonoid pinocembrin provides cerebral protection and improves functional recovery. Most importantly, we used multiple noninvasive structural, functional, and molecular MRI techniques to examine whether the pinocembrin-related neuroprotection and attenuation of neuroinflammation can be detected in vivo. Significant increases in cerebral blood flow (CBF) and amide proton transfer-weighted (APTw) MRI signals were observed in the perilesional areas in untreated TBI rats at 3days and could be attributed to increased glial response. In addition, increased apparent diffusion coefficient and decreased magnetization transfer ratio signals in untreated TBI rats over time were likely due to edema. Post-treatment with pinocembrin decreased microglial/macrophage activation at 3days, consistent with the recovery of CBF and APTw MRI signals in regions of secondary injury. These findings suggest that pinocembrin provides cerebral protection for TBI and that multiple MRI signals, CBF and APTw in particular, are sensitive biomarkers for identification and assessment of neuroinflammation and drug efficacy in the TBI model.

The Immunomodulatory Effects of Plant Extracts and Plant Secondary Metabolites on Chronic Neuroinflammation and Cognitive Aging: A Mechanistic and Empirical Review

Advances in healthcare have considerably improved the life expectancy of the human population over the last century and this has brought about new challenges. As we live longer the capacity for cognitive aging increases. Consequently, it has been noted that decline in cognitive performance in the elderly in domains of reasoning, problem solving skills, attention, processing speed, working memory and episodic memory is a significant societal problem. Despite the enormity of this issue there are relatively few interventions for cognitive aging. This may be due to our current state of knowledge on biological factors that underpin cognitive aging. One of the biological contributors to cognitive aging is chronic neuroinflammation. This review will provide an overview of the peripheral and central mechanisms involved in chronic neuroinflammation and how neuroinflammation may be related to age-associated cognitive decline. Plant based extracts including herbal and nutritional supplements with anti-inflammatory properties will be examined in relation to their utility in treating age-related cognitive decline. Plant based extracts in particular offer interesting pharmacological properties that may be quickly utilized to prevent cognitive aging.

Pinocembrin attenuates gentamicin-induced nephrotoxicity in rats

Oxidative stress mediated apoptosis of renal tubular cells is a major pathology of gentamicin-induced nephrotoxicity, which is one of the prevailing causes of acute renal failure. Pinocembrin is a major flavonoid found in rhizomes of fingerroot (Boesenbergia pandurata). It has pharmacological and biological activities including antimicrobial, anti-inflammatory, and antioxidant effects. Preclinical studies have suggested that pinocembrin protects rat brain and heart against oxidation and apoptosis induced by ischemia–reperfusion. The aim of the current study was to investigate the mechanisms of renoprotection elicited by pinocembrin in gentamicin-induced nephrotoxicity. Nephrotoxicity was induced in rats by intraperitoneal injection (i.p.) of gentamicin, and pinocembrin was administered via i.p. 30 min before gentamicin treatment for 10 days. Gentamicin-induced nephrotoxicity was indicated by the reduced renal function and renal Oat3 function and expression. Gentamicin treatment also stimulated Nrf2, HO-1, and NQO1, as well as the pro-apoptotic proteins Bax and caspase-3, concomitant with the attenuation of Bcl-XL expression in the renal cortical tissues. Pinocembrin pretreatment improved renal function and renal Oat3 function and reduced oxidative stress and apoptotic conditions. These findings indicate that pinocembrin has a protective effect against gentamicin-induced nephrotoxicity, which may be due in part to its antioxidant and anti-apoptotic effects, subsequently leading to improved renal function.

Inhibition of beta-amyloid-induced neurotoxicity by pinocembrin through Nrf2/HO-1 pathway in SH-SY5Y cells

Amyloid beta peptide (Aβ) can cause neurotoxicity in Alzheimer's disease (AD). It evokes a cascade of oxidative damage to neurons. Pinocembrin (PCB), the most abundant flavonoid in propolis, has been proven to have neuroprotective effects in vivo and in vitro. In the present study, we investigated the neuroprotective effects of PCB on Aβ25-35-induced neurotoxicity. Exposure of SH-SY5Y cells to 25μM Aβ25-35 for 24h caused viability loss, apoptotic increase and reactive oxygen species (ROS) increase, pre-treatment with PCB for 4h significantly reduced the viability loss, apoptotic rate and attenuated Aβ-mediated ROS production. PCB strikingly inhibited Aβ25-35-induced mitochondrial dysfunctions, including lowered membrane potential, decreased Bcl-2/Bax ratio. In addition, PCB suppressed the release of cytochrome c and the cleavage of caspase-3. PCB treatment also resulted in an increase in Nrf2 protein levels and subsequent induction of heme oxygenase-1(HO-1) expression in SH-SY5Y cells. RNA interference-mediated knockdown of Nrf2 expression suppressed the PCB-induced HO-1 expression. Notably, we found that the HO-1 inhibitor zinc protoporphyrin IX (ZnPP) markedly diminished the neuroprotective effect of PCB against Aβ-mediated neurotoxicity. Taken together, these results indicated that PCB protects SH-SY5Y cells from Aβ25-35-induced neurotoxicity through activation of Nrf2/HO-1 pathways. Thus, activation of Nrf2/HO-1 pathways and inhibition of mitochondria-dependent apoptosis together may protect cells from Aβ25-35-induceded neurotoxicity.

Metabolomic investigation of regional brain tissue dysfunctions induced by global cerebral ischemia

Background

To get a broader view of global ischemia-induced cerebral disorders at the metabolic level, a nuclear magnetic resonance-based metabolomic study was performed to evaluate the metabolic profile changes on regional brain tissues of female and male mice upon bilateral common carotid arteries occlusion (BCCAO) operation.

Results

Significant metabolic disorders were observed in both cerebral cortex and hippocampus tissues of the experimental mice upon global cerebral ischemic attack. Multiple amino acids were identified as the dominantly perturbed metabolites. It was also shown that although the metabolic profile change patterns in the brain tissues were quite similar in male and female BCCAO mice, metabolic disorders in the cortex tissues were more severe in the female mice than in the male mice.

Conclusions

In the present study, significant changes in amino acid metabolic pathways were confirmed in the early stage of global ischemia. Meanwhile, cerebral metabolic dysfunctions were more severe in the female BCCAO mice than in the male mice, suggesting that gender may play a role in different metabolic responses to the ischemic attack, which may provide an important hypothesis for a better understanding of the clinically observed gender-dependent pathological outcome of cerebral ischemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-016-0256-9) contains supplementary material, which is available to authorized users.

Age-dependent effects of esculetin on mood-related behavior and cognition from stressed mice are associated with restoring brain antioxidant status

Dietary antioxidants might exert an important role in the aging process by relieving oxidative damage, a likely cause of age-associated brain dysfunctions. This study aims to investigate the influence of esculetin (6,7-dihydroxycoumarin), a naturally occurring antioxidant in the diet, on mood-related behaviors and cognitive function and its relation with age and brain oxidative damage. Behavioral tests were employed in 11-, 17- and 22-month-old male C57BL/6J mice upon an oral 35day-esculetin treatment (25mg/kg). Activity of antioxidant enzymes, GSH and GSSG levels, GSH/GSSG ratio, and mitochondrial function were analyzed in brain cortex at the end of treatment in order to assess the oxidative status related to mouse behavior. Esculetin treatment attenuated the increased immobility time and enhanced the diminished climbing time in the forced swim task elicited by acute restraint stress (ARS) in the 11- and 17-month-old mice versus their counterpart controls. Furthermore, ARS caused an impairment of contextual memory in the step-through passive avoidance both in mature adult and aged mice which was partially reversed by esculetin only in the 11-month-old mice. Esculetin was effective to prevent the ARS-induced oxidative stress mostly in mature adult mice by restoring antioxidant enzyme activities, augmenting the GSH/GSSG ratio and increasing cytochrome c oxidase (COX) activity in cortex. Modulation of the mood-related behavior and cognitive function upon esculetin treatment in a mouse model of ARS depends on age and is partly due to the enhancement of redox status and levels of COX activity in cortex.

Pinocembrin reduces cardiac arrhythmia and infarct size in rats subjected to acute myocardial ischemia/reperfusion

Oxidative stress plays an important role in the pathogenesis of ischemia/reperfusion (I/R) injury induced by cardiac dysfunction. Pinocembrin (5,7-dihydroxyflavanone) is a flavonoid found in propolis and in rhizomes of fingerroot (Boesenbergia pandurata) that is reported to have pharmacological properties including antimicrobial, antioxidant, and anti-inflammatory activities. The cardioprotective effects of pinocembrin in an I/R model were investigated in this study. Male Wistar rats (n = 20) were randomly divided into 2 groups to receive either pinocembrin (30 mg/kg body weight) or the vehicle intravenously. Thirty minutes later, the left anterior descending coronary artery of each rat was ligated for 30 min, and then reperfusion was allowed for 120 min. Cardiac function improved in the pinocembrin-treated group: the time to first ventricular fibrillation (VF) was significantly longer in the treated group (550 ± 54 s) than in the vehicle-only control group (330 ± 27 s) (p < 0.05). VF incidence and arrhythmia score were lower and infarcts were 49% smaller in the pinocembrin-treated group than in the control group (p < 0.05). In the pinocembrin-treated group, malondialdehyde levels and Bax/Bcl-2 ratios decreased, and the ratio of phosphorylated connexin 43 (phospho-Cx43) to total Cx43 increased in infarcted tissues compared with the non-infarcted area (p < 0.05). Pinocembrin exhibited cardioprotective effects during I/R, evidenced by improved cardiac function, fewer arrhythmias, and smaller infarcts in treated hearts than in controls. These benefits may be due to pinocembrin’s antiapoptotic and anti-oxidative stress effects and its ability to increase the phosphorylation of Cx43 in ischemic myocardium.

Traditional Chinese Herbal Medicine Penthorum chinense Pursh: A Phytochemical and Pharmacological Review

Penthorum chinense Pursh (ganhuangcao), a traditional Chinese medicine, is used for the prevention and treatment of liver diseases, including hepatitis B, hepatitis C, and alcoholic liver damage. A wide range of investigations have been carried out on this herbal medicine from pharmacognosy to pharmaceuticals, as well as pharmacology. The extract of P. chinense was reported to have significant liver protective effects through anti-oxidation, reduction of key enzyme levels, inhibition of hepatitis B virus DNA replication, and promotion of bile secretion. Based on the current knowledge, flavonoids and phenols are considered to be responsible for P. chinense's bioactivities. The main purpose of this review is to provide comprehensive and up-to-date knowledge of the phytochemical and pharmacological studies performed on P. chinense during the past few decades. Moreover, it intends to provide new insights into the research and development of this herbal medicine.

Pinocembrin inhibits matrix metalloproteinase expression in chondrocytes

Osteoarthritis (OA), the most common form of arthritis, affects millions of people worldwide. The degradation of extracellular matrix induced by matrix metalloproteinases (MMPs) is an important cause of cartilage destruction. Pinocembrin (PB) is one of the primary flavonoids abundant in propolis and extracted as a pure compound. The protective effects of PB in OA have not been reported before. In this study, we found that PB inhibits the expression of MMP-1, MMP-3, and MMP-13 at both mRNA levels and protein levels in human chondrocytes. Importantly, the results of luciferase reporter assay indicated that tumor necrosis factor-alpha (TNF-α) induced the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) was inhibited by the treatment with PB. It is also shown that TNF-α-induced p65 nuclear translocation was blocked by the treatment with PB. Mechanistically, PB treatment significantly inhibited TNF-α-induced phosphorylation and degradation of the NF-κB inhibitor IκBα in human chondrocytes. These results suggest a potential protective effect of PB in OA.

Curcuma ecalcarata - new natural source of pinocembrin and piperitenone

Phytochemical analysis of the rhizome extract of Curcuma ecalcarata, a hitherto uninvestigated south Western Ghats endemic species, resulted in the isolation and identification of the diaryl heptanoid trans, trans-1,7-diphenyl-5-hydroxy-4,6-heptadiene-3-one (1), steroid β-sitosterol (2), flavanone pinocembrin (4) and monoterpenoids piperitenone (3) and 8-hydroxy piperitone (5). HPTLC estimation of pinocembrin in the rhizome revealed the plant as a rich source of pinocembrin (0.37% dry wt.). The rhizome essential oil was isolated by hydrodistillation and analysed by GC-FID, GC-MS and (13)C NMR. Among the 30 constituents identified in the oil, monoterpenoids predominated (94.2%) followed by sesquiterpenoids (5.8%). The major compound consisting of 65.2% of the oil was isolated and identified as piperitenone (3). The study highlights the plant as a rich source of the flavanone pinocembrin and the volatile aroma compound piperitenone.

Pinocembrin alleviates memory impairment in transient global cerebral ischemic rats

The aim of the present study was to investigate the effect of pinocembrin on cognitive ability impairment in a rat model of transient global cerebral ischemia (TGCI). The TGCI model was established by inducing global cerebral ischemia for 20 min, followed by reperfusion for two weeks. The rats were divided into five experimental groups, including the sham group that were not subjected to ischemia, and four ischemic groups where the rats were exposed to TGCI. The sham and control TGCI groups were administered a vehicle intravenously immediately after reperfusion, while the other three groups were intravenously treated with 1, 5 and 10 mg/kg pinocembrin, respectively. In the present study, neurological scores were analyzed at 0 and 24 h after reperfusion, and the effect of pinocembrin on cognitive ability impairment in the TGCI rat model was investigated using a Morris water maze test. Neuronal loss was observed under an optical microscope with the assistance of Nissl staining. In addition, glial fibrillary acidic protein (GFAP)-positive cells were observed under an optical microscope by an immunohistochemistry assay. Pinocembrin treatment was found to alleviate the cognitive impairments, decrease the neurological scores, diminish neuronal loss in the hippocampus and reduce the number of GFAP-positive cells in the hippocampal CA1 region of the TGCI rats. Therefore, pinocembrin alleviated memory impairment in the TGCI rats.

Pinocembrin improves cognition and protects the neurovascular unit in Alzheimer related deficits

Amyloid-β (Aβ) peptides accumulate in the brain and initiate a cascade of pathologic events in Alzheimer's disease. The receptor for advanced glycation end products (RAGE) has been implicated to mediate Aβ-induced perturbations in the neurovascular unit (NVU). We demonstrated that pinocembrin exhibits neuroprotection through inhibition of the Aβ and/or RAGE pathway, but the therapeutic role and mechanism involved are not ascertained. Here, we report that a 3-month treatment with pinocembrin prevents the cognition decline in APP/PS1 transgenic mice without altering Aβ burden and oxidative stress. Instead, pinocembrin is effective in conferring neurovascular protection through maintenance of neuropil ultrastructure, reduction of glial activation and levels of inflammatory mediators, preservation of microvascular function, improving the cholinergic system by conserving the ERK-CREB-BDNF pathway, and modulation of RAGE-mediated transduction. Furthermore, in an in vitro model, pinocembrin provides the NVU protection against fibrillar Aβ₁₋₄₂, accompanied by regulation of neurovascular RAGE pathways. Our findings indicate that pinocembrin improves cognition, at least in part, attributable to the NVU protection, and highlights pinocembrin as a potential therapeutic strategy for the prevention and/or treatment of Alzheimer's disease.

Hydrogen-rich saline attenuates neuronal ischemia--reperfusion injury by protecting mitochondrial function in rats

BACKGROUND

Hydrogen, a popular antioxidant gas, can selectively reduce cytotoxic oxygen radicals and has been found to protect against ischemia-reperfusion (I/R) injury of multiple organs. Acute neuronal death during I/R has been attributed to loss of mitochondrial permeability transition coupled with mitochondrial dysfunction. This study was designed to investigate the potential therapeutic effect of hydrogen-rich saline on neuronal mitochondrial injury from global cerebral I/R in rats.

MATERIALS AND METHODS

We used a four-vessel occlusion model of global cerebral ischemia and reperfusion, with Sprague-Dawley rats. The rats were divided randomly into six groups (n = 90): sham (group S), I/R (group I/R), normal saline (group NS), atractyloside (group A), hydrogen-rich saline (group H), and hydrogen-rich saline + atractyloside (group HA). In groups H and HA, intraperitoneal hydrogen-rich saline (5 mL/kg) was injected immediately after reperfusion, whereas the equal volume of NS was injected in the other four groups. In groups A and HA, atractyloside (15 μL) was intracerebroventricularly injected 10 min before reperfusion, whereas groups NS and H received equal NS. The mitochondrial permeability transition pore opening and mitochondrial membrane potential were measured by spectrophotometry. Cytochrome c protein expression in the mitochondria and cytoplasm was detected by western blot. The hippocampus mitochondria ultrastructure was examined with transmission electron microscope. The histologic damage in hippocampus was assessed by hematoxylin and eosin staining.

RESULTS

Hydrogen-rich saline treatment significantly improved the amount of surviving cells (P < 0.05). Furthermore, hydrogen-rich saline not only reduced tissue damage, the degree of mitochondrial swelling, and the loss of mitochondrial membrane potential but also preserved the mitochondrial cytochrome c content (P < 0.05).

CONCLUSIONS

Our study showed that hydrogen-rich saline was able to attenuate neuronal I/R injury, probably by protecting mitochondrial function in rats.

Pharmacological Activities of Sijunzi Decoction Which Are Related to Its Antioxidant Properties

This paper introduces the antioxidant constituents and pharmacological effects of Sijunzi decoction by looking up literatures in recent years. Sijunzi decoction is composed of Ginseng, Atractylodes, Tuckahoe, and Glycyrrhiza. The antioxidant ingredients of Sijunzi decoction include paeonol, dauricine, naringin, and isoliquiritigenin. The study has proved that it possesses wide pharmacological effects of anticardiovascular diseases, antinervous system disease, antidiabetes, antimetabolic syndrome, and antitumor. Research on the antioxidant components of Sijunzi decoction and their targets is a promising study area in the future.

Pinocembrin protects rats against cerebral ischemic damage through soluble epoxide hydrolase and epoxyeicosatrienoic acids

AIM

To investigate the relationship between cerebroprotection of pinocembrin and epoxyeicosatrienoic acids (EETs) and their regulating enzyme soluble epoxide hydrolase (sEH).

METHODS

Rats underwent middle cerebral artery occlusion (MCAO) to mimic permanent focal ischemia, and pinocembrin was administrated via tail vein injection at 10 min, 4 h, 8 h and 23 h after MCAO. After 24 MCAO, rats were re-anesthetized, and the blood and brain were harvested and analyzed.

RESULTS

Pinocembrin displayed significant protective effects on MCAO rats indicated by reduced neurological deficits and infarct volume. Importantly, co-administration of 0.2 mg·kg(-1) 14, 15-EEZE, a putative selective EET antagonist, weakened the beneficial effects of pinocembrin. 14, 15-EET levels in the blood and brain of rats after 24 h MCAO were elevated in the presence of pinocembrin. In an assay for hydrolase activity, pinocembrin significantly lowered brain sEH activity of MCAO rats and inhibited recombinant human sEH activity in a concentration-dependent manner (IC50, 2.58 μmol·L(-1)). In addition, Western blot and immunohistochemistry analysis showed that pinocembrin at doses of 10 mg·kg(-1) and 30 mg·kg(-1) significantly down-regulated sEH protein in rat brain, especially the hippocampus CA1 region of MCAO rats.

CONCLUSION

Inhibiting sEH and then increasing the potency of EETs may be one of the mechanisms through which pinocembrin provides cerebral protection.

Pinocembrin: a novel natural compound with versatile pharmacological and biological activities

Pinocembrin (5,7-dihydroxyflavanone) is one of the primary flavonoids isolated from the variety of plants, mainly from Pinus heartwood, Eucalyptus, Populus, Euphorbia, and Sparattosperma leucanthum, in the diverse flora and purified by various chromatographic techniques. Pinocembrin is a major flavonoid molecule incorporated as multifunctional in the pharmaceutical industry. Its vast range of pharmacological activities has been well researched including antimicrobial, anti-inflammatory, antioxidant, and anticancer activities. In addition, pinocembrin can be used as neuroprotective against cerebral ischemic injury with a wide therapeutic time window, which may be attributed to its antiexcitotoxic effects. Pinocembrin exhibits pharmacological effects on almost all systems, and our aim is to review the pharmacological and therapeutic applications of pinocembrin with specific emphasis on mechanisms of actions. The design of new drugs based on the pharmacological effects of pinocembrin could be beneficial. This review suggests that pinocembrin is a potentially promising pharmacological candidate, but additional studies and clinical trials are required to determine its specific intracellular sites of action and derivative targets in order to fully understand the mechanism of its anti-inflammatory, anticancer, and apoptotic effects to further validate its medical applications.

Protection of mice against lipopolysaccharide-induced endotoxic shock by pinocembrin is correlated with regulation of cytokine secretion

Natural products have been used as potentially important sources of anti-inflammatory drugs. This study examined the effects of pinocembrin against lipopolysaccharide (LPS)-induced endotoxemia to ascertain whether pinocembrin could protect mice from ensuing death. Cytokine responses were also assessed in serum isolated from blood collected at 0, 2, 4, 6, 8, and 24 h after LPS administration of the mice (with or without drug treatment). The results showed that there was a lower production of TNFα, IL-6, and IL-1β in the serum of LPS-challenged mice that had been pre-treated with pinocembrin. In addition, pre-treatment with pinocembrin improved host survival against the LPS-induced lethal endotoxemia. These results suggest that this new flavonoid could potentially be a novel candidate for preventing development/mitigation progression of septic shock.

Subinhibitory concentrations of pinocembrin exert anti-Staphylococcus aureus activity by reducing α-toxin expression

AIMS

Natural products have been used as potentially important sources of novel antibacterials in combating pathogenic Staphylococcus aureus isolates, a major problem around the world. In this study, we aimed to investigate the antibacterial effects of pinocembrin (PNCB) against Staph. aureus pneumonia in a murine model and its influence on the production of Staph. aureus α-haemolysin (Hla).

METHODS AND RESULTS

The in vitro activities of PNCB on α-haemolysin production were determined using haemolysis, Western blot and real-time RT-PCR assays. The viability and cytotoxicity assays were performed to evaluate the influence of PNCB on α-toxin-mediated injury of human alveolar epithelial cells. Moreover, through histopathologic analysis, we further determined the in vivo effects of PNCB on Staph. aureus pneumonia in a mouse model. In vitro, PNCB at low concentrations exhibited inhibitory activity against α-haemolysin production and attenuated α-haemolysin-mediated cell injury. Furthermore, the in vivo findings demonstrated that PNCB protected mice from Staph. aureus pneumonia.

CONCLUSIONS

We have provided new evidence of the effects of PNCB, which suggest that PNCB attenuated α-haemolysin-mediated cell injury and protected mice from Staph. aureus pneumonia.

SIGNIFICANCE AND IMPACT OF THE STUDY

The findings indicate that PNCB may be used as a basis for anti-Staphylococcus agent.

Pinocembrin, a major flavonoid in propolis, improves the biological functions of EPCs derived from rat bone marrow through the PI3K-eNOS-NO signaling pathway

The number and quality of endothelial progenitor cells (EPCs) are damaged to varying degrees in patients at risk for developing atherosclerosis. The improvement of the quantity and functions of EPCs can enhance repair of injured endothelial monolayer resulting in inhibiting atherosclerosis. The purpose of this study was to investigate the effect of pinocembrin (PIN), a major flavonoid in propolis on the differentiation and biological functions of EPCs and the potential mechanisms of these effects. Flow cytometry analysis revealed that PIN treatment increased the number of CD34(+), CD133(+), FLK-1(+), CD133(+)/FLK-1(+) and CD34(+)/FLK-1(+) mononuclear cells (MNCs) in the peripheral blood of apoE(-/-) mice compared to untreated control mice. In vitro PIN treatment significantly increased the number of CD34(+), CD133(+), FLK-1(+) and CD133(+)/FLK-1(+) MNCs derived from SD bone marrow compared to untreated controls by 42.1, 84.6, 165.9 and 23.1 %, respectively. Additionally, PIN can improve biological functions of EPCs, such as proliferation, migration, adhesion, and in vitro tube formation and NO release. All of these improvements were inhibited by LY294002, while L-NAME only inhibited the PIN-induced increase in EPC proliferation and adhesion. We conclude that PIN can both promote the differentiation of EPCs in vitro and ex vivo and improve the biological functions of EPCs. The PI3K-eNOS-NO signaling pathway may be involved in the PIN-induced increase in the proliferation and adhesion of EPCs.

Pinocembrin protects against β-amyloid-induced toxicity in neurons through inhibiting receptor for advanced glycation end products (RAGE)-independent signaling pathways and regulating mitochondrion-mediated apoptosis

BACKGROUND

It is known that amyloid-β peptide (Aβ) plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). Interaction between Aβ and the receptor for advanced glycation end products (RAGE) has been implicated in neuronal degeneration associated with this disease. Pinocembrin, a flavonoid abundant in propolis, has been reported to possess numerous biological activities beneficial to health. Our previous studies have demonstrated that pinocembrin has neuroprotective effects on ischemic and vascular dementia in animal models. It has been approved by the State Food and Drug Administration of China for clinical use in stroke patients. Against this background, we investigated the effects of pinocembrin on cognitive function and neuronal protection against Aβ-induced toxicity and explored its potential mechanism.

METHODS

Mice received an intracerebroventricular fusion of Aβ25-35. Pinocembrin was administrated orally at 20 mg/kg/day and 40 mg/kg/day for 8 days. Behavioral performance, cerebral cortex neuropil ultrastructure, neuronal degeneration and RAGE expression were assessed. Further, a RAGE-overexpressing cell model and an AD cell model were used for investigating the mechanisms of pinocembrin. The mechanisms underlying the efficacy of pinocembrin were conducted on target action, mitochondrial function and potential signal transduction using fluorescence-based multiparametric technologies on a high-content analysis platform.

RESULTS

Our results showed that oral administration of pinocembrin improved cognitive function, preserved the ultrastructural neuropil and decreased neurodegeneration of the cerebral cortex in Aβ25-35-treated mice. Pinocembrin did not have a significant effect on inhibiting Aβ1-42 production and scavenging intracellular reactive oxygen species (ROS). However, pinocembrin significantly inhibited the upregulation of RAGE transcripts and protein expression both in vivo and in vitro, and also markedly depressed the activation of p38 mitogen-activated protein kinase (MAPK)-MAPKAP kinase-2 (MK2)-heat shock protein 27 (HSP27) and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK)-c-Jun pathways and the downstream nuclear factor κB (NFκB) inflammatory response subsequent to Aβ-RAGE interaction. In addition, pinocembrin significantly alleviated mitochondrial dysfunction through improving mitochondrial membrane potential and inhibiting mitochondrial oxidative stress, and regulated mitochondrion-mediated apoptosis by restoration of B cell lymphoma 2 (Bcl-2) and cytochrome c and inactivation of caspase 3 and caspase 9.

CONCLUSIONS

Pinocembrin was shown to infer cognitive improvement and neuronal protection in AD models. The mechanisms of action of the compound were illustrated on RAGE-dependent transduction inhibition and mitochondrion protection. It appears to be a promising candidate for the prevention and therapy of AD.

Physical and functional interaction of NCX1 and EAAC1 transporters leading to glutamate-enhanced ATP production in brain mitochondria

Glutamate is emerging as a major factor stimulating energy production in CNS. Brain mitochondria can utilize this neurotransmitter as respiratory substrate and specific transporters are required to mediate the glutamate entry into the mitochondrial matrix. Glutamate transporters of the Excitatory Amino Acid Transporters (EAATs) family have been previously well characterized on the cell surface of neuronal and glial cells, representing the primary players for glutamate uptake in mammalian brain. Here, by using western blot, confocal microscopy and immunoelectron microscopy, we report for the first time that the Excitatory Amino Acid Carrier 1 (EAAC1), an EAATs member, is expressed in neuronal and glial mitochondria where it participates in glutamate-stimulated ATP production, evaluated by a luciferase-luciferin system. Mitochondrial metabolic response is counteracted when different EAATs pharmacological blockers or selective EAAC1 antisense oligonucleotides were used. Since EAATs are Na⁺-dependent proteins, this raised the possibility that other transporters regulating ion gradients across mitochondrial membrane were required for glutamate response. We describe colocalization, mutual activity dependency, physical interaction between EAAC1 and the sodium/calcium exchanger 1 (NCX1) both in neuronal and glial mitochondria, and that NCX1 is an essential modulator of this glutamate transporter. Only NCX1 activity is crucial for such glutamate-stimulated ATP synthesis, as demonstrated by pharmacological blockade and selective knock-down with antisense oligonucleotides. The EAAC1/NCX1-dependent mitochondrial response to glutamate may be a general and alternative mechanism whereby this neurotransmitter sustains ATP production, since we have documented such metabolic response also in mitochondria isolated from heart. The data reported here disclose a new physiological role for mitochondrial NCX1 as the key player in glutamate-induced energy production.

Pinocembrin attenuates blood-brain barrier injury induced by global cerebral ischemia-reperfusion in rats

Blood-brain barrier (BBB) disruption is a major consequence of cerebral ischemia/reperfusion. Several studies have reported the neuroprotection of pinocembrin on cerebral ischemia in vivo and in vitro, but the effects of pinocembrin on BBB and its underlying mechanisms are not clear. In this study, we investigated the effects of pinocembrin on BBB functions in the global cerebral ischemia/reperfusion (GCI/R) model in rats. Neurological scores and brain edema were evaluated. BBB permeability was assessed by detecting the concentrations of Evan's blue (EB) and fluorescein sodium (NaF) in brain tissue. The pathological changes of BBB ultrastructure were observed by transmission electron microscopy. Cerebral blood flow (CBF) was measured by laser Doppler flowmetry. The effects of pinocembrin on primary cultured rat cerebral microvascular endothelial cells (RCMECs) against oxygen-glucose deprivation/reoxygenation (OGD/R) were also investigated. The results showed pinocembrin decreased neurological score and lessened brain edema induced by GCI/R. Pinocembrin also reduced the concentrations of EB and NaF in brain tissue of the GCI/R rats. And pinocembrin alleviated the ultrastructural changes of cerebral microvessels, astrocyte end-feet and neurons, and improved CBF in the GCI/R rats. In addition, pinocembrin increased the viability and mitochondrial membrane potential of cultured RCMECs induced by OGD/R. In conclusion, these data demonstrate that pinocembrin alleviates blood-brain barrier injury induced by GCI/R in rats.

Chronic cerebral hypoperfusion in rats causes proteasome dysfunction and aggregation of ubiquitinated proteins

The deposition of abnormal protein aggregates is a feature of several neurodegenerative diseases. We have employed a rat model to investigate whether chronic cerebral hypoperfusion (CCH) induces proteasome dysfunction and the accumulation of ubiquitinated proteins and aggregates in the CNS. Protein aggregation was analyzed by ethanolic phosphotungstic acid (EPTA) electron microscopy (EM), immunogold EM, laser-scanning confocal microscopy, and Western blotting. Proteasome peptidase activity was studied by peptidase activity assays. EPTA EM and immunogold EM revealed that CCH led to the accumulation of protein aggregates in rat hippocampal CA1 neurons. High-resolution confocal microscopy demonstrated the presence of ubiquitin-positive protein aggregates surrounding nuclei and along dendrites. Western blotting revealed that levels of free ubiquitin were significantly reduced and that levels of ubiquitinated proteins were markedly increased in the hippocampus of CCH rats. Direct activity measurements revealed that proteasome peptidase activity in the hippocampal region of rats was decreased after CCH induction. These data suggest that reduced proteasome activity following CCH could impair the removal of abnormally folded proteins via the ubiquitin-proteasome pathway, leading to the accumulation of potentially toxic protein aggregates that could contribute to neurodegeneration.

Pinocembrin protects the neurovascular unit by reducing inflammation and extracellular proteolysis in MCAO rats

The purpose of the present study was to examine the protective action and mechanisms of pinocembrin (1) on the neurovascular unit (NVU) in permanent cerebral ischemic rats. Focal cerebral ischemia was induced by occlusion of middle cerebral artery (MCAO) in rats. Compound 1 (3, 10, or 30 mg/kg) was intravenously injected at 0, 8, 16 h after MCAO. At 24 h of occlusion, 1 alleviated neuronal apoptosis, edema of astrocytic end-feet, and the deformation of endothelial cells and capillaries as revealed by the transmission electron microscopy study. To understand the mechanisms of action, the anti-inflammation effect of 1 was examined. Compound 1 reduced the expressions of tumor necrosis factor-alpha, interleukin-1beta, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, inducible NO synthase and aquaporin-4; inhibited the activation of microglias and astrocytes; and downregulated the expression of matrix metalloproteinases (MMPs) in the ischemic brain. The ischemia-induced decreases in mRNA expressions of tight junction constituent proteins, occludin and ZO-1, were also inhibited by 1. These results indicated that 1 can protect the rat brain against ischemia injury by inhibiting the inflammatory cascade, reducing the expression of MMP-9, and preventing the integrity of tight junction. This resulted in the protective action of 1 on the NVU.

Behavioral alterations associated with a down regulation of HCN1 mRNA in hippocampal cornus ammon 1 region and neocortex after chronic incomplete global cerebral ischemia in rats

It has been suggested that hyperpolarization-activated cyclic-nucleotide-gated cation non-selective channel (HCN) 1 is primarily expressed in the hippocampus and can be regulated in many pathological settings. However, little is known about its change under ischemic conditions. In the present study, we performed neurophysiological recordings of sham-operated and chronic ischemic rats with hypoperfusion during the resolution of the neurological deficits respectively. In situ hybridization methods and reverse transcriptase-polymerase chain reaction (RT-PCR) assays were used to investigate whether and how HCN1 mRNA may be altered in global incomplete chronic cerebral ischemic rat model. Our results suggested that attenuated spatial learning and memory function of rats shown by longer escape latency, shorter time spent in the target quadrant and impaired long-term potentiation (LTP) after chronic cerebral ischemia. In the in situ hybridization cytochemistry experiment, HCN1 mRNA declined to 52.00% and 46.00% of the control values in the cornus ammon 1 (CA1) regions of hippocampus and neocortex separately after chronic cerebral ischemia. HCN1 mRNA in the hippocampal CA1 region and neocortex was markedly down regulated by ischemia, reaching 48.90% and 45.80% of the control values respectively in the semi-quantitative RT-PCR experiment. The phenomenon opened new insights for further investigation of the physiological and pathological significances of HCN1 in chronic incomplete global cerebral ischemia.