Distribution of α-asarone in brain following three different routes of administration in rats

The novel anti-fibrillary effects of volatile compounds α-asarone and β-caryophyllene on tau protein: Towards promising therapeutic agents for Alzheimer's disease

The abnormal deposition of tau protein is one of the critical causes of tauopathies including Alzheimer's disease (AD). In recent years, there has been great interest in the use of essential oils and volatile compounds in aromatherapy for treating AD, since volatile compounds can directly reach the brain through intranasal administration. The volatile compounds α-asarone (ASA) and β-caryophyllene (BCP) have revealed various important neuroprotective properties, useful in treating AD. In this study, the volatile compounds ASA and BCP were assessed for their effectiveness in preventing tau fibrillation, disassembly of pre-formed tau fibrils, and disaggregation of tau aggregates. SDS-PAGE and AFM analyses revealed that ASA and BCP inhibited tau fibrillation/aggregation and decreased the mean size of tau oligomers. Tau samples treated with ASA and BCP, showed a reduction in ThT and ANS fluorescence intensities, and a decrease in the β-sheet content. Additionally, ASA and BCP disassembled the pre-formed tau fibrils to the granular and linear oligomeric intermediates. Treatment of neuroblastoma SH-SY5Y cells with tau samples treated with ASA and BCP, revealed protective effects as shown by reduced toxicity of the cells, due to the inhibition of tau fibrillation/aggregation. Overall, ASA and BCP appeared to be promising therapeutic candidates for AD.

A comprehensive review of natural products with anti-hypoxic activity

Natural products exhibit substantial impacts in the field of anti-hypoxic traetment. Hypoxia can cause altitude sickness and other negative effect on the body. Headache, coma, exhaustion, vomiting and, in severe cases, death are some of the clinical signs. Currently, hypoxia is no longer just a concern in plateau regions; it is also one of the issues that can not be ignored by urban residents. This review covered polysaccharides, alkaloids, saponins, flavonoids, peptides and traditional Chinese compound prescriptions as natural products to protect against hypoxia. The active ingredients, effectiveness and mechanisms were discussed. The related anti-hypoxic mechanisms involve increasing the hemoglobin (HB) content, glycogen content and adenosine triphosphate (ATP) content, removing excessive reactive oxygen species (ROS), reducing lipid peroxidation, regulating the levels of related enzymes in cells, protecting the structural and functional integrity of the mitochondria and regulating the expression of apoptosis-related genes. These comprehensive summaries are beneficial to anti-hypoxic research and provide useful information for the development of anti-hypoxic products.

Molecular Mechanisms and Therapeutic Potential of α- and β-Asarone in the Treatment of Neurological Disorders

Neurological disorders are important causes of morbidity and mortality around the world. The increasing prevalence of neurological disorders, associated with an aging population, has intensified the societal burden associated with these diseases, for which no effective treatment strategies currently exist. Therefore, the identification and development of novel therapeutic approaches, able to halt or reverse neuronal loss by targeting the underlying causal factors that lead to neurodegeneration and neuronal cell death, are urgently necessary. Plants and other natural products have been explored as sources of safe, naturally occurring secondary metabolites with potential neuroprotective properties. The secondary metabolites α- and β-asarone can be found in high levels in the rhizomes of the medicinal plant Acorus calamus (L.). α- and β-asarone exhibit multiple pharmacological properties including antioxidant, anti-inflammatory, antiapoptotic, anticancer, and neuroprotective effects. This paper aims to provide an overview of the current research on the therapeutic potential of α- and β-asarone in the treatment of neurological disorders, particularly neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), as well as cerebral ischemic disease, and epilepsy. Current research indicates that α- and β-asarone exert neuroprotective effects by mitigating oxidative stress, abnormal protein accumulation, neuroinflammation, neurotrophic factor deficit, and promoting neuronal cell survival, as well as activating various neuroprotective signalling pathways. Although the beneficial effects exerted by α- and β-asarone have been demonstrated through in vitro and in vivo animal studies, additional research is required to translate laboratory results into safe and effective therapies for patients with AD, PD, and other neurological and neurodegenerative diseases.

Phase II Metabolism of Asarone Isomers In Vitro and in Humans Using HPLC-MS/MS and HPLC-qToF/MS

(1) Background: Metabolism data of asarone isomers, in particular phase II, in vitro and in humans is limited so far. For the first time, phase II metabolites of asarone isomers were characterized and human kinetic as well as excretion data after oral intake of asarone-containing tea infusion was determined. (2) Methods: A high pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-qTOF-MS) approach was used to identify phase II metabolites using liver microsomes of different species and in human urine samples. For quantitation of the respective glucuronides, a beta-glucuronidase treatment was performed prior to analysis via high pressure liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). (3) Results: Ingested beta-asarone and erythro and threo-asarone diols were excreted as diols and respective diol glucuronide conjugates within 24 h. An excretion rate about 42% was estimated. O-Demethylation of beta-asarone was also indicated as a human metabolic pathway because a corresponding glucuronic acid conjugate was suggested. (4) Conclusions: Already reported O-demethylation and epoxide-derived diols formation in phase I metabolism of beta-asarone in vitro was verified in humans and glucuronidation was characterized as main conjugation reaction. The excretion rate of 42% as erythro and threo-asarone diols and respective asarone diol glucuronides suggests that epoxide formation is a key step in beta-asarone metabolism, but further, as yet unknown metabolites should also be taken into consideration.

Natural Phytochemicals as Novel Therapeutic Strategies to Prevent and Treat Parkinson's Disease: Current Knowledge and Future Perspectives

Parkinson's disease (PD) is the second-most common neurodegenerative chronic disease affecting both cognitive performance and motor functions in aged people. Yet despite the prevalence of this disease, the current therapeutic options for the management of PD can only alleviate motor symptoms. Research has explored novel substances for naturally derived antioxidant phytochemicals with potential therapeutic benefits for PD patients through their neuroprotective mechanism, targeting oxidative stress, neuroinflammation, abnormal protein accumulation, mitochondrial dysfunction, endoplasmic reticulum stress, neurotrophic factor deficit, and apoptosis. The aim of the present study is to perform a comprehensive evaluation of naturally derived antioxidant phytochemicals with neuroprotective or therapeutic activities in PD, focusing on their neuropharmacological mechanisms, including modulation of antioxidant and anti-inflammatory activity, growth factor induction, neurotransmitter activity, direct regulation of mitochondrial apoptotic machinery, prevention of protein aggregation via modulation of protein folding, modification of cell signaling pathways, enhanced systemic immunity, autophagy, and proteasome activity. In addition, we provide data showing the relationship between nuclear factor E2-related factor 2 (Nrf2) and PD is supported by studies demonstrating that antiparkinsonian phytochemicals can activate the Nrf2/antioxidant response element (ARE) signaling pathway and Nrf2-dependent protein expression, preventing cellular oxidative damage and PD. Furthermore, we explore several experimental models that evaluated the potential neuroprotective efficacy of antioxidant phytochemical derivatives for their inhibitory effects on oxidative stress and neuroinflammation in the brain. Finally, we highlight recent developments in the nanodelivery of antioxidant phytochemicals and its neuroprotective application against pathological conditions associated with oxidative stress. In conclusion, naturally derived antioxidant phytochemicals can be considered as future pharmaceutical drug candidates to potentially alleviate symptoms or slow the progression of PD. However, further well-designed clinical studies are required to evaluate the protective and therapeutic benefits of phytochemicals as promising drugs in the management of PD.

α-Asarone, β-asarone, and γ-asarone: Current status of toxicological evaluation

Asarone isomers are naturally occurring in Acorus calamus Linné, Guatteria gaumeri Greenman, and Aniba hostmanniana Nees. These secondary plant metabolites belong to the class of phenylpropenes (phenylpropanoids or alkenylbenzenes). They are further chemically classified into the propenylic trans- and cis-isomers α-asarone and β-asarone and the allylic γ-asarone. Flavoring, as well as potentially pharmacologically useful properties, enables the application of asarone isomers in fragrances, food, and traditional phytomedicine not only since their isolation in the 1950s. However, efficacy and safety in humans are still not known. Preclinical evidence has not been systematically studied, and several pharmacological effects have been reported for extracts of Acorus calamus and propenylic asarone isomers. Toxicological data are rare and not critically evaluated altogether in the 21st century yet. Therefore, within this review, available toxicological data of asarone isomers were assessed in detail. This assessment revealed that cardiotoxicity, hepatotoxicity, reproductive toxicity, and mutagenicity as well as carcinogenicity were described for propenylic asarone isomers with varying levels of reliability. The toxicodynamic profile of γ-asarone is unknown except for mutagenicity. Based on the estimated daily exposure and reported adverse effects, officials restricted or published recommendations for the use of β-asarone and preparations of Acorus calamus. In contrast, α-asarone and γ-asarone were not directly addressed due to a limited data situation.

Lipid Nanoparticles Improve the Uptake of α-Asarone Into the Brain Parenchyma: Formulation, Characterization, In Vivo Pharmacokinetics, and Brain Delivery

Treatment of brain-related diseases is one of the most strenuous challenges in drug delivery research due to numerous hurdles, including poor blood-brain barrier penetration, lack of specificity, and severe systemic toxicities. Our research primarily focuses on the delivery of natural therapeutic compound, α-asarone, for the treatment of brain-related diseases. However, α-asarone has poor aqueous solubility, bioavailability, and stability, all of which are critical issues that need to be addressed. This study aims at formulating a lipid nanoparticulate system of α-asarone (A-LNPs) that could be used as a brain drug delivery system. The physicochemical, solid-state properties, stability, and in vitro and in vivo studies of the A-LNPs were characterized. The release of α-asarone from the A-LNPs was prolonged and sustained. After intravenous administration of A-LNPs or free α-asarone, significantly higher levels of α-asarone from the A-LNPs were detected in murine plasma and brain parenchyma fractions, confirming the ability of A-LNPs to not only maintain a therapeutic concentration of α-asarone in the plasma, but also transport α-asarone across the blood-brain barrier. These findings confirm that lipid nanoparticulate systems enable penetration of natural therapeutic compound α-asarone through the blood-brain barrier and may be a candidate for the treatment of brain-related diseases.

Nose to brain drug delivery - A promising strategy for active components from herbal medicine for treating cerebral ischemia reperfusion

Cerebral ischemia reperfusion injury (CIRI), one of the major causes of death from stroke in the world, not only causes tremendous damage to human health, but also brings heavy economic burden to society. Current available treatments for CIRI, including mechanical therapies and drug therapies, are often accompanied by significant side-effects. Therefore, it is necessary to discovery new strategies for treating CIRI. Many studies have confirmed that the herbal medicine has the advantages of abundant resources, good curative effect and little side effects, which can be used as potential drug for treatment of CIRI through multiple targets. It's known that oral administration commonly has low bioavailability, and injection administration is inconvenient and unsafe. Many drugs can't delivery to brain through routine pathways due to the blood-brain-barrier (BBB). Interestingly, increasing evidences have suggested the nasal administration is a potential direct route to transport drug into brain avoiding the BBB and has the characteristics of high bioavailability for treating brain diseases. Therefore, intranasal administration can be treated as an alternative way to treat brain diseases. In the present review, effective methods to treat CIRI by using active ingredients derived from herbal medicine through nose to brain drug delivery (NBDD) are updated and discussed, and some related pharmacological mechanisms have also been emphasized. Our present study would be beneficial for the further drug development of natural agents from herbal medicines via NBDD.

Positive effects of α-asarone on transplanted neural progenitor cells in a murine model of ischemic stroke

BACKGROUND

Some traditional Oriental herbal medicines, such as Acorus tatarinowii and Acorus gramineus, produce beneficial effects for cognition enhancement. An active compound in rhizomes and the bark of these plants is α-asarone.

PURPOSE

This study investigated the effects of α-asarone on the proliferation and differentiation of neural progenitor cells (NPCs) in a primary culture and a murine model of ischemic stroke.

METHODS

NPCs were isolated from mouse fetal cerebral cortices on embryonic day 15, and all experiments were performed using passage 3 NPCs. We utilized a cell counting kit-8 assay, flow cytometry, western blot, and immunohistochemical analysis to assess proliferation and differentiation of NPCs and employed α-asarone in NPC transplanted ischemic stroke mice to evaluate stroke-related functional recovery using behavioral and immunohistochemical analysis.

RESULT

Treatment with 1 µM, 3 µM, or 10 μM α-asarone induced significant NPC proliferation compared to vehicle treatment. Induced NPCs expressed the neuronal marker neuronal nuclei (NeuN) or the astrocyte marker S100 calcium-binding protein B (S100β). Both immunohistochemistry and flow cytometry revealed that treatment with α-asarone increased the number of NeuN-immunoreactive cells and decreased the number of S100β-immunoreactive cells. Treatment with α-asarone also increased the expression of β-catenin, cyclin D1, and phosphorylated extracellular signal-regulated kinase (ERK) compared to vehicle treatment. In a murine model of ischemic stroke, treatment with α-asarone and transplanted NPCs alleviated stroke-related functional impairments. The corner and rotarod test results revealed that treatment with α-asarone in the NPC transplanted group had greater-than-additive effects on sensorimotor function and motor balance. Moreover, α-asarone treatment promoted the differentiation of transplanted NPCs into NeuN-, glial fibrillary acidic protein (GFAP)-, platelet-derived growth factor-α (PDGFR-α)-, and 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)-immunoreactive cells.

CONCLUSION

α-asarone may promote NPC proliferation and differentiation into neuron-lineage cells by activating β-catenin, cyclin D1, and ERK. Moreover, α-asarone treatment facilitated neurofunctional recovery after NPC transplantation in a murine model of ischemic stroke. Therefore, α-asarone is a potential adjunct treatment to NPC therapy for functional restoration after brain injuries such as ischemic stroke.

Intranasal delivery of α-asarone to the brain with lactoferrin-modified mPEG-PLA nanoparticles prepared by premix membrane emulsification

Alpha-asarone is a bioactive component of Acorus tatarincuii Schott with low bioavailability, which is often used for treatments of various brain diseases in clinical setting. This study was to formulate biodegradable methoxy polyethylene glycol-polylactic acid (mPEG-PLA) nanoparticles (NPs) surface-modified by lactoferrin (Lf), for delivering α-asarone into the brain following intranasal administration. Alpha-asarone NPs were prepared by premix membrane emulsification. The relative parameters were optimized by a Box-Behnken experimental design. The particle size, zeta potential, and dispersibility index of NPs and Lf-NPs were characterized. Their ex vivo permeation, pharmacokinetics, distribution in the brain and other tissue, brain targeting, and toxicity were investigated. Following intranasal administration, Lf-NPs had a better permeability and no significant poor bioavailability compared to NPs; the area under curve from 0 to 12 h of α-asarone in Lf-NPs of the olfactory bulb, hippocampus, olfactory bundles, and thalamus were 2.14-, 4.17-, 3.62-, and 1.96-fold of those in NP group, respectively. Lactoferrin could enhance the efficacy of brain targeting with NPs and reduce its liver accumulation. Toxicity of NPs on nasal mucosal cilia and epithelial cells was also decreased by Lf. To summarize, these results demonstrate that Lf-NPs of α-asarone have potential as a carrier for nose-to-brain delivery of α-asarone for brain diseases.

A Modified Chinese Herbal Decoction (Kai-Xin-San) Promotes NGF-Induced Neuronal Differentiation in PC12 Cells via Up-Regulating Trk A Signaling

Kai-Xin-San (KXS), a Chinese herbal decoction, has been applied to medical care of depression for thousands of years. It is composed of two functional paired-herbs: Ginseng Radix et Rhizoma (GR)-Polygalae Radix (PR) and Acori Tatarinowii Rhizoma (ATR)-Poria (PO). The compatibility of the paired-herbs has been frequently changed to meet the criteria of syndrome differentiation and treatment variation. Currently, a modified KXS (namely KXS₂₀₁₂) was prepared by optimizing the combinations of GR-PR and ATR-PO: the new herbal formula was shown to be very effective in animal studies. However, the cellular mechanism of KXS₂₀₁₂ against depression has not been fully investigated. Here, the study on KXS₂₀₁₂-induced neuronal differentiation in cultured PC12 cells was analyzed. In PC12 cultures, single application of KXS₂₀₁₂ showed no effect on the neuronal differentiation, but which showed robust effects in potentiating nerve growth factor (NGF)-induced neurite outgrowth and neurofilament expression. The potentiating effect of KXS₂₀₁₂ was mediated through NGF receptor, tropomyosin receptor kinase (Trk) A: because the receptor expression and activity was markedly up-regulated in the presence of KXS₂₀₁₂, and the potentiating effect was blocked by k252a, an inhibitor of Trk A. Our current results in cell cultures fully support the therapeutic efficacy of KXS₂₀₁₂ against depression.

Pharmacology and toxicology of α- and β-Asarone: A review of preclinical evidence

BACKGROUND

Asarone is one of the most researched phytochemicals and is mainly present in the Acorus species and Guatteria gaumeri Greenman. In preclinical studies, both α- and β-asarone have been reported to have numerous pharmacological activities and at the same time, many studies have also revealed the toxicity of α- and β-asarone.

PURPOSE

The purpose of this comprehensive review is to compile and analyze the information related to the pharmacokinetic, pharmacological, and toxicological studies reported on α- and β-asarone using preclinical in vitro and in vivo models. Besides, the molecular targets and mechanism(s) involved in the biological activities of α- and β-asarone were discussed.

METHODS

Databases including PubMed, ScienceDirect and Google scholar were searched and the literature from the year 1960 to January 2017 was retrieved using keywords such as α-asarone, β-asarone, pharmacokinetics, toxicology, pharmacological activities (e.g. depression, anxiety).

RESULTS

Based on the data obtained from the literature search, the pharmacokinetic studies of α- and β-asarone revealed that their oral bioavailability in rodents is poor with a short plasma half-life. Moreover, the metabolism of α- and β-asarone occurs mainly through cytochrome-P450 pathways. Besides, both α- and/or β-asarone possess a wide range of pharmacological activities such as antidepressant, antianxiety, anti-Alzheimer's, anti-Parkinson's, antiepileptic, anticancer, antihyperlipidemic, antithrombotic, anticholestatic and radioprotective activities through its interaction with multiple molecular targets. Importantly, the toxicological studies revealed that both α- and β-asarone can cause hepatomas and might possess mutagenicity, genotoxicity, and teratogenicity.

CONCLUSIONS

Taken together, further preclinical studies are required to confirm the pharmacological properties of α-asarone against depression, anxiety, Parkinson's disease, psychosis, drug dependence, pain, inflammation, cholestasis and thrombosis. Besides, the anticancer effect of β-asarone should be further studied in different types of cancers using in vivo models. Moreover, further dose-dependent in vivo studies are required to confirm the toxicity of α- and β-asarone. Overall, this extensive review provides a detailed information on the preclinical pharmacological and toxicological activities of α-and β-asarone and this could be very useful for researchers who wish to conduct further preclinical studies using α- and β-asarone.

A method to predict different mechanisms for blood-brain barrier permeability of CNS activity compounds in Chinese herbs using support vector machine

The blood-brain barrier (BBB), a highly selective barrier between central nervous system (CNS) and the blood stream, restricts and regulates the penetration of compounds from the blood into the brain. Drugs that affect the CNS interact with the BBB prior to their target site, so the prediction research on BBB permeability is a fundamental and significant research direction in neuropharmacology. In this study, we combed through the available data and then with the help of support vector machine (SVM), we established an experiment process for discovering potential CNS compounds and investigating the mechanisms of BBB permeability of them to advance the research in this field four types of prediction models, referring to CNS activity, BBB permeability, passive diffusion and efflux transport, were obtained in the experiment process. The first two models were used to discover compounds which may have CNS activity and also cross the BBB at the same time; the latter two were used to elucidate the mechanism of BBB permeability of those compounds. Three optimization parameter methods, Grid Search, Genetic Algorithm (GA), and Particle Swarm Optimization (PSO), were used to optimize the SVM models. Then, four optimal models were selected with excellent evaluation indexes (the accuracy, sensitivity and specificity of each model were all above 85%). Furthermore, discrimination models were utilized to study the BBB properties of the known CNS activity compounds in Chinese herbs and this may guide the CNS drug development. With the relatively systematic and quick approach, the application rationality of traditional Chinese medicines for treating nervous system disease in the clinical practice will be improved.

Acute oral toxicity and biodistribution study of zinc-aluminium-levodopa nanocomposite

Layered double hydroxide (LDH) is an inorganic-organic nano-layered material that harbours drug between its two-layered sheets, forming a sandwich-like structure. It is attracting a great deal of attention as an alternative drug delivery (nanodelivery) system in the field of pharmacology due to their relative low toxic potential. The production of these nanodelivery systems, aimed at improving human health through decrease toxicity, targeted delivery of the active compound to areas of interest with sustained release ability. In this study, we administered zinc-aluminium-LDH-levodopa nanocomposite (ZAL) and zinc-aluminium nanocomposite (ZA) to Sprague Dawley rats to evaluate for acute oral toxicity following OECD guidelines. The oral administration of ZAL and ZA at a limit dose of 2,000 mg/kg produced neither mortality nor acute toxic signs throughout 14 days of the observation. The percentage of body weight gain of the animals showed no significant difference between control and treatment groups. Animal from the two treated groups gained weight continuously over the study period, which was shown to be significantly higher than the weight at the beginning of the study (P < 0.05). Biochemical analysis of animal serum showed no significant difference between rats treated with ZAL, ZA and controls. There was no gross lesion or histopathological changes observed in vital organs of the rats. The results suggested that ZAL and ZA at 2,000 mg/kg body weight in rats do not induce acute toxicity in the animals. Elemental analysis of tissues of treated animals demonstrated the wider distribution of the nanocomposite including the brain. In summary, findings of acute toxicity tests in this study suggest that zinc-aluminium nanocomposite intercalated with and the un-intercalated were safe when administered orally in animal models for short periods of time. It also highlighted the potential distribution ability of Tween-80 coated nanocomposite after oral administration.