Effects of asarone and beta-asarone on conditioned responses, fighting behaviour and convulsions

Status analysis of herbal drug therapies in epilepsy: advancements in the use of medicinal plants with anti-inflammatory properties

BACKGROUND

Use of plants and plant products in health care has shown exponential increase in past two decades.

INTRODUCTION

In-spite of the availability of well-established pharmacotherapy for epilepsy, a large no of population still explores alternative treatments due to refractory seizures, adverse effects of drugs, chronic treatment, inaccessibility of standard therapies in rural areas and the social stigma attached to the disease. Various studies on medicinal plants showed the protective effect of herbals in animal models of epilepsy.

METHOD

In the present review, a status analysis of the traditional use of various medicinal plants in epilepsy with a special focus on plats having anti-inflammatory potential is recorded.

RESULT AND CONCLUSION

The shortcomings of research on medicinal plants which needs to be explored further in order to tackle the growing need of safer and effective drugs for epilepsy are discussed. Overall, there is a huge scope of herbal drugs in CNS disorders especially epilepsy, either as an adjunct by reducing the dose and thus side effects of standard anti-epileptic drugs or as standalone agent . Although, there is still an urgent need of well planned randomized controlled clinical trials to validate their efficacy and safety.

The Effects of Various Essential Oils on Epilepsy and Acute Seizure: A Systematic Review

Many essential oils (EOs) have anticonvulsant activity and might benefit people with epilepsy. Lemongrass, lavender, clove, dill, and other EOs containing constituents such as asarone, carvone, citral, eugenol, or linalool are good candidates for evaluation as antiepileptic drugs. On the other hand, some EOs have convulsant effects and may trigger seizures in both epileptic and healthy individuals. Internal use of EOs like sage, hyssop, rosemary, camphor, pennyroyal, eucalyptus, cedar, thuja, and fennel can cause epileptic seizures because they contain thujone, 1,8-cineole, camphor, or pinocamphone, which have been identified as convulsive agents. While more research is needed to confirm their mechanisms of action, it appears that the convulsant or anticonvulsant properties of essential oils are largely due to (1) their ability to modulate the GABAergic system of neurotransmission and (2) their capacity to alter ionic currents through ion channels. This review presents a systematic analysis of the current research on EOs and epilepsy, including human case studies, animal models, and in vitro studies.

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.

Ayurveda and botanical drugs for epilepsy: Current evidence and future prospects

The understanding of epilepsy has progressed since its earliest impression as a disease associated with paranormal and superstitious beliefs. Landmark advances have been made in deciphering the pathophysiological substrates involved in the disease process, and treatment advances have contributed significantly to ameliorating the seizures. However, disease-modifying agents are yet to be discovered. Ayurveda is a system of medicine that stresses a holistic approach to disease, and treatment is focused on disease modification and symptom management. Herbs form the core of Ayurveda medicine; though many of them have been studied for their anticonvulsant activity, very few actually mention the reference of these herbs in Ayurveda literature. Other therapeutic interventions used in Ayurveda are relatively unexplored, and future research will need to focus on this. The current manuscript briefly discusses the understanding of epilepsy as per Ayurveda and reviews herbs that have been studied for their anticonvulsant activity mentioned in Ayurveda literature. This article is part of a Special Issue entitled "Botanicals for Epilepsy".

Alpha-Asarone Protects Endothelial Cells from Injury by Angiotensin II

α -Asarone is the major therapeutical constituent of Acorus tatarinowii Schott. In this study, the potential protective effects of α -asarone against endothelial cell injury induced by angiotensin II were investigated in vitro. The EA.hy926 cell line derived from human umbilical vein endothelial cells was pretreated with α -asarone (10, 50, 100 µmol/L) for 1 h, followed by coincubation with Ang II (0.1 µmol/L) for 24 h. Intracellular nitric oxide (NO) and reactive oxygen species (ROS) were detected by fluorescent dyes, and phosphorylation of endothelial nitric oxide synthase (eNOS) at Ser(1177) was determined by Western blotting. α -Asarone dose-dependently mitigated the Ang II-induced intracellular NO reduction (P < 0.01 versus model) and ROS production (P < 0.01 versus model). Furthermore, eNOS phosphorylation (Ser(1177)) by acetylcholine was significantly inhibited by Ang II, while pretreatment for 1 h with α -asarone partially prevented this effect (P < 0.05 versus model). Additionally, cell viability determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay (105~114.5% versus control, P > 0.05) was not affected after 24 h of incubation with α -asarone at 1-100 µmol/L. Therefore, α -asarone protects against Ang II-mediated damage of endothelial cells and may be developed to prevent injury to cardiovascular tissues.

Identification of both GABAA receptors and voltage-activated Na(+) channels as molecular targets of anticonvulsant α-asarone

Alpha (α)-asarone, a major effective component isolated from the Chinese medicinal herb Acorus tatarinowii, is clinically used as medication for treating epilepsy, cough, bronchitis, and asthma. In the present study, we demonstrated that α-asarone targets central nervous system GABAA receptor as well as voltage-gated Na(+) channels. Using whole-cell patch-clamp recording, α-asarone inhibited spontaneous firing of output neurons, mitral cells (MCs), in mouse olfactory bulb brain slice preparation and hyperpolarized the membrane potential of MCs. The inhibitory effect of α-asarone persisted in the presence of ionotropic glutamate receptor blockers but was eliminated after adding a GABAA receptor blocker, suggesting that GABAA receptors mediated the inhibition of MCs by α-asarone. This hypothesis was supported by the finding that α-asarone evoked an outward current, but did not influence inhibitory postsynaptic currents (IPSCs). In addition to inhibiting spontaneous firing, α-asarone also inhibited the Nav1.2 channel, a dominant rat brain Na(+) channel subtype. The effects of α-asarone on a defined Nav1.2 were characterized using transfected cells that stably expressed the Nav1.2 channel isoform. α-Asarone displayed strong tonic inhibition of Nav1.2 currents in a concentration- and membrane potential-dependent fashion. α-Asarone reduced channel availability in steady-state inactivation protocols by enhancing or stabilizing Na(+) channel inactivation. Both Na(+) channel blockade and activation of GABAA receptors provide a possible mechanism for the known anti-epileptic effects of α-asarone. It also suggests that α-asarone could benefit patients with cough possibly through inhibiting a Na(+) channel subtype to inhibit peripheral and/or central sensitization of cough reflexes.

Critical evaluation of ayurvedic plants for stimulating intrinsic antioxidant response

Oxidative damage caused by free radicals plays an important role in the causation and progression of many diseases, including aging. Free-radical damage is countered by many mechanisms, including both active antioxidant enzymatic activity in our body and passive antioxidants. Antioxidant response of our body can accommodate increased oxidative damage in diseased states to a level but beyond that level, additional antioxidants are required to combat the increased stress. Apart from the regular dietary sources of antioxidants, many traditional herbal medicines demonstrate a potential to boost antioxidant activity. Rasayana chikitsa that deals with rejuvenation and revitalization is a branch of the Indian traditional medical system of ayurveda. We review some select herbs described in rasayana chikitsa that have been assessed by modern means for stimulating intrinsic antioxidant responses in humans. A critical evaluation of rasayana chikitsa will likely provide urgently needed, actual stimulants of our physiological antioxidant responses and not just more passive antioxidants to add to an already large catalog.

Positive GABA(A) receptor modulators from Acorus calamus and structural analysis of (+)-dioxosarcoguaiacol by 1D and 2D NMR and molecular modeling

In a two-microelectrode voltage clamp with Xenopus laevis oocytes, a petroleum ether extract of Acorus calamus rhizomes enhanced the GABA-induced chloride current through GABA(A) receptors of the α₁β₂γ(2S) subtype by 277% ± 9.7% (100 μg/mL). β-Asarone (1), (+)-dioxosarcoguaiacol (2), (+)-shyobunone (3), and (+)-preisocalamenediol (4) were subsequently identified as main active principles through HPLC-based activity profiling and targeted isolation. The compounds induced maximum potentiation of the chloride current ranging from 588% ± 126% (EC₅₀: 65.3 ± 21.6 μM) (2) to 1200% ± 163% (EC(50): 171.5 ± 34.6 μM) (1), whereas (-)-isoshyobunone (5) and (-)-acorenone (6) exhibited weak GABA(A) modulating properties (5: 164% ± 42.9%; EC₅₀: 109.4 ± 46.6 μM and 6: 241% ± 23.1%; EC₅₀: 34.0 ± 6.7 μM). The relative configuration of 2 was established as 4R*8S*10R* by NOESY experiments and conformational analysis.

Modeling robust QSAR. 1. Coding molecules in 3D-QSAR--from a point to surface sectors and molecular volumes

Shape analysis is a powerful tool in chemistry and drug design. In the current work, we compare the results of CoMFA and Comparative Molecular Surface Analysis (CoMSA), the 3D-QSAR method, for a series of hypolipidemic and antiplatelet asarones and antifungal N-myristoyltransferase inhibitors. In this publication we show that a sector CoMSA formalism enables an analysis of the biological activity that is more directly related to the molecular shape and individual molecular functionalities than the traditional uniform and directionless CoMFA field. Iterative Variable Elimination allowed us to identify the potential pharmacophoric sites. We modeled QSARs for both series and demonstrate that sector-based molecular descriptors give very predictive models and allow one to generate a spatial interpretation of the QSAR models. In particular, we identified the central aromatic ring and carbonyl functions as the moieties determining the activity of the asarones series, while the pattern of substitution of the aromatic ring determines the activity of N-myristoyltransferase inhibitors.

The mechanism of the tranquillizing action of asarone from Acorus calamus Linn

Asarone, the active principle of the indigenous Indian plant Acorus calamus Linn., did not cause any change in the noradrenaline content of whole brain of rats. Unlike tetrabenazine, pretreatment with asarone failed to block the effect of reserpine on the spontaneous motor activity and ptosis of mice, as well as the conditioned avoidance response of trained rats. These findings show that, though in chemical structure asarone resembles a part of the reserpine molecule, its mechanism of action is different from this drug. In animals in which brain noradrenaline has been lowered by pretreatment with α-methyl-l-tyrosine, the effects of asarone, namely, hypothermia, potentiation of barbiturate hypnosis and specific blockade of conditioned avoidance response, were found to be markedly enhanced. It seems that the sedative effect of asarone is dependent on the depression of the ergotropic division of the hypothalamus.