Apigenin and Structurally Related Flavonoids Allosterically Potentiate the Function of Human α7-Nicotinic Acetylcholine Receptors Expressed in SH-EP1 Cells

Phytochemicals, such as monoterpenes, polyphenols, curcuminoids, and flavonoids, are known to have anti-inflammatory, antioxidant, neuroprotective, and procognitive effects. In this study, the effects of several polyhydroxy flavonoids, as derivatives of differently substituted 5,7-dihydroxy-4H-chromen-4-one including apigenin, genistein, luteolin, kaempferol, quercetin, gossypetin, and phloretin with different lipophilicities (cLogP), as well as topological polar surface area (TPSA), were tested for induction of Ca2+ transients by α7 human nicotinic acetylcholine (α7 nACh) receptors expressed in SH-EP1 cells. Apigenin (10 μM) caused a significant potentiation of ACh (30 μM)-induced Ca2+ transients, but did not affect Ca2+ transients induced by high K+ (60 mM) containing solutions. Co-application of apigenin with ACh was equally effective as apigenin preincubation. However, the effect of apigenin significantly diminished by increasing ACh concentrations. The flavonoids tested also potentiated α7 nACh mediated Ca2+ transients with descending potency (highest to lowest) by genistein, gossypetin, kaempferol, luteolin, phloretin, quercetin, and apigenin. The specific binding of α7 nACh receptor antagonist [125I]-bungarotoxin remained unchanged in the presence of any of the tested polyhydroxy flavonoids, suggesting that these compounds act as positive allosteric modulators of the α7-nACh receptor in SH-EP1 cells. These findings suggest a clinical potential for these phytochemicals in the treatment of various human diseases from pain to inflammation and neural disease

Small Molecules from Nature Targeting G-Protein Coupled Cannabinoid Receptors: Potential Leads for Drug Discovery and Development

The cannabinoid molecules are derived from Cannabis sativa plant which acts on the cannabinoid receptors types 1 and 2 (CB1 and CB2) which have been explored as potential therapeutic targets for drug discovery and development. Currently, there are numerous cannabinoid based synthetic drugs used in clinical practice like the popular ones such as nabilone, dronabinol, and Δ9-tetrahydrocannabinol mediates its action through CB1/CB2 receptors. However, these synthetic based Cannabis derived compounds are known to exert adverse psychiatric effect and have also been exploited for drug abuse. This encourages us to find out an alternative and safe drug with the least psychiatric adverse effects. In recent years, many phytocannabinoids have been isolated from plants other than Cannabis. Several studies have shown that these phytocannabinoids show affinity, potency, selectivity, and efficacy towards cannabinoid receptors and inhibit endocannabinoid metabolizing enzymes, thus reducing hyperactivity of endocannabinoid systems. Also, these naturally derived molecules possess the least adverse effects opposed to the synthetically derived cannabinoids. Therefore, the plant based cannabinoid molecules proved to be promising and emerging therapeutic alternative. The present review provides an overview of therapeutic potential of ligands and plants modulating cannabinoid receptors that may be of interest to pharmaceutical industry in search of new and safer drug discovery and development for future therapeutics

Apigenin Alleviates Autistic-like Stereotyped Repetitive Behaviors and Mitigates Brain Oxidative Stress in Mice

Studying the involvement of nicotinic acetylcholine receptors (nAChRs), specifically α7-nAChRs, in neuropsychiatric brain disorders such as autism spectrum disorder (ASD) has gained a growing interest. The flavonoid apigenin (APG) has been confirmed in its pharmacological action as a positive allosteric modulator of α7-nAChRs. However, there is no research describing the pharmacological potential of APG in ASD. The aim of this study was to evaluate the effects of the subchronic systemic treatment of APG (10–30 mg/kg) on ASD-like repetitive and compulsive-like behaviors and oxidative stress status in the hippocampus and cerebellum in BTBR mice, utilizing the reference drug aripiprazole (ARP, 1 mg/kg, i.p.). BTBR mice pretreated with APG (20 mg/kg) or ARP (1 mg/g, i.p.) displayed significant improvements in the marble-burying test (MBT), cotton-shredding test (CST), and self-grooming test (SGT) (all p \u3c 0.05). However, a lower dose of APG (10 mg/kg, i.p.) failed to modulate behaviors in the MBT or SGT, but significantly attenuated the increased shredding behaviors in the CST of tested mice. Moreover, APG (10–30 mg/kg, i.p.) and ARP (1 mg/kg) moderated the disturbed levels of oxidative stress by mitigating the levels of catalase (CAT) and superoxide dismutase (SOD) in the hippocampus and cerebellum of treated BTBR mice. In patch clamp studies in hippocampal slices, the potency of choline (a selective agonist of α7-nAChRs) in activating fast inward currents was significantly potentiated following incubation with APG. Moreover, APG markedly potentiated the choline-induced enhancement of spontaneous inhibitory postsynaptic currents. The observed results propose the potential therapeutic use of APG in the management of ASD. However, further preclinical investigations in additional models and different rodent species are still needed to confirm the potential relevance of the therapeutic use of APG in ASD

Seismic Soil Structure interaction for Shear wall structures

For soft soil subjected to earthquake loading, the soil non linearity could significantly amplify the ground motion. This paper presents a 3D numerical study on the influence of soil non linearity on the seismic soil structure interaction for shear wall structures. Numerical simulations are conducted for both elastic and elastoplastic behaviour for the soil. Real ground motions records are used in the study. The analysis is focused on the seismic induced response of the soil and the structure in terms of displacement and velocity. The results show that considering elastic model for the soil behaviour is not sufficient and could significantly affect the seismic induced response of the system

Anticonvulsant and reproductive toxicological studies of the imidazole-based histamine H3R antagonist 2-18 in mice

The imidazole-based H3R antagonist 2-18 with high in vitro H3R antagonist affinity, excellent in vitro selectivity profile, and high in vivo H3R antagonist potency was tested for its anticonvulsant effect in maximal electroshock (MES)-induced convulsions in mice having valproic acid (VPA) as a reference antiepileptic drug (AED). Additionally, H3R antagonist 2-18 was evaluated for its reproductive toxicity in the same animal species. The results show that acute systemic administration (intraperitoneal; i.p.) of H3R antagonist 2-18 (7.5, 15, 30, and 60 mg/kg, i.p.) significantly and dose dependently protected male as well as female mice against MES-induced convulsion. The protective action observed for H3R antagonist 2-18 in both mice sexes was comparable to that of VPA and was reversed when mice were pretreated with the selective H3R agonist (R)-alpha-methylhistamine (RAMH, 10 mg/kg, i.p.). Moreover, the results show that acute systemic administration of single (7.5, 15, 30, or 60 mg/kg, i.p.) or multiple doses (15×3 mg/kg, i.p.) of H3R antagonist 2-18 on gestation day (GD) 8 or 13 did not affect the maternal body weight of mice when compared with the control group. Furthermore, no significant differences were observed in the average number of implantations and resorptions between the control and H3R antagonist 2-18-treated group at the early stages of gestation and the organogenesis period. However, oral treatment with H3R antagonist 2-18 (15 mg/kg) on GD 8 induced a reduced number of live embryos when compared with the i.p.-treated mice. In addition, no significant changes in the fetal body and placental weights were observed after injection of H3R antagonist 2-18 with all selected doses. However, three dose groups of i.p. and oral 15 mg/kg on GD 13 significantly affected the placental weight when compared with control group. Notably, the treatment of pregnant female with the H3R antagonist 2-18 did not produce significant malformation in the fetus in both groups. In conclusion, the novel H3R antagonist 2-18 proves to be a very safe compound and displays a low incidence of malformations, demonstrating that H3R antagonist 2-18 may have a potential future therapeutic value in epilepsy

The neuroprotective effects of histamine H3 receptor antagonist E177 on pilocarpine-induced status epilepticus in rats

Epilepsy is a multifaceted neurological disorder which severely a ects neuronal function. Some patients may experience status epilepticus (SE), a life-threatening state of ongoing seizure activity linked to cognitive dysfunction, necessitating an immediate intervention. The potential of histamine H3 receptors in several neuropsychiatric diseases including epilepsy is well recognized. In the current study, we aimed to explore the e ect of H3R antagonist E177 on prevention and termination of pilocarpine (PLC)-induced SE in rats as well as evaluating the e ects of E177 on the levels of oxidative stress in hippocampus tissues. The results showed that the survival rate of animals pretreated with E177 (5 and 10 mg/kg, intraperitoneal (i.p.)) was significantly increased during the first hour of observation, and animals were protected from SE incidence and showed a prolonged average of latency to the first seizure when compared with animals pretreated with PLC (400 mg/kg, i.p.). Moreover, the protective e ect of E177 (10 mg/kg) on SE was partially reversed when rats were co- administered with H3R agonist R-( )-methylhistamine (RAM) and with the H2R antagonist zolantidine (ZOL), but not with the H1R antagonist pyrilamine (PYR). Furthermore, pretreatment with E177 (5 and 10 mg/kg) significantly decreased the abnormal levels of malondialdehyde (MDA), and increased levels of glutathione (GSH) in the hippocampal tissues of the treated rats. However, E177 failed to modulate the levels of catalase (CAT), superoxide dismutase (SOD), or acetylcholine esterase activity (AChE). Our findings suggest that the newly developed H3R antagonist E177 provides neuroprotection in a preclinical PLC-induced SE in rats, highlighting the histaminergic system as a potential therapeutic target for the therapeutic management of SE

Non-imidazole-based histamine H3 receptor antagonists with anticonvulsant activity in different seizure models in male adult rats

A series of twelve novel non-imidazole-based ligands (3-14) was developed and evaluated for its in vitro binding properties at the human histamine H3 receptor (hH3R). The novel ligands were investigated for their in vivo protective effects in different seizure models in male adult rats. Among the H3R ligands (3-14) tested, ligand 14 showed significant and dose-dependent reduction in the duration of tonic hind limb extension in maximal electroshock (MES)-induced seizure model subsequent to acute systemic administration (5, 10, and 20 mg/kg, intraperitoneally), whereas ligands 4, 6, and 7 without appreciable protection in MES model were most promising in pentylenetetrazole (PTZ) model. Moreover, the protective effect observed for ligand 14 in MES model was lower than that observed for the reference drug phenytoin and was entirely abrogated when rats were co-administered with the brain-penetrant H1R antagonist pyrilamine (PYR) but not the brain-penetrant H2R antagonist zolantidine (ZOL), demonstrating that histaminergic neurotransmission by activation of postsynaptically located H1Rs seems to be involved in the protective action. On the contrary, PYR and ZOL failed to abrogate the full protection provided by 4 in PTZ model and the moderate protective effect by 14 in strychnine (STR) model. Moreover, the experimental and in silico estimation of properties such as metabolism was performed for five selected test compounds. Also, lipophilicity using planar reversed-phase thin-layer chromatography method was included for better understanding of the molecular properties of the tested compounds. Additionally, the absorption, distribution, metabolism, and elimination and toxicity parameters were evaluated for the most promising compounds 2, 4, 6, 7, and 14 utilizing in vitro methods. These interesting results highlight the potential of H3R ligands as new antiepileptic drugs or as adjuvants to available epilepsy medications