A dual radioligand binding and electrophysiological study, focusing on a range of ligand-gated ion channels, was performed with a chemically-validated essential oil derived from Melissa officinalis (MO), which has shown clinical benefit in treating agitation. MO inhibited binding of [35S] t-butylbicyclophosphorothionate (TBPS) to the rat forebrain gamma-aminobutyric acid (GABA)(A) receptor channel (apparent IC50 0.040+/-0.001 mg mL(-1)), but had no effect on N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropianate (AMPA) or nicotinic acetylcholine receptors. Electrophysiological analyses with primary cultures of rat cortical neurons demonstrated that MO reversibly inhibited GABA-induced currents in a concentration-dependent manner (0.01-1 mg mL(-1)), whereas no inhibition of NMDA- or AMPA-induced currents was noted. Interestingly, MO elicited a significant dose-dependent reduction in both inhibitory and excitatory transmission, with a net depressant effect on neurotransmission (in contrast to the classical GABA(A) antagonist picrotoxinin which evoked profound epileptiform burst firing in these cells). The anti-agitation effects in patients and the depressant effects of MO in in-vitro we report in neural membranes are unlikely to reflect a sedative interaction with any of the ionotropic receptors examined here.

Evidence demonstrated that glial cells, mainly astrocytes, regulate glutamate uptake, which is regulated by several glutamate transporters. Among these glutamate transporters, glutamate transporter 1 (GLT-1; its human homolog is excitatory amino acid transporter-2) is responsible for the majority of glutamate uptake by glial cells. Cystine-glutamate antiporter (xCT) is another glial protein critical in regulating glutamate transmission. Several studies from our laboratory demonstrated that attenuation of ethanol intkae was associated in part with upregulation of xCT and GLT suggesting the important role of these transporters in the treatment of ethanol dependence. We found recently that β-lactam antibiotic, ampicillin, upregulated GLT-1 expression in the prefrontal cortex (PFC) and nucleus accumbens (NAc) and consequently reduced ethanol intake in alcohol-preferring (P) rats. In this study, we investigated the effects of ampicillin on the expressions of xCT and GLT-1 isoforms (GLT-1a and GLT-1b) as well as on GLAST expression. We found that ampicillin reduced ethanol intake as compared to the saline (control)-treated group. In addition, we found that ampicillin induced upregulation of xCT, GLT-1a, and GLT-1b expressions in both the PFC and NAc, but had no effect on GLAST expression. Our findings provide significant role of ampicillin on upregulating xCT and GLT-1 isoforms expressions, might be suggested as possible tragets for the attenuation of ethanol consumption.

Butyrylcholinesterase (BChE) plays an important role in the progression of the Alzheimer’s disease. In this study, we used a structure-based virtual screening (VS) approach to discover new BChE inhibitors. A ligand database was filtered and docked to the BChE protein using Glide program. The outcome from VS was filtered and the top ranked hits were thoroughly examined for their fitting into the protein active site. Consequently, the best 38 hits were selected for in vitro testing using Ellman’s method, and six of which showed inhibition activity for BChE. Interestingly, the most potent hit (Compound 4) exhibited inhibitory activity against the BChE enzyme in the low micromolar level with an IC50 value of 8.3 µM. Hits obtained from this work can act as a starting point for future SAR studies to discover new BChE inhibitors as anti-Alzheimer agents.