Restoration of acetylcholinesterase activity by Euphorbia hirta in discrete brain regions of chronically stressed rats

Two pairs of bioactive cyclohexene alkaloid enantiomers from the roots of Piper nigrum

Two pairs of cyclohexene amide alkaloid enantiomers were obtained from the root of Piper nigrum. Their plane structures were established by NMR and HRESIMS spectra. The absolute configurations of 1a/1b and 2a/2b were determined by the comparison between the experimental and calculated electronic circular dichroism (ECD) spectra. All identified compounds were tested for inhibitory effects on acetylcholinesterase (AChE) in vitro. Notably, compounds 1b and 2b showed strong inhibitory effects on AChE and the interaction between proteins and compounds was discussed by molecular docking studies.

Euphorfistrines A-G, cytotoxic and AChE inhibiting triterpenoids from the roots of Euphorbia fischeriana

Seven new triterpenoids including two cycloartanes (1-2), a lanostane (3), a tirucallane (4), a dammarane (5), an ursane (6), and an oleanane (7), along with nineteen known triterpenoids (8-26), have been obtained from the roots of Euphorbia fischeriana. Their structures were established by NMR, HRESIMS, single-crystal X-ray diffraction analysis, Mosher's method, NMR calculations, ECD analysis, and comparison with structurally related known analogues. Among them, compounds 1 and 8 were a pair of cycloartane-type triterpenoids epimers. Our bioassays have established that compounds 1-5 and 10 displayed moderate cytotoxic effects, and the structure-activity relationships of cycloartane-type triterpenoids (CTTs) were further examined. Notably, some triterpenoids displayed moderate inhibitory effects against AChE by an in vitro screened experiment. Triterpenoid 7 (Euphorfistrine G, ETG) displayed the potent inhibitory effect with IC₅₀ = 2.45 and K_i = 2.30 μM (inhibition kinetic). And, in silico docking analyses have been performed to investigate the inhibitory mechanism of compound 7.

Medicinal plants with acetylcholinesterase inhibitory activity

Alzheimer's disease, a progressive neurodegenerative disease, is characterised by hypofunction of acetylcholine (ACh) neurotransmitter in the distinct region of brain. Acetylcholinesterase (AChE) is an enzyme that metabolises the ACh at synaptic cleft resulting in Alzheimer's disease. Medicinal plants have been used to treat numerous ailments and improve human health from ancient time. A traditional system of medicine is long recognised for its effective management of neurological disorders. The present review confers the scope of some common medicinal plants with a special focus on AChE-mediated central nervous system complications especially Alzheimer's disease. Literature suggests that medicinal plants reduce neuronal dysfunctions by reducing AChE activity in different brain regions. In some instances, activation of AChE activity by medicinal plants also showed therapeutic potential. In conclusion, medicinal plants have a wide scope and possess therapeutic potential to efficiently manage neurological disorders associated with AChE dysregulation.

Mouse repeated electroconvulsive seizure (ECS) does not reverse social stress effects but does induce behavioral and hippocampal changes relevant to electroconvulsive therapy (ECT) side-effects in the treatment of depression

Electroconvulsive therapy (ECT) is an effective treatment for depression, but can have negative side effects including amnesia. The mechanisms of action underlying both the antidepressant and side effects of ECT are not well understood. An equivalent manipulation that is conducted in experimental animals is electroconvulsive seizure (ECS). Rodent studies have provided valuable insights into potential mechanisms underlying the antidepressant and side effects of ECT. However, relatively few studies have investigated the effects of ECS in animal models with a depression-relevant manipulation such as chronic stress. In the present study, mice were first exposed to chronic social stress (CSS) or a control procedure for 15 days followed by ECS or a sham procedure for 10 days. Behavioral effects were investigated using an auditory fear conditioning (learning) and expression (memory) test and a treadmill-running fatigue test. Thereafter, immunohistochemistry was conducted on brain material using the microglial marker Iba-1 and the cholinergic fibre marker ChAT. CSS did not increase fear learning and memory in the present experimental design; in both the control and CSS mice ECS reduced fear learning and fear memory expression. CSS induced the expected fatigue-like effect in the treadmill-running test; ECS induced increased fatigue in CSS and control mice. In CSS and control mice ECS induced inflammation in hippocampus in terms of increased expression of Iba-1 in radiatum of CA1 and CA3. CSS and ECS both reduced acetylcholine function in hippocampus as indicated by decreased expression of ChAT in several hippocampal sub-regions. Therefore, CSS increased fatigue and reduced hippocampal ChAT activity and, rather than reversing these effects, a repeated ECS regimen resulted in impaired fear learning-memory, increased fatigue, increased hippocampal Iba-1 expression, and decreased hippocampal ChAT expression. As such, the current model does not provide insights into the mechanism of ECT antidepressant function but does provide evidence for pathophysiological mechanisms that might contribute to important ECT side-effects.

SANTHANARAJ, ER H. The effects of Euphorbia hirta on the ultrastructure of the murine liver, kidney and aorta

Euphorbia hirta is widely used in traditional remedies and has been used cross-culturally for generations against maladies such as asthma, skin ailments and hypertension. Previous studies have demonstrated that Euphorbia hirta has antibacterial activity, and have also indicated certain antimolluscidal, antimalarial and anti-inflammatory properties, the latter of which have been suggested to be more pronounced than those of the rheumatological drug, etanercept. To date, no studies have identified the anatomical effects of this herb on the organs of test animals. This study aimed to identify the effects of Euphorbia hirta on the ultrastructure of the murine liver, kidney and aorta. A total of 32 adult male Sprague-Dawley rats were divided into four groups; three groups were fed with aqueous extracts of Euphorbia hirta at doses of 1, 10 and 50 mg/kg, respectively, every alternate day for 50 days, while one group served as a control. The animals were later sacrificed and the liver, kidney and aorta harvested for examination by electron microscopy. The aorta showed no ultrastructural changes across the groups. Renal and hepatic tissue from the treated groups demonstrated dose-dependent injuries, which showed architectural damage beginning in the nuclei and spreading outwards. Taking into consideration the properties of Euphorbia hirta that have been described in previous studies, in addition to the results from the present study, it appears that the herb may exhibit similar effects to those of the quinolone group of antibiotics. Further in-depth investigations are required into the potential effects of Euphorbia hirta, deleterious and otherwise.

Chronic escitalopram treatment restores spatial learning, monoamine levels, and hippocampal long-term potentiation in an animal model of depression

RATIONALE

The neural basis of depression-associated cognitive impairment remains poorly understood, and the effect of antidepressants on learning and synaptic plasticity in animal models of depression is unknown. In our previous study, learning was impaired in the neonatal clomipramine model of endogenous depression. However, it is not known whether the cognitive impairment in this model responds to antidepressant treatment, and the electrophysiological and neurochemical bases remain to be determined.

OBJECTIVES

To address this, we assessed the effects of escitalopram treatment on spatial learning and memory in the partially baited radial arm maze (RAM) task and long-term potentiation (LTP) in the Schaffer collateral-CA1 synapses in neonatal clomipramine-exposed rats. Also, alterations in the levels of biogenic amines and acetylcholinesterase (AChE) activity were estimated.

RESULTS

Fourteen days of escitalopram treatment restored the mobility and preference to sucrose water in the forced swim and sucrose consumption tests, respectively. The learning impairment in the RAM was reversed by escitalopram treatment. Interestingly, CA1-LTP was decreased in the neonatal clomipramine-exposed rats, which was restored by escitalopram treatment. Monoamine levels and AChE activity were decreased in several brain regions, which were restored by chronic escitalopram treatment.

CONCLUSIONS

Thus, we demonstrate that hippocampal LTP is decreased in this animal model of depression, possibly explaining the learning deficits. Further, the reversal of learning and electrophysiological impairments by escitalopram reveals the important therapeutic effects of escitalopram that could benefit patients suffering from depression.