Promising selective MAO-B inhibition by sesamin, a lignan from Zanthoxylum flavum stems

Imperatorin Influences Depressive-like Behaviors: A Preclinical Study on Behavioral and Neurochemical Sex Differences

Imperatorin, a naturally derived furanocoumarin, exerts promising neuropharmacological properties. Therefore, it might be applicable in the treatment of brain diseases such as depression. In the present project, we aimed to investigate the sex-dependent effects of imperatorin (1, 5, and 10 mg/kg) on behavior and neurochemistry associated with antidepressant effects. The depressive-like behaviors of male and female Swiss mice were investigated in a forced swim test (FST). Subsequently, High-Performance Liquid Chromatography (HPLC) was used to evaluate the level of serotonin, its metabolite, 5-HIAA, and noradrenaline, in mouse brains. The study revealed that only males responded to imperatorin (1 and 5 mg/kg) treatment and caused an antidepressant effect, such as with respect to depressive-like behaviors, lowering immobility time and increasing immobility latency. The HPLC analysis demonstrated that serotonin levels in the prefrontal cortex of females decreased with the middle dose of imperatorin (5 mg/kg), while in the male prefrontal cortex, the lower dose (1 mg/kg) boosted serotonin levels. There were no evident changes observed with respect to noradrenaline and serotonin metabolite levels in the male hippocampus. To conclude, we propose that imperatorin has antidepressant potential, seemingly only in males, influencing brain serotonin level, but the direct mechanism of action requires further investigation.

Selected Natural Products in Neuroprotective Strategies for Alzheimer's Disease-A Non-Systematic Review

Neurodegenerative disorders such as Alzheimer's disease (AD) are distinguished by the irreversible degeneration of central nervous system function and structure. AD is characterized by several different neuropathologies-among others, it interferes with neuropsychiatrical controls and cognitive functions. This disease is the number one neurodegenerative disorder; however, its treatment options are few and, unfortunately, ineffective. In the new strategies devised for AD prevention and treatment, the application of plant-based natural products is especially popular due to lesser side effects associated with their taking. Moreover, their neuroprotective activities target different pathological mechanisms. The current review presents the anti-AD properties of several natural plant substances. The paper throws light on products under in vitro and in vivo trials and compiles information on their mechanism of actions. Knowledge of the properties of such plant compounds and their combinations will surely lead to discovering new potent medicines for the treatment of AD with lesser side effects than the currently available pharmacological proceedings.

Effects of Sesamin, the Major Furofuran Lignan of Sesame Oil, on the Amplitude and Gating of Voltage-Gated Na+ and K+ Currents

Sesamin (SSM) and sesamolin (SesA) are the two major furofuran lignans of sesame oil and they have been previously noticed to exert various biological actions. However, their modulatory actions on different types of ionic currents in electrically excitable cells remain largely unresolved. The present experiments were undertaken to explore the possible perturbations of SSM and SesA on different types of ionic currents, e.g., voltage-gated Na⁺ currents (I_Na), erg-mediated K⁺ currents (I_K(erg)), M-type K⁺ currents (I_K(M)), delayed-rectifier K⁺ currents (I_K(DR)) and hyperpolarization-activated cation currents (I_h) identified from pituitary tumor (GH₃) cells. The exposure to SSM or SesA depressed the transient and late components of I_Na with different potencies. The IC₅₀ value of SSM needed to lessen the peak or sustained I_Na was calculated to be 7.2 or 0.6 μM, while that of SesA was 9.8 or 2.5 μM, respectively. The dissociation constant of SSM-perturbed inhibition on I_Na, based on the first-order reaction scheme, was measured to be 0.93 μM, a value very similar to the IC₅₀ for its depressant action on sustained I_Na. The addition of SSM was also effective at suppressing the amplitude of resurgent I_Na. The addition of SSM could concentration-dependently inhibit the I_K(M) amplitude with an IC₅₀ value of 4.8 μM. SSM at a concentration of 30 μM could suppress the amplitude of I_K(erg), while at 10 μM, it mildly decreased the I_K(DR) amplitude. However, the addition of neither SSM (10 μM) nor SesA (10 μM) altered the amplitude or kinetics of I_h in response to long-lasting hyperpolarization. Additionally, in this study, a modified Markovian model designed for SCN8A-encoded (or Na_V1.6) channels was implemented to evaluate the plausible modifications of SSM on the gating kinetics of Na_V channels. The model demonstrated herein was well suited to predict that the SSM-mediated decrease in peak I_Na, followed by increased current inactivation, which could largely account for its favorable decrease in the probability of the open-blocked over open state of Na_V channels. Collectively, our study provides evidence that highlights the notion that SSM or SesA could block multiple ion currents, such as I_Na and I_K(M), and suggests that these actions are potentially important and may participate in the functional activities of various electrically excitable cells in vivo.