Wajahat Mahmood

2-(Hetero(aryl)methylene)hydrazine-1-carbothioamides as Potent Urease Inhibitors

A small series of 2‐(hetero(aryl)methylene) hydrazine‐1‐carbothioamides including two aryl derivatives was synthesized and tested for their inhibitory activity against urease. Compound (E)‐2‐(Furan‐2‐ylmethylene) hydrazine‐1‐carbothioamide (3f), having a furan ring, was the most potent inhibitor of urease with an IC50 value of 0.58 μm. Molecular modeling was carried out through docking the designed compounds into the urease binding site to predict whether these derivatives have analogous binding mode to the urease inhibitors. The study revealed that all of the tested compounds bind with both metal atoms at the active site of the enzyme. The aromatic ring of the compounds forms ionic interactions with the residues, Ala(440), Asp(494), Ala(636), and Met(637).

Saponins: the phytochemical with an emerging potential for curing clinical depression

Depression is on the rise globally and expected to lead in global burden of diseases by 2030. The current therapy has serious limitations in terms of safety, efficacy, tolerability and therapeutic success. This review, based on the literature of the last decade, is aimed at exploring the preclinical profile of plant-based saponins (the abundant secondary metabolite) as an emerging therapy for depression. Enough scientific evidences reflect that saponins promote neurogenesis, restore monoaminergic tone and enhance neurotrophic factors. In multiple stress models, they have exhibited adaptogenic effects via normalising hypothalamus–pituitary–adrenal axis, corticosterone levels and oxidative stress. Scientific data revealed neuroprotective effect of saponins by inhibiting apoptosis and intraneuronal calcium dynamics. Many plants possessing saponins as their principal antidepressant moiety need investigation at clinical level. Last decade literature revealed numerous preclinical reports supporting the role of saponins as natural cure for depression and justified their inclusion in antidepressant drug discovery programs.

Cinnamomum cassia: an implication of serotonin reuptake inhibition in animal models of depression

The aim of the study was to explore the traditional use of Cinnamomum cassia against depression. The standardised methanolic extract of the bark of C. cassia was evaluated for antidepressant activity using various behavioural tests, i.e. tail suspension test (TST), forced swim test (FST) and locomotor activity test. The serotonergic and noradrenergic modulation was assessed using 5-hydroxytryptophan (5-HTP)-induced head twitches and yohimbine potentiation tests, respectively. The fluoxetine and phenelzine were used as positive controls in the study. The C. cassia extract significantly decreased the immobility time in TST (maximum effective dose tested was 50 mg/kg) while no effect was observed in FST and locomotor activity test. The extract significantly increased the 5-HTP-induced head twitches while yohimbine-induced lethality remained unaltered. The aforementioned results are similar to that caused by fluoxetine. The standardised methanolic extract of C. cassia demonstrated antidepressant activity that can be attributed to rise in serotonin levels.

β-glucan attenuated scopolamine induced cognitive impairment via hippocampal acetylcholinesterase inhibition in rats.

β-glucan (polysaccharide) rich diet has been reported to enhance cognition in humans but the mechanism remained elusive. Keeping this in mind, the present study was designed to investigate the interaction of β-glucan with central cholinergic system. Briefly, in-silico analysis revealed promising interactions of β-glucan with the catalytic residues of acetylcholinesterase (AChE) enzyme. In line with this outcome, the in vitro assay (Ellmans method) also exhibited inhibition of AChE by β-glucan (IC50=0.68±0.08μg/µl). Furthermore, the in vivo study (Morris water maze) showed significant dose dependent reversal of the amnesic effect of scopolamine (2mg/kg i.p.) by β-glucan treatment (5, 25, 50 and 100mg/kg, i.p.). Finally, the hippocampi of aforementioned treated animals also revealed dose dependent inhibition of AChE enzyme. Hence, it can be deduced that β-glucan possesses potential to enhance central cholinergic tone via inhibiting AChE enzyme. In conclusion, the present study provides mechanistic insight to the cognition enhancing potential of β-glucan. Keeping in mind its dietary use and abundance in nature, it can be considered as economic therapeutic option against cognitive ailments associated with decline in cholinergic neurotransmission.

6-Methoxyflavanone attenuates mechanical allodynia and vulvodynia in the streptozotocin-induced diabetic neuropathic pain

BACKGROUND Diabetic neuropathy is the most prevalent, persistent and debilitating complication of diabetes mellitus often coupled with vulvodynia that may present as an isolated symptom or as a part of constellation of other neuropathic abnormalities. OBJECTIVE Flavonoids have selective affinity for GABA receptors and 6-methoxyflavanone (6-MeOF) is a positive allosteric modulator of GABA responses at human recombinant GABAA receptors. GABAergic and opioidergic system inhibition have been shown to facilitate neuropathic pain. METHODS 6-MeOF was evaluated for analgesic effect in the hot plate test and streptozotocin-induced diabetic neuropathic pain in female rats using von Frey hairs. The possible involvement of opioidergic and GABAergic mechanisms was investigated using naloxone and pentylenetetrazole (PTZ) antagonists, respectively. The biodistribution of 6-MeOF in plasma and CNS was examined using a validated HPLC/UV analytical method. The binding affinity of 6-MeOF with opioid and GABA receptors was studied using molecular docking simulation approach. RESULTS 6-MeOF (10 and 30mg/kg) attenuated the acute phasic thermal nociception in the hot plate test while in the case of streptozotocin-induced diabetic neuropathy model, 6-MeOF (10 and 30mg/kg) produced static/dynamic anti-allodynic (increased paw withdrawal threshold and latency) as well as static/dynamic anti-vulvodynic effects (increased flinching response threshold and latency), when compared to the vehicle and standard gabapentin (75mg/kg). In silico studies depicted the preference of 6-MeOF for the delta- and kappa-opioid and GABAA receptors. Moreover, the pharmacokinetic profile revealed a quick appearance of 6-MeOF in the systemic circulation and brain areas with maximum concentration observed after 30min in the amygdala, brain stem and cerebral cortex. CONCLUSION 6-MeOF readily crosses the blood brain barrier and may be effective in attenuating the diabetes-induced allodynia as well as vulvodynia, probably through interactions with the GABAergic and opioidergic systems.

Recent progress on the role of GABAergic neurotransmission in the pathogenesis of Alzheimer's disease.

Abstract Despite their possible causative role, targeting amyloidosis, tau phosphorylation, acetylcholine esterase, glutamate, oxidative stress and mitochondrial metabolism have not yet led to the development of drugs to cure Alzheimer’s disease (AD). Recent preclinical and clinical reports exhibit a surge in interest in the role of GABAergic neurotransmission in the pathogenesis of AD. The interaction among GABAergic signaling, amyloid-β and acetylcholine is shown to affect the homeostasis between excitation (glutamate) and inhibition (GABA) in the brain. As a consequence, over-excitation leads to neurodegeneration (excitotoxicity) and impairment in the higher level functions. Previously, the glutamate arm of this balance received the most attention. Recent literature suggests that over-excitation is primarily mediated by dysfunctional GABA signaling and can possibly be restored by rectifying anomalous metabolism observed in the GABAergic neurons during AD. Additionally, neurogenesis and synaptogenesis have also been linked with GABAergic signaling. This association may provide a basis for the needed repair mechanism. Furthermore, several preclinical interventional studies revealed that targeting various GABA receptor subtypes holds potential in overcoming the memory deficits associated with AD. In conclusion, the recent scientific literature suggests that GABAergic signaling presents itself as a promising target for anti-AD drug development.

Thymoquinone inhibition of acquisition and expression of alcohol-induced behavioral sensitization

Repeated low doses of alcohol have been shown to progressively enhance locomotor activity in mice, and this phenomenon is designated as behavioral sensitization. Thymoquinone, a major active component of Nigella sativa oil has been investigated in a number of studies for its neuroprotective effects against a variety of ailments. This study was conducted to explore the therapeutic potential of thymoquinone on the acquisition and expression of alcohol‐induced behavioral sensitization. Mice treated with alcohol (2.2 g/kg/day) or saline for 13 days and subsequently challenged with an acute alcohol dose (2.2 g/kg) 5 days later were orally administered acute doses of thymoquinone (10, 20 and 30 mg/kg). Thymoquinone subacute treatment with all doses throughout alcohol exposure significantly inhibited both the development and expression phases of alcohol behavioral sensitization in a dose‐dependent manner. However, acute treatment with thymoquinone (30 mg/kg) only reversed the expression phase of sensitization. These findings are explained in terms of the known GABA promoting action of thymoquinone in relation to the motive circuit within the limbic component of the basal ganglia. It is concluded that thymoquinone may be a potential therapeutic option for the treatment and prevention of alcohol induced behavioral sensitization. Copyright

Gamma-linolenic acid ameliorated glycation-induced memory impairment in rats

Abstract Context: γ-Linolenic acid (GLA) is an important constituent of anti-ageing supplements. Objective: The current study investigates the anti-ageing effect of GLA in Sprague-Dawley rats. Materials and methods: GLA (0.1, 0.2, 0.4, 2, 10, 20 and 24 μM) was initially evaluated for its effect on the formation of advanced glycation end products (AGEs) in vitro. For in vivo assessment (1, 5 or 15 mg/kg), the rat model of accelerated ageing was developed using d-fructose (1000 mg/kg (i.p.) plus 10% in drinking water for 40 days). Morris water maze was used to evaluate impairment in learning and memory. The blood of treated animals was used to measure glycosylated haemoglobin (HbA1c) levels. The interaction of GLA with active residues of receptor of AGE (RAGE) was analyzed using AutoDock Vina. Results: Our data showed that GLA inhibited the production of AGEs (IC50 = 1.12 ± 0.05 μM). However, this effect was more significant at lower tested doses. A similar pattern was also observed in in vivo experiments, where the effect of fructose was reversed by GLA only at lowest tested dose of 1 mg/kg. The HbA1c levels also revealed significant reduction at lower doses (1 and 5 mg/kg). The in silico data exhibited promising interaction of GLA with active residues (Try72, Arg77 and Gln67) of RAGE. Conclusion: The GLA, at lower doses, possesses therapeutic potential against glycation-induced memory decline.

Microbial Biotransformation of Dexamethasone by Bacillus Subtilis (ATCC 6051)

This article reports microbial biotransformation of dexamethasone, a synthetic glucocorticoid, by Bacillus subtilis. This bacterium can be used as a microbial metabolic model to investigate the metabolism of other synthetic glucocorticoids as it mimics mammalian metabolism to a certain extent. Incubation of dexamethasone with B. subtilis for 7 days yielded three compounds identified as 6-hydroxydexamethasone, 17-oxodexamethasone, and 6-hydroxy-17-oxodexamethasone. Structure elucidation of these compounds was done using 1H-NMR and 13C-NMR spectroscopy techniques.

Novel hydroquinone derivatives alleviate algesia, inflammation and pyrexia in the absence of gastric ulcerogenicity

Purpose : To synthesize and characterize novel hydroquinone compounds that exhibit an aspirin-like pharmacological profile devoid of ulcerogenic side effects. Methods : Two novel hydroquinone derivatives, viz, 2,5-bis(piperidinomethyl)hydroquinone and 2,5- bis(pyrrolidinomet hyl)hydroquinone, were synthesized by refluxing hydroquinone, paraformaldehyde and secondary amines (piperidine or pyrrolidine) in ethanol. The structures were authenticated by infrared (IR) spectroscopy, elemental analysis, mass spectrometry (MS) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopic techniques. The synthesized derivatives were evaluated for antinociceptive, anti-inflammatory and antipyretic activities along with gastric-ulcerogenicity using wellknown testing paradigms. Aspirin served as reference standard. Results : The newly synthesized hydroquinone derivatives, significantly attenuated tonic visceral chemically-induced nociception at 10 mg/kg (p < 0.01, p < 0.001), 20 and 40 mg/kg (p < 0.001), inhibited the temporal-inflammatory reaction at 50 mg/kg (2 - 5 h, p < 0.05, p < 0.001), 100 and 150 mg/kg (1 - 5 h, p < 0.05, p < 0.01, p < 0.001) in addition to alleviating the febrile-response at test doses during 0.5 h (p < 0.05, p < 0.01, p < 0.001), 1 and 1.5 h (p < 0.001) of the study period. The synthesized compounds exhibited improved gastric tolerability profile since they were devoid of aspirin-associated biochemical and ulcerative changes. The in silico studies predicted high binding affinity of the hydroquinone derivatives to the active site of the cyclooxygenase 2 (COX-2) enzyme. Conclusion : The synthesized hydroquinone compounds possess analgesic, antipyretic and antiinflammatory properties with low gastric-ulcerogenic potential. This may be credited to preferential inhibition of the COX-2 enzyme and the beneficial basic rather than acidic chemical nature of the compounds. However, further molecular studies are required to substantiate these findings. Keywords : 2,5-Bis(piperidinomethyl)hydroquinone], 2,5- is(pyrrolidinomethyl)hydroquinone, Antiinflammatory, Antinociceptive, Antipyretic, Gastric-ulcerogenicity, Algesia