Nisar Ahmad

Anti-Alzheimer’s Studies on β-Sitosterol Isolated from Polygonum hydropiper L.

The family Polygonaceae is known for its traditional use in the management of various neurological disorders including Alzheimer’s disease (AD). In search of new anti-AD drugs, β-sitosterol isolated from Polygonum hydropiper was subjected to in vitro, in vivo, behavioral and molecular docking studies to confirm its possibility as a potential anti-Alzheimer’s agent. The in vitro AChE, BChE inhibitory potentials of β-sitosterol were investigated following Ellman’s assay. The antioxidant activity was tested using DPPH, ABTS and H2O2 assays. Behavioral studies were performed on a sub-strain of transgenic mice using shallow water maze (SWM), Y-maze and balance beam tests. β-sitosterol was tested for in vivo inhibitory potentials against cholinesterase’s and free radicals in the frontal cortex (FC) and hippocampus (HC). The molecular docking study was performed to predict the binding mode of β-sitosterol in the active sites of AChE and BChE as inhibitor. Considerable in vitro and in vivo cholinesterase inhibitory effects were observed in the β-sitosterol treated groups. β-sitosterol exhibited an IC50 value of 55 and 50 μg/ml against AChE and BChE respectively. Whereas, the activity of these enzymes were significantly low in FC and HC homogenates of transgenic animals. Molecular docking studies also support the binding of β-sitosterol with the target enzyme and further support the in vitro and in vivo results. In the antioxidant assays, the IC50 values were observed as 140, 120, and 280 μg/ml in the DPPH, ABTS and H2O2 assays respectively. The free radicals load in the brain tissues was significantly declined in the β-sitosterol treated animals as compared to the transgenic-saline treated groups. In the memory assessment and coordination tasks including SWM, Y-maze and balance beam tests, β-sitosterol treated transgenic animals showed gradual improvement in working memory, spontaneous alternation behavior and motor coordination. These results conclude that β-sitosterol is a potential compound for the management of memory deficit disorders like AD.

Topical gabapentin gel alleviates allodynia and hyperalgesia in the chronic sciatic nerve constriction injury neuropathic pain model

Systemic gabapentin is a mainstay treatment for neuropathic pain though there are side‐effects. Localized therapy may curtail such side‐effects so a topical gabapentin dermal application was examined in the chronic constriction injury (CCI) model of neuropathic pain.

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.

Characterization of 6-methoxyflavanone as a novel anxiolytic agent: A behavioral and pharmacokinetic approach

ABSTRACT Benzodiazepines are regularly prescribed for treatment of anxiety though there are side effects. Flavonoids have selective affinity for GABAA receptors implicated in anxiolytic‐like activity in rodents, but are devoid of the unwanted side effects of benzodiazepines. In this study, 6‐methoxyflavanone (6‐MeOF), a positive allosteric modulator of &ggr;‐amino butyric acid (GABA) responses at human recombinant GABAA receptors, was evaluated for its behavioral profile in the elevated plus‐maze as well as the staircase‐ plus and open‐field tests in mice. In addition, the distribution of 6‐MeOF in selected brain areas involved in anxiety (amygdala and cerebral cortex) was also examined using a validated high performance liquid chromatography ultraviolet detection (HPLC/UV) method. 6‐MeOF (10, 30 and 50 mg/kg) exerted an anxiolytic‐like effect, increasing entries and time spent in the open arm and the central platform, as well as head‐dipping frequency in the mouse elevated plus‐maze assay. It also decreased rearing incidence without suppressing the number of steps ascended in the staircase test. Whereas, in the open‐field anxiety test, 6‐MeOF had no effect on locomotor activity at lower doses, a decrease was observed at the highest dose (100 mg/kg). 6‐MeOF additionally produced an anxiolytic‐like increase in the time spent at the center of the open‐field apparatus. These effects were preferentially antagonized by pentylenetetrazole (15 mg/kg). Furthermore, pharmacokinetic studies disclosed a rapid appearance of 6‐MeOF in the plasma and discrete brain areas. Taken together, our findings suggest that 6‐MeOF readily crosses the blood brain barrier (BBB) generating anxiolytic activity, mediated through the GABAergic system.

A Novel Pregabalin Functionalized Salicylaldehyde Derivative Afforded Prospective Pain, Inflammation, and Pyrexia Alleviating Propensities

A novel pregabalin derivative named as pregsal ((S,E)‐3‐(((2‐hydroxybenzylidene)amino)methyl)‐5‐methylhexanoic acid) was synthesized by a simple imination reaction between pregabalin and salicylaldehyde and was evaluated in the in vivo testing paradigms. The compound was characterized by UV, IR, 1H, 13C NMR, HR ESI‐MS, and elemental analysis. It was screened (30, 50, 75, and 100 mg/kg) for antinociceptive, anti‐inflammatory, and antipyretic activities in relation to pregabalin. The synthesized compound significantly attenuated the tonic acetic acid‐induced nociceptive pain (30 mg/kg (P < 0.05), 50 mg/kg (P < 0.01), 75 and 100 mg/kg (P < 0.001)), and thermal‐induced hyperalgesia (P < 0.001). These activities were succinctly antagonized (P < 0.05, P < 0.01, P < 0.001) by naloxone and pentylenetetrazole, implicating the involvement of opioidergic and GABAergic mechanisms. The compound also inhibited the temporal inflammatory response and alleviated the yeast‐induced pyrexia (P < 0.05, P < 0.01, and P < 0.001). These findings suggest that the synthesized compound possessed prospective pain, inflammation, and pyrexia relieving propensities and therefore may serve as a potential drug candidate for the therapeutic management of chronic pain conditions.

Olanzapine induced biochemical and histopathological changes after its chronic administration in rats

Objective: Olanzapine is a second generation antipsychotic acting mainly as a dopamine D2 and serotonine 5-HT2 receptors antagonist prescribed in the treatment of schizophrenia and various other psychiatric illnesses. Even though olanzapine is widely used in psychiatry, its effects on the architecture of pancreas, liver and kidneys are little known. The histology of pancreas especially has never been studied. For these reasons, the current study was designed to elucidate the toxic effects of chronic administration of olanzapine on pancreas, liver and kidneys and the enzymes released by these tissues in an escalating dose manner. Methods: Fourteen male rats were divided into two groups equally, the olanzapine group and the controls. Olanzapine was administered in a dose of 5 mg/kg/d for the first eight weeks, 10 mg/kg/d for next four weeks and 15 mg/kg/d through the last two week period of 14 weeks experiment. The controls received acidified saline only. Both the groups received restricted diet (20 g/12 h). The body weight and level of random blood sugar (RBS) were measured on a weekly basis. The levels of lipase, amylase, alanine transaminase (ALT) and aspartate transaminase (AST) were determined terminally. At the end of the experiment, the tissues were dissected out for histopathological evaluation. Results: Significant loss in body weight, change in the level of random blood sugar (∗∗P < 0.05, ∗∗∗P < 0.001) and significant rise in amylase and lipase levels (∗P < 0.05, ∗∗∗P < 0.001) were observed. However, the same treatment has shown no significant change in the levels of alanine and aspartate transaminases (P > 0.05). The pancreas has shown derangement of beta cells and fibrotic growth. A mild to moderate focal increase in glomerular cellularity, cellular proliferation and glomerular capsules with negligible basement membranes were observed in the kidneys. No changes were observed in the architecture of the liver. Conclusion: The findings of this study indicated that the incidence of adverse effects associated with olanzapine could be prevented/alleviated/delayed by allowing restricted diet.

Gabapentin and its salicylaldehyde derivative alleviate allodynia and hypoalgesia in a cisplatin-induced neuropathic pain model

ABSTRACT Cisplatin is an effective chemotherapeutic agent indicated in cancer chemotherapy. However, its clinical use is associated with peripheral neuropathy that invariably impairs patient quality of life. Gabapentin (GBP) is an effective analgesic for neuropathic pain conditions but its clinical efficacy in cisplatin‐induced neuropathic pain (CINP) is limited, in addition to generating unwanted side‐effects. In this study, a gabapentin‐salicylaldehyde derivative [gabapentsal (GPS)] was synthesized and evaluated to explore any potential benefit in comparison with GBP in a rat model of CIPN. Administration of cisplatin (3.0 mg/kg/week, i.p.) for five consecutive weeks generated reproducible mechanical‐allodynia (decreased paw withdrawal threshold to von Frey filament application; PWT, g) and thermal hypoalgesia (increased nociceptive reaction latency in the hot plate paradigm; s). Treatment with GBP or its derivative on the 37th day of the experimental protocol, dose dependently attenuated cisplatin‐induced nocifensive behaviors. Accordingly, doses of GBP (50–100 mg/kg, i.p.) and GPS (25–100 mg/kg, i.p.) suppressed the expression of CINP by normalizing the PWT and hot plate response latency 1 h and 3 h post administration. In the rotarod paradigm, GBP at all doses markedly impaired motor performance, whilst GPS was devoid of motor incoordination except at the highest dose, when a mild impairment occurred. Salicylaldehyde alone had no effect on CINP or rotarod performance and neither was there any synergism when coadministered with GBP. These findings suggest that both GBP and GPS have beneficial effects in the neuropathic pain model though GPS may be potentially more useful in the management of CINP.

The flavonoid 6-methoxyflavone allays cisplatin-induced neuropathic allodynia and hypoalgesia

Chemotherapy-induced peripheral neuropathy (CIPN) is a major dose limiting side-effect of several commonly used chemotherapeutic agents (such as cisplatin) that profoundly impairs patient quality of life. Unfortunately, neither prophylactic strategies nor symptomatic treatments have proven useful in this condition. Flavonoids are found ubiquitously in fruits and vegetables and exert a multiplicity of beneficial effects. In this study, the antinociceptive activity of 6-methoxyflavone (6-MF) was investigated and evaluated in comparison with gabapentin in a rat model of CIPN. The effect on motor balance was also assessed using the rotarod and footprint analysis paradigms. 6-MF possessed both peripheral and central antinociceptive activities against tonic and phasic nociceptive stimuli. Cisplatin administration (3.0mg/kg/week, i.p.) for four consecutive weeks generated temporal mechanical allodynia (decreased paw withdrawal threshold; PWT) and thermal hypoalgesia (increased paw thermal threshold; PTT) in the bilateral hindpaws. Daily treatment with 6-MF (25, 50 and 75mg/kg/day, i.p) for four weeks attenuated the cisplatin-induced expression of nocifensive behaviors observed as a significant increase in PWT and alleviation of PTT during the third and fourth weeks of cisplatin administration. Accordingly, daily gabapentin (75mg/kg, i.p) suppressed the expression of CIPN by normalizing the PWT and hotplate response latency. However, these antinociceptive actions were associated with motor impairment exemplified by a significant decrease in rotarod endurance latency and a deficit in the uniformity of step alternation. In contrast, 6-MF was devoid of these adverse side-effects. These findings suggested that 6-MF afforded desirable neuropathic pain alleviating effects in CIPN and it was devoid of gabapentin-like unwanted motor side-effects.