Gautam Palit

Adaptogenic effect of Bacopa monniera (Brahmi)

As stress is linked to many diseases, research on an effective antistress agent (adaptogen) from plants has gained importance. We report the investigations on the adaptogenic property of a standardized extract of Bacopa monniera against acute (AS) and chronic stress (CS) models in rats. Panax root powder (Panax quinquefolium) was taken as a standard. Male SD rats, weighing 180-200 g, exposed to immobilization stress for 150 min once only for AS and for seven consecutive days in CS, were fed with B. monniera or Panax root powder daily for 3 days in AS and for 7 days in CS, 45 min prior to each exposure of stress. Rats were sacrificed immediately after stress, the blood was collected, and the plasma was separated out for biochemical estimation. Adrenals, spleen, and thymus were dissected for organ weight and stomach for ulcer score. AS exposure significantly increased the ulcer index, adrenal gland weight, plasma glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and creatine kinase (CK) but significantly decreased the spleen weight. Pretreatment with B. monniera at 40 mg/kg po significantly reduced the AS-induced increase in the ulcer index, adrenal gland weight, plasma glucose, AST, and CK. A dose of 80 mg/kg po significantly reversed the AS-induced changes in adrenal gland weight, spleen weight, plasma glucose, ALT, and AST. Panax root powder, 100 mg/kg po, significantly reversed the AS-induced changes in spleen weight, plasma ALT, AST, and CK. CS exposure resulted in a significant increase in the ulcer index, adrenal gland weight, plasma AST, and CK with a significant decrease in the thymus and spleen weight, plasma triglyceride, and cholesterol. Pretreatment with low dose of B. monniera extract at 40 mg/kg significantly reversed changes in ulcer index and plasma AST only, whereas the pretreatment with higher dose significantly reversed CS-induced changes in ulcer index, adrenal gland weight, CK, and AST. Panax root powder significantly reversed CS-induced increase in ulcer index, adrenal gland weight, CK, and AST. On the basis of our result, it is concluded that the standardized extract of B. monniera possesses a potent adaptogenic activity.

Alterations in monoamine levels and oxidative systems in frontal cortex, striatum, and hippocampus of the rat brain during chronic unpredictable stress.

Stress plays a key role in the induction of various clinical disorders by altering monoaminergic response and antioxidant defenses. In the present study, alterations in the concentrations of dopamine (DA), serotonin (5-HT) and their metabolites, and simultaneous changes in the antioxidant defense system and lipid peroxidation in different brain regions (frontal cortex, striatum, and hippocampus) were investigated immediately and 24 h after exposure to chronic unpredictable stress (CUS). CUS involved subjecting Sprague–Dawley rats to two different types of stressors varying from mild to severe intensity every day in an unpredictable manner, over a period of 7 days. CUS significantly decreased DA and 5-HT concentrations, with increased DA turnover ratios in the selected brain regions. In the frontal cortex and striatum, DA metabolite concentrations were increased; however, in the hippocampus they remained unaltered. Further, a decrease of 5-hydroxyindoleacetic acid content was observed in the frontal cortex and striatum, with no significant alteration in the hippocampus. CUS also reduced the activities of superoxide dismutase and catalase, with increased lipid peroxidation and decreased glutathione levels in the selected brain regions. Glutathione peroxidase activity was increased in the frontal cortex and hippocampus only. The pattern of CUS-induced monoamine and oxidative changes immediately after the last stressor and 24 h later were similar when compared with the control group, indicating that the observed changes were due to the chronic exposure to the various stressors and were not merely acute effects of the last stressor. The altered redox state in the striatum and frontal cortex might be related to the perturbed DA and/or 5HT levels, while the hippocampus seems to be less influenced by CUS in terms of monoamine metabolite changes. These results suggest that the perturbed monoamine levels could interact with the oxidative load during CUS. Hence, the current study has implications for pharmacological interventions targeting both central monoamines and cellular antioxidants as a potential stress management strategy for protecting against central stress-induced disorders.

Gedunin and photogedunin of Xylocarpus granatum show significant anti-secretory effects and protect the gastric mucosa of peptic ulcer in rats.

In the present study, the gastroprotective mechanism of Xylocarpus granatum fruit and its active constituents gedunin and photogedunin was investigated. Chloroform fraction (Fr-CHCl(3)) of X. granatum fruit was evaluated against cold restraint (CRU), aspirin (AS), alcohol (AL) and pyloric ligation (PL) induced gastric ulcer models in rats and histamine (HA) induced duodenal ulcer model in guinea pigs. Potential anti-ulcer activity of Fr-CHCl(3) was observed against CRU (58.28%), AS (67.81%), AL (84.38%), PL (65.66%) and HA (61.93%) induced ulcer models. The standard drug omeprazole (10mg/kg, p.o.) showed 68.25% protection against CRU, 57.08% against AS and 69.42% against PL model and 70.79% against HA induced duodenal ulcer. Sucralfate, another standard drug (500 mg/kg, p.o.) showed 62.72% protection in AL induced ulcer model. Fr-CHCl(3) significantly reduced free acidity (51.42%), total acidity (30.76%) and upregulated mucin secretion by 58.37% respectively. Phytochemical investigations of Fr-CHCl(3) yielded gedunin (36%), photogedunin (2%). Further, Fr-CHCl(3) and its compounds gedunin and photogedunin significantly inhibited H(+) K(+)-ATPase activity in vitro with IC(50) of 89.37, 56.86 and 66.54 microg/ml respectively as compared to the IC(50) value of omeprazole (30.24 microg/ml) confirming their anti-secretory activity. Conclusively, Fr-CHCl(3) of Xylocarpus granatum was found to possess anti-ulcerogenic activity which might be due to its anti-secretory activity and subsequent strengthening of the defensive mechanism. This study is the first of its kind to show significant anti-secretory effect of gedunin and photogedunin. Therefore it could act as a potent therapeutic agent against peptic ulcer disease.

Discovery and synthesis of novel 3-phenylcoumarin derivatives as antidepressant agents

A series of 3-phenylcoumarins were synthesized and screened for potential antidepressant activity by tail suspension test (TST) in mice. Three compounds (6, 7 and 13) exhibited impressive antidepressant activity, measured in terms of percentage decrease in immobility duration (% DID). In addition, the active antidepressant compounds were subsequently studied at their most effective dose and activity of these compounds were confirmed in forced swimming test (FST) animal model, in which the compounds at a low dose of 0.5 mg/kg significantly decreased the immobility time and exhibited greater efficacy than the reference standards fluoxetine and imipramine. The potent compounds did not show any neurotoxicity in the rotarod test and the preliminary results are promising enough to warrant further studies around this scaffold.

Adaptogenic and anti-amnesic properties of Evolvulus alsinoides in rodents.

Evolvulus alsinoides (EA) is well known for its memory enhancement, antiepileptic and immunomodulatory properties in the traditional Indian system of medicine, Ayurveda. In view of the increasing attention towards plants offering non-specific resistance (adaptogens) towards stress, we have evaluated crude ethanolic extract of EA for its adaptogenic and memory enhancing properties in rodents. Adaptogenic activity was assessed in rats subjected to acute and chronic unpredictable stress. Male Sprague-Dawley rats, weighing 180-200 g were immobilized for 150 min once only in acute stress (AS) model, whereas in chronic unpredictable stress (CUS) model rats were subjected to different types of stressors daily for 7 days. Stress exposure has induced gastric ulceration with increase in adrenal gland weight, plasma creatine kinase (CK), and corticosterone level in AS and CUS. However plasma glucose was increased only in AS. Rats were treated with graded doses of crude ethanolic extract of EA (100, 200 and 400 mg/kg p.o.) for 3 days and subjected to AS on 3 day after 45 min of last dose. In CUS, EA at a dose of 200 mg/kg p.o. found effective in acute studies was administered 45 min prior to stress regimen for 7 days. EA reduced the stress induced perturbations similar to Panax quinquefolium (PQ) (100 mg/kg p.o.), a well known adaptogen. EA (100 mg/kg) administered orally for 3 days in adult male Swiss mice, was effective in decreasing scopolamine induced deficit in passive avoidance test. The improvement in the peripheral stress markers and scopolamine induced dementia by EA in the present study indicates the adaptogenic and anti-amnesic properties of EA.

Exploring indian medicinal plants for antiulcer activity

Peptic ulcer disease (PUD) is a serious gastrointestinal disorder that requires a well targeted therapeutic strategy. A number of drugs including proton pump inhibitors and H2 receptor antagonists are available for the treatment of peptic ulcer, but clinical evaluation of these drugs has shown incidence of relapses, side effects, and drug interactions. This has been the rationale for the development of new antiulcer drugs and the search for novel molecules has been extended to herbal drugs that offer better protection and decreased relapse. Drugs of plant origin are gaining popularity and are being investigated for a number of disorders, including peptic ulcer. The present article reviews the antiulcerogenic and ulcer healing property of Ocimum sanctum , Allophylus serratus , Desmodium gagenticum, Azadirachta indica , Hemidesmus racemosus , Asparagus racemosus, and Musa sapientum. We have highlighted some of the important plants reported for their anti-ulcer and ulcer healing properties, in our laboratory and elsewhere during the last few years. Ayurvedic knowledge supported by modern science is necessary to isolate, characterise, and standardise the active constituents from herbal sources for antiulcer activity.

Melatonin protects against experimental reflux esophagitis

Abstract:  Reflux esophagitis (RE), a major gastrointestinal disorder results from excess exposure of the esophageal mucosa to acidic gastric juice or bile‐containing duodenal contents refluxed via an incompetent lower esophageal sphincter. Recent studies implicated oxygen derived free radicals in RE induced esophageal mucosal damage resulting in mucosal inflammation. Thus, control over free radical generation and modulation of inflammatory responses might offer better therapeutic effects to counteract the severity of RE. In this context we investigated the effect of melatonin against experimental RE in rats. Melatonin pretreatment significantly reduced the haemorrhagic lesions and decreased esophageal lipid peroxidation aggravated by RE. Moreover, the depleted levels of superoxide dismutase and glutathione observed in RE were replenished by melatonin signifying its free radical scavenging properties and antioxidant effects resulting in the improvement of esophageal defense mechanism. Further melatonin repressed the upregulated levels of expression of proinflammatory cytokines like, TNF‐α, IL‐1β and IL‐6 in RE. However, increased levels of the anti‐inflammatory cytokine IL‐10 remained unaltered after melatonin administration signifying its immunomodulatory effect through suppression of Th1‐mediated immune responses. The involvement of receptor dependent actions of melatonin against RE were also investigated with MT2 receptor antagonist, luzindole (LUZ). LUZ failed to antagonize melatonin’s protective effects against RE indicating that melatonin mediated these beneficial effects in a receptor‐independent fashion. Thus, esophageal mucosal protection elicited by melatonin against experimental RE is not only dependent on its free radical scavenging activity but also mediated in part through its effect on the associated inflammatory events in a receptor‐independent manner.

Antidepressant and anxiolytic effects of amentoflavone isolated from Cnestis ferruginea in mice

The root decoction of Cnestis ferruginea (CF) Vahl DC (Connaraceae) is used in traditional African medicine in the management of psychiatric disorders. This study presents the antidepressant and anxiolytic effects of amentoflavone (CF-2) isolated from the root extract of C. ferruginea. The antidepressant effect was studied using the forced swimming (FST) and tail suspension tests (TST) while the hole-board, elevated plus maze (EPM) and light/dark tests were used to evaluate the anxiolytic effect. Acute treatment with CF extract and amentoflavone significantly (p<0.001) reduced the duration of immobility in FST and TST with peak effects observed at 100 and 50mg/kg respectively in comparison to control treated. Antidepressant effects of CF and amentoflavone were significantly higher (p<0.05) when compared to imipramine in FST but comparable to the fluoxetine treated group in TST. The pretreatment of mice with metergoline (4mg/kg, i.p., a 5-HT2 receptor antagonist), prazosin (62.5μg/kg, i.p., an α1-adrenoceptor antagonist), and yohimbine (1mg/kg, i.p., an α2-adrenoceptor antagonist), but not sulpiride (50mg/kg, i.p., a dopamine D2 receptor antagonist), cyproheptadine (3mg/kg, i.p., a 5-HT2 receptor antagonist), atropine (1mg/kg, i.p., a muscarinic receptor antagonist) 15mins before the administration of amentoflavone (50mg/kg; p.o.) significantly prevented its antiimmobility effect in the FST. CF extract and CF-2 significantly (p<0.05) attenuated anxiety by increasing the number of head-dips in the hole-board test, the time spent on the open arms in the EPM, and the exploration of the light chamber in the light/dark test. Pretreatment with flumazenil (3mg/kg, i.p., ionotropic GABA receptor antagonist) 15min before oral administration of amentoflavone (25mg/kg) significantly reduced the time spent in the open arms in EPM. It is concluded from the results obtained that amentoflavone produces its antidepressant effect through interaction with 5-HT2 receptor and α1-, and α2-adrenoceptors while the anxiolytic effect involved the ionotropic GABA receptor.

Eugenol as an anti-stress agent: modulation of hypothalamic-pituitary-adrenal axis and brain monoaminergic systems in a rat model of stress.

Stress is the leading psychopathological cause for several mental disorders. Physiological and psychological responses to stress are mediated by the hypothalamic–pituitary–adrenal (HPA), sympathoadrenal system (SAS), and brain monoaminergic systems (BMS). Eugenol is reported to substantially modulate brain functions by regulating voltage-gated cation channels and release of neurotransmitters. This study was designed to evaluate the anti-stress effect of eugenol in the 4-h restraint model using rats. Ulcer index was measured as a parameter of the stress response. HPA axis and the SAS were monitored by estimating plasma corticosterone and norepinephrine (NE), respectively. Analysis of NE, serotonin (5-HT), dopamine, and their metabolites in discrete brain regions was performed to understand the role of BMS in the anti-stress effect of eugenol. Stress exposure increased the ulcer index as well as plasma corticosterone and NE levels. Eugenol pretreatment for 7 days decreased the stress-induced increase in ulcer index and plasma corticosterone but not NE levels, indicating a preferential effect on the HPA axis. Furthermore, eugenol showed a “U”-shaped dose–response curve in decreasing ulcer index and plasma corticosterone levels. Eugenol also reversed the stress-induced changes in 5-HT levels in all brain regions, whereas NE levels were reversed in all brain regions except hippocampus. These results suggest that eugenol possesses significant anti-stress activity in the 4-h restraint model and the effect is due to modulation of HPA and BMS.

Sir-2.1 modulates ‘calorie-restriction-mediated’ prevention of neurodegeneration in Caenorhabditis elegans: Implications for Parkinson’s disease

The phenomenon of aging is known to modulate many disease conditions including neurodegenerative ailments like Parkinsons disease (PD) which is characterized by selective loss of dopaminergic neurons. Recent studies have reported on such effects, as calorie restriction, in modulating aging in living systems. We reason that PD, being an age-associated neurodegenerative disease might be modulated by interventions like calorie restriction. In the present study we employed the transgenic Caenorhabditis elegans model (P(dat-1)::GFP) expressing green fluorescence protein (GFP) specifically in eight dopaminergic (DA) neurons. Selective degeneration of dopaminergic neurons was induced by treatment of worms with 6-hydroxy dopamine (6-OHDA), a selective catecholaminergic neurotoxin, followed by studies on effect of calorie restriction on the neurodegeneration. Employing confocal microscopy of the dopaminergic neurons and HPLC analysis of dopamine levels in the nematodes, we found that calorie restriction has a preventive effect on dopaminergic neurodegeneration in the worm model. We further studied the role of sirtuin, sir-2.1, in modulating such an effect. Studies employing RNAi induced gene silencing of nematode sir-2.1, revealed that presence of Sir-2.1 is necessary for achieving the protective effect of calorie restriction on dopaminergic neurodegeneration. Our studies provide evidence that calorie restriction affords, an sir-2.1 mediated, protection against the dopaminergic neurodegeneration, that might have implications for neurodegenerative Parkinsons disease.