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Articles by Vikas Kumar
Total Records ( 6 ) for Vikas Kumar
  Arky Jane Langstieh , Preeti Verma , Ajit Kumar Thakur , Shyam Sunder Chatterjee and Vikas Kumar
  Background: Ayurvedic practitioners have known diverse health benefits of Brassica juncea since centuries. Its edible green leaves are enriched in vitamins and other health promoting phytochemicals with therapeutically interesting pharmacological properties. Available information on bioactivity profiles of hydro-alcoholic extracts of Brassica juncea leaves and numerous such phytochemicals, also encountered in other edible plants, suggest that they could have diverse stress response desensitising properties. Experiments designed to experimentally verify such possibilities are reported. Method: Effects of graded oral doses of a standardized Brassica juncea leaf extract and salicylic, para-hydroxybenzoic, sinapic and nicotinic acids administered for 11 consecutive days on daily handling and intermittent foot-shock stress triggered changes on body weights, core temperatures, stress induced transient hyperthermic responses, tail suspension test and pentobarbitone hypnosis in male mice were quantified. For comparison sake, diazepam or imipramine or metformin were used as reference drugs in different experiments. Results: Each test agent and reference drug tested had their own therapeutically interesting bioactivity profile in the bioassay and their observed effects became apparent or more pronounced after their repeated daily doses. These observations add further experimental evidences in support of the conviction that anti-stress or adaptogenic activities of drugs and phytochemicals in dictating their therapeutically interesting bioactivity profiles and that some ubiquitously present in phytochemical in almost all medicinally used herbal extracts can also contribute to their therapeutic efficacy. Conclusion: The bioassay system could be used for identifying bioactive constituents of almost all traditionally known adaptogenic and other herbs.
  Binod Kumar Rauniyar , Anshul Shakya , Ajit Kumar Thakur , Shyam Sunder Chatterjee and Vikas Kumar
  Background and Objectives: Phloroglucinols are secondary metabolites that occur naturally in certain plant species. Microorganisms such as brown algae or bacteria also produce phloroglucinols. Phloroglucinols has potential health effect and it is used as a treatment for gallstones, spasmodic pain and other related gastrointestinal disorders. The objective of the study was to evaluate phloroglucinol and its tri-methyl ether for anti-stress activity and its beneficial effect on stress-induced perturbations. Method: Stress-induced hyperthermia and pentobarbital sedation models were used for pilot study cum relative dose response study at single and repeated per-oral doses of 3-300 mg kg–1 day–1. Further study was performed to evaluate phloroglucinol (1-16 mg kg–1 day–1, p.o., for 7 days) for anti-stress activity using validated animal models of stress viz., foot-shock stress and cold-restraint stress. Stress-induced perturbations were evaluated in stressed rats by using sexual behaviour, elevated zero maze and behavioural despair tests. Results: The observations revealed that phloroglucinol and its tri-methyl ether protect mice against stress-induced hyperthermia only after its daily administrations. After fairly low oral doses, phloroglucinol inhibited not only stress-induced gastric ulcers but also the exaggerated anxiety and depression observed in stressed animals. In the same dose range, it also improved sexual behaviour and suppressed adrenal hypertrophy and spleen atrophy in stressed animals. Conclusions: These observations strongly suggest that plasma or urinary levels of phloroglucinol are not proper indicators of its therapeutic benefits and that its observed anti-stress activity could as well be due to its actions on the microbiota-gut-brain axis.

  Ajit Kumar Thakur and Vikas Kumar
  Background and Objective: Andrographis paniculata (Burm. F.) Wall. Ex Nees is an Ayurvedic medicinal plant and it has been traditional used for treatment liver disease, diabetes, cold, fever and diarrhoea. Present study investigated the mechanistic activity of standardized extract of Andrographis paniculata (AP) and its isolated pure andrographolide in diabetic rodents for the potential neurotransmitters modulating effect. Materials and Methods: Diabetes was induced by single dose of streptozotocin (65 mg kg–1, i.p.) and nicotinamide (120 mg kg–1, i.p.). Rodents with blood glucose levels higher than 250 mg dL–1 were used as diabetic rodents. In this study, AP (50, 100 and 200 mg kg–1/day, p.o.) or andrographolide (15, 30 and 60 mg kg–1/day, p.o.) was administered for ten consecutive days. Neurotransmitters modulating effects of AP and andrographolide were evaluated in 5-Hydroxytryptophan (5-HTP) head twitches test in mice, spontaneous locomotor activity in rats and L-dopa potentiation test in mice. Results: Diabetic rodents demonstrated significant (p<0.05) decrease in head twitches, increase in locomotor activity and decrease in behaviour score compared to nondiabetic rodents during respective behavioural tests. However, AP and andrographolide treated rodents demonstrated significant (p<0.05) increase in head twitches, decrease in locomotor activity and increase in behaviour score compared to diabetic control during respective tests. Conclusion: The potential anti-depressant activity of AP and andrographolide in diabetic rodents might be due to modulation of central serotonergic and dopaminergic transmission.
  Vikas Kumar , Gulam Mohammad Husain , Michael Nöldner and Egon Koch
  Background and Objectives: Rhodiola rosea L. has been widely used in folk medicine to improve endurance and work productivity and to relief symptoms of mental and physical stress. Thus, the present study was undertaken to evaluate the stress adaptogenic activity of a proprietary extract from roots and rhizomes of Rhodiola rosea L. (WS® 1375) and to elucidate its possible mechanism of action. Methodology: Rats were subjected to electrical foot shocks for 1 h by means of a grid floor in a standard conditioning chamber for 14 consecutive days to produce a state of chronic stress. WS® 1375 was orally administered in parallel at doses of 50, 150 or 450 mg kg–1 once daily 1 h before the induction of stress. Experiments were conducted 1 h after the last stress procedure on day 14. Gastric ulceration as well as weight of adrenal glands and spleens were observed to assess the intensity of stress. Stress induced behavioural perturbations were analyzed by behavioural despair test, learned helplessness test and inhibition of male sexual behaviour. Stress induced cognitive dysfunction was quantified using active and passive avoidance tests. Animals were sacrificed immediately after the last stress regimen and blood was withdrawn for corticosterone estimation. Brain samples of rats were collected and monoamine concentrations were measured. General neuropharmacological screening of WS® 1375 was also performed. Results: The investigations reveal that WS® 1375 has pronounced stress-preventive activity and significantly normalized the levels of brain nor-epinephrine, 5-HT and dopamine in a dose-dependent manner. Plasma corticosterone levels in animals treated with WS® 1375 (150 and 450 mg kg–1) were significantly lower when compared to vehicle-treated rats. While WS® 1375 exhibited CNS stimulant activity, it did not cause muscle ataxia and failed to significantly improve stress-induced cognitive impairment. Conclusion: Based on these observations, it is concluded that WS® 1375 has a great potential for therapeutic use as an adaptogen.
  Vikas Kumar and Kamal Rai Aneja
  Trianthema portulacastrum L. (Horse purslane) is an annual broadleaf troublesome weed of tropical and subtropical areas throughout the world. In India, it has been observed as a problematic weed in many states. Remarkable biological and ecological behavior of this weed has enabled its easy and rapid spread and naturalization in a wide range of habitats. Various pre and post-emergence herbicides are used for controlling this weed. With increasing global concern about pesticide residues in the biosphere and public demand for pesticide free-food, alternative pesticides, such as bioherbicides are becoming important. Presently, there are over 17 mycoherbicides against different weeds, which are commercially being used in the developed countries. Of these, 8 are registered in the USA, 4 in Canada, 2 in South Africa and 1 each in Netherland, Japan and China. A total of 9 fungal pathogens have been reported on this weed around the globe. Of these, Gibbago trianthemae has the potential to be developed as a mycoherbicide of horse purslane in the USA and India. In this study, attempts have been made to present distribution, menace and management of horse purslane, a notorious agricultural weed by mechanical, chemical and bioherbicidal means.
  Vikas Kumar , Yuh- Jiin I. Jong and Karen L. O’Malley
  Recently we have shown that the metabotropic glutamate 5 (mGlu5) receptor can be expressed on nuclear membranes of heterologous cells or endogenously on striatal neurons where it can mediate nuclear Ca2+ changes. Here, pharmacological, optical, and genetic techniques were used to show that upon activation, nuclear mGlu5 receptors generate nuclear inositol 1,4,5-trisphosphate (IP3) in situ. Specifically, expression of an mGlu5 F767S mutant in HEK293 cells that blocks Gq/11 coupling or introduction of a dominant negative Gaq construct in striatal neurons prevented nuclear Ca2+ changes following receptor activation. These data indicate that nuclear mGlu5 receptors couple to Gq/11 to mobilize nuclear Ca2+. Nuclear mGlu5-mediated Ca2+ responses could also be blocked by the phospholipase C (PLC) inhibitor, U73122 [GenBank] , the phosphatidylinositol (PI) PLC inhibitor 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphorylcholine (ET-18-OCH3), or by using small interfering RNA targeted against PLCß1 demonstrating that PI-PLC is involved. Direct assessment of inositol phosphate production using a PIP2/IP3 "biosensor" revealed for the first time that IP3 can be generated in the nucleus following activation of nuclear mGlu5 receptors. Finally, both IP3 and ryanodine receptor blockers prevented nuclear mGlu5-mediated increases in intranuclear Ca2+. Collectively, this study shows that like plasma membrane receptors, activated nuclear mGlu5 receptors couple to Gq/11 and PLC to generate IP3-mediated release of Ca2+ from Ca2+-release channels in the nucleus. Thus the nucleus can function as an autonomous organelle independent of signals originating in the cytoplasm, and nuclear mGlu5 receptors play a dynamic role in mobilizing Ca2+ in a specific, localized fashion.

 
 
 
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