Browsing by Author "Praveen K. Singh"

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Age dependent levels of plasma homocysteine and cognitive performance
(Elsevier, 2015) Aruna Agrawal; K. Ilango; Praveen K. Singh; Dipankar Karmakar; G.P.I. Singh; Rinki Kumari; G.P. Dubey
Elevated plasma homocysteine (hcy) levels, also known as hyperhomocysteinemia (hhcy), have been associated with cognitive impairment and neurodegenerative disorders. Hhcy has been attributed to deficiency of B vitamins which can adversely affect the brain and result in memory loss and poor attention power. Monitoring hcy levels and the use of vitamin supplementation to treat hhcy may therefore prove advantageous for the prevention and management of cognitive impairment. With this in consideration, we measured plasma hcy, folate and vitamin B12 levels in 639 subjects from different age groups in two sub-regions of India. Cognitive function was also measured using attention span and immediate and delayed memory recall tests. Depression scores were obtained using the Beck Depression Inventory-II and functional impairment was assessed using the functional activities questionnaire (FAQ) score. As hhcy has also been linked to inflammation, plasma levels of high sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) were also measured. The results demonstrated significant negative correlations between hcy levels and folic acid levels, vitamin B12 levels and cognitive performance (attention span and delayed but not immediate memory recall) along with significant positive correlations between hcy levels and depression scores and hsCRP (but not IL-6) levels. A positive correlation was also observed between hcy levels and FAQ scores, however this was not found to be significant. Based on these results, folic acid and vitamin B12 intervention in people with elevated hcy levels in India could prove to be effective in lowering hcy levels and help maintain or improve cognitive function. © 2015 Elsevier B.V.
An aroylhydrazone as chelating agent : 4f metal complexes of 2, 6-diacetylpyridine bis(2-furoylhydrazone)
(Marcel Dekker Inc., 1996) B. Singh; Pramod K. Singh; Praveen K. Singh
Two types of complexes, [Ln2Cl4(H2dapf) (H2O)6]Cl2, and [Ln(Hdapf)(OH)2]2 [Ln = La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III) and Dy(III); H2dapf = 2,6-diacetylpyridine bis(2-furoylhydrazone)], having coordinated neutral (H2dapf) or uninegative (Hdapf) hydrazones, respectively, have been isolated from the reaction of the lanthanide chloride and the hydrazone in neutral and slightly alkaline solutions, respectively. The complexes were characterized by elemental analyses, molar conductance, TGA and DTA, magnetic susceptibility, electronic, infrared and NMR (1H and 13C) spectral data. The nephel auxetic ratio (β), covalency (δ) and bonding (b1/2) parameters have been evaluated for the Nd(III) complexes.
How virtuous are the bias corrected CMIP6 models in the simulation of heatwave over different meteorological subdivisions of India?
(Elsevier B.V., 2024) Saumya Singh; R.K. Mall; Praveen K. Singh; R. Bhatla; Pawan K. Chaubey
With rising global temperatures, extreme weather events have become more frequent, intense and of longer duration. CMIP6 GCMs provide improved climate simulations that need robust evaluation for historical period for reliable future projections. The present study assesses the ability of bias corrected CMIP6 14 Global Climate Models (GCMs) in simulating heat wave over India for March–June during the historical period (1951–2014). Heat waves were identified using IITM criteria. Model biases were removed using variance scaling bias correction method that showed higher correlation (0.93) and lower root mean square error (2.15) and improvement in approximating the inter-annual variability as well as spatial patterns as observed maximum temperature after bias correction. Evaluation of model performance for 95th and 99th percentile maximum temperature and heatwaves showed that most of the models simulate these extremes similar to observation. Northwestern, Central and South-central regions recorded highest number of heatwaves with a frequency of 50 heatwave days/decade, which were captured by the most of the GCMs varying in decadal frequency over the region. Among the GCM, although all models were found competent, ACCESS-ESM1–5, MPI-ESM1–2HR and MRI-ESM2–0 models were found to be the best performing models for extreme indices and heat wave simulation over India. The study will aid to the current understanding of CMIP6-GCMs performances over the different meteorological subdivisions of India and pave way for future projection of heat waves as well as reduction in uncertainty among the models. © 2024 Elsevier B.V.
Lanthanide complexes of 2-aminoacetophenone and 2-acetylaminoacetophenone 2-thenoylhydrazone
(1998) Praveen K. Singh; B. Singh
The reaction of lanthanide chlorides with 2-aminoacetophenone-2- thenoylhydrazone and 2-acetylaminoacetophenone-2-thenoylhydrazone yield complexes of the type [Ln(aath)2)Cl2(H2)O]Cl and] Ln(acaath)2Cl2]Cl. These complexes have been characterized by molar conductance, magnetic susceptibility, TGA, DTA and various spectroscopic techniques such as mass, IR, NMR, UV-visible and emission spectra. Mass spectral data indicate the aath complexes to be monomeric. Thermal stability of the complexes and presence of one water molecule in aath complex is indicated by TGA and DTA studies. Electronic spectra of Pr(III) and Nd(III) complexes show the coordination number to be nine and eight around the metal ions in the aath and acaath complexes, respectively. This has also been inferred from the spectral features of the hypersensitive transition in the Nd(III) complexes. The lowering in coordination number from aath to acaath complexes may be attributed to increase in chelate ring size and/or steric/inductive effect of methyl group. Emission spectral studies of the [Eu(aath)2Cl2(H2O]Cl and [Eu(acaath)2Cl2]Cl suggest tricapped trigonal prismatic (D3h) and square antiprismatic (D4d) geometry, respectively.
Molecular structure of lanthanide complexes of 2-aminothiazole
(Elsevier, 1996) B. Singh; Praveen K. Singh
[No abstract available]
Quantitative analysis of heavy metals in medicinal plants collected from environmentally diverse locations in India for use in a novel phytopharmaceutical product
(Kluwer Academic Publishers, 2015) Ananya Sadhu; Prabhat Upadhyay; Praveen K. Singh; Aruna Agrawal; Kaliappan Ilango; Dipankar Karmakar; Gur Prit Inder Singh; Govind Prasad Dubey
It is important to monitor the quality of the phytopharmaceutical product as its therapeutic potential depends on standardized delivery of active ingredients present in the botanical source. Minimal presence of toxic impurities like heavy metals (HMs) is warranted to ensure product safety and prevent hazardous health impacts. In the present study, conducted as part of the development of a novel phytopharmaceutical product, the chemical profile of 13 heavy metals (Fe, Cu, Mn, Zn, Ni, Co, Mo, V, Cr, As, Pb, Hg, and Cd) was studied in the whole plant, fruit, and rhizome of Bacopa monnieri, Hippophae rhamnoides, and Dioscorea bulbifera, respectively, from environmentally diverse regions in India. Most samples had HM profiles within permissible limits as established by regulatory authorities, with the exception of Cd and Hg in low-altitude regions. This study indicates geographical regions in India suitable for procuring raw materials to develop and manufacture phytopharmaceutical products. © 2015, Springer International Publishing Switzerland.
Regulation of serotonin in depression: Efficacy of ayurvedic plants
(Taylor and Francis, 2017) Rinki Kumari; Aruna Agrawal; Govind Prasad Dubey; Praveen K. Singh; Gur Prit Inder Singh
Depression is an etiologically heterogeneous group of chronic psychiatric illnesses associated with significant morbidity, mortality, and disability. Among the several theories behind the pathophysiological basis of depression, imbalances of the monoamine neurotransmitters (monoamine hypothesis), especially serotonin, have been the most extensively investigated. Several antidepressant drugs targeting the serotonin system have been developed (e.g., selective serotonin reuptake inhibitors) with the intended physiological effect to enhance serotonin signaling at the synapse. Although these drugs represent popular and effective treatments for depression, they are also associated with side effects and limitations in their efficacy. Herbal remedies, often employed as part of traditional systems of medicine and generally associated with favorable safety profiles, have the potential to provide effective alternatives to currently employed modern synthetic antidepressants. Ayurveda is one of the oldest systems of medicine in the world and has been practiced for centuries in India. Ayurveda has described the use of several medicinal plants to prevent, treat, and manage numerous diseases. The following chapter discusses a selection of ayurveda medicinal plants with serotonergic properties that are currently used or have the potential to be developed as antidepressants. The plants discussed here include Areca catechu, Withania somnifera, Bacopa monnieri, Berberis aristata, Tinospora cordifolia, Curcuma longa, Nyctanthes arbor-tristis, Zingiber officinale, and Ocimum sanctum. To date, the major scientific evidence signifying the antidepressant properties of these plants comes from animal depression models such as the forced-swim and tail suspension tests coupled with biochemical and/or pharmacological studies, demonstrating that these plants modulate the serotonin system in the brain. Moving forward, standardization of drug products derived from these plants coupled with well-designed clinical studies and further investigations into the molecular mechanisms behind their serotonergic properties will be important to realize their potential to alleviate the global burden of depressive disorders. © 2017 by Taylor & Francis Group, LLC.
Revalidation of the neuroprotective effects of a United States patented polyherbal formulation on scopolamine induced learning and memory impairment in rats
(Elsevier Masson SAS, 2018) Prabhat Upadhyay; Ananya Sadhu; Praveen K. Singh; Aruna Agrawal; K. Ilango; Suresh Purohit; Govind Prasad Dubey
Objective Alzheimer's disease (AD) is the most common cause of dementia yet treatment options are extremely limited. The disease is associated with cognitive impairment as well as structural irregularities, accumulation of plaques and neurofibrillary tangles, diminished levels of acetylcholine, oxidative stress, and inflammation in the brain. We have previously reported on the positive effects of a united states patented (US 7,273,626 B2) poly herbal test formulation, consisting of Bacopa monnieri, Hippophae rhamnoides and Dioscorea bulbifera extracts, on cognitive deficits in AD patients. The present study was conducted to investigate the mechanism(s) of action of the formulation using scopolamine treated rats as an AD model. Method The formulation was administered daily along with scopolamine for a period of 14 days following which the elevated plus maze, passive avoidance, and Morris water maze tests were performed to assess learning and memory. Rats treated with scopolamine or vehicle only were also included in the experiment. Acetylcholine levels and activities of acetylcholinesterase (AChE) and anti-oxidant enzymes in the brain were also measured at the end of the treatment period. Results The study demonstrate that scopolamine treatment resulted in learning and memory deficits which were partially and significantly ameliorated by the formulation. The formulation also counteracted scopolamine-induced decreases in acetylcholine levels, increases in AChE activity, and decreases in activities of the antioxidant enzymes. Conclusion The study demonstrates the ability of the test formulation to reverse scopolamine-induced learning and memory deficits in rats which may at least partially be explained by the reversal of scopolamine-induced reductions in brain acetylcholine levels and antioxidant activities by the test formulation. © 2017
Safety evaluation of a polyherbal formulation containing hydroalcoholic extracts of Hippophae salicifolia, Nyctanthes arbor-tristis, Ocimum tenuiflorum, and Reinwardtia indica in rodents
(Nanjing Medical University, 2016) Rinki Kumari; Aruna Agrawal; G.P. Dubey; K. Ilango; Praveen K. Singh; G.P.I. Singh
[No abstract available]
Synthesis and characterization of heterobinuclear (La-Zn, Pr-Zn, Nd-Zn, Sm-Zn, Eu-Zn, Gd-Zn, Tb-Zn, Dy-Zn) azine-bridged complexes
(1997) Bachcha Singh; Ashutosh K. Srivastav; Praveen K. Singh
Zinc(II) complex of 2-acetylpyridine salicyl aldazine (Haps) of the type Zn(aps)2(H2O)2 has been synthesised. The reaction of Zn(aps)2(H2O)2 with lanthanide chlorides, LnCl3 (where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) yields azine-bridged heterobinuclear complexes of the formulae LnCl3Zn(aps)2(H2O)2. These complexes have been characterized by elemental analyses, molecular weight, conductance (solid and solution) and magnetic susceptibility measurements, mass, IR and electronic spectral data. X-ray powder diffraction data indicate the tetragonal unit lattice for Zn(aps)2(H2O)2 and PrCl3Zn(aps)2(H2O)2.
Synthesis and characterization of La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III) & Dy(III) complexes of 2- acetylfuran-2-thenoylhydrazone
(1998) B. Singh; Praveen K. Singh
The reaction of 2-acetylfuran-2-thenoylhydrazone(afth) with Ln(III) trichlorides yields complexes of the type [Ln(afth)Cl 2(H 2O)(EtOH)]Cl. [Ln(III) = La, Pr, Nd, Sm, Eu, Gd. Tb and Dy]. The complexes have been characterized by molar conductance, magnetic susceptibility and TGA and DTA measurements. FAB mass, infrared, proton NMR. electronic absorption and emission spectra. The terbium complex is found to be monomer from the FAB mass spectrum. The IR and NMR spectra suggest neutral tridentate behaviour of the Schiff base. A coordination number seven is proposed around the metal ions. Emission spectra suggests C 3v, symmetry around the metal ion with capped octahedron geometry for the europium complex.
Synthesis and characterization of some lanthanide complexes with 4-acetylpyridine-2-furoylhydrazone
(Marcel Dekker Inc., 1998) B. Singh; Preeti Sahai; Praveen K. Singh
New lanthanide compounds of the formulae [Ln(apfh)2Cl2]Cl and [Nd(apfh')2Cl2]Cl [apfh = 4-acetylpyridine-2-furoylhydrazone; apfh' = 3-acetylpyridine-2-furoylhydrazone; Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy] have been synthesized and characterized. IR spectroscopy indicates that the apfh is bonded in tridentate manner through the carbonyl oxygen, and the azomethine and pyridine nitrogens which is further ascertained from NMR spectroscopy. UV-VIS spectra in conjunction with the stoichiometry and electrical conductance of the complexes and the bonding behaviour of apfh suggest a coordination number of eight around the lanthanide ions in the solid state as well as in solution.
Synthesis and characterization of template lanthanide complexes
(1996) B. Singh; Preeti Sahai; Praveen K. Singh
Some lanthanide(III) chelates have been synthesized through template reaction of the lanthanide chloride, 2,4-pentanedione and 2-furoylhydrazine in neutral and alkaline solutions. The analytical, magnetic and molar conductance data suggest empirical formulae [Ln(Haafh)2Cl2]Cl and Ln(aafh)(OH)(H2O)3 for the isolated compounds. The terbium complexes are found to be monomeric from the FAB mass spectra. The bonding, stereochemistry and symmetry of the complexes have been investigated by infrared, electronic, emission and 1H NMR spectra.