MyMedR

Fulltext Role-playing lecturing: a method for teaching neuroscience to medical students

Kumar RS, Narayanan SN

Adv Physiol Educ, 2008 Dec;32(4):329-31.

PMID: 19047513 DOI: 10.1152/advan.90105.2008

An improved light dark box test by using a real-time video tracking system

Narayanan SN, Kumar RS

Acta. Biol. Hung., 2018 Dec;69(4):371-384.

PMID: 30587025 DOI: 10.1556/018.69.2018.4.1

In the behavioral science field, many of the oldest tests have still most frequently been used almost in the same way for decades. The subjective influence of human observer and the large inter-observer and interlab differences are substantial among these tests. This necessitates the possibility of using technological innovations for behavioral science to obtain new parameters, results and insights as well. The light-dark box (LDB) test is a characteristic tool used to assess anxiety in rodents. A complete behavioral analysis (including both anxiety and locomotion parameters) is not possible by performing traditional LDB test protocol, as it lacks the usage of a real-time video recording of the test. In the current report, we describe an improved approach to conduct LDB test using a real-time video tracking system.

Student-involved demonstration approach to teach the physiology of vestibular apparatus for undergraduate medical students

Narayanan SN, Kumar RS, Nayak S

Teach Learn Med, 2011 Jul-Sep;23(3):269-77.

PMID: 21745063 DOI: 10.1080/10401334.2011.586930

It is quite difficult to teach complex topics like the physiology of vestibular apparatus to undergraduate students. Understanding the orientation and mode of stimulation of receptors in vestibular apparatus is also quite challenging for the students. As faculty we attempt to use innovative methods to teach physiology and enhance student learning.

Fulltext Ascorbic acid protects against restraint stress-induced memory deficits in Wistar rats

Kumar RS, Narayanan SN, Nayak S

Clinics (Sao Paulo), 2009;64(12):1211-7.

PMID: 20037710 DOI: 10.1590/S1807-59322009001200012

Chronic stress has been shown to cause oxidative damage in the central nervous system. Although stress-induced impairments in learning and memory have been studied extensively, very few studies have investigated possible ways to prevent their ill effects. The present work was designed to study the protective effects of ascorbic acid in memory loss induced by chronic restraint stress.

Ionic liquid mediated synthesis of mono- and bis-spirooxindole-hexahydropyrrolidines as cholinesterase inhibitors and their molecular docking studies

Kia Y, Osman H, Kumar RS, Basiri A, Murugaiyah V

Bioorg Med Chem, 2014 Feb 15;22(4):1318-28.

PMID: 24461561 DOI: 10.1016/j.bmc.2014.01.002

One pot, three-component reaction of 1-acryloyl-3,5-bisarylmethylidenepiperidin-4-ones with isatin and sarcosine in molar ratios of 1:1:1 and 1:2:2 furnished to mono- and bis-spiropyrrolidine heterocyclic hybrids comprising functionalized piperidine, pyrrolidine and oxindole structural motifs. Both mono and bis-spiropyrrolidines displayed good inhibitory activity against acetylcholinesterase (AChE) with IC₅₀ values of 2.36-9.43 μM. For butyrylcholinesterase (BChE), mono-cycloadducts in series 8 with IC₅₀ values of lower than 10 μM displayed better inhibitory activities than their bis-cycloadduct analogs in series 9 with IC₅₀ values of 7.44-19.12 μM. The cycloadducts 9j and 8e were found to be the most potent AChE and BChE inhibitors with IC₅₀ values of 2.35 and 3.21 μM, respectively. Compound 9j was found to be competitive inhibitor of AChE while compound 8e was a mixed-mode inhibitor of BChE with calculated Ki values of 2.01 and 6.76 μM, respectively. Molecular docking on Torpedo californica AChE and human BChE showed good correlation between IC₅₀ values and free binding energy values of the synthesized compounds docked into the active site of the enzymes.

Effect of ascorbic acid on the monosodium glutamate-induced neurobehavioral changes in periadolescent rats

Narayanan SN, Kumar RS, Paval J, Nayak S

Bratisl Lek Listy, 2010;111(5):247-52.

PMID: 20568412

In the current study we evaluated adverse effects of monosodium glutamate (MSG) on memory formation and its retrieval as well as the role of ascorbic acid (Vitamin-C) in prevention of MSG-induced alteration of neurobehavioral performance in periadolescent rats.

Fulltext An expedient synthesis, acetylcholinesterase inhibitory activity, and molecular modeling study of highly functionalized hexahydro-1,6-naphthyridines

Almansour AI, Kumar RS, Arumugam N, Basiri A, Kia Y, Ali MA

Biomed Res Int, 2015;2015:965987.

PMID: 25710037 DOI: 10.1155/2015/965987

A series of hexahydro-1,6-naphthyridines were synthesized in good yields by the reaction of 3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones with cyanoacetamide in the presence of sodium ethoxide under simple mixing at ambient temperature for 6-10 minutes and were assayed for their acetylcholinesterase (AChE) inhibitory activity using colorimetric Ellman's method. Compound 4e with methoxy substituent at ortho-position of the phenyl rings displayed the maximum inhibitory activity with IC50 value of 2.12 μM. Molecular modeling simulation of 4e was performed using three-dimensional structure of Torpedo californica AChE (TcAChE) enzyme to disclose binding interaction and orientation of this molecule into the active site gorge of the receptor.

Cholinesterase inhibitory activity versus aromatic core multiplicity: a facile green synthesis and molecular docking study of novel piperidone embedded thiazolopyrimidines

Basiri A, Murugaiyah V, Osman H, Kumar RS, Kia Y, Hooda A, et al.

Bioorg Med Chem, 2014 Jan 15;22(2):906-16.

PMID: 24369842 DOI: 10.1016/j.bmc.2013.11.020

Novel thiazolopyrimidine derivatives have been synthesized via microwave assisted, domino cascade methodology in ionic liquid and evaluated in vitro for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities. Among the newly synthesized compounds 6d, 6a, 6e and 6b displayed higher AChE inhibitory activity than standard drug, galanthamine, with IC50 values of 0.53, 1.47, 1.62 and 2.05μM, respectively. Interestingly, all the compounds except for 6m-r and 6x displayed higher BChE inhibitory potentials than galanthamine with IC50 values ranging from 1.09 to 18.56μM. Molecular docking simulations for 6d possessing the most potent AChE and BChE inhibitory activities, disclosed its binding interactions at the active site gorge of AChE and BChE enzymes.

An efficient ionic liquid mediated synthesis, cholinesterase inhibitory activity and molecular modeling study of novel piperidone embedded α,β-unsaturated ketones

Kia Y, Osman H, Kumar RS, Murugaiyah V, Basiri A, Khaw KY, et al.

Med Chem, 2014;10(5):512-20.

PMID: 24138113

A series of hitherto unreported piperidone embedded α,β-unsaturated ketones were synthesized efficiently in ionic solvent and evaluated for cholinesterase inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Most of the synthesized compounds displayed good enzyme inhibition; therein compounds 7i and 7f displayed significant activity against AChE with IC50 values of 1.47 and 1.74 µM, respectively. Compound 6g showed the highest BChE inhibitory potency with IC50 value of 3.41 µM, being 5 times more potent than galanthamine. Molecular modeling simulation was performed using AChE and BChE receptors extracted from crystal structure of human AChE and human BChE to determine the amino acid residues involved in the binding interaction of synthesized compounds and their relevant receptors.

An expedient, ionic liquid mediated multi-component synthesis of novel piperidone grafted cholinesterase enzymes inhibitors and their molecular modeling study

Basiri A, Murugaiyah V, Osman H, Kumar RS, Kia Y, Awang KB, et al.

Eur J Med Chem, 2013 Sep;67:221-9.

PMID: 23871902 DOI: 10.1016/j.ejmech.2013.06.054

Series of hitherto unreported piperidone grafted pyridopyrimidines synthesized through ionic liquid mediated multi-component reaction. These compounds were evaluated for their inhibitory activities against AChE and BChE enzymes. All the compounds displayed considerable potency against AChE with IC50 values ranging from 0.92 to 9.11 μM, therein compounds 6a, 6h and 6i displayed superior enzyme inhibitory activities compared to standard drug with IC50 values of 0.92, 1.29 and 2.07 μM. Remarkably, all the compounds displayed higher BChE inhibitory activity compared to galantamine with IC50 values of 1.89-8.13 μM. Molecular modeling, performed for the most active compounds using three dimensional crystal structures of TcAChE and hBChE, disclosed binding template of these inhibitors into the active site of their respective enzymes.

Fulltext Synthesis and discovery of new bisadducts derived from heterocyclic aldehydes and active methylene compounds as potent antitubercular agents

Asad M, Oo CW, Kumar RS, Osman H, Ali MA

Acta Pol Pharm, 2013 Mar-Apr;70(2):221-8.

PMID: 23614277

A series of some new bisadducts possessing five, six membered and coumarin subunits were synthesized by the condensation of heterocyclic aldehydes with active methylene compounds and characterized by IR, NMR and X-ray crystallographic studies and were assayed as antitubercular agents. Among the bisadducts, 4-hydroxy-3-[(4-hydroxy-2-oxo-2H-3-chromenyl)(3-thienyl)methyl]-2H-2-chromenone 3a was found to be the most promising compound, active against Mycobacterium tuberculosis (Mtb) H37Rv and isoniazid resistant Mycobacterium tuberculosis (INHR-Mtb) with minimum inhibitory concentration 5.22 and 8.34 microM, respectively.

Microwave assisted synthesis, cholinesterase enzymes inhibitory activities and molecular docking studies of new pyridopyrimidine derivatives

Basiri A, Murugaiyah V, Osman H, Kumar RS, Kia Y, Ali MA

Bioorg Med Chem, 2013 Jun 1;21(11):3022-31.

PMID: 23602518 DOI: 10.1016/j.bmc.2013.03.058

A series of hitherto unreported pyrido-pyrimidine-2-ones/pyrimidine-2-thiones were synthesized under microwave assisted solvent free reaction conditions in excellent yields and evaluated in vitro for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes inhibitory activity. Among the pyridopyrimidine derivatives, 7e and 7l displayed 2.5- and 1.5-fold higher enzyme inhibitory activities against AChE as compared to standard drug, galanthamine, with IC50 of 0.80 and 1.37 μM, respectively. Interestingly, all the compounds except 6k, 7j and 7k displayed higher inhibitory potential against BChE enzyme in comparison to standard with IC50 ranging from 1.18 to 18.90 μM. Molecular modeling simulations of 7e and 7l was performed using three-dimensional structure of Torpedo californica AChE (TcAChE) and human butyrylcholinesterase (hBChE) enzymes to disclose binding interaction and orientation of these molecule into the active site gorge of respective receptors.

Analysis of emotionality and locomotion in radio-frequency electromagnetic radiation exposed rats

Narayanan SN, Kumar RS, Paval J, Kedage V, Bhat MS, Nayak S, et al.

Neurol Sci, 2013 Jul;34(7):1117-24.

PMID: 22976773 DOI: 10.1007/s10072-012-1189-4

In the current study the modulatory role of mobile phone radio-frequency electromagnetic radiation (RF-EMR) on emotionality and locomotion was evaluated in adolescent rats. Male albino Wistar rats (6-8 weeks old) were randomly assigned into the following groups having 12 animals in each group. Group I (Control): they remained in the home cage throughout the experimental period. Group II (Sham exposed): they were exposed to mobile phone in switch-off mode for 28 days, and Group III (RF-EMR exposed): they were exposed to RF-EMR (900 MHz) from an active GSM (Global system for mobile communications) mobile phone with a peak power density of 146.60 μW/cm(2) for 28 days. On 29th day, the animals were tested for emotionality and locomotion. Elevated plus maze (EPM) test revealed that, percentage of entries into the open arm, percentage of time spent on the open arm and distance travelled on the open arm were significantly reduced in the RF-EMR exposed rats. Rearing frequency and grooming frequency were also decreased in the RF-EMR exposed rats. Defecation boli count during the EPM test was more with the RF-EMR group. No statistically significant difference was found in total distance travelled, total arm entries, percentage of closed arm entries and parallelism index in the RF-EMR exposed rats compared to controls. Results indicate that mobile phone radiation could affect the emotionality of rats without affecting the general locomotion.

Fulltext Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behaviour and hippocampal morphology in Wistar rats

Narayanan SN, Kumar RS, Potu BK, Nayak S, Bhat PG, Mailankot M

Ups. J. Med. Sci., 2010 May;115(2):91-6.

PMID: 20095879 DOI: 10.3109/03009730903552661

The interaction of mobile phone radio-frequency electromagnetic radiation (RF-EMR) with the brain is a serious concern of our society.

Synthesis and discovery of novel piperidone-grafted mono- and bis-spirooxindole-hexahydropyrrolizines as potent cholinesterase inhibitors

Kia Y, Osman H, Kumar RS, Murugaiyah V, Basiri A, Perumal S, et al.

Bioorg Med Chem, 2013 Apr 1;21(7):1696-707.

PMID: 23454132 DOI: 10.1016/j.bmc.2013.01.066

Three-component reaction of a series of 1-acryloyl-3,5-bisbenzylidenepiperidin-4-ones with isatin and L-proline in 1:1:1 and 1:2:2 molar ratios in methanol afforded, respectively the piperidone-grafted novel mono- and bisspiro heterocyclic hybrids comprising functionalized piperidine, pyrrolizine and oxindole ring systems in good yields. The in vitro evaluation of cholinesterase enzymes inhibitory activity of these cycloadducts disclosed that monospiripyrrolizines (8a-k), are more active with IC50 ranging from 3.36 to 20.07 μM than either the dipolarophiles (5a-k) or bisspiropyrrolizines (9a-k). The compounds, 8i and 8e with IC50 values of 3.36 and 3.50 μM, respectively showed the maximum inhibition of acethylcholinesterase (AChE) and butrylylcholinestrase (BuChE). Molecular modeling simulation, disclosed the binding interactions of the most active compounds to the active site residues of their respective enzymes. The docking results were in accordance with the IC50 values obtained from in vitro cholinesterase assay.

A facile chemo-, regio- and stereoselective synthesis and cholinesterase inhibitory activity of spirooxindole-pyrrolizine-piperidine hybrids

Kia Y, Osman H, Kumar RS, Murugaiyah V, Basiri A, Perumal S, et al.

Bioorg Med Chem Lett, 2013 May 15;23(10):2979-83.

PMID: 23570788 DOI: 10.1016/j.bmcl.2013.03.027

A series of novel hybrid spiro heterocycles comprising pyrrolizine, spiroxindole and piperidine moieties was synthesized chemo-, regio- and stereoselectively in good yields from 1,3-dipolar cycloaddition reaction of a series of 1-acryloyl-3,5-bisarylmethylidenepiperidin-4-ones with azomethine ylides generated in situ from 5-choloroisatin and l-proline in methanol. These cycloadducts displayed significant cholinesterase inhibitory activity. Among the compounds screened, 8g and 8e, showed maximum inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinestrase (BChE) with IC50 values of 3.33 and 3.13μM, respectively.

A facile three-component [3+2]-cycloaddition for the regioselective synthesis of highly functionalised dispiropyrrolidines acting as antimycobacterial agents

Wei AC, Ali MA, Yoon YK, Ismail R, Choon TS, Kumar RS

Bioorg Med Chem Lett, 2013 Mar 1;23(5):1383-6.

PMID: 23352268 DOI: 10.1016/j.bmcl.2012.12.069

A series of fourteen dispiropyrrolidines were synthesized using [3+2]-cycloaddition reactions and were screened for their antimycobacterial activity against Mycobacterium tuberculosis H(37)Rv in HTS (High Throughput Screen). Most of the compounds showed moderate to good activity with MIC of less than 20 μM. Compound 4'-(4-bromophenyl)-1'-methyldispiro[acenaphthylene-1,2'-pyrrolidine-3',2″-indane]-2,1″(1H)-dione (4c) was found to be the most active with MIC of 12.50 μM.

Radiofrequency electromagnetic radiation-induced behavioral changes and their possible basis

Narayanan SN, Jetti R, Kesari KK, Kumar RS, Nayak SB, Bhat PG

Environ Sci Pollut Res Int, 2019 Oct;26(30):30693-30710.

PMID: 31463749 DOI: 10.1007/s11356-019-06278-5

The primary objective of mobile phone technology is to achieve communication with any person at any place and time. In the modern era, it is impossible to ignore the usefulness of mobile phone technology in cases of emergency as many lives have been saved. However, the biological effects they may have on humans and other animals have been largely ignored and not been evaluated comprehensively. One of the reasons for this is the speedy uncontrollable growth of this technology which has surpassed our researching ability. Initiated with the first generation, the mobile telephony currently reaches to its fifth generation without being screened extensively for any biological effects that they may have on humans or on other animals. Mounting evidences suggest possible non-thermal biological effects of radiofrequency electromagnetic radiation (RF-EMR) on brain and behavior. Behavioral studies have particularly concentrated on the effects of RF-EMR on learning, memory, anxiety, and locomotion. The literature analysis on behavioral effects of RF-EMR demonstrates complex picture with conflicting observations. Nonetheless, numerous reports suggest a possible behavioral effect of RF-EMR. The scientific findings about this issue are presented in the current review. The possible neural and molecular mechanisms for the behavioral effects have been proposed in the light of available evidences from the literature.

Anti-arthritic potential of the plant Justicia gendarussa Burm F

Paval J, Kaitheri SK, Potu BK, Govindan S, Kumar RS, Narayanan SN, et al.

Clinics (Sao Paulo), 2009;64(4):357-62.

PMID: 19488595

OBJECTIVE: To evaluate the anti-arthritic potential of the plant Justicia gendarussa using two different rat models.

MATERIALS AND METHOD: The anti-arthritic potential of the alcoholic extract of the plant Justicia gendarussa was evaluated using the Freund's adjuvant-induced and collagen-induced arthritic rat models. The rats were treated with the ethanolic extract of Justicia gendarussa and with standard aspirin.

RESULTS: The ethanolic extract of Justicia gendarussa showed significant anti-arthritic activity that was statistically similar to that of aspirin. Our results suggest that the alcoholic extract of Justicia gendarussa exhibits significant anti-arthritic potential.

Spatial memory performance of Wistar rats exposed to mobile phone

Narayanan SN, Kumar RS, Potu BK, Nayak S, Mailankot M

Clinics (Sao Paulo), 2009;64(3):231-4.

PMID: 19330250

INTRODUCTION: With the tremendous increase in number of mobile phone users world wide, the possible risks of this technology have become a serious concern.

OBJECTIVE: We tested the effects of mobile phone exposure on spatial memory performance.

MATERIALS AND METHODS: Male Wistar rats (10-12 weeks old) were exposed to 50 missed calls/day for 4 weeks from a GSM (900/1800 MHz) mobile phone in vibratory mode (no ring tone). After the experimental period, the animals were tested for spatial memory performance using the Morris water maze test.

RESULTS: Both phone exposed and control animals showed a significant decrease in escape time with training. Phone exposed animals had significantly (approximately 3 times) higher mean latency to reach the target quadrant and spent significantly (approximately 2 times) less time in the target quadrant than age- and sex-matched controls.

CONCLUSION: Mobile phone exposure affected the acquisition of learned responses in Wistar rats. This in turn points to the poor spatial navigation and the object place configurations of the phone-exposed animals.

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