Displaying publications 441 - 460 of 758 in total

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  1. Tahlan S, Narasimhan B, Lim SM, Ramasamy K, Mani V, Shah SAA
    Mini Rev Med Chem, 2020;20(15):1559-1571.
    PMID: 30179132 DOI: 10.2174/1389557518666180903151849
    BACKGROUND: Various analogues of benzimidazole are found to be biologically and therapeutically potent against several ailments. Benzimidazole when attached with heterocyclic rings has shown wide range of potential activities. So, from the above provided facts, we altered benzimidazole derivatives so that more potent antagonists could be developed. In the search for a new category of antimicrobial and anticancer agents, novel azomethine of 2-mercaptobenzimidazole derived from 3-(2- (1H-benzo[d]imidazol-2-ylthio)acetamido)benzohydrazide were synthesized.

    RESULTS AND DISCUSSION: The synthesized analogues were characterized by FT-IR, 1H/13C-NMR and MS studies as well C, H, N analysis. All synthesized compounds were evaluated for in vitro antibacterial activity against Gram-positive (B. subtilis), Gram-negative (E. coli, P. aeruginosa, K. pneumoniae and S. typhi) strains and in vitro antifungal activity against C. albicans and A. niger strains by serial dilution method, the minimum inhibitory concentration (MIC) described in μM/ml. The in vitro anticancer activity of synthesized compounds was determined against human colorectal carcinoma cell line (HCT- 116) using 5-fluorouracil as standard drug.

    CONCLUSION: In general, most of the synthesized derivatives exhibited significant antimicrobial and anticancer activities. Compounds 8, 10, 15, 16, 17, 20 and 22 showed significant antimicrobial activity towards tested bacterial and fungal strains and compound 26 exhibited significant anticancer activity.

  2. Atif M, Bhatti HN, Haque RA, Iqbal MA, Ahamed Khadeer MB, Majid AMSA
    Appl Biochem Biotechnol, 2020 Jul;191(3):1171-1189.
    PMID: 32002729 DOI: 10.1007/s12010-019-03186-9
    Synthesis and anticancer studies of three symmetrically and non-symmetrically substituted silver(I)-N-Heterocyclic carbene complexes of type [(NHC)2-Ag]PF6 (7-9) and their respective (ligands) benzimidazolium salts (4-6) are described herein. Compound 5 and Ag-NHC-complex 7 were characterized by the single crystal X-ray diffraction technique. Structural studies for 7 showed that the silver(I) center has linear C-Ag-C coordination geometry (180.00(10)o). Other azolium and Ag-NHC analogues were confirmed by H1 and C13-NMR spectroscopy. The synthesized analogues were biologically characterized for in vitro anticancer activity against three cancer cell lines including human colorectal cancer (HCT 116), breast cancer (MCF-7), and erythromyeloblastoid leukemia (K-562) cell lines and in terms of in vivo acute oral toxicity (IAOT) in view of agility and body weight of female rats. In vitro anticancer activity showed the values of IC50 in range 0.31-17.9 μM in case of K-562 and HCT-116 cancer cell lines and 15.1-35.2 μM in case of MCF-7 while taking commercially known anticancer agents 5-fluorouracil, tamoxifen, and betulinic acid which have IC50 values 5.2, 5.5, and 17.0 μM, respectively. In vivo study revealed vigor and agility of all test animals which explores the biocompatibility and non-toxicity of the test analogues.
  3. Sharma D, Kumar S, Narasimhan B, Ramasamy K, Lim SM, Shah SAA, et al.
    BMC Chem, 2019 Dec;13(1):60.
    PMID: 31384808 DOI: 10.1186/s13065-019-0575-x
    In order to overcome the challenges of microbial resistance as well as to improve the effectiveness and selectivity of chemotherapeutic agents against cancer, a novel series of 4-(4-bromophenyl)-thiazol-2-amine derivatives was synthesized and its molecular structures were confirmed by physicochemical and spectral characteristics. The synthesized compounds were further evaluated for their in vitro antimicrobial activity using turbidimetric method and anticancer activity against oestrogen receptor positive human breast adenocarcinoma cancer cell line (MCF7) by Sulforhodamine B (SRB) assay. The antimicrobial activity results revealed that compound p2, p3, p4 and p6 exhibited promising antimicrobial activity that are comparable to standard norfloxacin (antibacterial) and fluconazole (antifungal). Anticancer screening results demonstrated that compound p2 was found to be the most active one against cancer cell line when compared to the rest of the compounds and comparable to the standard drug (5-fluorouracil). The molecular docking study demonstrated that compounds, p2, p3, p4 and p6 displayed good docking score within binding pocket of the selected PDB ID (1JIJ, 4WMZ and 3ERT) and showed promising ADME properties.
  4. Tahlan S, Kumar S, Ramasamy K, Lim SM, Shah SAA, Mani V, et al.
    BMC Chem, 2019 Dec;13(1):50.
    PMID: 31384798 DOI: 10.1186/s13065-019-0567-x
    Background: Nitrogen containing heterocycles are widely used and investigated by pharmaceutical industry, as they are important in discovery and designing of new drug molecules. Drugs with a benzimidazole nucleus possess exclusive structural features and electron-rich atmosphere, which enable them to bind to a number of biologically important targets and result in a wide range of activities. This has served as the basis of the present study whereby new scaffolds with benzimidazole moiety were designed and synthesized.

    Methods: The structures of synthesized compounds were confirmed by physicochemical and spectral means. The synthesized compounds were screened for their antimicrobial and antiproliferative activities by tube dilution and Sulforhodamine B (SRB) assays, respectively.

    Results and conclusion: The in vitro biological screening results revealed that compound Z24 exhibited promising antimicrobial and anticancer activities which are comparable to standards.

  5. Sharma D, Kumar S, Narasimhan B, Ramasamy K, Lim SM, Shah SAA, et al.
    BMC Chem, 2019 Dec;13(1):46.
    PMID: 31384794 DOI: 10.1186/s13065-019-0564-0
    To combat the antimicrobial and anticancer drug resistance by pathogens and cancerous cells, efforts has been made to study the pharmacological activities of newly synthesized N-(4-(4-bromophenyl)thiazol-2-yl)-2-chloroacetamide derivatives. The molecular structures of the synthesized derivatives were confirmed by their physicochemical properties and spectroanalytical data (NMR, IR and elemental). The synthesized compounds were evaluated for their in vitro antimicrobial activity against bacterial (Gram positive and Gram negative) and fungal species using turbidimetric method and anticancer activity against oestrogen receptor positive human breast adenocarcinoma cancer cell line (MCF7) by Sulforhodamine B (SRB) assay. Molecular docking studies were carried out to study the binding mode of active compounds with receptor using Schrodinger v11.5. The antimicrobial activity results revealed that compounds d1, d2 and d3 have promising antimicrobial activity. Anticancer screening results indicated that compounds d6 and d7 were found to be the most active ones against breast cancer cell line. Furthermore, the molecular docking study demonstrated that compounds d1, d2, d3, d6 and d7 displayed good docking score within binding pocket of the selected PDB ID (1JIJ, 4WMZ and 3ERT) and has the potential to be used as lead compounds for rational drug designing.
  6. Tahlan S, Ramasamy K, Lim SM, Shah SAA, Mani V, Narasimhan B
    BMC Chem, 2019 Dec;13(1):12.
    PMID: 31384761 DOI: 10.1186/s13065-019-0533-7
    Background: Dihydrofolate reductase (DHFR) is an important target for antimetabolite class of antimicrobials because it participates in purine synthesis. 2-mercaptobenzimidazole (2MBI) has similar structural features as purine nucleotides. Given that benzimidazole and similar heteroaromatics have been broadly examined for their anticancer potential, so, we hereby report the design, synthesis and biological studies (i.e. antimicrobial and anticancer studies) of 2MBI derivatives.

    Methodology: The antimicrobial activity of synthesized 2MBI derivatives were evaluated against Gram positive and Gram negative bacterial species as well as fungal species by tube dilution technique whereas their anticancer activity was assessed against human colorectal carcinoma cell line (HCT116) by Sulforhodamine B (SRB) assay. They were also structurally characterized by IR, NMR, MS and elemental analyses.

    Results discussion and conclusion: The antimicrobial activity findings revealed that compound N1 (MIC
    bs,st,
    ca
     = 1.27, 2.54, 1.27 µM), N8 (MIC
    ec
    = 1.43 µM), N22 (MIC
    kp,an
    = 2.60 µM), N23 and N25 (MIC
    sa
    = 2.65 µM) exhibited significant antimicrobial effects against tested strains, i.e. Gram-positive, Gram-negative (bacterial) and fungal strains. The anticancer screening results demonstrated that compounds N9, N18 (IC50 = 5.85, 4.53 µM) were the most potent compounds against cancer cell line (HCT116) even more than 5-FU, the standard drug (IC50 = 9.99 µM).

  7. Kumar S, Sharma D, Narasimhan B, Ramasamy K, Shah SAA, Lim SM, et al.
    BMC Chem, 2019 Dec;13(1):96.
    PMID: 31355369 DOI: 10.1186/s13065-019-0613-8
    Heterocyclic 1,3-diazine nucleus is a valuable pharmacophore in the field of medicinal chemistry and exhibit a wide spectrum of biological activities. PharmMapper, a robust online tool used for establishing the target proteins based on reverse pharmacophore mapping. PharmMapper study is carried out to explore the pharmacological activity of 1,3-diazine derivatives using reverse docking program. PharmMapper, an open web server was used to recognize for all the feasible target proteins for the developed compounds through reverse pharmacophore mapping. The results were analyzed via molecular docking with maestro v11.5 (Schrodinger 2018-1) using GTPase HRas as possible target. The molecular docking studies displayed the binding behavior of 1,3-diazine within GTP binding pocket. From the docking study compounds s3 and s14 showed better docked score with anticancer potency against cancer cell line (HCT116). Hence, the GTPase HRas may be the possible target of 1,3-diazine derivatives for their anticancer activity where the retrieved information may be quite useful for developing rational drug designing. Furthermore the selected 1,3-diazine compounds were evaluated for their in vitro anticancer activity against murine macrophages cell line. 1,3-Diazine compounds exhibited good selectivity of the compounds towards the human colorectal carcinoma cell line instead of the murine macrophages. The toxicity study of the most active compounds was also performed on non cancerous HEK-293 cell line.
  8. Kumar S, Kaushik A, Narasimhan B, Shah SAA, Lim SM, Ramasamy K, et al.
    BMC Chem, 2019 Dec;13(1):85.
    PMID: 31384832 DOI: 10.1186/s13065-019-0601-z
    Pyrimidine nucleus is a significant pharmacophore that exhibited excellent pharmacological activities. A series of pyrimidine scaffolds was synthesized and its chemical structures were confirmed by physicochemical and spectral analysis. The synthesized compounds were evaluated for their antimicrobial potential towards Gram positive and negative bacteria as well as fungal species. They were also assessed for their anticancer activity toward a human colorectal carcinoma cell line (HCT116). Whilst results of antimicrobial potential revealed that compounds Ax2, Ax3, Ax8 and Ax14 exhibited better activity against tested microorganisms, the results of antiproliferative activity indicated that compounds Ax7 and Ax10 showed excellent activity against HCT116. Further, the molecular docking of pyrimidine derivatives Ax1, Ax9 and Ax10 with CDK8 (PDB id: 5FGK) protein indicated that moderate to better docking results within the binding pocket. Compounds Ax8 and Ax10 having significant antimicrobial and anticancer activities may be selected as lead compounds for the development of novel antimicrobial and anticancer agent, respectively.
  9. Sattar A, Aziz-Ur-Rehman -, Abbasi MA, Siddiqui SZ, Rasool S, Ali Shah SA
    Pak J Pharm Sci, 2020 Jul;33(4):1697-1705.
    PMID: 33583804
    A series of propanamide compounds 6a-l was derived by N-substitution reactions, encompassing tosyl, piperidine and 1,3,4-oxadiazole moieties. The intended array of compounds 6a-l was afforded by a series of five steps reaction scheme. 1-Tosylpiperidin-4-carboxylate (1) was synthesized by the reaction of tosyl chloride (a) with ethyl isonipecotate (b) under mild basic conditions. Compound 1 was subjected to nucleophillic substitution by hydrazine to synthesize 1-tosylpiperidin-4-carbohydrazide (2). The compound, 5-(1-tosylpiperidin-4-yl)-1,3,4-oxadiazole-2-thiol (3) was synthesized by intermolecular cyclization of compound 2 by CS2 under strong basic conditions. The target compounds, 6a-l, were finally synthesized from 3 by reacting with different electrophiles, 5a-l, in an aprotic polar solvent with sodium hydride as an activator. The different propanamoyl electrophiles, 5a-l, were synthesized by the reaction of different aromatic and aliphatic amines, 4a-l, with 3-bromopropionyl chloride under mild basic conditions. The structural elucidation was carried out using modern spectroscopic techniques including IR, 1H-NMR and EI-MS. The antibacterial potential of synthesized compounds was assessed against five bacterial strains. Compounds 6a, 6c, 6d, 6e and 6f were found to be potent antibacterial agents.
  10. Abbasi MA, Ijaz M, Aziz-Ur-Rehman -, Siddiqui SZ, Ali Shah SA, Shahid M, et al.
    Pak J Pharm Sci, 2020 Jul;33(4):1609-1616.
    PMID: 33583794
    In the planned research work, the nucleophilic substitution reaction of 1-[(E)-3-phenyl-2-propenyl]piperazine (1) was carried out with different sulfonyl chlorides (2a-g) at pH 9-10 to synthesize its different N-sulfonated derivatives (3a-g). The structures of the synthesized compounds were characterized by their proton-nuclear magnetic resonance (1H-NMR), carbon-nuclear magnetic resonance (13C-NMR) and Infra Red (IR) spectral data, along with CHN analysis. The inhibition potential of the synthesized molecules was ascertained against two bacterial pathogenic strains i.e. Bacillus subtilis and Escherichia coli. It was inferred from the results that some of the compounds were very suitable inhibitors of these bacterial strains. Moreover, their cytotoxicity was also profiled and it was outcome that most of these molecules possessed moderate cytotoxicity.
  11. Khan MUA, Haider S, Shah SA, Razak SIA, Hassan SA, Kadir MRA, et al.
    Int J Biol Macromol, 2020 May 15;151:584-594.
    PMID: 32081758 DOI: 10.1016/j.ijbiomac.2020.02.142
    Arabinoxylan (AX) is a natural biological macromolecule with several potential biomedical applications. In this research, AX, nano-hydroxyapatite (n-HAp) and titanium dioxide (TiO2) based polymeric nanocomposite scaffolds were fabricated by the freeze-drying method. The physicochemical characterizations of these polymeric nanocomposite scaffolds were performed for surface morphology, porosity, swelling, biodegradability, mechanical, and biological properties. The scaffolds exhibited good porosity and rough surface morphology, which were efficiently controlled by TiO2 concentrations. MC3T3-E1 cells were employed to conduct the biocompatibility of these scaffolds. Scaffolds showed unique biocompatibility in vitro and was favorable for cell attachment and growth. PNS3 proved more biocompatible, showed interconnected porosity and substantial mechanical strength compared to PNS1, PNS2 and PNS4. Furthermore, it has also showed more affinity to cells and cell growth. The results illustrated that the bioactive nanocomposite scaffold has the potential to find applications in the tissue engineering field.
  12. Kumari M, Tahlan S, Narasimhan B, Ramasamy K, Lim SM, Shah SAA, et al.
    BMC Chem, 2021 Jan 21;15(1):5.
    PMID: 33478538 DOI: 10.1186/s13065-020-00717-y
    BACKGROUND: Triazole is an important heterocyclic moiety that occupies a unique position in heterocyclic chemistry, due to its large number of biological activities. It exists in two isomeric forms i.e. 1,2,4-triazole and 1,2,3-triazole and is used as core molecule for the design and synthesis of many medicinal compounds. 1,2,4-Triazole possess broad spectrum of therapeutically interesting drug candidates such as analgesic, antiseptic, antimicrobial, antioxidant, anti-urease, anti-inflammatory, diuretics, anticancer, anticonvulsant, antidiabetic and antimigraine agents.

    METHODS: The structures of all synthesized compounds were characterized by physicochemical properties and spectral means (IR and NMR). The synthesized compounds were evaluated for their in vitro antimicrobial activity against Gram-positive (B. subtilis), Gram-negative (P. aeruginosa and E. coli) bacterial and fungal (C. albicans and A. niger) strains by tube dilution method using ciprofloxacin, amoxicillin and fluconazole as standards. In-vitro antioxidant and anti-urease screening was done by DPPH assay and indophenol method, respectively. The in-vitro anticancer evaluation was carried out against MCF-7 and HCT116 cancer cell lines using 5-FU as standards.

    RESULTS, DISCUSSION AND CONCLUSION: The biological screening results reveal that the compounds T5 (MICBS, EC = 24.7 µM, MICPA, CA = 12.3 µM) and T17 (MICAN = 27.1 µM) exhibited potent antimicrobial activity as comparable to standards ciprofloxacin, amoxicillin (MICCipro = 18.1 µM, MICAmo = 17.1 µM) and fluconazole (MICFlu = 20.4 µM), respectively. The antioxidant evaluation showed that compounds T2 (IC50 = 34.83 µg/ml) and T3 (IC50 = 34.38 µg/ml) showed significant antioxidant activity and comparable to ascorbic acid (IC50 = 35.44 µg/ml). Compounds T3 (IC50 = 54.01 µg/ml) was the most potent urease inhibitor amongst the synthesized compounds and compared to standard thiourea (IC50 = 54.25 µg/ml). The most potent anticancer activity was shown by compounds T2 (IC50 = 3.84 μM) and T7 (IC50 = 3.25 μM) against HCT116 cell lines as compared to standard 5-FU (IC50 = 25.36 μM).

  13. Oteh M, Azarisman SM, Azreen SA, Jamaluddin AR, Aszrin A, Ting CK, et al.
    Hypertens Res, 2011 Mar;34(3):319-24.
    PMID: 21150917 DOI: 10.1038/hr.2010.239
    The prevalence of hypertension in Malaysia is alarmingly high. The National Survey in 2006 showed 43% of people aged ≥30 had hypertension and among treated patients, only 26% reached the target blood pressure (BP) of <140/90 mmHg. We evaluated BP control in tertiary institutions in Malaysia and the difference in hypertension control between genders and within specific cardiovascular risk factor groups. This cross-sectional study aimed at determining BP control among hypertensive patients attending three specialist institutions in Malaysia, located in Kuala Lumpur, Kuantan and Kota Bharu. A total of 950 patients with known hypertension for at least 6 months were recruited between January 2007 and July 2008. There were more males (n=548, 57.7%) with a mean age of 60.3±10.5 (±s.d.) years. The mean systolic BP (SBP) and diastolic BP were 138.8±20.3 mmHg and 79.6±11.3 mmHg, respectively. In total, 48.5% of all the patients had good BP control (<140/90 mmHg). Males had better SBP control compared with female (SBP: 135.9±18.7 vs. 142.8±21.7 mmHg, P<0.001). Overall, 54.6% of the patients had ischemic heart disease (IHD), 24.2% had undergone coronary revascularization, 50.1% were diabetic, 68.6% hyperlipidemic, 17.3% smokers and 27.5% had renal impairment. Males and small numbers of antihypertensives used were independently associated with better treatment outcome. In summary, our data reveal a poorer BP control, secondary to higher SBP levels in women. Moreover, the gender difference is more pronounced in patients with concomitant diabetes mellitus, renal impairment and IHD.
  14. Ishaq K, Mat Zin NA, Rosdi F, Jehanghir M, Ishaq S, Abid A
    PeerJ Comput Sci, 2021;7:e496.
    PMID: 34084920 DOI: 10.7717/peerj-cs.496
    Learning a new language is a challenging task. In many countries, students are encouraged to learn an international language at school level. In particular, English is the most widely used international language and is being taught at the school level in many countries. The ubiquity and accessibility of smartphones combined with the recent developments in mobile application and gamification in teaching and training have paved the way for experimenting with language learning using mobile phones. This article presents a systematic literature review of the published research work in mobile-assisted language learning. To this end, more than 60 relevant primary studies which have been published in well-reputed venues have been selected for further analysis. The detailed analysis reveals that researchers developed many different simple and gamified mobile applications for learning languages based on various theories, frameworks, and advanced tools. Furthermore, the study also analyses how different applications have been evaluated and tested at different educational levels using different experimental settings while incorporating a variety of evaluation measures. Lastly, a taxonomy has been proposed for the research work in mobile-assisted language learning, which is followed by promising future research challenges in this domain.
  15. Chandrawathani P, Nurulaini R, Adnan M, Premalaatha B, Khadijah S, Jamnah O, et al.
    Trop Biomed, 2009 Apr;26(1):11-5.
    PMID: 19696722 MyJurnal
    This paper reports the occurrence of helminth and protozoan infections on small ruminants from eight farms situated in Kinta and Perak Tengah district, Perak. The results of this survey indicate that helminthiasis and coccidiosis is rampant in sheep and goat farms. Several anthelmintics have been used for the control of helminths. The smallholders depended on health and extention services from the State Veterinary Department. This survey is part of an ongoing programme by the Department of Veterinary Services to upgrade services and report the current status of parasitic diseases in the state.
  16. Chandrawathani P, Chang KW, Nurulaini R, Waller PJ, Adnan M, Zaini CM, et al.
    Trop Biomed, 2006 Jun;23(1):23-30.
    PMID: 17041548 MyJurnal
    This study was conducted to evaluate the anthelmintic effect of neem (Azadirachta indica) on nematode parasites of sheep. Twelve Santa Ines cross bred sheep from a government farm were randomly selected and equally divided into control (n = 6) and treated groups (n =6). Faecal egg counts (FEC) using the modified McMaster technique and the FAMACHA score for assessing clinical anaemia were carried out daily and recorded for 6 weeks. At the end of the study all the animals were slaughtered and the total worm count (TWC) was done. The results of FEC showed that there was no significant difference between the control and treated group (p = 0.081). However, worm burden estimations showed that the number of parasites was significantly higher in the control group compared to the treated group (p < 0.05). This result indicated that feeding Neem had an effect on worm numbers in sheep, but was not reflected in their faecal egg counts. Further work is needed to reconfirm the effect of Neem on helminth infections of sheep.
  17. Wan-Nor-Asyikeen WA, Siti-Azrin AH, Jalil NA, Othman NH, Zain AA
    Asian Pac J Cancer Prev, 2016;17(6):2867-70.
    PMID: 27356704
    BACKGROUND: Endometrial cancer is the most common gynecological malignancy among females worldwide, approximately 320,000 women being diagnosed with the disease each year and 76,000 dying. To date, there is limited knowledge of endometrial cancer in Malaysia.

    OBJECTIVES: To identify the epidemiological profile and prognostic factors of survival.

    MATERIALS AND METHODS: A list of endometrial cancer patients in 2000-2011 was obtained from the hospital Record Department. Only cases confirmed by histopathology examination were included. We excluded those with incomplete medical records or referral cases. Simple and multiple Cox regression approaches were used for data analysis.

    RESULTS: Only 108 cases were included with a mean (SD) age of 62.7 (12.3) years, with 87.0% Malay ethnicity. Grade of cancer was: 29.1% grade 1, 43.7% grade 2 and 27.2% grade 3. The majority of patients had non-endometrioid type (60.2%), with myometrial invasion (82.2%) and lymphovascular invasion (57.3%). The significant prognostic factors were age (HR 1.05; 95% CI: 1.02, 1.08, p=0.002) and having lymphovascular invasion (HR 2.15; 95% CI: 1.08, 4.29; p=0.030).

    CONCLUSIONS: Endometrial cancer patients should be diagnosed earlier to reduce the risk of mortality. The public should be given education on the signs and symptoms of the disease.

  18. Nor Azizah A, Mohd Nor F, Mohamad M, Zainal Abidin AS, Ariza A, Mohd Nor NS, et al.
    Med J Malaysia, 2016 Jun;71(3):117-21.
    PMID: 27495884 MyJurnal
    Bacteremia continues to be one of the major causes of morbidity and mortality despite the existence of numerous antimicrobial agents. this study aimed to provide a Malaysian perspective on paediatric community-acquired bacteraemia based on the documentation of epidemiology and antimicrobial profile of the isolated pathogens.
  19. Liaqat M, Gani A, Anisi MH, Ab Hamid SH, Akhunzada A, Khan MK, et al.
    PLoS One, 2016 Sep 22;11(9):e0161340.
    PMID: 27658194 DOI: 10.1371/journal.pone.0161340
    A wireless sensor network (WSN) comprises small sensor nodes with limited energy capabilities. The power constraints of WSNs necessitate efficient energy utilization to extend the overall network lifetime of these networks. We propose a distance-based and low-energy adaptive clustering (DISCPLN) protocol to streamline the green issue of efficient energy utilization in WSNs. We also enhance our proposed protocol into the multi-hop-DISCPLN protocol to increase the lifetime of the network in terms of high throughput with minimum delay time and packet loss. We also propose the mobile-DISCPLN protocol to maintain the stability of the network. The modelling and comparison of these protocols with their corresponding benchmarks exhibit promising results.
  20. Abdelaziz A, Fong AT, Gani A, Garba U, Khan S, Akhunzada A, et al.
    PLoS One, 2017;12(4):e0174715.
    PMID: 28384312 DOI: 10.1371/journal.pone.0174715
    Software Defined Networking (SDN) is an emerging promising paradigm for network management because of its centralized network intelligence. However, the centralized control architecture of the software-defined networks (SDNs) brings novel challenges of reliability, scalability, fault tolerance and interoperability. In this paper, we proposed a novel clustered distributed controller architecture in the real setting of SDNs. The distributed cluster implementation comprises of multiple popular SDN controllers. The proposed mechanism is evaluated using a real world network topology running on top of an emulated SDN environment. The result shows that the proposed distributed controller clustering mechanism is able to significantly reduce the average latency from 8.1% to 1.6%, the packet loss from 5.22% to 4.15%, compared to distributed controller without clustering running on HP Virtual Application Network (VAN) SDN and Open Network Operating System (ONOS) controllers respectively. Moreover, proposed method also shows reasonable CPU utilization results. Furthermore, the proposed mechanism makes possible to handle unexpected load fluctuations while maintaining a continuous network operation, even when there is a controller failure. The paper is a potential contribution stepping towards addressing the issues of reliability, scalability, fault tolerance, and inter-operability.
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