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Subject: Biotechnology × End date: 2014 × Start date: 2014 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Identification of lead compounds with anti-tuberculosis activity in indegenous spices of Kerala
    (College of Agriculture, Vellayani, 2014) Arun, Jyothi P V; KAU; Sreekumar, S
    Tuberculosis (TB) caused by Mycobacterium tuberculosis is the second worldwide killer infectious disease and it kills annually 1.4 million people globally and 30,000 people in India. Although drugs are available to treat tuberculosis they have several limitations including long term treatment, side effects, emergence of multidrug-resistant (MDR) and extensively drug resistant (XDR) mutants and adverse effect to immune system in patients co-infection with HIV. Therefore, discovery of novel faster, cheaper and better drug is become the need of the hour. Since time immemorial several herbal remedies have been used against tuberculosis in the traditional systems of treatment especially in India and in African countries. The indigenous spices of Kerala are well known for its use to treat human respiratory system. But its efficacies and mode of action are seldom investigated. In the present study the phytomolecules reported from Elettaria cardamomum, Curcuma longa and Zingiber officinale were screened through in silico and in vitro methods. For in silico screening Decaprenylphosphoryl-beta-D-ribose epimerase (DprE1), an enzyme responsible for the synthesis of arabinan, the virulent factor in M., tuberculosis was selected as the target molecule. The 3-D structure of the molecule was retrieved from PDB (PDB id 4FDO). The active site DprE1 was detected using the tool PDBsum. Information regarding the chemical molecules reported in the selected spices was collected through literature survey and databases. The canonical SMILES of the phytochemicals were retrieved from open access chemical databases and 3D structures were created using CORINA. Total 448 phytochemicals (C. longa – 211, Z. officinale – 183 and ¬E. cardamomum – 54) were screened. Out of 448 phytochemicals structures of 373 (C. longa –137, Z. officinale –182 and ¬E. cardamomum –0) were retrieved from databases and remaining compound’s structures were created using Chemsketch. All selected phytochemicals were docked into the binding site of DprE1 using the tool, AutoDock 4.2. The docked structures having ΔG less than -5 kcal mol-1 were selected as best hit molecules. Out of 211 compounds screened in C. longa 101, out of 183 compounds screened in Z. officinale 63 and out of 54 compounds screened in E. cardamomum 22 of them showed free energy of binding  -5 kcal mol-1 and these molecules were further analysed by Lipinski's rule of Five. To nullify the errors in lead identification the top ranked hit molecules were again docked using the tools Hex server, iGEMDOCK, FireDock and SwissDock. The docked results were statistically analysed following DST and Zhang rule and selected the top ranked molecules from each plant viz. 2-methyl-6-(4-hydroxy-3-methylphenyl)-2-hepten-4-one from C. longa, Alpha-ylangene from E. cardamomum and Farnesal from Z. officinale as lead molecules. Mature seeds of E. cardamomum and mature rhizomes of Z. officianale and C. longa were air dried and extracted with 99% ethanol using a Soxhlet apparatus for 6-8 hours. The extracts were concentrated to dryness using a rotary evaporator and tested anti-mycobacterial activity by Luciferase reporter phage (LRP) assay against standard strain of M. tuberculosis H37RV at three different concentrations (25, 250 and 500 μg/ml). The results revealed that all the three plants have potential antituberculosis activity. In the order of merit Z. officinale rank first E. cardamomum rank second and C. longa rank third respectively. The results revealed the efficacy of anti-tuberculosis activity and the responsible phytomolecules in each plant. It also insights the discovery of novel drugs with desirable qualities from these plants that should be safe, effective and affordable to the poor people.