The Novel Compounds Against Mycobacterium Tuberculosis

Published Date: 02 Nov 2017

Niteesh kanungo (12msb0117), Prof. Siva Kumar A.

Email - [email protected]

Abstract- DNA Gyrase finds out to be very important in validating the development of various antibacterial compounds. Fluoroquinolones are already existing inhibitors of DNA Gyrase. In treatment of tuberculosis. Fluoroquinolones accounted to be a class of compounds with pharmacokinetic and antimicrobial properties against many pathogenic bacteria’s. Fluoroquinolones said to have less effect on mycobacterium but research with new Fluoroquinolones suggested and demonstrated to be having a good activity against M. Tuberculosis. Fluoroquinolones are already used as second line drugs. In the present studies we came across 10 synthetic compounds that do have fundamental properties like DNA Gyrase inhibition activity. In this study we are docking the Novel Ligands into the active site of DNA Gyrase. We want it to investigate inhibitory activities through in-silico analysis.

INTRODUCTION

The infection caused by Mycobacterium tuberculosis result in highest number of deaths world Wide. Fluoroquinolones are used as a secondary line of drugs against mycobacterial diseases. With the emergence of Extensive drug resistant tuberculosis (XDRTB) and Multi drug resistant tuberculosis (MDRTB) the need to develop better resolution and anti-bacterial drugs are in need . New Drug with efficient design against mycobacterium tuberculosis can help in development of anti â€"TB drugs [1]. Mycobacterium tuberculosis found to have very unusual possession with only one type II Isomerase, DNA Gyrase [2]. The DNA Gyrase of Mycobacterium tuberculosis with such unusual activities still shows a enhanced activity in DNA cleavage, and deactivation activities.

The molecular structure of DNA Gyrase consist if two Sub Units, Gyrase A (Gyr A) and Gyrase B (GyrB) which together they form a heterodimer structure A2B2. The main function of GyrA subunit is to break and then re unite the bacterial DNA. While the function of Gyr B is ATP-ase activity. If the ATP is absent then the DNA catalyses the relaxation of supercoiled DNA.[4,5] The Bacterial DNA Gyrase, is found to be the main target of the antibacterial chemotherapy. Fluoroquinolones are a type of synthetic drug found to show inhibition activity against the DNA Gyrase and topoisomerase IV and causes cell death. They found to be very effective as anti- microbial agent.

Fluoroquinolones interact with DNA Gyrase and Topoisomerase IV, they specifically binds with the complex formed in between the DNA and the Enzyme, resulting in the stabilization of the covalent enzyme Tyrosyl DNA ester, which is a an intermediate that has been found in the intermediate reaction, Which results in accumulation of Double Stranded DNA fragments leading to cell death.

The new sets of Fluoroquinolones designed possess a good potential in treatment, they show very effective in vitro activity against mycobacteria. They possess a good potential to reduce the Tuberculosis treatment regime from 6 months to 4 months or even less. The important factor about the Fluoroquinolones is that there activity strictly relates to that of the inhibitory activities to DNA Gyrase. The development of resistance by Fluoroquinolones still uncommon by the strains of Mycobacterium Tuberculosis, the factor is because of rhe putative Fluoroquinolones binding between the Mycobacterium gyr-A encoded A sub Unit of DNA Gyrase. Thus Mycobacterium tuberculosis is one of the validated targets for anti-tubercular drug discovery. On all research based studies progressed till date for the point of human testing on tuberculosis the quinolone holds potential in reducing the time of treatment, coming up with new activities against Multi Drug resistant Tuberculosis (MDR-TB) and in the improvement of the therapy given against Tuberculosis HIV Co- Infection. The Fluoroquinolones are also found to be good medication in respiratory diseases like the Respiratory tract infection, UTIs, found helpful in curing other skin disorders and from sexually transmitted diseases.

EXTRACTION OF FLUOROQUINOLONES

Nalidixic acid is the main synthetic derivative of all clinically important Fluoroquinolones. Nalidixic acid is the first member of quinolone class which is 1,8 napthyridine. It has a quinolone nucleus or a modified dual ring system. The current Fluoroquinolones agents are the result of two separate modifications of 1,8 napthyridine. 1 is involved in an additional 8-methoxyside chain, which led to the development of moxifloxacin and gatifloxacin. Enoxacinwas developed by structural alterations to the naphthyridine core, and trovafloxacin was produced by a 7azabicyclo modification to this core molecule. And the other one is involved a carbon-for-nitrogen substitution at position 8 of the 6-fluoro, 7-piperazinyl quinolone, in addition to other side-chain modifications.

THE ROLE OF FLUOROQUINOLONES IN TUBERCULOSIS

Fluoroquinolones shows effects against variety of Important Micro Organisms. Fluoroquinolones have been found in to have a good suppressing effect on respiratory diseases. Oflaxacin was the amongst the first Fluoroquinolones that has showed activity against Pulmonary Tuberculosis. Strains of Mycobacterium tuberculosis have been developed that can easily resist Ofloxacin and Ciprofloxacin. Spafloxacin have been determined to block the development of resistant mutants. A new variety of Fluroqunolimes have been introduced in the market which could have a better activity against that of the resistant organism. One such drug named C-8-methoxy Fluoroquinolones (Moxiflocin and Gatifloxin), being used against wide variety of pathogens. The agent exhibits a very good quality activity against Tuberculosis. Follow up studies of with the various drug combination shows that the combination of such drugs could lead to reduce the time needed to eradicate tuberculosis further studies also revealed that the follow up time needed to shorten up the duration of the therapy.

MECHANISM OF ACTION

The mechanism of quinolone basically involve inhibition of DNA gyrase in gram negative bacteria which inhibits replication and transcription of bacterial DNA . this inhibition leads to rapid cell death. The primary target in gram positive bacteria i.e topoisomerase lV is also inhibited by quinolones. The newer Fluoroquinolones has decrease susceptibility due to mutation in gyrA , parC, and parE genes.

Molecular Modelling.

Molecular modelling studies of the interaction of the Ligands at the active sites of the Protein molecule can help in providing valuable information and assisting in the design of the future drug inhibitor. The Literature available online for the testing of the drug against Mtb DNA gyrase, for the studies. Heavily customised docking studies using Software’s like Accelrys Draw and taking reference with other software’s like Discovery tools and online servers like Patch Dock and Me Dock. As it is not clear, as both the chains kept for the docking solution are entirely similar, we have choose only the GyrA for the possibilities of finding different binding site. In this protocol, the recently revealed crystal structure of Mtb DNA Gyrase GyrA N-terminal domain (3ILW) was employed. The next step is to find out the Active Site and pockets. The Docking Studies are implemented and assigned using AutoDock’s two different versions available, The first Docking tool is from the MGL tools package number 1.5.6 and the the other version is 1.5.6rc, release candidate version for next release.

Results

Compound name

Ki

Î"G

S21

355.79

-0.61

S22

87.25

-1.45

S23

40.52

-1.9

S24

171.96

-1.04

S25

-1.59

-0.16

S26

86.11

-1.45

S27

8.74

10.29

S28

-1.47

5.13

S29

92.3

98.14

S30

91.81

-1.41

Table1. Comparison of Fluoroquinolone Compounds in Antibacterial Activities and and Activities Against M.tuberculosis DNA Gyrase.

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Binding Site for S28 Ligand.

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Binding Site for S24 Ligand.

ADVERSE EFFECTS

GI effect such as nausea vomiting and diarrhoea skin disturbances and CNS effects, including headaches and dizziness are the most common effects of Fluoroquinolones. Sleep disturbances, hallucinations, depression, and seizures are less common adverse effects. Patients receiving co administered cyclosporine and ciprofloxacin are reported with Nephrotoxicity. Maculopapular or Urticarial are dermatologic effects. Pain at the injection site has been reported with IV formulation. “3, 34 Overgrowth of Clostridium diflicile has been identified as the cause of 10% to 25% of cases of antibiotic-associated diarrhoea and almost all cases of antibiotic-associated PMC.“5 Diarrheal and pseudomembranous colitis (PMC) have long been associated with the use of antibiotics. A well-known cause of antibiotic induced diarrhoea is clindamycin but all other antibiotics may be responsible . about 878 cases of antibiotic induced PMC has been studied. Derivatives of penicillin are also associated with haemorrhagic colitis, included cefixime,

amoxicillin-clavulanic acid, amoxicillin, ofloxacin, and trimethoprim-sulfamethoxazole; are the most frequently used antibiotic and cefaclor, cefuroxime axetil, and tetracyclines are less frequently used.. Long-term steroid treatment that can increase the risk of tendon inflammation. Studies shows that tendons are the most common site for Fluoroquinolones-induced tendinopathy under high stress, including the Achilles tendon . therefore it is suggested that if any sign of inflammation appears , treatment with Fluoroquinolones should be discontinued. arthralgia with or without effusion has been documented, it occurs at a relatively low rate (11.5%) and resolves completely once drug therapy is discontinued, with no evidence of serious or long-termsequelae. However none of these antibiotics can be used for children’s. They can be used under clinical circumstances eg, cystic fibrosis patients with multidrug resistant gram-negative infection).these drugs were also examined on fracture healing quinolones have demonstrated chondrotoxicity in developing articular cartilage in juvenile mammals.

DISCUSSION AND CONCLUSIONS

The Fluoroquinolones helps in providing variety of medication with respect to various Infections. With the given number of possible Quinolones in nature the difficult choice is the selection and is a very important task. The research studies conducted in different hospitals showed the adverse effect, of nearly 25% of them getting infection from Drug or after math of the Drugs. Drug designing is a very important note in the objective. The selection profile into the administration and design, a lot of important factors should be kept in mind. Taking the base knowledge from literature provided from different Infections around the world, and the number of drugs that has been administered as well as the long term effect, All these points should be given importance before successfully testing or before post marketing trials and records.

ABBREVIATIONS

DNA = Deoxyribonucleic acid

RNA = Ribonucleic acid

ATP = Adenosine triphosphate

MDR-TB = multiple drug resistant tuberculosis

XDR-TB = Extremely/extensively drug resistant

tuberculosis

QR-MDR-TB = Quinolone resistance- multiple drug resistant

tuberculosis

TB-HIV = Tuberculosis/Human immunodeficiency

virus

ADPNP = 5’-adenylyl 􀀁,-imidodiphosphate

GyrA-NTD = N-terminal domain of DNA gyrase subunit A

GyrA-CTD = C- terminal domain of DNA gyrase subunit A

QRDR = Quinolone resistance determining region

ARV = Anti-retroviral

SAR = Structure/Activity relationship