Cancer is a multifactorial disease that involves legion familial defects and characterized by unnatural growing of cells. It may impact about all types of tissues in human existences and over 200 types of malignant neoplastic disease has been identified, characterized and reported. Cancer is a taking cause of decease worldwide. From a sum of 58 million deceases worldwide in 2005, malignant neoplastic disease histories for 7.6 million ( or 13 % ) of all deceases. The chief types of malignant neoplastic disease taking to overall malignant neoplastic disease mortality are:
Lung ( 1.3 million deaths/year ) ;
Stomach ( about 1 million deaths/year ) ;
Liver ( 662,000 deaths/year ) ;
Colon ( 655,000 deaths/year ) and
Breast ( 502,000 deaths/year ) .
More than 70 % of all malignant neoplastic disease deceases in 2005 occurred in low and in-between income states. Deaths from malignant neoplastic disease in the universe are projected to go on lifting, with an estimated 9 million people deceasing from malignant neoplastic disease in 2015 and 11.4 million death in 20301.
Major hazard factors of malignant neoplastic disease includes Diet, baccy and smoke, chronic infection and redness, and hormonal instability. Less of import hazard factors includes business, pollution, exposure to sunlight and familial factors. These factors interferes with the written text of cistrons commanding cell rhythm events. An instability between activator and represser cistron commanding cell rhythm events is the major ground taking to malignant neoplastic disease. Such instability happens either due to the interaction of external factor ( I ) with the signal transduction mechanism in cytol which in bend affects atomic events or ( two ) with Deoxyribonucleic acid in nucleus straight, which consequences in mutant of cistrons taking to cancer2. The mutant may take to any one or more of the undermentioned events in the pathogenesis of malignant neoplastic disease,
Activation of ONCOGENES,
Repression of ANTI-ONCOGENES ( Tumor Suppressor Genes ) ,
Suppression of APOPTOSIS,
Suppression of DNA fix mechanism and
In order to stamp down the patterned advance of malignant neoplastic disease, an anticancer agent ( s ) must be designed to turn to more than one of the above listed factors. Till late 1970, medicative chemists designed their drugs for an complaint based on the earlier literature available and tested their molecules in carnal theoretical account. Success of such a molecule is strictly based on their consequence due to its action on multiple marks which were non known at that clip. Most of the drugs were good for the intervention but at the same clip with some major side effects. After 1980, as field of biochemistry and biotechnology started uncovering the molecular mechanism underlying a disease, people began to research it to understand mechanism of action of a drug molecule with ground for its unwanted side effects at molecular degree. This is the clip people started naming the less specific drugs as “ DIRTY or PROMISCUOUS ” drugs and looking frontward to plan a molecule to aim a specific protein responsible for a disease pathogenesis. The construct of “ MAGIC BULLET ” to hit a specific mark started ruling drug find sphere from so to till date3.
But 20 old ages down the line people started recognizing the fact that this mark based attack does non ever warrant success in instance of multifactorial disease such as malignant neoplastic disease, neurodegenerative upsets, cardiovascular upsets, HIV etc. , . For the intervention of such a disease one demand to depend on more than one “ Charming Bullet ” at all the clip which complicates the things at all the degree.
At industry degree, investing for drug find procedure multiplies depending on the figure of marks they are choosing for a peculiar disease,
At clinical degree, more drugs means more side effects with increased opportunity of drug interaction, and
At consumer degree, job of affordability and conformity.
This fact made the scientists in the industry every bit good as in academic to believe of planing a drug to hit multiple mark responsible for a disease4. With the cognition of complex interdependent factors responsible for pathogenesis of disease and computational chemical science, scientists have already began to plan a molecule aiming more than one protein. Simple construct is to include all the pharmacophoric characters of inhibitors of marks selected in a individual molecule. It is apparent from the fact that more than 300 articles has been published on multifunctional molecules between the period 1990-2004. Compared with articles reported for charming slugs, the figure of articles reported for multifunctional molecules were really less during this period but increasing in per centum every twelvemonth. In following few old ages the drug find sphere will witness a sea alteration with reversal of the form which is bing today5.
Our research proposal is to plan and synthesise bifunctional anticancer molecule aiming both Histone deacetylase and Ribonucleotide reductase.
The basic protein Histone is an octomer, which is rich in histidine and lysine. Histone plays a major function in the organisation of DNA into nucleosome-chromatin-chromosome. This organisation restricts the binding of transcriptional activator/repressor to DNA. In order to prefer the binding of transcriptional activator/repressor to DNA, chromatin has to undergo reconstructing ( chromatin kineticss ) . Post-translational alteration of Histone is one of the manner it adopts for the intent. The site specific station translational alteration of histone tail in a specific form permits the binding or unbinding of specific transcriptional activator/repressor taking to initiate/repress the written text of a specific cistron is known as HISTONE CODE. The good characterized Post-translational alteration is Acetylation/Deacetylation of Histone tail ( N-terminus-lysine residues ) . Balanced activity of Histone acetyl transferase ( HAT ) and Histone deacetylase ( HDAC ) controls the written text of cistrons responsible for normal cell rhythm events. Over look of HDAC represses the written text of tumour suppresser cistron which regulates the entry of cell from G1 stage to S stage taking uncontrolled cell division and consequences in malignant neoplastic disease. Over look of HDAC has been reported in most of the malignant neoplastic disease types. Inhibition of this enzyme has been shown to stamp down malignant neoplastic disease in in vitro every bit good as in vivo theoretical accounts. HDAC inhibitors arrests cell rhythm at G1 to S and induces Differentiation and Apoptosis. Almost all HDAC inhibitors activate written text of the Cyclin-dependent kinase ( CDK ) inhibitor WAF1 ( besides known as CIP1, p21 ; encoded by the CDKN1A venue ) , which can suppress Cyclin E-CDK2 and Cyclin A-CDK2, and many HDAC inhibitors down regulate Cyclin A and D, which prevents entry of cell from G1 stage to S stage.
Ribonucleotide reductase ( RR ) catalyzes the decrease of Ribonucleotide to their corresponding deoxyribonucleotides, which are the edifice blocks for DNA reproduction and fix in all life cells. Since the decrease of Ribonucleotide is the rate-limiting measure of DNA synthesis, inactivation of RR stops DNA synthesis, which inhibits cell proliferation. The of import function of RR in DNA synthesis and fix has made it an of import mark for anticancer. Increased RR activity has been associated with malignant transmutation and malignant neoplastic disease metastasis. The consequence of RR inactivation in cells includes lessenings of intracellular concentrations of the Deoxy base triphosphates ( dNTPs ) , suppression of DNA synthesis, suppression of DNA fix in quiescent cells, and cell rhythm apprehension at S-phase and programmed cell death.
Design of intercrossed inhibitor:
Hydroxamates are the major Class of agents reported as HDAC inhibitors. Hydroxamate Pharmacophore has three basic constituents ( a ) a hydroxamic acid mediety ; required for metal ion chelation ( Zn2+ ) , ( B ) a hydrophobic spacer ; required to interact with the hydrophobic channel and ( degree Celsius ) a hydrophobic cap ; which determines selectivity8. Many parallels were reported with the assorted alterations in the last two constituents, ( B ) Spacer and ( degree Celsius ) Cap. Many additive and cyclic hydrophobic spacers ( alicyclic and aromatic ) were reported with many different heteroaromatic rings and macro cyclic rings as hydrophobic cap9. Small molecule inhibitor of RR can be tried in the topographic point of cap of HDAC inhibitors. Design and synthesis of a Hybrid molecule with both pharmacophoric features of HDAC inhibitors and RR inhibitors are expected to be more powerful and effectual.
To plan Hybrid Molecule aiming both HDAC and CDK from the molecules reported earlier in the literature utilizing QSAR/Docking Softwares, and to suggest Novel Hybrid inhibitor.
To develop suited man-made methodological analysis for the synthesis of proposed intercrossed inhibitor.
To synthesise and qualify the proposed intercrossed inhibitors.
To subject the synthesized intercrossed inhibitors for in vitro enzyme based checks and so to malignant neoplastic disease cell line based checks
To set about farther QSAR surveies on Hybrid inhibitors.
III. Plan of work and Methodology:
Proposed activity will be carried out in three Phases.
Making a Database of HDAC inhibitors and RR inhibitors, which are reported already with their IC50 value.
Carrying-out QSAR surveies with the inhibitors reported already to develop a theoretical account utilizing Open beginning QSAR Softwares.
Testing of designed intercrossed inhibitors in the QSAR theoretical account developed and necessary use will be done to acquire molecules with best predicted activity.
Further polish will be carried by docking the molecules with their several mark protein utilizing Open beginning Docking Softwares.
Novel Hybrid inhibitor will be proposed for synthesis.
Man-made methodological analysis will be developed and optimized for the synthesis of proposed Hybrid inhibitors.
Attempts will be made to synthesise and qualify ( preliminary, TLC, MP, IR and CHNS analysis ) all possible Hybrid inhibitors proposed.
Further word picture and showing of synthesized intercrossed inhibitors will be carried out.
Characterization includes H1NMR, C13NMR and MS analysis and their reading.
Screening includes in vitro enzyme based check followed by malignant neoplastic disease cell line check.
Attempts will be made to analyze and develop a QSAR theoretical account for the freshly synthesized Novel intercrossed inhibitors utilizing Open beginning QSAR Softwares.
IV. Scope of proposed work:
The rationale attack to plan a drug to hit multiple marks of malignant neoplastic disease is the country yet to be explored. Any positive result of the proposed work will direct a strong message to scientific community to near drug design from a different way which is precisely opposing the present signifier of drug find attack. Besides this attack may cut down national economic load due to any multifactorial disease such as malignant neoplastic disease.
Hydroxamates Pharmacophore of HDAC inhibitors offers a greater chance to pull strings its Cap part without much upseting its ability to suppress HDAC. Other anticancer protein inhibitors can besides be tried in the cap part of HDAC inhibitors.
Cancer, Fact sheet NA° 297, World Health Organization, February 2006.
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