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Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5927_Библиотеки_им_академика_М_И_Перельмана

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40
Drug Repurposing and Computational Drug Discovery: Strategies and Advances
TNF-α (tumor necrosis factor), MMP-9 (matrix metalloprotien), and MPO
human myelo peroxidase. Druglikliness (Molinspiration and Molsoft) and ADMET (pkCSM) were evaluated by online computational tools. The active site on target proteins was analyzed (CASTp 3.0). Molecular dynamic simulations (GROMACS 2018.1 software and amber algorithms) revealed a stable ligand–protein complex for mesalamine and coumarin derivatives in the aqueous system along with highest binding affinity toward all the proteins investigated in comparison with mesalamine alone. Further, these computational results were confirmed by in vivo studies on the acetic acid induced ulcerative colitis rat model which revealed that the synthesized mesalamine-coumarin diazo derivatives were potent in reducing ulcerative
109
colitis.
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2.3.1 TARGET-BASED APPROACH
There are several computational processes, including visualization tools, which assist the drug design/discovery process decision systems using
110–112
target-based drug design methodologies.
The prospective lead or therapeutic compounds are shaped mostly by biological targets. Target-based drug discovery has had some success. It is not only for small molecules but also has an active role in identifying antibody medicines, protein biologics, gene therapies, and nucleic acid-based treatments.
113,114
Moreover, these approaches are often quicker, simpler, and less expensive to build and operate. It would target specific active site of the candidate by the principle of SARs.
115
Figure 2.3 depicts the schematic representation of a target-based
drug discovery approach.
2.3.2 KNOWLEDGE-BASED APPROACH
The information-driven recent trends in the drug development method are becoming more prevalent. When combined with structural knowledge about their target proteins, structural, physicochemical, and ADMET property with standard or potent ligands have shown to be greatly significant for
116,117
early-stage drug development etiquette.
The integument of advance chemo-informatics tools, which are used to evaluate the structures and characteristics of effective compounds, has also grown dramatically in the
41 Computational Drug Discovery and Drug Repurposing
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last several years. Recently, authentic databases are playing a key role in the knowledge-based approach system.
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These are categorized with various forms in Table 2.5. Preliminarily, emphasis on the physicochemical charac­teristics of drug is most important for clinical approval. These parameters are molecular weight, H-bond acceptor, donor, cLogP, TPSA; number of rotatable bonds and rings. Among all, H-bond accepter parameter is a major factor in determining efficacies of drug.
119
Sl No. Database Link
World drug index https://www.daylight.com/about/index.html MDDR database http://www.akosgmbh.de/accelrys/databases/mddr.
htm SuperDrug http://bioinf.charite.de/superdrug Comprehensive medicinal
chemistry (CMC) GPCR-PEnDB https://gpcr.utep.edu/database
http://www.akosgmbh.de/accelrys/databases/cmc-3d.
htm
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Drug Repurposing and Computational Drug Discovery: Strategies and Advances
2.3.3 SIGNATURE-BASED APPROACH
In the beginning, the drug discovery and development depends upon the disease of interest. The screening of a leading compound is now the most important stage by the identification of their drug-likeness properties and
113,120
toxicity using high-throughput technology.
Moreover, one of the most important requirements in compound profiling and drug discovery is to evaluate the effects of these compounds on cellular activities by utilizing a large number of key proteins. Firstly, the unique molecular state of a phenotypic that differs from the wild-type or healthy state is referred to as the disease signature. Generally, heterogeneous biological data, such as gene expression in organs and protein composition in the microbiome, may be used to describe these signatures. Second, drug signatures are similar to disease signatures (Fig. 2.4). Drug fingerprints are perturbed by therapy exposure rather than disease condition.
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FIGURE 2.4 Schematic representation of the disease of interest.
2.3.4 NETWORK-BASED APPROACH
For the development of effective inhibitors, a new technique that incorporates networks-based methods is being explored. For the purpose of determining
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the quantitative structure–activity relationship (QSAR) among the known inhibitors by using the first-principles quantum mechanical approach, phys­ical characteristics of neural networks, such as electronegativity and molar
122
volume, would be plausible.
This would be effective for early-stage drug development. Figure 2.5 shows schematic representation of network-based drug design.
FIGURE 2.5 Schematic representation of network-based drug design.
Moreover, the integration of omics experiments with route- and network­based methods for early drug development is intended to bridge the gap between fundamental research on pathway models and the actual require­ments of the early drug development pipeline, evidently. Topology-based route analysis techniques may aid in the reduction of false positives during the target analysis process, the prioritization of target validation, the selec­tion of optimum hits, and the progression from hit to lead during the hit to
lead step. There are very few limits and difculties to overcome, despite
the fact that including pathway- and network-based drug development may
increase the rate of success for nding new drugs. For example, network topology databases provide a large number of contradictory ndings, and
the accuracy of these reports is questionable in many cases. Network-based
computational techniques will benet from the advances made possible by the development and distribution of disease- and drug-specic omics data.
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This will provide a new route toward a more evolved drug development pipeline with reduced attrition rates.
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Drug Repurposing and Computational Drug Discovery: Strategies and Advances
2.3.5 TARGET MECHANISM-BASED APPROACH
Considering that it is a multifactorial disease, the paradigm shifts from “one drug-one target” called target-based drug development. Moreover, the main goal of either the multitarget strategy is to provide single-molecular entities with a broader pharmacological spectrum through the use of multiple drugs. When it comes to the development of new therapeutic armaments against disease, target-based drug design offers a strong strategy.
125,126
However, the druggability of hybrid compounds that have been created by rationally integrating different pharmacophoric characteristics may be severely compromised, particularly if their molecular weight is raised and their water solubility is reduced. In this regard, recent advancements
in early-stage ADMET will help to ease some of the difculties associated
with target-based drug design and development. On the other hand, it must
still conrm the efcacy of multitarget treatment in fact before it can be
implemented. This makes this task very appealing, but it also explains why “Pharmaceutical industries” are disengaged from target-based drug creation, particularly for different indications. However, the integration of a chemobioinformatic method may aid in bridging the gap that currently exists between the demand for disease-oriented drug design and the desire
127,128
for target-based drug design.
When developing a multitarget drug, it is important to consider the fundamental molecular characteristics that are required for successful interaction with each intended biological target. To accomplish this objective, several drug design methods, most of which are inspired by ligand-based and target-based approaches, have been proposed.
Signicant people have attempted in past few years to integrate the vast
quantity of diverse information in an attempt to develop predictive multi­target designs by integrating the information.
2.3.6 EXAMPLES OF SUCCESSFUL DRUG REPOSITIONING: CASE STUDIES
Research into drug repositioning often involves integrating existing knowledge about diseases, pathways, targets, and ligands into new studies. This endeavor seems to be very difficult, given the wide range of terms and circumstances under which experimental and clinical data may be collected in various formats. Because of this, substantial and
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coordinated community efforts are required for effective use of existing biological and clinical information as well as extraction of knowledge from this information, which may aid in the better repositioning of already available medicines in the marketplace. A large number of research are presently ongoing that are aimed at the annotation, curation, and integra­tion of information regarding chemical–biological interactions and their mechanisms.
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In computational drug repositioning is gaining popularity across the world these days, owing to the availability of a huge quantity of informa­tion on protein structures, pharmacophores, illness data, clinical studies,
and gene expression proles of pharmaceutical compounds. Furthermore,
the proliferation of public social networking technologies, as well as the availability of computational access to genetic information, has signi­cantly helped the computer methods in their attempts to anticipate novel indicators. As a result, current bioinformatics or computational tools are
being used by the majority of pharmaceutical rms to reposition drugs
from a variety of chemical regions. Any pharmaceutical business wishes
to prot from the improved speed and lower costs offered by strong
in silico technology. This is the ultimate goal of every pharmaceutical
company. New computational techniques for focused proling of small
compounds have been created in response to the rise in drug-related data. These methods have higher levels of recall and accuracy than previous methods.
8
These techniques enhance the repositioning process by using chemoin­formatics, bioinformatics, network biology, systems biology, or genomic information to uncover previously undiscovered targets or processes of authorized medicines in a shorter amount of time than traditional methods. As a result, computational drug repositioning techniques may be generally
classied into the following categories: target-based, knowledge-based,
signature-based, network-based, and targeted-mechanism-based. Based on
the computational ndings, a selection of compounds may be selected for
additional experimental testing to ensure that the computational insights are correct. A hybrid method that incorporates both computational and experimental tests is thus required to repurpose medicines for new illnesses, and the majority of pharmaceutical companies have already embraced this strategy to assess the therapeutic effectiveness of new indications.
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Table 2.6 lists some successful drug repositioning.
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TABLE 2.6 List of Some Successful Drug Repositioning.
Drug Initial References
Drug Repurposing and Computational Drug Discovery: Strategies and Advances
Suggested
Parkinson’s disease [133]
Attention deficit hyperactivity disorder
Depression [134,144]
Obesity
Depression [135]
Diabetic-neuropathy
Analgesia and [136] depression
Premature ejaculation
Immunosuppressant [137]
Pancreatic neuroendocrine tumors
Drug Initial References
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Suggested
Depression [138]
Gastrointestinal stromal tumor
Chronic myeloid [139] leukemia
Pregnancy termination [140]
Cushing’s syndrome
47 Computational Drug Discovery and Drug Repurposing
Depression [141]
Fibromyalgia syndrome
Cancer [142]
Restenosis
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Drug Initial References
Drug Repurposing and Computational Drug Discovery: Strategies and Advances
Suggested
Epilepsy [143]
Migraine
Opioid addiction [144]
Obesity
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DISCOVERY
Despite availability of a wide range of tools and resources in computational drug discovery, developing a robust computational model is a complex process and associated with many challenges. Besides, complexity of mapping these theoretical approaches to predict behavior of living beings, inaccurate, missing, or biased data are some of the major challenges in putting these approaches into action. For example, it may be quite difficult to define a reliable gene expression signature profile because of variations in experimental conditions such as patient’s age, environment factors across different experiments; this may lead to discrepancies in gene expression data. When such inaccurate or biased data are utilized to build models it may lead to unreliable results. Further, unavailability of high-resolution structural data of drug targets makes it difficult to identify interactions between drug and target. Lack of gold-standard datasets to evaluate models performance is yet another challenge in computational drug discovery. Therefore, researchers have to either split their dataset into test, training, and validation sets and the
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use k-fold cross validation and evaluation metrics or build their own dataset and use prevalent metrics such as specificity, sensitivity, recall, F1 score, accuracy, etc., to evaluate the model and to avoid over fitted model.
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Despite all these challenges, integration of multisource data related to disease, drugs, and how these drug and diseases affect the body is important aspect in computational drug discovery models. Availability and integration of these datasets could improve the performance of the models. However, there are several diseases that still lack treatments and inspire the researchers all over the world to develop novel and leading candidates for treatment of unknown and rare diseases.
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In summary, computational drug discovery and repurposing can be of immense benefit for speeding up the drug development process as well as increasing the plausibility for the failed or withdrawn drug to get a second chance to reach the market. While extra supports toward computational drugs repurposing are the need of the hour for the researchers and scientists to make further efforts to come up with new finding in this area. With this in mind, availability of open-source databases/tools, workflow systems, pipelines in the form of codes, software tools that are more robust, reproducible, and easy access to validate the analysis could be helpful for the computational drug discovery process.
KEYWORDS
• bioinformatics
• chemoinformatics
• drug discovery
• drug repurposing
• network biology
REFERENCES
1. Dudley, J. T.; Desphande, T.; Butte, A. J. Exploiting Drug–Disease Relationships for Computational Drug Repositioning. Brief Bioinform. 2011, 12 (4), 303–311.