**4. Target identification and characterization**

Target identification and elucidation of its action mechanism have played vital roles in probing small molecules and drug discovery. Target identification has been based on biological and technologically advanced cell-based assays [51].

#### **4.1 Disease association and target validation**

Identification of the molecules and their underlying pathophysiological mechanisms contribute towards the discovery of targets that can be modulated therapeutically [52]. Each drug target is linked to a disease using integrated genome-wide data from a broad range of data sources. The target validation reveals the evidence that associates a target with a disease [53].

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*Chemical Biology Toolsets for Drug Discovery and Target Identification*

gies have been developed for validation of the drugs.

Bioactive small molecules are preferred as lead structures for the target validation. These small molecules isolated from phenotypic screen play a crucial role in chemical biology [54, 55]. Many genomic, proteomic, and bioinformatic technolo-

To identify the selective potent drugs, the first step is to find the protein interference. In signal transductions, protein-protein interactions are involved in the complex cellular networks that govern the different processes [56]. The deregulated transcription factors are involved in playing significant roles in human pathological abnormalities, but the complicated nature of protein-protein networks has made the transcription-targeted therapeutics impractical. Recent technological advancements are the ray of hope regarding the modulation of

Exosomes are highly adequate for drug carriers as a cell-based model. Due to the association of multiple proteins with cellular membranes, the exosomes are well-known in cell to cell communication, and they are the novel approach for the delivery of potent drugs. Exosome-based drug technique is applied for a variety of

Drug target discovery and validation demand complicated and expensive frameworks which may pose heavy financial load on pharmaceutical industry. Target validation is referred to as the direct involvement of a certain molecular target in pathological

The following approaches are used in target validation during the discovery and

Firstly access the antibody fitness towards a specific target. Then, standardized procedures are obligatory to ensure the quality of the sample in test procedures; hence, utilizing only a single approach will not work in all situations [59]. Mass spectrometry is used to identify the validation of the antibody. This type of technique confirms the validity for antibodies or their fragments against the targets. The antibody is able to bind to its natural antigen in cell lysates among thousands of

CETSA is used to assess the capability of a ligand to bind with its targets (cells or tissue samples). The basis of this method lies on the ligand-induced thermodynamic

conformity; hence, its reversal or inflection may have a therapeutic effect [12].

other proteins, DNA, RNA, and other cellular components [60].

disorders such as cancer and various neurodegenerative disorders [58].

*DOI: http://dx.doi.org/10.5772/intechopen.91732*

**4.2 Bioactive small molecules**

**4.3 Protein interactions**

protein interaction networks [57].

**5.1 Approaches to target validation**

*5.1.2 Cellular thermal shift assay (CETSA)*

**5. Target validation**

development of drug.

*5.1.1 Antibodies*

**4.4 Cell-based models and target validation**
