This strategy integrates the structure-based information about the key elements in protein-ligand binding with the dual ligand-based pharmacophore model derived from experimentally known dual inhibitors to design multitarget drugs. for dual inhibition. Finally, three structurally diverse hit compounds that showed key interactions at both active sites, mapped well upon the dual pharmacophore, and exhibited lowest binding energies were regarded as possible dual inhibitors of hTS and hDHFR. Furthermore, optimization studies were performed for final dual hit compound and eight optimized dual hits demonstrating excellent binding features at target systems were also regarded as possible dual inhibitors of hTS and hDHFR. In general, the strategy used in the current study could be a promising computational approach and may be generally applicable to other dual target drug designs. Introduction Drug design is the inventive process of finding new medications based on the knowledge of the biological target. The notion of one molecule C one target C one disease has been a prevalent paradigm in pharmaceutical industry. The main idea of this approach is the identification of a single protein target whose inhibition leads to a successful treatment of the examined disease. The predominant assumption is usually that highly selective ligands would avoid unwanted side effects caused by binding to secondary nontherapeutic targets. Many successful drugs have been transpired from this procedure. However, the diligence of inherent redundancy and robustness in many biological networks and pathways depicts that inhibiting a single target might fall short of producing the desired therapeutic effect [1]C[3]. As simultaneous intervention of two or multiple targets relevant to a disease has shown improved therapeutic efficacy, there has been a move toward multiple target drugs [4]. Across the pharmaceutical industry, this strategy of multitarget drugs has become an active field and around 20 multitarget drugs have been approved or are in advanced development stages [5]. Multitarget therapeutic strategy can be used to inhibit two or more enzymes, act on an enzyme and a receptor, or affect an ion channel and a transporter. Multitarget therapeutic strategy can be accomplished by one of the following approaches: (i) acting upon different targets to create a combination effect (e.g., Bactrim, which acts on two targets in the folate biosynthesis pathway in bacteria), (ii) altering the ability of another to reach the target, and (iii) binding the different sites on the same target to create a combination effect [6]. Modulating multiple targets in the biological network simultaneously is usually renowned to be beneficial for treating a range of diseases, such as acquired immune deficiency syndrome (AIDS), atherosclerosis, cancer, and depression, and this recognition has escorted to a growing tendency to devise multiple-target drugs [7]C[9]. Several multicomponent drugs have been launched, such as (4 S,7 S,10a S)-5- oxo-4-[(2 S)-3-phenyl-2-sulfanylpropanoyl]amino-2,3,4,7,8,9,10,10a-octahydropyrido[6,1-] [1], [3]thiazepine-7-carboxylic acid (omapatrilat) (a dual angiotensin-converting enzyme and neutral endopeptidase inhibitor) and 5-((6-((2-fluorophenyl) methoxy)-2-naphthalenyl) methyl)-2,4-thiazolidinedione (netoglitazone) (a peroxisome proliferator-activated receptor (PPAR)-R and PPAR- agonist) [10]. Many multitarget drugs are in clinical use today, but the discovery process is usually serendipitous, and their modes of action are usually elucidated retrospectively. Although, there is an increasing interest in developing drugs that take effect on multiple targets but designing multitarget inhibitors with predefined biological profiles is usually concurrently a great challenge for medicinal chemists. A very few computer-aided multitarget methods have been introduced in designing multitarget drugs. For instance, early design strategies tried to link the pharmacophores of known inhibitors; however these methods often lead to high molecular weight and low ligand efficacy. Moreover, sequential docking has also been implemented in designing multitarget drugs [11]. However, this docking methodology is usually computationally expensive for large-scale database screening. Another computational methodology merging molecular docking with common pharmacophore mapping was also applied for design of multitarget drugs. But, this approach used a.Molecular docking studies were carried out using GOLD (Genetic Optimization for Ligand Docking) 5.1 program from Cambridge Crystallographic Data Center, UK. binding energies were regarded as possible dual inhibitors of hTS and hDHFR. Furthermore, optimization studies were performed for final dual hit compound and eight optimized dual hits demonstrating excellent binding features at target systems were also regarded as possible dual inhibitors of hTS and hDHFR. In general, the strategy used in the current study could be a promising computational approach and may be generally applicable to other dual target drug designs. Introduction Drug design is the inventive process of finding new medications Enclomiphene citrate based on the knowledge of the biological target. The notion of one molecule C one target C one disease has been a prevalent paradigm in pharmaceutical industry. The main idea of this approach is the identification of a single protein target whose inhibition leads to a successful treatment of the examined disease. The predominant assumption is usually that highly selective ligands would avoid unwanted side effects caused by binding to secondary nontherapeutic targets. Many successful drugs have been transpired from this procedure. However, the diligence of inherent redundancy and robustness in many biological networks and pathways depicts that inhibiting a single target might fall short of producing the desired therapeutic effect [1]C[3]. As simultaneous intervention of two or multiple targets relevant to a disease has shown improved therapeutic efficacy, there has been a move toward multiple target drugs [4]. Across the pharmaceutical industry, this strategy of multitarget drugs has become an active field and around 20 multitarget drugs have been approved or are in advanced development stages [5]. Multitarget therapeutic strategy can be used to inhibit two or more enzymes, act on an enzyme and Enclomiphene citrate a receptor, or affect an ion channel and a transporter. Multitarget therapeutic strategy can be accomplished by one of the following approaches: (i) acting upon different targets to create a combination effect (e.g., Bactrim, which acts on Enclomiphene citrate two targets in the folate biosynthesis pathway in bacteria), (ii) altering the ability of another to reach the target, and (iii) binding the different sites on the same target to create a combination effect [6]. Modulating multiple targets in the biological network simultaneously is usually renowned to be beneficial for treating a range of diseases, such as acquired immune deficiency syndrome (AIDS), atherosclerosis, cancer, and depression, and this recognition has escorted to a growing tendency to devise multiple-target drugs [7]C[9]. Several multicomponent drugs have been launched, such as (4 S,7 S,10a S)-5- oxo-4-[(2 S)-3-phenyl-2-sulfanylpropanoyl]amino-2,3,4,7,8,9,10,10a-octahydropyrido[6,1-] [1], [3]thiazepine-7-carboxylic acid (omapatrilat) FRP-1 (a dual angiotensin-converting enzyme and neutral endopeptidase inhibitor) and 5-((6-((2-fluorophenyl) methoxy)-2-naphthalenyl) methyl)-2,4-thiazolidinedione (netoglitazone) (a peroxisome proliferator-activated receptor (PPAR)-R and PPAR- agonist) [10]. Many multitarget drugs are in clinical use today, but the discovery process is usually serendipitous, and their modes of action are usually elucidated retrospectively. Although, there is an increasing interest in developing drugs that take effect on multiple targets but designing multitarget inhibitors with predefined biological profiles is usually concurrently a great challenge for medicinal chemists. A very few computer-aided multitarget methods have been introduced in designing multitarget drugs. For instance, early design strategies tried to link the pharmacophores of known inhibitors; however these methods often lead to high molecular weight and low ligand efficacy. Moreover, sequential docking has also been implemented in designing multitarget drugs [11]. However, this docking methodology is computationally expensive for large-scale database screening. Another computational methodology merging molecular docking with common pharmacophore mapping was also applied for design of multitarget drugs. But, this approach used a single conformation inhibitor-protein complex [12]. Thus, more effective computational methods for the identification and.