Determination of Novel SARS-CoV-2 Inhibitors by Combination of Machine Learning and Molecular Modeling Methods.

INTRODUCTION: Within the scope of the project, this study aimed to find novel inhibitors by combining computational methods. In order to design inhibitors, it was aimed to produce molecules similar to the RdRp inhibitor drug Favipiravir by using the deep learning method. METHODS: For this purpose, a Trained Neural Network (TNN) was used to produce 75 molecules similar to Favipiravir by using Simplified Molecular Input Line Entry System (SMILES) representations. The binding properties of molecules to Viral RNA-dependent RNA polymerase (RdRp) were studied by using molecular docking studies. To confirm the accuracy of this method, compounds were also tested against 3CL protease (3CLpro), which is another important enzyme for the progression of SARS-CoV-2. Compounds having better binding energies and RMSD values than favipiravir were searched with similarity analysis on the ChEMBL drug database in order to find similar structures with RdRp and 3CLpro inhibitory activities. RESULTS: A similarity search found new 200 potential RdRp and 3CLpro inhibitors structurally similar to produced molecules, and these compounds were again evaluated for their receptor interactions with molecular docking studies. Compounds showed better interaction with RdRp protease than 3CLpro. This result presented that artificial intelligence correctly produced structures similar to favipiravir that act more specifically as RdRp inhibitors. In addition, Lipinski's rules were applied to the molecules that showed the best interaction with RdRp, and 7 compounds were determined to be potential drug candidates. Among these compounds, a Molecular Dynamic simulation study was applied for ChEMBL ID:1193133 to better understand the existence and duration of the compound in the receptor site. CONCLUSION: The results confirmed that the ChEMBL ID:1193133 compound showed good Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF), hydrogen bonding, and remaining time in the active site; therefore, it was considered that it could be active against the virus. This compound was also tested for antiviral activity, and it was determined that it did not delay viral infection, although it was cytotoxic between 5mg/mL-1.25mg/mL concentrations. However, if other compounds could be tested, it might provide a chance to obtain activity, and compounds should also be tested against the enzymes as well as the other types of viruses.

Synthesis and Anticancer Activity of Novel Indole Derivatives as Dual EGFR/SRC Kinase Inhibitors.

BACKGROUND: Recent studies showed that the cooperation between c-SRC and EGFR is responsible for more aggressive phenotype in diverse tumors, including glioblastomas and carcinomas of the colon, breast, and lung. Studies show that combination of SRC and EGFR inhibitors can induce apoptosis and delay the acquired resistance to chemotherapy. Therefore, such combination may lead to a new therapeutic strategy for the treatment of EGFR-mutant lung cancer. Osimertinib was developed as a third-generation EGFR-TKI to combat the toxicity of EGFR mutant inhibitors. Due to the resistance and adverse reaction of osimertinib and other kinase inhibitors, 12 novel compounds structurally similar to osimertinib were designed and synthesized. BACKGROUND: Recent studies showed that the cooperation between c-SRC and EGFR is responsible for more aggressive phenotype in diverse tumors, including glioblastomas and carcinomas of the colon, breast, and lung. Studies show that combination of SRC and EGFR inhibitors can induce apoptosis and delay the acquired resistance to chemotherapy. Therefore, such combination may lead to a new therapeutic strategy for the treatment of EGFR-mutant lung cancer. Osimertinib was developed as a third-generation EGFR-TKI to combat the toxicity of EGFR mutant inhibitors. Due to the resistance and adverse reaction of osimertinib and other kinase inhibitors, 12 novel compounds structurally similar to osimertinib were designed and synthesized. METHODS: Compounds were synthesized by developing novel original synthesis methods and receptor interactions were evaluated through a molecular docking study. To evaluate their inhibitory activities against EGFR and SRC kinase, in vitro enzyme assays were used. Anticancer potencies were determined using lung, breast, prostate (A549, MCF6, PC3) cancer cell lines. Compounds were also tested against normal (HEK293) cell line to evaluate their cyctotoxic effects. RESULTS: Although, none of compounds showed stronger inhibition compared to osimertinib in the EGFR enzyme inhibition studies, compound 16 showed the highest efficacy with an IC50 of 1.026 µM. It also presented potent activity against SRC kinase with an IC50 of 0.002 µM. Among the tested compounds, the urea containing derivatives 6-11 exhibited a strong inhibition profile (80.12-89.68%) against SRC kinase in comparison to the reference compound dasatinib (93.26%). Most of the compounds caused more than 50% of cell death in breast, lung and prostate cancer cell lines and weak toxicity for normal cells in comparison to reference compounds osimertinib, dasatinib and cisplatin. Compound 16 showed strong cytotoxicity on lung and prostate cancer cells. Treatment of prostate cancer cell lines with the most active compound, 16, significantly increased the caspase-3 (8-fold), caspase-8 (6-fold) and Bax (5.7-fold) levels and decreased the Bcl-2 level (2.3-fold) compared to the control group. These findings revealed that the compound 16 strongly induces apoptosis in the prostate cancer cell lines. CONCLUSION: Overall kinase inhibition, cytotoxicity and apoptosis assays presented that compound 16 has dual inhibitory activity against SRC and EGFR kinases while maintaining low toxicity against normal cells. Other compounds also showed considerable activity profiles in kinase and cell culture assays.

Investigating the Activity of Indole-2-on Derivative Src Kinase Inhibitors Against Chronic Myeloid Leukemia Cells.

BACKGROUND: Src family tyrosine kinases play a potential role in Bcr-Abl-induced leukemogenesis. Src kinase inhibitors are reported as selective inhibitors of chronic myeloid leukemia. OBJECTIVE: Since Src kinase inhibitors have an inhibitive effect on chronic myeloid leukemia, indole derivatives (C-1, C-2, C-3) previously found as potent inhibitors of Src kinase were tested against chronic myeloid leukemia in this study. METHODS: Cell viability of K562 and R/K562 cells, antiproliferative and antioxidant effects, and inhibition profiles of Bcr-Abl kinase of indole derivatives were determined compared to dasatinib and imatinib. RESULTS: The results showed that compounds affected cell proliferation and decreased the levels of Bcr/Abl. These results confirmed that the antileukemic activity of compounds was related to Bcr/Abl expression. Docking studies also presented that compounds are inhibitors of both Src and Abl kinases. Calculation of drug-like properties showed that compounds could be potential drug candidates. CONCLUSION: Among indole-2-on derivatives, previously identified as Src kinase inhibitors, C-2 has been discovered to be a strong anticancer drug that is active against susceptible and resistant K562 cell lines and induces apoptosis.

Drug Repurposing in the Development of Anticancer Agents.

BACKGROUND: Research into repositioning known drugs to treat cancer other than the originally intended disease continues to grow and develop, encouraged in part, by several recent success stories. Many of the studies in this article are geared towards repurposing generic drugs because additional clinical trials are relatively easy to perform and the drug safety profiles have previously been established. OBJECTIVE: This review provides an overview of anticancer drug development strategies which is one of the important areas of drug restructuring. METHODS: Repurposed drugs for cancer treatments are classified by their pharmacological effects. The successes and failures of important repurposed drugs as anticancer agents are evaluated in this review. RESULTS AND CONCLUSION: Drugs could have many off-target effects, and can be intelligently repurposed if the off-target effects can be employed for therapeutic purposes. In cancer, due to the heterogeneity of the disease, often targets are quite diverse, hence a number of already known drugs that interfere with these targets could be deployed or repurposed with appropriate research and development.

SAHAquines, Novel Hybrids Based on SAHA and Primaquine Motifs, as Potential Cytostatic and Antiplasmodial Agents.

We report the synthesis of SAHAquines and related primaquine (PQ) derivatives. SAHAquines are novel hybrid compounds that combine moieties of suberoylanilide hydroxamic acid (SAHA), an anticancer agent with weak antiplasmodial activity, and PQ, an antimalarial drug with low antiproliferative activity. The preparation of SAHAquines is simple, cheap, and high yielding. It includes the following steps: coupling reaction between primaquine and a dicarboxylic acid monoester, hydrolysis, a new coupling reaction with O-protected hydroxylamine, and deprotection. SAHAquines 5 a-d showed significant reduction in cell viability. Among the three human cancer cell lines (U2OS, HepG2, and MCF-7), the most responsive were the MCF-7 cells. The antibodies against acetylated histone H3K9/H3K14 in MCF-7 cells revealed a significant enhancement following treatment with N-hydroxy-N'-{4-[(6-methoxyquinolin-8-yl)amino]pentyl}pentanediamide (5 b). Ethyl (2E)-3-({4-[(6-methoxyquinolin-8-yl)amino]pentyl}carbamoyl)prop-2-enoate (2 b) and SAHAquines were the most active compounds against both the hepatic and erythrocytic stages of Plasmodium parasites, some of them at sub-micromolar concentrations. The results of our research suggest that SAHAquines are promising leads for new anticancer and antimalarial agents.

Overview on Anticancer Drug Design and Development.

BACKGROUND: Many impediments of current anti-cancer therapies have urged scientists to discover new agents. As a result of growing spectrums of new targets and strategies and recent biological and biotechnological progresses, many anti-cancer agents such as monoclonal antibodies, small molecule tyrosine kinase inhibitors and epigenetic drugs have been reached to clinical trials. OBJECTIVES: This review helps to understand the rationale for the development of inhibitors against major targets such as cell growth, proliferation, survival, angiogenesis and recent targets such as proteasome, heat shock proteins, and epigenetics. METHODS: Recent approaches of the target-based anti-cancer drug developments were highlighted to giving some examples from approved agents. Many factors, such as metabolic change, hypoxia, cancer precursors and cancer resistant cells, and their effect on drug resistance mechanisms were discussed. The impacts of advanced computational techniques to identify targets of cancer and designing more selective inhibitors were explained. RESULTS: Contributions of recent techniques such as a network analysis, the precise modes of action and computational methodologies especially simulation of bio-molecular processes to clarify targets, mechanism actions and reasons of lack of efficacy of anti-cancer drugs have been explained. The relationship between the several mechanisms and molecular design strategies has been discussed. CONCLUSION: This review provides an overview of important targets and design strategies of anti-cancer drugs, advantages and disadvantages of these methods and evaluation of some currently used anticancer targets in clinical studies.

The Effects of 1,3,5-trisubstituted Indole Derivatives on Cell Growth, Apoptosis and MMP-2/9 mRNA Expression of MCF-7 Human Breast Cancer Cells.

BACKGROUND: Matrix metalloproteinases are known as extracellular matrix degrading enzymes and have important role on tumor progression. OBJECTIVE: This study reports the effects of 1,3,5-trisubstituted indole derivatives on cytotoxicity, apoptosis and MMP- 2/MMP-9 mRNA expression of MCF-7 human breast carcinoma cells. METHOD: The cytotoxic effects of the compounds on MCF-7 cells were performed by MTT test, and cell proliferation was determined via BrdU incorporation. The apoptotic effects were observed by cell death detection elisa. The effects of the compounds on MMP-2/-9 enzyme activity and mRNA expression were also performed. RESULTS: The compounds inhibited the proliferation of MCF-7 breast carcinoma cells significantly in a dose dependent manner. All compounds were able to induce DNA fragmentation, especially compound 1. The IC50 values of compound 2 and 4 for MMP-2 were 0.42 µM and 1.88 µM, respectively. MMP-2 mRNA expression results were correlated with the inhibition of enzyme activity, such compound 4 inhibited MMP-2 mRNA expression at all treated concentrations. Docking simulation has also been performed to analyze the binding mode of compounds and the results showed that compound 2, the most active compound, formed a hydrogen bond with Glu202 for binding to the MMP-2 active site. In addition, the hydrophobic parts of compound 2 are in contact with nonpolar surface areas of MMP-2, such as His201, His211, Tyr223 and Tyr193. CONCLUSION: According to the molecular docking results along with the biological assay data, it is suggested that compound 2 might be used for further design and development of MMP-2 inhibitors.

Design Strategies, Structures and Molecular Interactions of Small Molecule Src Inhibitors.

In recent years, several small molecules approved by FDA for clinical studies are promising anti-cancer agent. Among the kinases, Abelson Leukaemia (Abl), sarcoma (Src), epidermal growth factor receptor (EGFR) and vascular endotelhial growth factor receptor (VEGFR) are considered as primary molecular targets for selective inhibition and the best successful targeted therapy of tyrosine kinase inhibitors (TKIs) has been achieved in the treatment of Bcr (break point cluster)-Abl leukemia. The majority of type 1 kinase inhibitors target the active conformation of ATP binding site. In consequence of intensive studies on kinases, type 2, type 3 (allosteric) and type 4 (covalent) inhibitors have been discovered beyond the type 1 inhibitors. Although the selectivity is a major problem for type 1 inhibitors, these new type of inhibitors are promising for finding new selective compounds, which may provide other therapeutic options for cancer therapy. They may also be a solution to overcome drug resistance that remains unresolved yet. Threedimensional structural determination provides the development of specific and highly binding properties of compounds. Studying the prediction of a binding mode of inhibitors, homology model developments from kinase- ligand co-crystal structures and isosteric replacements have been used to improve binding properties of inhibitors. In this review, critical results related to the design strategies of kinase specifically targeted to Src and Bcr-Abl kinases and therapeutic potential of novel inhibitors will be evaluated. The readers will be endowed with the functional role of Src and Bcr-Abl kinases that lead inhibitor design, the structural analysis of binding modes of kinase inhibitors, the current progress in terms of therapeutic interventions and the mission of leading groups in the field.

Synthesis, Biological, and Computational Evaluation of Novel 1,3,5-Substituted Indolin-2-one Derivatives as Inhibitors of Src Tyrosine Kinase.

Several substituted indolin-2-one derivatives were synthesized and evaluated for their activities against Src kinase. Several compounds showed activity against Src, with IC50 values in the low micromolar range. Among them, compound 2f showed the most significant activity with an IC50 value of 1.02 µM. Molecular docking studies have been performed for evaluation of the binding modes of compound 2f into the Src active site. The docking structure of compound 2f disclosed that the indole NH forms a hydrogen bond with the carbonyl of Met341. These results suggest that our novel compound 2f is a promising compound for the further development of indole-based drugs targeting Src kinase.

N-substituted Indole-2 and 3-carboxamide derivatives as inhibitors of human protein kinase CK2: in vitro assay and molecular modelling study.

Protein kinase CK2 (Casein Kinase 2) is involved in cell growth; proliferation and suppression of apoptosis. Hence, it strongly promotes cell survival and can be considered an important target for human cancers. In the present study, a series of N-substituted indole-2- and 3-carboxamide derivatives were tested for inhibitions of human recombinant protein kinase CK2 to evaluate their anticancer properties. The inhibition test revealed that the most active compound 4 (1-benzyl-N-(2,4-dichlorobenzyl)-1H-indole-2-carboxamide) showed an IC50 value of 14.6 µM towards human protein kinase CK2. A molecular docking study of the compounds with CK2 was performed and revealed the binding mode of the most active compound 4, underlying its inhibitory activity.

Recent development of new substituted indole and azaindole derivatives as anti-HIV agents.

Human immunodeficiency virus-1 (HIV-1) infections cause global health problems. Indole derivatives have been considered as one of the promising HIV inhibitors. Recent inventions have focused on substituted indole and azaindole derivatives that possess unique antiviral activities against HIV-1. In this review, the evaluation of recent advances in substituted indole and azaindole derivatives for the treatment or prevention of HIV-1 and acquired immune deficiency syndrome (AIDS) has been focused. In this respect, compounds having drug and bio-active properties, including their synthesis and pharmacologic properties have been reported. In addition, anti-HIV properties of compounds, the structural features of inhibitors, the current progress in terms of therapeutic interventions and the leading groups in the field are discussed. Moreover, clinical and ADME (Absorption, Distribution, Metabolism, Elimination) properties of some clinically important compounds such as BMS-378806, L-737126 and IDX899 are reported.

Synthesis, biological evaluation and docking studies of new pyrrolo[2,3-d] pyrimidine derivatives as Src family-selective tyrosine kinase inhibitors.

In this study, the synthesis and potential enzyme interactions of new Pyrrolo[2,3-d]pyrimidine derivatives along with their inhibitory activity against SFK enzymes such as Fyn, Lyn, Hck, and c-Src were reported. The results indicated that compounds were slightly active of tested SFK enzymes in comparison with PP2 for Fyn, A-419259 for Lyn and CGP77675 for c-Src. Compound N-((2-amino-4-oxo-4,7-dihydro-3H-pyrrolo[2,3-d]pyrimidin-5-yl)methyl)-4-(3,4-dimethoxyphenyl)butanamide (5) was identified as a non-selective slight inhibitor against Fyn, Lyn and c-Src. However, compounds did not show any inhibitory effects on Hck. Docking studies were performed to analyze the binding mode of compounds against SFKs. The best interaction was obtained between compound 5 and the active site of Fyn and c-Src enzymes in comparison with reference compounds PP2 and CGP77675, respectively.

Synthesis of new indole-2-carboxamide and 3-acetamide derivatives and evaluation their antioxidant properties.

In recent years, antioxidant compounds play an important role as a health-protecting factor. Antioxidants protect cells against the damaging effects of reactive oxygen species (ROS). An imbalance between antioxidants and ROS results in oxidative stress, which leads to cellular damage and it is linked to many vital diseases. It was shown that heme oxygenase (HO) provides efficient cytoprotection against oxidative stress. In this study, a series of indole-2-carboxamide and 3-acetamide derivatives was tested for in vitro effects on HO activity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition. Among the synthesized compounds, N-[3-(dimethylamino)propyl]-1H-indole-2-carboxamide 3 was found as the most activator of HO and N-(2-(dimethylamino)ethyl)-2-(1H-indol-3-yl)acetamide 8 was found the most potent inhibitor for DPPH at 10(-4) M concentration.

Autodisplay of catalytically active human hyaluronidase hPH-20 and testing of enzyme inhibitors.

Hyaluronic acid (HA) is the major biopolymer of the extracellular matrix and contributes significantly to cell proliferation and migration. Human hyaluronidase hPH-20 has been identified as a tumor marker for breast and laryngeal cancer. A hPH-20-autotransporter fusion protein for cell surface display was transformed into Escherichia coli BL21 (DE3) and hPH-20 was displayed on the surface of E. coli. Enzymatic activity, however, was not detectable due to competitive inhibition by lipopolysaccharide (LPS). Finally, expression in E. coli F470, a strain missing the O-polysaccharide of LPS, yielded cells with sufficient hyaluronidase activity. 6-Palmitoyl-l-ascorbic acid (Vcpal) and two indole-carboxamides, N-(4-fluorobenzyl)-1-benzyl-1H-indole-2-carboxamide (1) and N-(4-chlorobenzyl)-1-(4-fluorobenzyl)-1H-indole-3-carboxamide (2), were tested on inhibition of hPH-20. Vcpal with a concentration of 5 µM inhibited hPH-20 to 93% at pH 7, compounds 1 and 2 showed 61% and 21% inhibition at a concentration of 50 µM. At the same inhibitor concentrations the most frequently used bovine testes hyaluronidase (BTH) was inhibited by Vcpal to a similar extent (95%), whereas compound 1 (80%) and compound 2 (66%) showed much differing inhibition. Thus it can be assumed that BTH is not applicable as an alternative to human PH-20. These results indicate that Autodisplay enables the expression of human target enzymes normally forming inclusion bodies in E. coli and accelerates inhibitor testing as shown by the example of human hyaluronidase PH-20.

Evaluation of novel aminomethyl indole derivatives as Src kinase inhibitors and antioxidant agents.

BACKGROUND: Oxidative stress has been implicated in aging and in a variety of diseases affecting the nervous, respiratory, cardiovascular and gastrointestinal system in humans. Reactive oxygen species (ROS) have been associated with mechanisms to activate kinases, such as protein tyrosine kinases, which may initiate malignant transformation. Significant evidences of the activation of protein kinases by oxidative stress brought increased attention to the role of antioxidants in these mechanisms. Therefore, recent efforts have focused on revealing the relationship between protein kinase inhibition and the levels of ROS production. METHODS: Antioxidant properties of aminomethyl indole derivatives were investigated by employing various in vitro systems, microsomal NADPH-dependent inhibition of lipid peroxidation (LP), interaction of 2,2-diphenyl-1-picrylhydrazyl and scavenging of superoxide anion radical by virtue of superoxide dismutase inhibitory activity. In vitro tyrosine kinase assays of the aminomethyl indole derivatives were evaluated by changes in the enzymatic activity of pp60(c-Src) tyrosine kinase through alterations in the phosphorylation level of immobilized kinase substrate. RESULTS: Analysis of the antioxidant effects of indole 1a-c, bromo indole 2a-c and phenyl indole 3a-c derivatives revealed almost equal inhibition against LP for 5-bromo indole 2a-c and phenyl indole 3a-c derivatives and slight inhibition against superoxide dismutase only for 1a and 1c. Nonsubstituted compounds at position 5 showed half-inhibition of LP. Compound 1a has tyrosine kinase inhibition with an IC(50) of 102.6 ± 1.16 µM. CONCLUSION: The substitution feature at position 5 of the indole ring certainly plays an important role in both tyrosine kinase inhibition and antioxidant capacity. While certain lipophilicity of this substitution is important for antioxidant activity, it may, on the other hand, have a negative impact on the inhibition of Src kinase.

Investigation of aminomethyl indole derivatives as hyaluronidase inhibitors.

Hyaluronidase inhibitors are of potential therapeutic value for the treatment of a variety of diseases, such as cancer, arthrosis, or bacterial infections. Potent and selective hyaluronidase inhibitors are not known so far, and current approaches to the development of hyaluronidase inhibitors are limited. Elevated levels of hyaluronan (HA) are connected with most malignant tumours. Therefore, the search for drugs modulating the hyaluronidase activity became very important. In the present study, a new series of aminomethyl indole derivatives (AMIDs) were tested for inhibition of bovine testes hyaluronidase (BTH). In vitro assays were performed using stains-all at pH 7 and Morgan-Elson reaction at pH 3.5. Among the AMIDs, 3-[(4-methylpiperazin-1-yl)methyl]-5-phenyl-1H-indole (9) was found to be active with 23% inhibition at 50 microM and pH 7. All the other inhibitors showed less activity at pH 3.5 and pH 7. These activity results demonstrated that compounds with phenyl substitution at position 5 have higher activity. The results confirmed that more lipophilic compounds have better inhibition against the hyaluronidase enzyme.

N-substituted indole-3-imine derivatives and their amine congeners: antioxidant and Src kinase inhibitory effects.

Current evidences demonstrated that the activity of protein kinases can be controlled through oxidative stress induced by reactive oxygen species (ROS) and normalized by antioxidants. Recent studies with ROS, generated by mitochondria, suggested the potential signalling role of these species, where ROS, especially hydrogen peroxide, were proposed as membrane-related signalling components. The protein regulation by cellular redox states has shown that protein tyrosine kinase members, such as Src kinase and some of the members of the Src family kinases (SFKs), are proteins regulated by the cellular oxidation and reduction status. In this context, the oxidant or antioxidant potential of the synthetic Src kinase inhibitors previously synthesized and studied by our research group, such as N-substituted indole-3-imine and -amine derivatives, were investigated employing various acellular in vitro methods including microsomal NADPH-dependent inhibition of lipid peroxidation (LP), interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and scavenging of superoxide anion radicals. Here, we report that some of the synthetic inhibitors designed for Src kinase target have both antioxidant and kinase inhibition properties.

The role of fluorine substitution in biphenyl methylene imidazole-type CYP17 inhibitors for the treatment of prostate carcinoma.

It has been established that the growth of most prostate carcinomas depends on androgen stimulation. The inhibition of cytochrome P450-17 (CYP17) to block androgen biosynthesis is therefore regarded as a promising approach to therapy. Based on our previously identified lead compound Ref 1, a series of fluorine-substituted biphenyl methylene imidazoles were designed, synthesized, and evaluated as CYP17 inhibitors to elucidate the influence of fluorine on in vitro and in vivo activity. It was found that meta-fluoro substitution at the C ring improved activity, whereas ortho substitution decreased potency. Docking studies performed with our human CYP17 homology model suggest the presence of multipolar interactions between fluorine and Arg109, Lys231, His235, and Glu305. As expected, introduction of fluorine also prolonged the half-life in plasma. The SARs obtained confirm the reliability of the protein model; compound 9 (IC(50)=131 nM) was identified as a strong CYP17 inhibitor, showing potent activity in rat, high bioavailability, and a long plasma half-life: 12.8 h.

Evaluation of new indole and bromoindole derivatives as pp60(c-Src) tyrosine kinase inhibitors.

A series of N-benzyl-indole-3-imine-, amine derivatives and their 5-bromo congeners were synthesized and their biological activity were evaluated against the pp60(c-Src) tyrosine kinase target. To afford the imine derivatives, aldehydes were reacted with substituted benzylamines and the corresponding amine derivatives were obtained by NaBH(4) reduction of these imines. Except insoluble N-benzyl-indole-3-imine derivatives, all the derivatives showed some activity against the kinase target. Screening of these compounds for their biological activity revealed that among N-benzyl-indole derivatives, those bearing 5-bromo substitution have the enhanced potency, where the amine derivatives were more active than imines.