Contents lists available at ScienceDirect Bioorganic Chemistry journal homepage: www.elsevier.com/locate/bioorg Uses of cyclohexane-1,3-dione for the synthesis of 1,2,4-triazine derivatives as anti-proliferative agents and tyrosine kinases inhibitors Nadia Y. Megally Abdo a , Rafat Milad Mohareb b, ⁎ , Peter A. Halim c a Chemistry Department, Faculty of Education, Alexandria University, 21526 Alexandria, Egypt b Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt c Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Cairo University, Cairo 11562, Egypt ARTICLEINFO Keywords: Cyclohexane-1,3-dione 1,2,4-Triazine Multi-component Anti-proliferative activity Tyrosine kinases ABSTRACT Tetrahydrobenzo[b]thiophene derivatives were well known to be biologically active compounds and many of them occupy a wide range as anticancer agent drugs. One of our main aim of this work was to synthesize target molecules not only possess anti-tumor activities but also kinase inhibitors. To achieve this goal, our strategy was to synthesize a series of novel 1,2,4-triazines as efcient anticancer drugs with low cytotoxicity and good bioavailability properties using cyclohexane-1,3-dione and 3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene-2- diazonium chloride to give the 2-(2-(2,6-dioxocyclohexylidene)hydrazinyl)-4,5,6,7-tetrahydrobenzo[b]thio- phene-3-carbonitrile (3) as the key starting material for many heterocyclization reactions. Compound 3 was reacted with phenylisothiocyanate to give the tetrahydrobenzo[e][1,2,4]triazine derivative 5 which reacted with hydrazines to give dihydrazone derivatives. In addition, it underwent multi-component reactions with aromatic aldehydes and either malononitrile or ethyl cyanoacetate in the presence of triethylamine or ammonium acetate to produce fused pyran and fused pyridine derivatives, respectively. Compounds obtained in this work were evaluated for their c-Met kinase inhibitory potency as well as in-vitro cytotoxic activity against the six typical cancer cell lines (A549, H460, HT-29, MKN-45, U87MG, and SMMC-7721). Molecular modeling studies were carried out for the most active compounds 5, 7a, 7b, 10c, 10e, 11c and 11f using Molecular Operating Environment (MOE) software. It was found that all the tested compounds displayed potent c-Met enzymatic activity with IC 50 values ranging from 0.24 to 9.36 nM. Ten of them (5, 7a, 7b, 10c, 10e, 10f, 11b, 11c, 11d and 11f) exhibited higher potency with IC 50 values less than 1.00 nM compared with foretinib (IC 50 = 1.16 nM). Also those compounds possessed moderate to strong cytotoxicity against the six tested cancer cell lines in the single-digit µM range. The synthesized compounds 5, 7a, 7b, 10c, 10e, 11c and 11f were ft on the active site of c-Met kinase, with almost the same binding pattern as foretinib and higher binding energy scores (from −16.38 to −18.21 kcal/mol) compared to foretinib (−16.37 kcal/mol). A series of novel 1,2,4-triazines were synthe- sized and displayed potent bioactivities, indicating that these compounds could be considered as a new lead for more investigation in the future. 1. Introduction 1,2,4-Triazine ring is widely described as scafold of many biolo- gical active compounds, natural or synthetic, with a great variety of pharmacological efects, especially active as antitumor agents, anti- AIDS agents [1], CRF receptor antagonists [2], antimicrobial and an- tiinfammatory agents [3]. The NCNN sequence of 1,2,4- triazine ring was considered fundamental for various pharmacological activities. Representative examples of drugs containing this nucleus are the anti- viral Azaribine [4], the antiepileptic Lamotrigine [5] and the anticancer Tirapazamine (TPZ) [6] Fig. 1. Recently two reviews on the chemistry and the biological properties of this class of compounds have been published [7,8]. The frst deals with 1,2,4-triazine derivatives posses- sing various biological activities [7]. The other one deals also with 1,2,4-triazines endowed with diferent biological activity but gives ample room to the chemistry as well as biological activities of 1,2,3- triazine derivatives [8]. Moreover, in the past few years, numerous small molecules possessing a 1,2,4-triazine scafold have been shown to exhibit a great variety of pharmacological efects. Several reports have been published on the application of these compounds, such as 5-li- poxygenase (5-LOX) inhibitors [9,10], herbicides, bactericides, fungi- cides, antimicrobials [11,12] and gonadotropin-releasing hormone https://doi.org/10.1016/j.bioorg.2020.103667 Received 8 December 2019; Received in revised form 2 February 2020; Accepted 12 February 2020 ⁎ Corresponding author. E-mail address: raafat_mohareb@yahoo.com (R. Milad Mohareb). Bioorganic Chemistry 97 (2020) 103667 Available online 13 February 2020 0045-2068/ © 2020 Elsevier Inc. All rights reserved. T