Structural characterization and cytotoxicity studies of ruthenium(II)–dmso–chloro complexes of chalcone and flavone derivatives Rishikesh Prajapati a , Santosh Kumar Dubey a , Ruchi Gaur a , Raj Kumar Koiri b , Brajesh Kumar Maurya b , Surendra Kumar Trigun b , Lallan Mishra a, * a Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221 005, India b Biochemistry and Molecular Biology Section, Centre of Advanced Studies in Zoology, Banaras Hindu University, Varanasi 221 005, India article info Article history: Received 16 September 2009 Accepted 13 November 2009 Available online 20 November 2009 Keywords: Chalcone and flavone Ru(II) complexes Single crystal X-ray Cytotoxic assay abstract A synthetic precursor cis-[Ru II Cl 2 (dmso) 4 ] is complexed separately with 3-(4-benzyloxyphenyl)-1-(2- hydroxylphenyl)-prop-2-en-1-one (L 1 H) and 2-(4-benzyloxyphenyl)-3hydroxy-chromen-4-one (L 2 H). The resulting complexes are assigned the composition fac-[RuCl(S-dmso) 3 (L 1 )] 1 and fac-[RuCl(S- dmso) 3 (L 2 )] 2 using elemental analyses, FAB mass data and spectroscopic (IR, 1 H NMR, UV–Vis, emission) spectral properties. The X-ray diffraction analysis shows that complexes self-associate through non-cova- lent interactions and provide 1D and 2D supramolecular structures. These complexes are assayed for their cytotoxicity studies on Dalton Lymphoma cell lines. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Ruthenium complexes introduced almost two decades ago for antitumor therapy have great potential as alternative drugs to cis- platin in view of their low toxicity and good selectivity for solid tu- mor metastasis [1–4]. Among several synthetic ruthenium-based anticancer agents, ruthenium–dmso complexes are believed to have great potential owing to their selectivity for solid tumor metastases and low toxicity against host [5]. Among the coordina- tion complexes of ruthenium–chloro–dmso containing heterocyclic ligands viz. NAMI, Na[trans-RuCl 4 (S-dmso)(im)] (dmso = dimethyl sulfoxide; im = imidazole) [6] and NAMI-A, [Him][trans-RuCl 4 (S- dmso)(im)] [7] have proved their potential candidature as drug in the treatment of cancer cells. Moreover, NAMI-A successfully fin- ished a Phase I clinical trial. It is worth to mention that in contrast to cisplatin and other platinum based compounds, biological testing of ruthenium–dmso compounds have indicated that DNA is not the only responsible target for their antimetastatic activity [8,9]. Additionally, chalcones and flavones are reported to exhibit a wide spectrum of biological activities, which include potential applications as new drugs, and agrochemicals [10–12]. Compounds such as 4 0 -ethoxy-2 0 -hydroxy-4,6 0 -dimethoxy chalcone and 4 0 ,6- dichloroflavone interact directly with viral capsid proteins causing their uncoating and subsequently liberating viral RNA. Flavone derivatives especially [5,7-dihydroxy-2-(3-hydroxy-4-methoxy phenyl)-4-1-benzopyran-4-one]-1 possess potential therapeutic activities hence are considered leading synthetic targets in the re- search area of medicinal chemistry [13]. Several metal complexes from our laboratory have already been reported as cytotoxic [14] in vitro as well as in vivo inducing apop- tosis in Dalton’s Lymphoma (DL) cells [15]. Thus in persuasion of our studies on cytotoxic ruthenium complexes, attempts are made to complex a representative chalcone (L 1 H) and flavone (L 2 H) with well known precursor cis-[Ru(dmso) 4 Cl 2 ] in anticipation to substi- tute its either two dmso or a dmso and a Cl substituent. The result- ing complexes fac-[RuCl(S-dmso) 3 (L 1 )] 1 and fac-[RuCl(S- dmso) 3 (L 2 )] 2, are structurally characterized. The preliminary level in vitro anticancer screening of these complexes using MTT assay on DL cell lines is also described. The DL cell lines have been chosen as tumor model in view of their successful applications for other anticancer drugs like cisplatin [16–18]. 2. Experimental 2.1. Materials and methods Starting materials were purchased from Sigma–Aldrich and used without further purification. Compounds were analyzed for C, H, N measurements from Central Drug Research Institute, Luc- know, India whereas Infrared, UV–Vis and luminescence spectra were recorded on VARIAN 3100 FTIR, Shimadzu UV-1601 and Perkin–Elmer LS-45 spectrophotometer, respectively. However, 1 H NMR spectra were recorded on JEOL AL 300 MHz spectrometer 0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2009.11.012 * Corresponding author. Tel.: +91 542 6702449; fax: +91 542 2368174. E-mail address: lmishrabhu@yahoo.co.in (L. Mishra). Polyhedron 29 (2010) 1055–1061 Contents lists available at ScienceDirect Polyhedron journal homepage: www.elsevier.com/locate/poly