Synthesis and biological evaluation of nitrogen-containing benzophenone analogues as TNF-a and IL-6 inhibitors with antioxidant activity Babasaheb P. Bandgar a,b, * , Sachin A. Patil b , Jalinder V. Totre b , Balaji L. Korbad b , Rajesh N. Gacche c , Baliram S. Hote b , Shivkumar S. Jalde b , Hemant V. Chavan a a Organic Chemistry Research Laboratory, School of Chemical Sciences, Solapur University, Solapur 413 255, India b Organic Chemistry Research Laboratory, School of Chemical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431 606, India c School of Life Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431 606, India article info Article history: Received 25 August 2009 Revised 30 December 2009 Accepted 1 February 2010 Available online 13 February 2010 Keywords: Nitrogen-containing benzophenone Anti-inflammatory TNF-a IL-6 Antioxidant activity abstract A series of nitrogen-containing benzophenone analogues were synthesized by Mannich reaction and evaluated for the inhibition of pro-inflammatory cytokines, TNF-a and IL-6. DPPH (1,1-diphenyl-2-picryl hydrazine) radical scavenging activity and its kinetics were studied to determine the antioxidant poten- tial of the test samples. All the synthesized compounds exhibited promising activity against IL-6 in a range of 81–89%, 09–42% at 10 and 1 lM, respectively, concentration. Exceptionally, the compound 20e was observed to be an effective inhibitor of TNF-a (54%) and IL-6 (97%), (47%) at 10 and 1 lM con- centrations with minimum toxicity (22%) against CCK-8 cells. With few exceptions, all other compounds were found to be excellent inhibitors of IL-6 and moderate to excellent inhibitors of TNF-a, however the toxicity profiles of these compounds need to be ameliorated in further optimization studies. Amongst the tested compounds, 16a, 17g, 18f, 18g, 19g and 20e were found to possess significant antioxidant activity. Ó 2010 Elsevier Ltd. All rights reserved. Inflammation is a multi-step and complex biological reaction involving variety of pro-inflammatory cellular proteins, enzymes and cytokines. The pro-inflammatory cytokines, interleukin-6 (IL- 6) and tumour necrosis factor-a (TNF-a) are implicated in the pathogenesis of various inflammatory disorders such as rheuma- toid arthritis (RA), inflammatory bowel disease, osteoarthritis, pso- riasis, endotoxemia and/or toxic shock syndrome. 1–9 Apart from pro-inflammatory attributes these cytokines have a wide array of functions for maintaining the normal cellular physiology. For example, TNF-a can induce apoptosis and secretion of cytokines such as IL-1, IL-6 and IL-10; it can also activate T cells and other inflammatory cells. However, an overabundance of TNF-a and IL- 6 is attributed to the development of various human ailments including inflammatory disorders. Targeting the inhibition of cyto- kines, in particular TNF-a, has been successful in several clinical trials for the treatment of RA. Nevertheless, the TNF-a inhibition has been identified as one of the attractive targets for the design and development of anti-inflammatory agents. 10 Upregulation of tumour necrosis factor-alpha (TNF-a) has several concerns for the onset and progression of a number of dis- eases such as diabetes, multiple sclerosis, RA, psoriatic arthritis, cachexia, sepsis, tumourigenesis and inflammatory bowel diseases. 11 Therapies that have successfully targeted TNF-a in man include biologics directed towards these cytokines such as adalimumab (Humira), etanercept (Enbrel) and infliximab (Remicade) which have demonstrated a significant efficacy in the treatment and management of RA. 12 However, these agents require administration via injection or infusion, therefore identification of an orally available small molecule therapy would provide an addi- tional benefit to the patients. In spite of enormous efforts, no small molecule has yet been approved to specifically inhibit TNF-a activ- ity. Therefore, there is a continuing interest in the search of small molecules that can block TNF-a signalling without side effects and general disadvantages associated with protein drugs. Amongst the pro-inflammatory cytokines, the IL-6 is a pleiotro- pic cytokine, that is, abundant in both the synovium and serum of RA patients and induces a broad range of cellular and physiological responses during the inflammation reaction. In addition to playing a role in inflammation and hematopoiesis, it is involved in other processes such as neuronal differentiation and bone loss. IL-6 is produced at the site of inflammation and plays a key role in acute phase response. IL-6 is a central regulator of inflammatory dis- eases, including end-stage renal disease and rheumatoid arthri- tis. 13 Till-date, designing the IL-6 inhibitory agents has remained a significant hope in the mainstream of anti-inflammatory drug development. Benzophenones, the precursors for the synthesis of the title compounds are essential due to their diverse biological and chemical properties. In recent years a vast body of literature has 0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.bmcl.2010.02.001 * Corresponding author. E-mail address: bandgar_bp@yahoo.com (B.P. Bandgar). Bioorganic & Medicinal Chemistry Letters 20 (2010) 2292–2296 Contents lists available at ScienceDirect Bioorganic & Medicinal Chemistry Letters journal homepage: www.elsevier.com/locate/bmcl