Journal name: Drug Design, Development and Therapy Article Designation: Original Research Year: 2016 Volume: 10 Drug Design, Development and Therapy Dovepress Running head verso: Alam et al Running head recto: Hybrid pyrazole analogues open access to scientific and medical research DOI: http://dx.doi.org/10.2147/DDDT.S118297 Open Access Full Text Article ORIGINAL RESEARCH Synthesis, anti-inflammatory, analgesic, COX1/2-inhibitory activity, and molecular docking studies of hybrid pyrazole analogues Md Jahangir Alam1 Abstract: This article reports on the design, synthesis, and pharmacological activity of a new Ozair Alam1 series of hybrid pyrazole analogues: 5a–5u. Among the series 5a–5u, the compounds 5u and 5s Suroor Ahmad Khan1 exhibited potent anti-inflammatory activity of 80.63% and 78.09% and inhibition of 80.87% and Mohd Javed Naim1 76.56% compared with the standard drug ibuprofen, which showed 81.32% and 79.23% inhibi- Mohammad Islamuddin2 tion after 3 and 4 hours, respectively. On the basis of in vivo studies, 12 compounds were selected Girdhar Singh Deora3 for assessment of their in vitro inhibitory action against COX1/2 and TNFα. The compounds 5u and 5s showed high COX2-inhibitory activity, with half-maximal inhibitory concentrations 1 Department of Pharmaceutical of 1.79 and 2.51 µM and selectivity index values of 72.73 and 65.75, respectively, comparable Chemistry, Faculty of Pharmacy, 2Parasite Immunology Laboratory, to celecoxib (selectivity index =78.06). These selected compounds were also tested for TNFα, For personal use only. Department of Biotechnology, Faculty cytotoxicity, and ulcerogenicity. Docking studies were also carried out to determine possible of Science, Jamia Hamdard, New Delhi, interactions of the potent compounds (5u and 5s), which also showed high docking scores 3Institute of Life Sciences, University of Hyderabad, Hyderabad, India of -12.907 and -12.24 compared to celecoxib, with a -9.924 docking score. These selective COX2 inhibitors were docked into the active site of COX2, and showed the same orientation and binding mode to that of celecoxib (selective COX2 inhibitor). Docking studies also showed that the SO2NH2 of 5u and 5s is inserted deep inside the selective pocket of the COX2-active site and formed a hydrogen-bond interaction with His90, Arg513, Phe518, Ser353, Gln192, and Ile517, which was further validated by superimposed docked pose with celecoxib. Keywords: anti-inflammatory activity, analgesic activity, selective COX2 inhibition, TNFα inhibition, molecular docking studies, pyrazole Introduction Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most widely used therapeutic Drug Design, Development and Therapy downloaded from https://www.dovepress.com/ by 130.194.145.11 on 19-Jun-2017 agents for the management of pain and inflammation.1 NSAIDs exert their pharmacological action by inhibiting COX enzymes, which catalyses the conversion of arachidonic acid to prostaglandins, prostacyclins, and thromboxanes.2 Two differ- ent isoforms of COX exist (COX1 [constitutive] and COX2 [inducible]), which are assumed to play a vital role in producing pathological and physiological prostaglandins, respectively.3 Currently used NSAIDs employ their anti-inflammatory action mostly by inhibition of both isoforms of COX.4–6 However, absence of selectivity and their Correspondence: Ozair Alam Department of Pharmaceutical long-term clinical use leads to various adverse effects, such as gastric ulceration, Chemistry, Room No 209, Faculty of gastrointestinal bleeding, cardiovascular toxicity, and nephrotoxicity, which are mainly Pharmacy, Jamia Hamdard, Hamdard associated with most of the reported nonselective NSAIDs, due to their inhibition of Nagar, Near Batra Hospital, New Delhi, Delhi 110062, India COX1-mediated physiological prostaglandins.7–9 Similarly, NFκB also plays a key role Tel +91 11 2605 9681 by activating the inflammatory response and releasing proinflammatory cytokines and Fax +91 11 2605 9666 Email [email protected] enzymes, such as TNFα, IL-1β, COX2, and iNOS.10,11 Improper regulation of NFκB submit your manuscript | www.dovepress.com Drug Design, Development and Therapy 2016:10 3529–3543 3529 Dovepress © 2016 Alam et al. 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Powered by TCPDF (www.tcpdf.org) 1 / 1 Alam et al Dovepress is directly linked to inflammation, together with improper continuation of our previous work, the present investigation immunodevelopment.12–14 describes the synthesis, anti-inflammatory, and analgesic Pyrazole, a key heterocyclic scaffold in medicinal chem- activities of substituted pyrazole analogues with the aim istry, possess an array of various biological activities, such of obtaining nonulcerogenic selective COX2 inhibitors as as antitumor,15 anticancer,16,17 antiviral,18 anticonvulsant,19 anti-inflammatory agents. Moreover, in order to increase antibacterial,20 and antifungal21 activity. The rationale for affinity for COX2, the bulky hydrophobic benzyloxyphenyl evaluating pyrazole analogues (5a–5u) as anti-inflammatory, group was incorporated in a manner similar to orientation analgesic, and COX inhibitors is based on successful of the trifluoromethyl group of celecoxib. Further, the marketed drugs containing pyrazole as the central core importance of this bulky hydrophobic group was noticed by (celecoxib, SC558, deracoxib, SC560, metamizole, anti- formation of one hydrogen bond with Arg120 in molecular pyrine, SC581, and lonazolac) (Figure 1). The design of docking studies. The high in vitro COX2-inhibition assay NSAIDs with higher therapeutic value and lower risk could results of compounds 5u and 5s encouraged us to perform be achieved by increasing specificity toward COX2 rather molecular docking studies to establish and understand than COX1.22–24 In the present study, the central pyrazole the ligand–protein interactions. The in vitro COX assay core linked with the phenylsulfonamide group of selective and docking study results showed that the N1 substituent COX2 inhibitors (celecoxib and SC558) was employed, and of the core pyrazole structure with benzene sulfonamide structural modification led to the design of new pyrazole moiety is important for selective COX2-inhibitory activity. analogues (Figure 2). Docking studies also revealed that the SO2NH2 group of Further the pyrazole moiety was linked to two aryl moi- 5u and 5s, as well as celecoxib,27 formed hydrogen bonds eties, of which one was linked through the –CH2NH linker with His90, Arg513, Phe518, Ser353, Gln192, and Ile517, and the other through the –OCH2 linker. The significance and was completely inserted in the selective pocket of the of our study is in bringing together the pyrazole (excellent COX2-active site. anti-inflammatory agent) and sulfonamide pharmacophore, Encouraged by all these facts, we designed a new For personal use only. known too for its wide range of biological activities, includ- series of hybrid pyrazole analogues (5a–5u) bearing the ing anti-inflammatory activities,25,26 to obtain a derivative N-phenyly/p-sulfonamide phenyl group involving various that is new and with a better pharmacological profile with electron-withdrawing and electron-releasing substituents fewer side effects. As part of our continuous research and and in vivo anti-inflammatory, analgesic, ulcerogenic, efforts to design and develop a novel pyrazole-based anti- in vitro COX1/COX2 selective, TNFα, iNOS and cytotoxic inflammatory agent with COX1/2-inhibition effect and activity. ) ) ) %U ) ) ) 2 ) &, ) ) ) ) 11 11 ) ) 11 11 Drug Design, Development and Therapy downloaded from https://www.dovepress.com/ by 130.194.145.11 on 19-Jun-2017 6 2 6 2 6 2 2 2 1+ 2 1+ 2 1+ &HOHFR[LE 6& 'HUDFR[LE 6& 2+ ) ) 2 2 ) 6 +2 2 2 ) &, 11 1 11 2 11 11 6 2 2 1+ 0HWDPL]ROH $QWLS\ULQH 6& /RQD]RODF Figure 1 Chemical structure of some pyrazole-containing anti-inflammatory drugs. 3530 submit your manuscript | www.dovepress.com Drug Design, Development and Therapy 2016:10 Dovepress Powered by TCPDF (www.tcpdf.org) 1 / 1 Dovepress Hybrid pyrazole analogues ) ) ) 1 6HU$ 3KH$ 1 %U ,OH$ *OQ$ $UJ$ 226 2 1+ 6HU$ +LV$ 6& /LQNHU $UJ$ 1 6XSHULPSRVHGRFNHGSRVHRIFHOHFR[LE 1 ) ) SLQN ZLWKFRPSRXQGX JUHHQ ) $UELWUDU\UHJLRQ 1 1 226 0ROHFXODUGRFNLQJRQ&2; 1+ 0HW 226 +\GRSKRELF 9DO 1+ SRFNHW /HX ,& 0 &HOHFR[LE DJDLQVW&2; $UJ +LV /HX ,QYLYRDQWLLQIODPPDWRU\DFWLYLW\ 0HW 2 7\U /HX ,QYLWUR&2;DVVD\ ,OH *O\ /HX 1 6HU $OD + 6HU 71)αDVVD\ 1 9DO 9DO 1 *O\ /HX L126LQKLELWRU\DFWLYLW\ $OD +\GRSKRELF 0HW SRFNHW *OQ 3KH 3KH For personal use only. 2 $QDOJHVLFDFWLYLW\ 6 2 ,OH +1 &\WRWR[LFLW\DQGXOFHURJHQLFLW\ 6HOHFWLYLW\ /HX SRFNHW 7\U 7US 'HVLJQHGFRPSRXQG Figure 2 Strategy for design of target compound with structural resemblance of reference ligand. Abbreviation: IC50, half-maximal inhibitory concentration. (DMSO)-d or CDCl as an NMR solvent. Ultraperformance Materials and methods 6 3 General chemistry liquid chromatography (UPLC) analysis