Angew Chem Int Ed Engl. (TXA2), PGD2, PGI2, PGF2, and PGE2, depending on different distal synthases.1, 2 Among these Pemetrexed (Alimta) prostanoids, PGE2 is well recognized as an important inflammatory mediator. PGE2 is usually isomerized from PGH2 catalyzed by three unique synthases, including microsomal prostaglandin E2 synthase-1 (mPGES-1), mPGES-2, and cytosolic prostaglandin E2 synthase.3 Unlike the other two constitutively expressed enzymes, the expression of mPGES-1, similar to that of COX-2, is highly inducible in response to pro-inflammatory stimuli.4 As two generations of anti-inflammatory drugs, traditional non-steroidal anti-inflammatory MDS1-EVI1 drugs (tNSAIDs) and coxibs symbolize the mainstream for the treatment of inflammation-related symptoms by either non-selectively inhibiting COX isozymes,5 or selectively inhibiting COX-2,6 respectively. However, both categories shut down the biosynthesis of all downstream prostanoids and, so, their application is usually associated with considerable adverse effects. The tNSAIDs trigger gastrointestinal (GI) ulceration because of the interference with COX-1-derived protective function in GI tract;7 coxibs, as specific COX-2 inhibitors, on the other hand, break the internal sense of balance of vasodilative PGI2 and vasoconstrictive TXA2 and thus result in cardiovascular risk.8 Since PGE2 is the major inducible PG in inflammation, inhibiting mPGES-1 is believed as a promising therapeutic approach in the development of the next generation of anti-inflammatory drugs.9 In the previous study, we reported the discovery of (data shown in Table 1, it was observed as compared to that without a side chain (7a and 8a), compounds with linear side chains (7b~7f and 8b~8f) were generally more potent against human mPGES-1, whereas benzyl substitution (7g and 8g), however, did not improve the inhibitory potency. Linear side chains with 4 or 6 carbons yielded compounds with highest potency, whereas longer side chains, such as octyl or decyl, did not show a more potent inhibition. Notably, compounds with 2-thiobarbituric acid heads were generally more potent as compared Pemetrexed (Alimta) to those with barbituric acid ones. We also changed the substituent in pyrazole-1-position from 4-chlorophenyl to phenyl group. In this case, 4c was used as starting substituted acetophenone. Followed the comparable protocol as layed out in Plan 2, 11 and 12 were prepared. These compounds (11 and 12) were slightly less potent than those with 4-chlorophenyl substituent (7c and 8c, respectively). Open in a separate window Plan 2 Reagents and conditions: (a) 5 % glacial AcOH in EtOH, reflux; (b) POCl3 (4.00 equiv.), DMF, 0 C~60 C; (c) EtOH/H2O (4:1, evaluation of these compounds, we first conducted the single-concentration screening at 10 M against human mPGES-1. Compounds that showed significant inhibition (70%) were tested further for their IC50 values against human mPGES-1. The protocol for the protein preparation and activity assays were the same as explained previously.10, 11, 18, 19 Further, the inhibitory activity against COX isozymes was also evaluated for some of the more encouraging compounds (with IC50 < 100 nM against human mPGES-1). As shown in Table 3, at a concentration as high as 100 M, compounds 8b~8f, 12, Pemetrexed (Alimta) 13f, 14a and 14f inhibited COX-1/2 for less than 20 %. So, these compounds are highly selective for the mPGES-1 over COX-1/2. Table 3 Inhibition against COX-1/2 for their inhibitory potency against human mPGES-1 and selectivity over COX-1/2, leading to discovery of various potent and selective inhibitors of human mPGES-1. The most potent one is 14f (IC50 = ~36 nM against human mPGES-1) without significant inhibition against COX-1/2. Acknowledgments This work was supported in part by the funding of the Molecular Modeling and Biopharmaceutical Center at the University or college of Kentucky College of Pharmacy, the National Science Foundation (NSF grant CHE-1111761), and the National Institutes of Health the National Center for Advancing Translational Sciences (UL1TR001998) grant. The authors also acknowledge the Computer Center at University or college of Kentucky for supercomputing time on a Dell Supercomputer Cluster consisting of 388 nodes or 4,816 processors. Footnotes Publisher’s Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the producing proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. REFERENCES AND NOTES 1. Norberg JK, Sells E, Chang HH, Alla SR, Zhang S, Meuillet EJ. Pharm Pat Anal. 2013;2:265. [PMC free article] [PubMed] [Google Scholar] 2. Garavito RM, DeWitt DL. Biochim Biophys Acta. 1999;1441:278. [PubMed] [Google Scholar] 3. Murakami M, Nakatani Y,.