Bioisosteric prototype design of biaryl imidazolyl and triazolyl competitive histamine H2-receptor antagonists

Thiazolo[4,5-d]pyridazine analogues as a new class of dihydrofolate reductase (DHFR) inhibitors: Synthesis, biological evaluation and molecular modeling study

A new series of 1,3-thiazoles and thiazolo[4,5-d]pyridazine both bearing the 2-thioureido function were designed, synthesized and evaluated for their invitro DHFR inhibition and antitumor activities. Compound 26 proved to be the most active DHFR inhibitor (IC₅₀ of 0.06μM). Compound 4, 20 and 21 showed in vitro antitumor activity against a collection of cancer cell lines. Compound 26 proved lethal to HS 578T breast cancer cell line with IC₅₀ value of 0.8μM, inducing cell cycle arrest and apoptosis. Molecular modeling studies concluded that recognition with key amino acids Phe 31 and Arg 22 is essential for DHFR binding. The obtained model could be useful for the development of new class of DHFR inhibitors.

Design, Synthesis and Structure-Activity Relationships of Novel Diaryl Urea Derivatives as Potential EGFR Inhibitors

Two novel series of diaryl urea derivatives 5a–i and 13a–l were synthesized and evaluated for their cytotoxicity against H-460, HT-29, A549, and MDA-MB-231 cancer cell lines in vitro. Therein, 4-aminoquinazolinyl-diaryl urea derivatives 5a–i demonstrated significant activity, and seven of them are more active than sorafenib, with IC₅₀ values ranging from 0.089 to 5.46 μM. Especially, compound 5a exhibited the most active potency both in cellular (IC₅₀ = 0.15, 0.089, 0.36, and 0.75 μM, respectively) and enzymatic assay (IC₅₀ = 56 nM against EGFR), representing a promising lead for further optimization.

Nonclassical antifolates, part 4. 5-(2-aminothiazol-4-yl)-4-phenyl-4H-1,2,4-triazole-3-thiols as a new class of DHFR inhibitors: synthesis, biological evaluation and molecular modeling study

A new series of compounds possessing 5-(2-aminothiazol-4-yl)-4-phenyl-4H-1,2,4-triazole-3-thiol skeleton was designed, synthesized, and evaluated for their in vitro DHFR inhibition, antimicrobial, antitumor and schistosomicidal activities. Four active compounds were allocated, the antibacterial 22 (comparable to gentamicin and ciprofloxacin), the schistosomicidal 29 (comparable to praziquantel), the DHFR inhibitor 34 (IC₅₀ 0.03 μM, 2.7 fold more active than MTX), and the antitumor 36 (comparable to doxorubicin). Molecular modeling studies concluded that recognition with key amino acid Leu4 and Val1 is essential for DHFR binding. Flexible alignment and surface mapping revealed that the obtained model could be useful for the development of new class of DHFR inhibitors.

Discovery of riociguat (BAY 63-2521): a potent, oral stimulator of soluble guanylate cyclase for the treatment of pulmonary hypertension

Soluble guanylate cyclase (sGC) is a key signal-transduction enzyme activated by nitric oxide (NO). Impairments of the NO-sGC signaling pathway have been implicated in the pathogenesis of cardiovascular and other diseases. Direct stimulation of sGC represents a promising therapeutic strategy particularly for the treatment of pulmonary hypertension (PH), a disabling disease associated with a poor prognosis. Previous sGC stimulators such as the pyrazolopyridines BAY 41-2272 and BAY 41-8543 demonstrated beneficial effects in experimental models of PH, but were associated with unfavorable drug metabolism and pharmacokinetic (DMPK) properties. Herein we disclose an extended SAR exploration of this compound class to address these issues. Our efforts led to the identification of the potent sGC stimulator riociguat, which exhibits an improved DMPK profile and exerts strong effects on pulmonary hemodynamics and exercise capacity in patients with PH. Riociguat is currently being investigated in phase III clinical trials for the oral treatment of PH.

A divergent synthesis of minor groove binders with tail group variation

A new synthesis of polyamide minor groove binders in which diversity is introduced by the nucleophilic substitution of a 2-sulfido-1,3,2-diazaphospholidinyloxy substituent by volatile secondary amine nucleophiles is described. Such a method has potential value for economically investigating structure-activity relationships in this important class of compounds through library synthesis. As an example using this method are prepared two new minor groove binders with pyrrolidinyl or piperidinyl tail groups that are close relatives of highly active antibacterial minor groove binders with morpholinyl tail groups. The antibacterial activity found against Staphylococcus aureus and Mycobacterium spp. indicates that the pK(a) of this set of compounds is not the dominant factor in determining the antibacterial activity.