The Novel, Clinical-Stage Soluble Guanylate Cyclase Activator BI 685509 Protects from Disease Progression in Models of Renal Injury and Disease.

Activation of soluble guanylate cyclase (sGC) to restore cyclic guanosine monophosphate (cGMP) and improve functionality of nitric oxide (NO) pathways impaired by oxidative stress is a potential treatment of diabetic and chronic kidney disease. We report the pharmacology of BI 685509, a novel, orally active small molecule sGC activator with disease-modifying potential. BI 685509 and human sGC α1/ß1 heterodimer containing a reduced heme group produced concentration-dependent increases in cGMP that were elevated modestly by NO, whereas heme-free sGC and BI 685509 greatly enhanced cGMP with no effect of NO. BI 685509 increased cGMP in human and rat platelet-rich plasma treated with the heme-oxidant ODQ; respective EC50 values were 467 nM and 304 nM. In conscious telemetry-instrumented rats, BI 685509 did not affect mean arterial pressure (MAP) or heart rate (HR) at 3 and 10 mg/kg (p.o.), whereas 30 mg/kg decreased MAP and increased HR. Ten days of BI 685509 at supratherapeutic doses (60 or 100 mg/kg p.o., daily) attenuated MAP and HR responses to a single 100 mg/kg challenge. In the ZSF1 rat model, BI 685509 (1, 3, 10, and 30 mg/kg per day, daily) coadministered with enalapril (3 mg/kg per day) dose-dependently reduced proteinuria and incidence of glomerular sclerosis; MAP was modestly reduced at the higher doses versus enalapril. In the 7-day rat unilateral ureteral obstruction model, BI 685509 dose-dependently reduced tubulointerstitial fibrosis (P < 0.05 at 30 mg/kg). In conclusion, BI 685509 is a potent, orally bioavailable sGC activator with clear renal protection and antifibrotic activity in preclinical models of kidney injury and disease. SIGNIFICANCE STATEMENT: BI 685509 is a novel small soluble guanylate cyclase (sGC) molecule activator that exhibits an in vitro profile consistent with that of an sGC activator. BI 685509 reduced proteinuria and glomerulosclerosis in the ZSF1 rat, a model of diabetic kidney disease (DKD), and reduced tubulointerstitial fibrosis in a rat 7-day unilateral ureteral obstruction model. Thus, BI 685509 is a promising new therapeutic agent and is currently in phase II clinical trials for chronic kidney disease and DKD.

(+)-Sorangicin A: evolution of a viable synthetic strategy.

An effective, asymmetric total synthesis of the antibiotic (+)-sorangicin A (1) has been achieved. Central to this venture was the development of first and second generation syntheses of the signature dioxabicyclo[3.2.1]octane core, the first featuring chemo- and stereoselective epoxide ring openings facilitated by a Co(2)(CO)(6)-alkyne complex, the second involving a KHMDS-promoted epoxide ring formation/opening cascade. Additional highlights include effective construction of the dihydro- and tetrahydropyran ring systems, respectively via a stereoselective conjugate addition/α-oxygenation protocol and a thioketalization/hydrostannane reduction sequence. Late-stage achievements entailed two Julia-Kociénski olefinations to unite three advanced fragments with high E-stereoselectivity, followed by a modified Stille protocol to introduce the Z,Z,E trienoate moiety, thereby completing the carbon skeleton. Mukaiyama macrolactonization, followed by carefully orchestrated Lewis and protic acid-promoted deprotections that suppressed isomerization and/or destruction of the sensitive (Z,Z,E)-trienoate linkage completed the first, and to date only, total synthesis of (+)-sorangicin A (1).

Total synthesis of (+)-sorangicin A.

The final synthetic challenges associated with (+)-sorangicin A have been overcome, thus leading to the first total synthesis of this complex macrolide antibiotic. Highlights of the highly convergent synthesis include two Julia-Kociénski olefinations to unite three advanced fragments with high E-stereoselectivity. Critical to the final-stage success was the use of a carefully defined Stille coupling and a Mukaiyama macrolactonization as well as Lewis and protic acid-promoted deprotections carefully designed to suppress E/Z isomerization and/or destruction of the delicate (Z,Z,E)-trienoate linkage.

Application of a domino intramolecular enyne metathesis/cross metathesis reaction to the total synthesis of (+)-8-epi-xanthatin.

[reaction: see text] The first total synthesis of the novel sesquiterpene lactone (+)-8-epi-xanthatin (1) has been achieved starting from the commercially available ester 8. The synthesis features an asymmetric aldol reaction and palladium-catalyzed carbonylation/lactonization sequence leading to 4 and a domino ring-closing enyne metathesis/cross metathesis reaction to afford 1.

Application of intramolecular enyne metathesis to the synthesis of aza[4.2.1]bicyclics: enantiospecific total synthesis of (+)-anatoxin-a.

A concise synthesis of the potent nAChR agonist (+)-anatoxin-a (1) has been completed in a series of only nine chemical operations and 27% overall yield from commercially available D-methyl pyroglutamate (4). The synthesis features a novel procedure for the diastereoselective preparation of cis-2,5-disubstituted pyrrolidines leading to 10, which underwent an intramolecular enyne metathesis to afford a bridged azabicyclic intermediate that was transformed into 1. [reaction: see text]