Methods for the detection and quantitation of angiotensin converting enzyme inhibitors in fermentation broths.

Abstract

Two procedures are described for the detection of inhibitors of angiotensin converting enzyme (ACE). The first is a new agar-plate method useful as a screening tool. Two ACE inhibitors produced by culture A58365 were discovered using this plate test. The second method is a modification of a previously reported spectrophotometric procedure.Both procedures utilize p-nitrobenzyl-oxycarbonylglycyl-(S-4-nitrobenzo-2-oxa-1,3-diazole)-L-cysteinylglycine as substrate.Angiotensin converting enzyme, ACE, (dipeptidyl carboxypeptidase EC 3.4.15.1) catalyzes the release of dipeptide from the carboxyl terminus of angiotensin I to yield the octapeptide angiotensin II, a potent vasoconstrictor.The same enzyme inactivates the vasodilator, bradykinin, by the hydrolytic release of one or more carboxyl-terminal dipeptide residues. Although the use of ACE inhibitors is well established in treatment of hypertension and congestive heart failure, there were no known fermentation derived inhibitors of ACE at the time this screening program was initiated. There is, however, ample precedent for screening for enzyme inhibitors in fermentation broths

Branching Out: Rhodium-Catalyzed Allylation with Alkynes and Allenes

“… Again, the first step establishes the stereocenter with 94% ee and also leads to the product in almost quantitative yield. Subsequent Pinnick oxidation and methylation lead to the ester intermediate, which can be readily transferred to numerous amino heterocycles, many of which show biological activitiy …”

“…Subsequent Pinnick oxidation and methylation lead to the ester intermediate, which can be readily transferred to numerous amino heterocycles, many of which show biological activitiy. 47…”

Indolizidine and quinolizidine alkaloids

“…The iminium ion was generated in situ from (93) by treatment with paraformaldehyde in aqueous acidic medium containing a large excess of iodide ions. Although alkynes are normally unreactive towards iminium ions, the presence of iodide, a strong nucleophile for carbon, induces a highly stereoselective cyclization which results in the formation of the isomerically pure indolizidine (94) and its C-1 1 epimer.…”

Pd-Catalyzed Regio- and Enantioselective Aminoarylation of Allenols with Aryl Iodides and 2-Pyridones

“…Chiral N -substituted 2-pyridones have emerged as useful motifs in many natural products and medicinally relevant agents, as exemplified by aspernigrin B isolated from Axinella damicornis and Aspergillus welwitschiae CUGBMF180262, respectively, human rhinovirus 3C protease inhibitors, GDC-0994 as an extracellular-signal-regulated kinase inhibitor (Figure ), and many others . In this context, the development of synthetic approaches to chiral N -substituted 2-pyridone derivatives became an important goal in pharmaceutical research and drug discovery.…”

“…In this context, the development of synthetic approaches to chiral N -substituted 2-pyridone derivatives became an important goal in pharmaceutical research and drug discovery. In general, they are prepared via stereoselective nucleophilic substitution of 2-pyridones to chiral electrophiles, or by the reaction of 2 H -pyran-2-ones with chiral amines. − However, asymmetric catalytic protocols for the synthesis of chiral N -substituted 2-pyridones from achiral starting materials are less explored. In 2010, Batey and co-workers reported first asymmetric catalytic method to access enantioenriched N-substituted 2-pyridones via Pd­(II)-catalyzed asymmetric [3,3] sigmatropic rearrangement of 2-allyloxy pyridines (Scheme a) .…”