Background: The FIDELIO-DKD trial evaluated the effect of the nonsteroidal, selective mineralocorticoid receptor antagonist finerenone on kidney and cardiovascular (CV) outcomes in patients with chronic kidney disease (CKD) and type 2 diabetes (T2D) with optimized renin-angiotensin system blockade. Compared with placebo, finerenone reduced the composite kidney and CV outcomes. We report the effect of finerenone on individual CV outcomes and in patients with and without history of atherosclerotic CV disease (CVD). Methods: This randomized, double-blind, placebo-controlled trial included patients with T2D and urine albumin-to-creatinine ratio 30-5000 mg/g and an estimated glomerular filtration rate (eGFR) ≥25-<75 mL/min/1.73 m 2 , treated with optimized renin-angiotensin system blockade. Patients with a history of heart failure with reduced ejection fraction were excluded. Patients were randomized 1:1 to receive finerenone or placebo. The composite CV outcome included time to CV death, myocardial infarction, stroke, or hospitalization for heart failure. Prespecified CV analyses included analyses of the components of this composite and outcomes according to CVD history at baseline. Results: Between September 2015 and June 2018, 13,911 patients were screened and 5674 were randomized; 45.9% of patients had CVD at baseline. Over a median follow-up of 2.6 years (interquartile range, 2.0-3.4 years), finerenone reduced the risk of the composite CV outcome compared with placebo (hazard ratio [HR], 0.86; 95% confidence interval [CI], 0.75-0.99; P=0.034), with no significant interaction between patients with and without CVD (HR, 0.85; 95% CI, 0.71-1.01 in patients with a history of CVD; HR, 0.86; 95% CI, 0.68-1.08 in patients without a history of CVD; P-value for interaction, 0.85). The incidence of treatment-emergent adverse events was similar between treatment arms, with a low incidence of hyperkalemia-related permanent treatment discontinuation (2.3% with finerenone vs 0.8% with placebo in patients with CVD and 2.2% with finerenone vs 1.0% with placebo in patients without CVD). Conclusions: Among patients with CKD and T2D, finerenone reduced incidence of the composite CV outcome, with no evidence of differences in treatment effect based on pre-existing CVD status. Clinical Trial Registration: URL: https://clinicaltrials.gov Unique Identifier: NCT02540993 (Funded by Bayer AG)

To study the biosynthesis of the pseudotrisaccharide antibiotic, validamycin A (1), a number of potential precursors of the antibiotic were synthesized in (2)H-, (3)H-, or (13)C-labeled form and fed to cultures of Streptomyces hygroscopicus var. limoneus. The resulting validamycin A from each of these feeding experiments was isolated, purified and analyzed by liquid scintillation counting, (2)H- or (13)C NMR or selective ion monitoring mass spectrometry (SIM-MS) techniques. The results demonstrate that 2-epi-5-epi-valiolone (9) is specifically incorporated into 1 and labels both cyclitol moieties. This suggests that 9 is the initial cyclization product generated from an open-chain C(7) precursor, D-sedoheptulose 7-phosphate (5), by a DHQ synthase-like cyclization mechanism. A more proximate precursor of 1 is valienone (11), which is also incorporated into both cyclitol moieties. The conversion of 9 into 11 involves first epimerization to 5-epi-valiolone (10), which is efficiently incorporated into 1, followed by dehydration, although a low level of incorporation of 2-epi-valienone (15) is also observed. Reduction of 11 affords validone (12), which is also incorporated specifically into 1, but labels only the reduced cyclitol moiety. The mode of introduction of the nitrogen atom linking the two pseudosaccharide moieties is not clear yet. 7-Tritiated valiolamine (8), valienamine (2), and validamine (3) were all not incorporated into 1, although each of these amines has been isolated from the fermentation, with 3 being most prevalent. Demonstration of in vivo formation of [7-(3)H]validamine ([7-(3)H]-3) from [7-(3)H]-12 suggests that 3 may be a pathway intermediate and that the nonincorporation of [7-(3)H]-3 into 1 is due to a lack of cellular uptake. We thus propose that 3, formed by amination of 12, and 11 condense to form a Schiff base, which is reduced to the pseudodisaccharide unit, validoxylamine A (13). Transfer of a D-glucose unit to the 4'-position of 13 then completes the biosynthesis of 1. Other possibilities for the mechanism of formation of the nitrogen bridge between the two pseudosaccharide units are also discussed.

The biosynthetic pathway leading to the mC7N cyclitol (valienamine) moiety of acarbose (1) in Actinoplanes sp. strain SN 223/29 has been studied using 3H-, 2H-, and 13C-labeled cyclitols. These precursors were synthesized from d-glucose or d-mannose as starting materials. The feeding experiments demonstrated that cyclitols having the same stereochemistry at C-2 as the valienamine moiety of acarbose; i.e., valienone, valienamine, valiolone, valiolamine, and 1-epi-valienol, were not incorporated and thus are not plausible intermediates in 1 biosynthesis. 2-epi-Valiolone (10b), which has the same stereochemistry as the presumed open-chain precursor, sedoheptulose 7-phosphate, was also not incorporated. However, its C-5 epimer (10a) was incorporated efficiently and specifically into the valienamine moiety of 1. Surprisingly, the dehydrated form of 2-epi-5-epi-valiolone, 2-epi-valienone, was not incorporated. This suggests that 2-epi-5-epi-valiolone must be converted directly into the pseudodisaccharide moiety of acarbose without the intervention of other free cyclitol intermediates. This may occur by linkage to the amino group of TDP-4-amino-4,6-dideoxyglucose to form the imine, epimerization at C-2 to the correct stereochemistry, dehydration between C-5 and C-6 aided by enamine formation, and finally reduction to the amine. It is proposed that these reaction steps all take place on a single enzyme without free intermediates. Alternative mechanistic possibilities are also discussed.

The formation of the structurally novel, mono-substituted cycloheptane ring in omega-cycloheptyl fatty acids in Alicyclobacillus cycloheptanicus (formerly Bacillus cycloheptanicus) has been examined. Feeding experiments with (13)C- and (2)H-labeled intermediates demonstrated that cycloheptanecarboxylic acid (3), probably as its CoA thioester, is the starter unit for omega-cycloheptyl fatty acid biosynthesis. Analysis of the resultant labeling pattern from a feeding experiment with [U-(13)C(6)]glucose suggested a shikimate pathway origin of 3 via aromatic amino acids. [1,2-(13)C(2)]Phenylacetic acid (6) was efficiently metabolized into the 3-derived moiety in a manner reminiscent of the seven-membered ring Pseudomonas metabolite thiotropocin. The fates of the aromatic and benzylic hydrogens of 6 were determined; these dictated various boundary conditions for the biosynthetic pathway from 6 to 3. Taken together with the results from feeding experiments with postulated cycloheptenylcarboxylate biosynthetic intermediates, the data lead us to propose a pathway which involves an oxidative ring-expansion of 6 to a hydroxynorcaradiene intermediate followed by a series of double bond reductions and dehydrations to the saturated 3.