The potent antibacterial lanthipeptide microvionin, isolated from a culture of Microbacterium arborescens, exhibits a new triamino-dicarboxylic acid moiety, termed avionin, and an unprecedented N-terminal guanidino fatty acid. We identified the corresponding biosynthetic gene cluster and reconstituted central steps of avionin biosynthesis in vitro. Genome mining and isolation of nocavionin from Nocardia terpenica revealed a widespread distribution of this lanthipeptide class, termed lipolanthines, which may be useful as future antimicrobial drugs.

Lanthipeptides are ribosomally synthesized peptides which undergo extensive post-translational modifications. In addition to novel structural features and bioactivities, the in vitro study on the biosynthesis of the class III lanthipeptide labyrinthopeptin revealed a unique C- to N-terminal directionality of biosynthetic processing. The recently described class III lanthipeptide curvopeptin allowed investigating the directionality aspect in much greater detail: Structural characterization of nine curvopeptin biosynthesis intermediates by high-resolution mass spectrometry combined with a deuterium-labeling approach enabled for the first time building a comprehensive biosynthesis model featuring all three post-translational modification reactions: phosphorylation, elimination, and cyclization. These results point to a nonlinear processing scheme with a predominant C → N-terminal directionality. Our data give important mechanistic insights into the concerted processing and directionality of the multifunctional class III modifying enzymes. The data are of significance in the light of obtaining a mechanistic understanding of the post-translational biosynthesis machinery of the growing variety of ribosomally synthesized and post-translationally modified peptides.

Lanthipeptides are ribosomally synthesized and post-translationally modified peptides bearing the characteristic amino acids lanthionine and/or labionin. Here, we report on the discovery and characterization of the stackepeptins, produced by the Actinomycete Stackebrandtia nassauensis DSM-44728(T). The stackepeptins are the first supersized class III lanthipeptides to be discovered. Unlike other class III lanthipeptides, they consist of three lanthionine/labionin moieties instead of two. In this study, both in vivo and in vitro maturation of the peptides have been investigated. Studies involving the wild type strain showed culture medium-dependent production of three stackepeptins consisting of one common N-terminal labionin ring and varying dehydration and cyclization patterns in the C-terminal rings. On the other hand, in vitro assessment of the heterologously expressed modifying enzyme StaKC, yielded one major product with an N-terminal lanthionine and C-terminal labionins. The discrepancy between in vivo and in vitro processing was discovered to be sequence-dependent and also implies that in vivo processing is facilitated by additional factors in the cell. Furthermore, a Ser → Ala scan revealed the importance of C-terminal ring formation for full in vitro maturation of the stackepeptins. StaKC showed promiscuity toward the phosphorylating cosubstrate with a significant preference for purine nucleotides. Finally, in contrast to other known class III lanthipeptides, in vitro experiments showed that the leader peptide might not be required for partial dehydration by the modifying enzyme.

The biotransformation and excretion of darolutamide were investigated in a phase I study. Six healthy male volunteers received a single dose of 300 mg 14 Cdarolutamide as oral solution in the fasted state. Plasma, urine, and feces samples were analyzed for mass balance evaluation by liquid scintillation counting (LSC).Metabolite profiling and identification were determined using liquid chromatography mass spectrometry with off-line radioactivity detection using LSC. Complete mass balance was achieved, with mean radioactivity recovery of 95.9% within 168 hours (63.4% in urine, 32.4% in feces). The administered 1:1 ratio of (S,R)-and (S,S)darolutamide changed to approximately 1:5, respectively, in plasma. Darolutamide and the oxidation product, keto-darolutamide, were the only components quantifiable by LSC in plasma, accounting for 87.4% of total radioactivity, with a 2.1-fold higher plasma exposure for keto-darolutamide. Aside from darolutamide, the most prominent metabolites in urine were O-glucoronide (M-7a/b) and N-glucuronide (M-15a/b) as well as pyrazole sulfates (M-29, M-24) and glucuronides (M-21, M-22)resulting from oxidative cleavage of the parent. The darolutamide diastereomers were mainly detected in feces. In vitro assays showed that darolutamide metabolism involves a complex interplay between oxidation and reduction, as well as glucuronidation. Interconversion of the diastereomers involves oxidation to ketodarolutamide, primarily mediated by CYP3A4, followed by reduction predominantly catalyzed by cytosolic reductase(s), with aldo-keto reductase 1C3 playing the major role. The latter reaction showed stereoselectivity with preferential formation of (S,S)darolutamide.