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Psilocybin (1) is the major alkaloid found in psychedelic mushrooms and acts as a prodrug to psilocin (2, 4-hydroxy-N,N-dimethyltryptamine), a potent psychedelic that exerts remarkable alteration of human consciousness. In contrast, the positional isomer bufotenin (7, 5-hydroxy-N,N-dimethyltryptamine) differs significantly in its reported pharmacology. A series of experiments was designed to explore chemical differences between 2 and 7 and specifically to test the hypothesis that the C-4 hydroxy group of 2 significantly influences the observed physical and chemical properties through pseudo-ring formation via an intramolecular hydrogen bond (IMHB). NMR spectroscopy, accompanied by quantum chemical calculations, was employed to compare hydrogen bond behavior in 4- and 5-hydroxylated tryptamines. The results provide evidence for a pseudo-ring in 2 and that sidechain/hydroxyl interactions in 4-hydroxytryptamines influence their oxidation kinetics. We conclude that the propensity to form IMHBs leads to a higher number of uncharged species that easily cross the blood-brain barrier, compared to 7 and other 5-hydroxytryptamines, which cannot form IMHBs. Our work helps understand a fundamental aspect of the pharmacology of 2 and should support efforts to introduce it (via the prodrug 1) as an urgently needed therapeutic against major depressive disorder.

Pathogenic bacteria of the Burkholderia pseudomallei group cause severe infectious diseases such as glanders and melioidosis. Malleicyprols were identified as important bacterial virulence factors, yet the biosynthetic origin of their cyclopropanol warhead has remained enigmatic. By a combination of mutational analysis and metabolomics we found that sulfonium acids, dimethylsulfoniumpropionate (DMSP) and gonyol, known as osmolytes and as crucial components in the global organosulfur cycle, are key intermediates en route to the cyclopropanol unit. Functional genetics and in vitro analyses uncover a specialized pathway to DMSP involving a rare prokaryotic SET‐domain methyltransferase for a cryptic methylation, and show that DMSP is loaded onto the NRPS‐PKS hybrid assembly line by an adenylation domain dedicated to zwitterionic starter units. Then, the megasynthase transforms DMSP into gonyol, as demonstrated by heterologous pathway reconstitution in E. coli., Sulfur cycle meets pathogen. Sulfonium acids known from global sulfur cycles were elucidated as the biosynthetic origin of the cyclopropanol warhead of malleicyprols, virulence factors of human‐pathogenic bacteria. The pathway involves a specialized S‐methyl transferase to form DMSP, which is activated by a zwitterion‐specific adenylation domain and transformed into the key intermediate gonyol.

The psychotropic effects of Psilocybe “magic” mushrooms are caused by the l‐tryptophan‐derived alkaloid psilocybin. Despite their significance, the secondary metabolome of these fungi is poorly understood in general. Our analysis of four Psilocybe species identified harmane, harmine, and a range of other l‐tryptophan‐derived β‐carbolines as their natural products, which was confirmed by 1D and 2D NMR spectroscopy. Stable‐isotope labeling with 13C11‐l‐tryptophan verified the β‐carbolines as biosynthetic products of these fungi. In addition, MALDI‐MS imaging showed that β‐carbolines accumulate toward the hyphal apices. As potent inhibitors of monoamine oxidases, β‐carbolines are neuroactive compounds and interfere with psilocybin degradation. Therefore, our findings represent an unprecedented scenario of natural product pathways that diverge from the same building block and produce dissimilar compounds, yet contribute directly or indirectly to the same pharmacological effects., Mind the metabolism: Metabolic profiling of five Psilocybe “magic” mushroom species identified β‐carbolines as their second group of amino acid‐derived natural products, in addition to the psychotropic psilocybin. β‐Carbolines inhibit monoamine oxidase which degrades psilocybin. Therefore, these two metabolite classes serve—directly or indirectly—the same bioactivity through dissimilar mechanisms.