Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria)

What is the form of muscimol from fly agaric mushroom (Amanita muscaria) in water? An insight from NMR experiment supported by molecular modeling

“…This structure was also supported by low level ab initio calculations . The possibility of the existence of this GABA agonist as neutral (hydroxylated) compound (b) and in the NH form (c) in the gas phase and DMSO was studied theoretically in our recent work . In addition, our detailed experimental 1 H and 13 C nuclear magnetic resonance (NMR) studies in DMSO also favored its NH form .…”

“…The possibility of the existence of this GABA agonist as neutral (hydroxylated) compound (b) and in the NH form (c) in the gas phase and DMSO was studied theoretically in our recent work . In addition, our detailed experimental 1 H and 13 C nuclear magnetic resonance (NMR) studies in DMSO also favored its NH form . However, no experimental NMR studies in water (D 2 O) were completed arbitrarily, assuming similar interaction of both polar solvents with solute molecules .…”

“…In addition, our detailed experimental 1 H and 13 C nuclear magnetic resonance (NMR) studies in DMSO also favored its NH form . However, no experimental NMR studies in water (D 2 O) were completed arbitrarily, assuming similar interaction of both polar solvents with solute molecules . Besides, no special attention was paid to routine shimming and a possibility of determination of very small H–H coupling constants …”

“…Thus, in the current study, we are interested in finding an answer to the question what is the form of muscimol in water? Is it the same as in polar DMSO solution or in crystal? Besides, is NMR spectroscopy alone (e.g., without hints from other techniques) sufficient to provide these answers, or do we need to support experiment with molecular modeling?…”

“…In these combined experimental NMR and theoretical studies, we will attempt to answer the above mentioned questions by measuring 1 H and 13 C NMR chemical shifts, proton–proton, and carbon–proton coupling constants in water and critically compare the measured and calculated parameters with the previously reported data in DMSO …”