5 research outputs found

    The biosynthetic pathway of potato solanidanes diverged from that of spirosolanes due to evolution of a dioxygenase

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    ジャガイモの毒α-ソラニンはトマトの苦味成分から分岐進化したことを解明. 京都大学プレスリリース. 2021-03-03.Potato (Solanum tuberosum), a worldwide major food crop, produces the toxic, bitter tasting solanidane glycoalkaloids α-solanine and α-chaconine. Controlling levels of glycoalkaloids is an important focus on potato breeding. Tomato (Solanum lycopersicum) contains a bitter spirosolane glycoalkaloid, α-tomatine. These glycoalkaloids are biosynthesized from cholesterol via a partly common pathway, although the mechanisms giving rise to the structural differences between solanidane and spirosolane remained elusive. Here we identify a 2-oxoglutarate dependent dioxygenase, designated as DPS (Dioxygenase for Potato Solanidane synthesis), that is a key enzyme for solanidane glycoalkaloid biosynthesis in potato. DPS catalyzes the ring-rearrangement from spirosolane to solanidane via C-16 hydroxylation. Evolutionary divergence of spirosolane-metabolizing dioxygenases contributes to the emergence of toxic solanidane glycoalkaloids in potato and the chemical diversity in Solanaceae

    Synthesis of γ-Lactams from Acrylamides by Single-Carbon Atom Doping Annulation

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    A protocol for single-carbon atom doping annulation is reported, which enables the conversion of acrylamides into homologated γ-lactams through the cleavage of two σ-bonds and the formation of four new σ-bonds at the single carbon center. The key strategy is the use of N-heterocyclic carbenes as an atomic carbon equivalent by acting as carbon atom donors through the loss of a 1,2-diimine moiety. Experimental and computational studies reveal that the reaction proceeds through a spirocyclic intermediate, followed by the disassembly of the N-heterocyclic carbene skeleton via proton transfer.Fujimoto H., Nakayasu B., Tobisu M.. Synthesis of γ-Lactams from Acrylamides by Single-Carbon Atom Doping Annulation. Journal of the American Chemical Society 145, 19518 (2023); https://doi.org/10.1021/jacs.3c07052

    Synthesis of γ-Lactams from Acrylamides by Single-Carbon Atom Doping Annulation

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    Fujimoto H., Nakayasu B., Tobisu M.. Synthesis of γ-Lactams from Acrylamides by Single-Carbon Atom Doping Annulation. Journal of the American Chemical Society 145, 19518 (2023); https://doi.org/10.1021/jacs.3c07052.A protocol for single-carbon atom doping annulation is reported, which enables the conversion of acrylamides into homologated γ-lactams through the cleavage of two σ-bonds and the formation of four new σ-bonds at the single carbon center. The key strategy is the use of N-heterocyclic carbenes as an atomic carbon equivalent by acting as carbon atom donors through the loss of a 1,2-diimine moiety. Experimental and computational studies reveal that the reaction proceeds through a spirocyclic intermediate, followed by the disassembly of the N-heterocyclic carbene skeleton via proton transfer

    Novel steroidal saponins from <i>Dioscorea esculenta</i> (Togedokoro)

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    <p>Fifteen steroidal saponins <b>1</b>–<b>15</b>, which include 4 furostanol glycosides <b>1</b>–<b>3</b> and <b>15</b>, and 11 spirostanol glycosides <b>4</b>–<b>14</b>, were isolated from the tubers and leaves of lesser yam (<i>Dioscorea esculenta,</i> Togedokoro). Their structures were identified by nuclear magnetic resonance and liquid chromatography mass spectroscopy. Four steroidal saponins <b>9</b>, <b>11</b>, <b>14</b>, and <b>15</b> were found to be novel compounds.</p> <p>Steroidal saponins from <i>Dioscorea esculenta</i>.</p
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