4 research outputs found
Biosynthesis and Conformational Properties of the Irregular Sesquiterpenoids Isothapsadiene and β‑Isothapsenol
A carbocation cyclization/rearrangement
mechanism for the biosynthesis
of isothapsadiene and β-isothapsenol is shown to be energetically
viable on the basis of density functional theory (DFT) calculations.
In addition, for both isothapsadiene and β-isothapsenol, variable-temperature
NMR experiments reveal two equilibrium conformers that undergo hindered
exchange. The identities of these conformers, which are related by
a chair-flip, are confirmed by DFT calculations on their structures,
energies, <sup>1</sup>H and <sup>13</sup>C chemical shifts, and interconversion
pathways
Biosynthesis and Conformational Properties of the Irregular Sesquiterpenoids Isothapsadiene and β‑Isothapsenol
A carbocation cyclization/rearrangement
mechanism for the biosynthesis
of isothapsadiene and β-isothapsenol is shown to be energetically
viable on the basis of density functional theory (DFT) calculations.
In addition, for both isothapsadiene and β-isothapsenol, variable-temperature
NMR experiments reveal two equilibrium conformers that undergo hindered
exchange. The identities of these conformers, which are related by
a chair-flip, are confirmed by DFT calculations on their structures,
energies, <sup>1</sup>H and <sup>13</sup>C chemical shifts, and interconversion
pathways
Biosynthesis and Conformational Properties of the Irregular Sesquiterpenoids Isothapsadiene and β‑Isothapsenol
A carbocation cyclization/rearrangement
mechanism for the biosynthesis
of isothapsadiene and β-isothapsenol is shown to be energetically
viable on the basis of density functional theory (DFT) calculations.
In addition, for both isothapsadiene and β-isothapsenol, variable-temperature
NMR experiments reveal two equilibrium conformers that undergo hindered
exchange. The identities of these conformers, which are related by
a chair-flip, are confirmed by DFT calculations on their structures,
energies, <sup>1</sup>H and <sup>13</sup>C chemical shifts, and interconversion
pathways
Quantification of Toxins in Soapberry (Sapindaceae) Arils: Hypoglycin A and Methylenecyclopropylglycine
Methylenecyclopropylglycine
(MCPG) and hypoglycin A (HGA) are naturally
occurring amino acids found in some soapberry fruits. Fatalities have
been reported worldwide as a result of HGA ingestion, and exposure
to MCPG has been implicated recently in the Asian outbreaks of hypoglycemic
encephalopathy. In response to an outbreak linked to soapberry ingestion,
the authors developed the first method to simultaneously quantify
MCPG and HGA in soapberry fruits from 1 to 10 000 ppm of both
toxins in dried fruit aril. Further, this is the first report of HGA
in litchi, longan, and mamoncillo arils. This method is presented
to specifically address the laboratory needs of public-health investigators
in the hypoglycemic encephalitis outbreaks linked to soapberry fruit
ingestion