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Several problems limit quantification of gluconeogenesis. We applied in vitro ²H-nuclear magnetic resonance (NMR) spectroscopy to simultaneously measure ²H in all glucose carbons for direct assessment of gluconeogenesis. This method was compared with ²H measurement in carbons 5 and 2 using gas chromatography-mass spectrometry (hexamethylenetetramine [HMT]) and with in vivo [sup.13]C magnetic resonance spectroscopy (MRS). After 14 h of fasting, and following ²[H.sub.2]O ingestion, blood was obtained from nine healthy and seven type 2 diabetic subjects. Glucose was purified, acetylated, and analyzed for ²H in carbons 1-6 with ²H-NMR. Using 5:2 ratios, gluconeogenesis increased (P < 0.05) over time and mean gluconeogenesis was lower in control subjects than in type 2 diabetic patients (63 ± 3 vs. 75 ± 2%, P < 0.01). [sup.13]C-MRS revealed higher hepatic glycogenolysis in control subjects (3.9 ± 0.4 vs. 2.3 ± 0.2 µmol * [kg.sup.-1] * [min.sup.-1]) yielding mean contribution of gluconeogenesis of 65 ± 3 and 77 ± 2% (P < 0.005). Measurement of gluconeogenesis by ²H-NMR correlated linearly with [sup.13]C-MRS (r = 0.758, P = 0.0007) and HMT (r = 0.759, P = 0.0007). In an additional protocol, ²H enrichments demonstrated a fast decline of gluconeogenesis from ~100 to ~68% (P < 0.02) within 4 h of galactose infusion after 40-44 h of fasting. Thus, in vitro ²H-NMR offers an alternative approach to determine fractional gluconeogenesis in good agreement with standard methods and allows monitoring of rapid metabolic alterations. Diabetes 52:2475-2482, 2003, In type 2 diabetic patients, gluconeogenesis primarily accounts for increased endogenous glucose production (EGP) and fasting plasma glucose concentrations (1). Previous methods for measuring gluconeogenesis yielded a wide range of [...]

Three flavonolignans derived from the flavone tricin were isolated from Avena sativa herb. This is the first report of the presence of flavonolignans in A. sativa. In the known compounds 1a and 1b, a coniferyl alcohol moiety is linked to the flavone by an ether bond; in the new natural product 2, it is linked by C−C bonds. Structure elucidation of compound 2 was performed by 1D and 2D NMR experiments, and the absolute configuration was determined from circular dichroic data.