Effects of Curcuma longa (turmeric) on postprandial plasma glucose and insulin in healthy subjects

<p>Abstract</p> <p>Background</p> <p>Previous animal studies have shown that <it>Curcuma (C.) longa </it>lowers plasma glucose. <it>C. longa </it>may thus be a promising ingredient in functional foods aimed at preventing type 2 diabetes. The purpose of the study is to study the effect of <it>C. longa </it>on postprandial plasma glucose, insulin levels and glycemic index (GI) in healthy subjects.</p> <p>Methods</p> <p>Fourteen healthy subjects were assessed in a crossover trial. A standard 75 g oral glucose tolerance test (OGTT) was administered together with capsules containing a placebo or <it>C. longa</it>. Finger-prick capillary and venous blood samples were collected before, and 15, 30, 45, 60, 90, and 120 min after the start of the OGTT to measure the glucose and insulin levels, respectively.</p> <p>Results</p> <p>The ingestion of 6 g <it>C. longa </it>had no significant effect on the glucose response. The change in insulin was significantly higher 30 min (<it>P </it>= 0.03) and 60 min (<it>P </it>= 0.041) after the OGTT including <it>C. longa</it>. The insulin AUCs were also significantly higher after the ingestion of <it>C. longa</it>, 15 (<it>P </it>= 0.048), 30 (<it>P </it>= 0.035), 90 (<it>P </it>= 0.03), and 120 (<it>P </it>= 0.02) minutes after the OGTT.</p> <p>Conclusions</p> <p>The ingestion of 6 g <it>C. longa </it>increased postprandial serum insulin levels, but did not seem to affect plasma glucose levels or GI, in healthy subjects. The results indicate that <it>C. longa </it>may have an effect on insulin secretion.</p> <p>Trial registration number</p> <p>NCT01029327</p

N-n-alkylnicotinium analogs, a novel class of antagonists at α4β2* Nicotinic acetylcholine receptors: Inhibition of S(-)-nicotine-evoked 86Rb+Efflux from rat thalamic synaptosomes

PyridineN-n-alkylation of S(-)-nicotine (NIC) affordsN-n-alkylnicotinium analogs, previously shown to competitively inhibit [3H]NIC binding and interact with α4β2* nicotinic receptors (nAChRs). The present study determined the ability of the analogs to inhibit NIC-evoked86Rb+ efflux from rat thalamic synaptosomes to assess functional interaction with α4β2* nAChRs. In a concentration-dependent manner, NIC evoked86Rb+ efflux (EC50=170 nmol/L). Analoginduced inhibition of NIC-evoked86Rb+ efflux varied over a ≈450-fold range. Analogs with longn-alkyl chain lengths (C9−C12) inhibited efflux in the low nmol/L range (IC50=9–20 nmol/L), similar to dihydro-β-erythroidine (IC50=19 nmol/L). Compounds with shortern-alkyl chain lengths (C1−C8) produced inhibition in the low μmol/L range (IC50 =3–12 μmol/L). C10 and C12 analogs completely inhibited NIC-evoked efflux, whereas C1–9 analogs produced maximal inhibition of only 10% to 60%. While the C10 analogN-n-decylnicotiniumiodide (NDNI) did not produce significant inhibition of NIC-evoked dopamine release in previously reported studies, NDNI possesses high affinity for [3H]NIC binding sites (Ki=90 nmol/L) and is a potent and efficacious inhibitor of NIC-evoked86Rb+ efflux as demonstrated in the current studies. Thus, NDNI is a competitive, selective antagonist at α4β2* nAChRs