Determination of major ginsenosides in Panax quinquefolius (American ginseng) using high-performance liquid chromatography.

In order to determine the active ingredients in root extracts of Panax quinquefolius (American ginseng), a gradient HPLC method involving UV photodiode array detection was applied to separate and quantify simultaneously the ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf and Rg1. All ginseng saponins were baseline-resolved under the selected conditions, and the detection limits were 1.0 microg/mL or less. The method has been applied to analyse ginsenosides extracted from American ginseng cultivated in both Wisconsin and Illinois. Ginsenosides Re and Rb1 were the two main ginseng saponins in the root. The amounts of Re in 5- and 7-year Illinois-cultivated samples were greater than those found in ginseng cultivated for 3 or 4 years in Wisconsin, whereas the levels of Rb1 were greater in the younger Wisconsin samples.

American ginseng leaf: ginsenoside analysis and hypoglycemic activity.

Previous studies showed that both American ginseng root and American ginseng berry extracts possess hypoglycemic properties. In this study, we investigated whether American ginseng leaves also have similar capabilities. We first analyzed the chemical constituents of American ginseng leaf and determined the content of six major ginsenosides, i.e., Rb(1), Rb(2), Rc, Rd, Re, and Rg(1), by high performance liquid chromatography (HPLC). Subsequently, we evaluated the hypoglycemic effect of American ginseng leaf extract (AGLE) in diabetic ob/ob adult mice. Animals received daily intraperitoneal injections of AGLE 50, 150 mg/kg or vehicle for 12 consecutive days. Fasting blood glucose levels, intraperitoneal glucose tolerance test (IPGTT), body weight and temperature were measured. On day 5, the 150 mg/kg AGLE group had significantly lower fasting blood glucose levels compared to vehicle-treated mice (223.0+/-13.9 mg/dl versus 258.0+/-14.0 mg/dl, P<0.05), while the blood glucose levels in 50 mg/kg group did not decrease significantly. On day 12, the glucose levels in both AGLE-treated groups were reduced significantly compared to vehicle group (180.0+/-10.0 mg/dl and 220.2+/-19.3 versus 268.0+/-10.0 mg/dl, P<0.01 and <0.05, respectively). IPGTT data showed that both AGLE 150 and 50 mg/kg groups significantly increased the glucose disposal on day 12 compared to the vehicle group. In addition, body weight decreased in ob/ob mice after AGLE treatment, and these body weight changes were accompanied by significant increases in body temperature (P<0.05). Our results suggest that AGLE possesses a significant anti-hyperglycemic and thermogenic activity and may prove to be beneficial in improving the management of type 2 diabetes.

Determination of methylnaltrexone in clinical samples by solid-phase extraction and high-performance liquid chromatography for a pharmacokinetics study.

A high-performance liquid chromatographic (HPLC) method with electrochemical detection and solid-phase extraction (SPE) using cartridges of weak cation-exchange capacity as the primary retention mechanism is described for the separation and determination of methylnaltrexone (MNTX) in small clinical samples of plasma or urine. The procedure was performed using a Phenomenex Prodigy ODS-2, 5 microm, 150x3.2 mm analytical column and 50 mM potassium acetate buffer, with 11% methanol as organic modifier at pH* 4.5 at a flow-rate of 0.5 ml/min. The detection potential was 700 mV. The six-point standard calibration curves were linear over three consecutive days in the range from 2 to 100 ng/ml. The average goodness of fit (r) was 0.9993. The lower limit of detection (LOD) and limit of quantification (LOQ) were found to be 2.0 and 5.0 ng/ml, respectively. At the LOQ, the coefficient of variation for the entire method was 8.0% and the accuracy was 10.0% (n = 10). Recovery of the drug from plasma was in the region of 94%. The method was applied to a pharmacokinetics study of methylnaltrexone after subcutaneous administration and in numerous assays of analytes in blood plasma and urine. The pharmacokinetics parameters for a single dose of 0.1 or 0.3 mg/kg in plasma were C(max) = 110 (+/-55) and 287 (+/-101) ng/ml and t(max) = 16.7 (+/-10.8) and 20.0 (+/-9.5) min, respectively. The method is simple, yet sensitive for the detection and determination of methylnaltrexone in biological samples at the level of the physiological response.

Effects of subcutaneous methylnaltrexone on morphine-induced peripherally mediated side effects: a double-blind randomized placebo-controlled trial.

Methylnaltrexone, the first peripheral opioid receptor antagonist, has the potential to prevent or reverse opioid-induced peripherally mediated side effects without affecting analgesia. In previous human trials, we demonstrated that intravenous methylnaltrexone prevented morphine-induced delay in gastrointestinal transit time. We also observed that the compound decreased some of the morphine-induced troublesome subjective effects. However, the effects of subcutaneous methylnaltrexone, a more convenient route of administration, have not been evaluated. In this controlled trial, we evaluated the efficacy of subcutanous methylnaltrexone in antagonizing morphine-induced delay in oral-cecal transit time. In addition, opioid-induced unpleasant subjective effects and pharmacokinetics were studied. We observed that in the first group (n = 6) morphine (0.05 mg/kg intravenously) increased the transit time from a baseline level of 85 +/- 20.5 min to 155 +/- 27.9 min (mean +/- S.D., P < 0.01). After 0.1 mg/kg subcutaneous methylnaltrexone plus morphine, the transit time reduced to 110 +/- 41.0 min. In the second group (n = 6), morphine increased the transit time from a baseline level of 98 +/- 49.1 min to 140 +/- 58.2 min (P < 0.01). After 0.3 mg/kg subcutaneous methylnaltrexone plus morphine, the transit time reduced to 108 +/- 59.6 min (P < 0.05 compared with placebo plus morphine). In addition, subcutaneous methylnaltrexone significantly decreased morphine-induced subjective rating changes. Pharmacokinetic data after subcutaneous drug injection were compared to the data obtained from previous intravenous and oral administrations. Our results suggest that subcutaneous methylnaltrexone may have clinical utility in treating opioid-induced constipation and reducing opioid-induced unpleasant subjective symptoms.