M. Van Boven

High-performance liquid-chromatography with electrochemical detection of buprenorphine and its major metabolite in urine

A procedure was developed for the simultaneous determination of buprenorphine and its major metabolite. N-desalkylbuprenorphine, by reversed-phase high-performance liquid chromatography with electrochemical detection. The detection limit is about 100 pg/ml for the major metabolite and 250 pg/ml for buprenorphine.

4-demethyl simmondsin from Simmondsia chinensis

Jojoba seed meal (Simmondsia chinensis) contains approximately 15% glucosides identified as simmondsin, 5-demethyl simmondsin, didemethyl simmondsin, along with simmondsin 2%-ferulate, 4-demethyl simmondsin 2%-ferulate, and 5-demethyl simmondsin ferulate. The new simmondsin derivative was isolated from jojoba meal by a combination of column chromatography and preparative HPLC and identified by 2D-NMR and L-SIMS as 2-(cyanomethylene)-3,4-dihydroxy-5-methoxycyclohexyl b-D-glucoside or 4-demethyl simmmondsin.

PEGylated cholecystokinin prolongs satiation in rats: dose dependency and receptor involvement

Acute intraperitoneal (i.p.) administration of cholecystokinin (CCK) is known to induce a significant, but short‐lasting, reduction in food intake, followed by recovery within hours. Therefore, we had covalently coupled CCK to a 10 kDa polyethylene glycol and showed that this conjugate, PEG‐CCK9, produced a significantly longer anorectic effect than unmodified CCK9. The present study assessed the dose–dependency of this response and the effect of two selective CCK1 receptor antagonists, with different abilities to cross the blood‐brain barrier (BBB), on PEG‐CCK9‐induced anorexia.

Routine detection of buprenorphine in horse urine: possibilities and limitations of the combined use of radioimmunoassay, liquid chromatography and gas chromatography-mass spectrometry

Abstract A radioimmunoassay developed for the determination of buprenorphine in human urine samples was examined for its applicability to screening post-race equine urine specimens. The detection limit of the immunoassay in equine urine is 0.1 ng ml −1 . Confirmation methods using liquid chromatography with electrochemical detection and gas chromatography—mass spectrometry have detection limits of 0.2 ng ml −1 (unchanged buprenorphine and N -desalkylbuprenorphine) and 0.1 ng ml −1 (after hydrolysis), respectively. The procedures were validated after in-field administration of 300 μg of buprenorphine to a test horse. The procedures were also applied to screening a large number of random post-race equine urine samples.

Cannabinoid mimics in chocolate utilized as an argument in court

Abstract A case is presented involving chocolate cannabinoid mimics which have been utilized in court by the defendant’s lawyer in order to clear the accused of smoking and dealing in marijuana after he was found positive for cannabis in a routine urine immunoassay screening test. The argumentation in this case was that the accused had supposedly eaten a massive amount of chocolate which contained anandamide-related lipids. These lipids inhibit anandamide hydrolysis in the brain, act as cannabinoid mimics and, according to the lawyer, were the cause of the positive cannabinoid test. To investigate this in detail, we synthesized N-oleoyl- and N-linoleoylethanolamide and spiked these compounds together with N-arachidonoylethanolamide in urine for immunological investigations. None of the samples were found positive, indicating that no cross-reactivity occurs with cannabinoids. As a result, the lawyer’s claim could be refuted and the accused was convicted.

The vagus nerve is involved in the anorexigenic effect of simmondsin in the rat

Simmondsin, 2-(cyanomethylene)-3 hydroxy 4,5 dimethoxy cyclohexyl beta-D-glucoside, from jojoba meal reduces food intake in rats. We investigated the mechanism of action simmondsin, by studying the effects of fasting or of vagotomy on the food intake reduction. The food intake reduction was significantly less in fasted rats than in non-fasted rats. The reduction of food intake was also significantly diminished after vagotomy. The results of the present experiments suggest that simmondsin reduces intake of food in rats through the augmentation of satiety, in part vagally mediated.

Reproductive performance of rats treated with defatted jojoba meal or simmondsin before or during gestation

The effects on food intake, growth and reproductive performance parameters of defatted jojoba meal and pure simmondsin, an extract from jojoba meal, were compared in female Wistar rats. Rats fed 0.15% simmondsin or 3% defatted jojoba meal (equivalent to 0.15% simmondsin) for 8 weeks before conception showed a similar reduction in food intake (about 20%) and a similar growth retardation compared with controls. Both treatments induced a reduction in the number of corpora lutea on gestation day 16: this effect could be ascribed to the lower food intake before conception because it was also observed in rats pair-fed to the treated ones. Rats given feed containing 0.15% simmondsin or 3% defatted jojoba meal during days 1-16 of gestation showed a similar reduction in food intake relative to controls. Foetal and placental weights were reduced, relative to controls, to a similar extent in both groups, and the reductions were slightly greater than in the corresponding pair-fed groups. We conclude that the effects on food intake, growth and reproductive performance that were seen after feeding rats defatted jojoba meal were due to the simmondsin content of the meal. The simmondsin induced reduction in food intake and probably also a relative protein shortage.

Combined gas-liquid chromatographic-mass spectrometric analysis of pemoline in biological samples

A description is given of a gas-liquid chromatographic (GLC) method for the detection and determination of pemoline in biological samples. On treatment with hydrochloric acid, pemoline is converted into 5-phenyl-2,4-dioxooxazolidine, an acidic compound, which can be easily extracted with dichloromethane and determined by GLC. A combined GLC-mass spectrometric method is described.

Extraction and liquid chromatographic method for the determination of simmondsin in plasma

A solid-phase method for the extraction of simmondsin from plasma was developed along with a liquid chromatographic method for the quantitative measurement of this compound. The extraction of simmondsin is realised with activated carbon. Chromatography is performed on a 25 x 0.46 cm I.D. RP-18, 5-micron HPLC column with a water-methanol (85:15, v/v) mobile phase and ultraviolet absorbance detection at 217 nm. The limit of detection is 100 ng (using 1 ml of plasma). The linear quantitation range is 0.1-200 micrograms/ml.

Effects of simmondsin on food intake, growth, and metabolic variables in lean (+/?) and obese (fa/fa) Zucker rats

Incorporation of 2.5 g/kg of the anorexigen, simmondsin, in the diet resulted in food intake reduction in both lean and obese Zucker rats; however, the obese rats were much more sensitive to the food intake-reducing activity of simmondsin. In both obese and lean simmondsin-treated Zucker rats, growth was slower than in control rats, but was the same as that in pair-fed animals. The 24 h heat production pattern showed a smaller diurnal variation and a lower mean in obese rats than in lean rats. Food intake reduction, as a result of either simmondsin treatment or pair feeding, caused a decrease in mean heat production. Simmondsin treatment, but not pair feeding, caused a decrease in the diurnal variation of heat production. Plasma total cholesterol levels were increased in both simmondsin-treated and pair-fed obese and lean Zucker rats compared with control animals; this increase was mainly due to an increase in HDL-cholesterol levels. Blood leptin levels in both obese and lean rats decreased with decreased food intake and decreased fat deposition, but in obese rats, simmondsin treatment resulted in an additional decrease in leptin levels. It is concluded that the food intake-reducing effect of simmondsin is more pronounced in obese Zucker rats than in their lean littermates, and except for the simmondsin-specific effects on leptin and total cholesterol values in obese littermates, the effects of simmondsin are related to food intake restriction in obese and lean Zucker rats.