Influence of feeding pattern on thyroid hormones in long-term food-restricted rats

The effect of a long-term 50% food restriction on plasma thyroid hormone levels was studied in adult male rats, which received their reduced daily amount of food either as one meal or 5 different meals. Compared to controls, a long-term food restriction reduced total 24 h-mean plasma T4, T3 and TSH concentrations. The total T4 level was more reduced in rats fed their reduced ration in one meal than in rats given food in several meals. This resulted in a higher T3/T4 ratio in the former group of rats than in the other groups (free access to food; food in several meals). In the control group and in the food-restricted group receiving their food in one meal, significant diurnal variations in total T4, T3 and TSH levels were seen. The T3 rhythm was abolished in food-restricted rats receiving their food spread over several meals, but T4 and TSH rhythms were not. We conclude that total peripheral thyroid hormone levels in food-restricted rats are influenced, not only by the amount of food but also by the feeding pattern.status: publishe

4-demethyl simmondsin from <I>Simmondsia chinensis</I>

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-methocyclohexayl beta-D-glucoside or 4-demethyl simmmondsin. (C) 2000 Elsevier Science B.V. All rights reserved.Laboratorium voor Toxicologie en bromatologie. Laboratorium voor Medicinale chemie. Subfaculteit Geneeskunde Campus Kortrijk. Laboratorium voor Fysiologie en immunologie der huisdieren.status: publishe

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.status: publishe

Mechanism of simmondsin decomposition during sodium hydroxide treatment

Jojoba seed meal shows appetite-suppressing activity due to the presence of simmondsin. This pharmacological activity disappears with treatment of the meal with sodium hydroxide. To elucidate this mechanism of inactivation, the reaction of simmondsin in 1 N NaOH at 20 degrees C was monitored as a function of time. The end products of the reaction as well as intermediates were isolated and identified. The half-life of simmondsin was approximately 60 min with d-glucose and 2-hydroxy-3-methoxyphenylacetonitrile as reaction end products. The reaction mechanism could be elucidated by the isolation of isosimmondsin and a simmondsin lactone derivative. Those compounds were isolated and purified by a combination of column chromatography and HPLC and identified mainly by HRMS and NMR spectroscopy.status: publishe