Eucommia leaves (Eucommia ulmoides Oliver) contain
chlorogenic acid (a
caffeic acid derivative) and
geniposidic acid and
asperuloside (ASP),
iridoid glucosides used in beverages. We used a
metabolic syndrome rat model, produced by feeding a 35 % high-fat diet (HFD), to examine potential anti-
obesity and anti-
metabolic syndrome effects and mechanisms of chronic administration of ASP. These effects were compared with Eucommia leaf extract (ELE), the positive control, which exhibits anti-
obesity effects. A total of six rats were studied for 3 months in five groups. ASP suppressed
body weight, visceral fat weight, food intake and circulating levels of
glucose,
insulin and
lipids, and increased the plasma
adiponectin level in rats on a HFD. These effects are similar to those of ELE, except for the influence on the plasma
glucose level. RT-PCR studies showed that ASP (like ELE with known anti-
obesity effects) diminished
isocitrate dehydrogenase 3α,
NADH dehydrogenase flavoprotein 1 (Comp I)
mRNA and
fatty acid synthase levels (white adipose tissue), increased
carnitine palmitoyltransferase 1α and
acyl-CoA dehydrogenase, very-long-chain mRNA levels (liver), and increased Glut4,
citrate synthase,
isocitrate dehydrogenase 3α,
succinyl CoA synthase, peroxisomal 3-ketoacyl-CoA thiolase,
dihydrolipoamide succinyl
transferase and
succinate dehydrogenase mRNA levels (skeletal muscle) under HFD conditions. Interestingly, ASP administration resulted in significantly increased
mRNA levels of
uncoupling protein 1 (UCP1) in the brown adipose tissue of HFD-fed rats; ELE did not affect the expression of UCP1. The increased expression of UCP1 may be negated by many ingredients other than ASP in the ELE. These findings suggest that chronic administration of ASP stimulates anti-
obesity and anti-
metabolic syndrome activity in HFD-fed rats across several organs, similar to ELE administration; thus, ASP may be an important ingredient of ELE.