Studies of Dehulled Adlay Active Fractions on the Lipid Metabolism in Hamsters

In this study, we used the Taichung select No.4 dehulled adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) as our experimental material to investigate the dehulled adlay active fractions on the lipid metabolism in hamsters.
First, we examined the hypolipidemic effect in hamsters fed high fat diets (10% corn oil + 1.0% cholesterol) that was substituted with different percents of dehulled adlay for 4 or 8 weeks. The results showed that after 4 weeks feeding period, 20 and 40% dehulled adlay substituted high fat diets could lower serum lipids concentration in hamsters. After 8 weeks, we found that 20 and 40% diet groups lowering levels of serum lipids and hepatic TC, TG and also showed increaseing fecal lipids excretion in hamsters.
Second, we investigated the dehulled adlay active fractions on the lipid metabolism in hamsters. The results showed that (1) the dehulled adlay extracted by 100℃ water for 30 min to obtain hot water-soluble fraction (ABW) and hot water-insoluble fraction (ABR). As hamsters fed with high fat diets (10% corn oil + 0.25% cholesterol) that were substituted 20, 40% ABW and 20, 50% ABR, showed hypolipidemic effect. So we could not isolate the hypolipidemic active components by means of fractionating dehulled adlay with boiling water extraction. (2) The dehulled adlay extracted by methanol and fractionated by n-hexane, ethyl acetate, 1-butanol and water. The methanol extract (AM) had lipid-lowering effect and reduced the plasma cholesteryl ester transfer protein (CEPT) activity, and that might be related with the ratio of extraction. As compared with AM, the AM-EA and AM-B fractions significantly inhibited the CETP activity in vitro and in vivo. Their IC50 were 55μg /mL and 65μg /mL. Moreover, 3 groups of hamsters were fed with AM-H, AM-W and AMR-W and the results showed different hypolipidemic effects. Therefore, our results demonstrated that the hypolipidemic effect of dehulled adlay was due to various active components. (3) The water-soluble dietary fiber enriched fraction of dehulled adlay (ACF) showed a hypolipidemic effect in hamsters and which was positively correlated with the amount of ACF. The insoluble and soluble fractions (ACF-EI and ACF-ES, respectively) of ACF that prepared by 40% ethanol concentration fractionation also showed hypolipidemic effects and which was influenced with their physicochemical properties. The apparent molecular-weights of ACF-EI and ACF-ES were 14.5 and 8.7 x 104 Daltons, respectively. Furthermore, the adlay 75% alcohol soluble fraction (ACE) could elevated plasma HDL cholesterol concentraction, and the possible hypolipidemic mechanism was due to its inhibitory CETP activity and further investigation about its active composition is needed. The hexane fraction (AH) of dehulled adlay also showed a hypolipidemic effect. The contents of 3 phytosterols, i.e. campesterol, stigmasterol and sitosterol in the dehulled adlay were 65±10, 34±7, 445±36 mg/100g, respectively.
In conclusion, we demonstrated that the dehulled adlay active fractions on the lipid metabolism in hamsters were their water-soluble dietary fiber enriched, and methanol, n-hexane and 75％ alcohol soluble fractions.