The objectives of this study were to develop a GC-MS method for determination of cholesterol oxidation products (COPs) in tea-leaf eggs and study the formation and inhibition of COPs as affected by heating time and various ingredients in marinated juice. The various COPs in egg and juice samples were extracted by a solvent system of chloroform/methanol (2:1, v/v), followed by purification using a silica cartridge and GC-MS for subsequent separation and quantitation, with high recovery ranges from 85.9 to 98.3% and from 83.1-100.1% being obtained for egg and juice, respectively. 5α-Cholestane was shown to be an appropriate internal standard for quantitation. A total of five COPs, including 7-keto, 5,6 β-EP, 7α-OH, 7β-OH, and triol, were formed in tea-leaf eggs during marinating, but not in marinated juice. A peak level of total COPs (2272.2 ng/g) was generated in tea-leaf eggs after 24 h of heating, but reduced to 1068.2 ng/g in 48 h. Both the total phenolic and flavonoid compounds in tea-leaf eggs showed a time-dependent increase during marinating and so did the pH and browning index in tea-leaf eggs and juice. The incorporation of soy sauce or black tea leaf into juice was effective in inhibiting COPs formation in tea-leaf eggs, with the latter being more pronounced than the former. The formation of Maillard reaction products during marinating as well as the presence of total phenolic and total flavonoid in black tea leaf was mainly responsible for COPs reduction in tea-leaf eggs.
Hyperlipidemia is an important risk factor for cardiovascular diseases. Agents for the treatment of hyperlipidemia are well-developed in the clinic while PPARα is a target for lipid-lowering agents. Shan-Zha (Crataegus pinnatifida) is a traditional Chinese medicine used to increase digestion. Also, Shan-Zha fruit extract showed merit to improve obesity and hyperlipidemia in hamsters; however, the mechanism remained obscure. In the present study, hypertriglycemia and hypercholesterolemia were induced by high fat diet in C57BL/6 J male mice. Then, they were orally administered with Shan-Zha fruit extract at an effective dose of 250 mg/kg for 7 days. The liver was removed to estimate the expressions of PPARα and β-oxidation-related enzyme. Oral intake of Shan-Zha extract significantly improved hyperlipidemia in high fat diet-fed mice with an increase of PPARα expression in liver. Also, expression of PPARα-regulated β-oxidation-related enzymes was raised in liver by Shan-Zha extract. However, adipose tissue and others were not modified by this treatment of Shan-Zha fruit extract. Thus, Shan-Zha can increase the expression of PPARα to facilitate β-oxidation-related enzymes in liver for lipid degradation and blood lipid decrement. Also, this is the first report showing Shan-Zha fruit extract can influence liver to lower hyperlipidemia prior to the action in adipose tissue.
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