title: Prevention Effects and Possible Molecular Mechanism of Mulberry Leaf Extract and its Formulation on Rats with Insulin-Insensitivity.
abstract: For centuries, mulberry leaf has been used in traditional Chinese medicine for the treatment of diabetes. This study aims to test the prevention effects of a proprietary mulberry leaf extract (MLE) and a formula consisting of MLE, fenugreek seed extract, and cinnamon cassia extract (MLEF) on insulin resistance development in animals. MLE was refined to contain 5% 1-deoxynojirimycin by weight. MLEF was formulated by mixing MLE with cinnamon cassia extract and fenugreek seed extract at a 6:5:3 ratio (by weight). First, the acute toxicity effects of MLE on ICR mice were examined at 5 g/kg BW dose. Second, two groups of normal rats were administrated with water or 150 mg/kg BW MLE per day for 29 days to evaluate MLE's effect on normal animals. Third, to examine the effects of MLE and MLEF on model animals, sixty SD rats were divided into five groups, namely, (1) normal, (2) model, (3) high-dose MLE (75 mg/kg BW) treatment; (4) low-dose MLE (15 mg/kg BW) treatment; and (5) MLEF (35 mg/kg BW) treatment. On the second week, rats in groups (2)-(5) were switched to high-energy diet for three weeks. Afterward, the rats were injected (ip) with a single dose of 105 mg/kg BW alloxan. After four more days, fasting blood glucose, post-prandial blood glucose, serum insulin, cholesterol, and triglyceride levels were measured. Last, liver lysates from animals were screened with 650 antibodies for changes in the expression or phosphorylation levels of signaling proteins. The results were further validated by Western blot analysis. We found that the maximum tolerance dose of MLE was greater than 5 g/kg in mice. The MLE at a 150 mg/kg BW dose showed no effect on fast blood glucose levels in normal rats. The MLE at a 75 mg/kg BW dose and MLEF at a 35 mg/kg BW dose, significantly (p < 0.05) reduced fast blood glucose levels in rats with impaired glucose and lipid metabolism. In total, 34 proteins with significant changes in expression and phosphorylation levels were identified. The changes of JNK, IRS1, and PDK1 were confirmed by western blot analysis. In conclusion, this study demonstrated the potential protective effects of MLE and MLEF against hyperglycemia induced by high-energy diet and toxic chemicals in rats for the first time. The most likely mechanism is the promotion of IRS1 phosphorylation, which leads to insulin sensitivity restoration.
authors.affiliation: Research and Development Center of Amway (China), Shanghai, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Beijing Institute for Drug Control (Beijing Center For Health Food And Cosmetics Control), Beijing, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Li
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing 100193, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Xie
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing 100193, China.
authors.forename: Xiuzhen
authors.initials: X
authors.lastname: Luo
authors.affiliation: Beijing Pepnoch Co., Ltd, Beijing, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Bao
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing 100193, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.affiliation: Beijing Institute for Drug Control (Beijing Center For Health Food And Cosmetics Control), Beijing, China.
authors.forename: Yuchi
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Botanic Century (Beijing) Co., Ltd, Beijing, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zhong
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, 151 Malianwa North Road, Haidian District, Beijing 100193, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Research and Development Center of Amway (China), Shanghai, China.
authors.forename: MinJie
authors.initials: M
authors.lastname: Li
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002935:Cinnamomum zeylanicum / Q000737:chemistry; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology; D005215:Fasting / Q000097:blood; D006943:Hyperglycemia / Q000097:blood / Q000139:chemically induced / Q000517:prevention & control; D007333:Insulin Resistance; D050356:Lipid Metabolism / Q000187:drug effects; D008297:Male; D051379:Mice; D031625:Morus / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012639:Seeds / Q000737:chemistry; D029910:Trigonella / Q000737:chemistry
chemical_list: D001786:Blood Glucose; D004365:Drugs, Chinese Herbal