Antioxidant Effects and Improvement of Lipid Metabolism of Mulberry fruit, Mulberry Leaves and Silkworm Powder with Different Mixing Ratios in Streptozotocin-Induced Diabetic Rats

Kwon, Eun Hye; Jung, Myung Ae; Rhee, Soon Jae; Choi, Sang Won; Cho, Sung Hee

Abstract

This study was conducted to investigate the effects of mulberry fruit, mulberry leaves and silkworm powder with different mixing ratios on hepatic antioxidative system and lipid metabolism in streptozotocin-induced diabetic rats. Sprague-Dawley male rats weighing 100+/-10 g were induced diabetic by 50 mg/kg bw streptozotocin and randomly assigned to following experimental groups; normal diet group (DM) , 0.3% and 0.6% mulberry fruit diet groups (F and 2F) , 0.3% mulberry leaves diet group (M) , 0.3% silkworm powder diet group (S), 0.15% mulberry fruit + 0.15% mulberry leaves diet group (FM), 0.15% mulberry fruit + 0.15% silkworm powder diet group (FS) , 0.1% mulberry fruit + 0.1% mulberry leaves + 0.1% silkworm powder diet group (FMS) . The experimental diets were fed for 4 weeks. Hepatic SOD activity was not changed significantly by any of single or combined supplementations of mulberry fruit, leaves and silkworm powder but GSH-px and catalase activities were increased by the groups supplemented with two or three of the test ingredients (FM, FS, FMS) as compared with the DM group. Hepatic TBARS value was not reduced significantly by any of the supplementations but lipofuscin contents were significantly reduced in the FM, FS and FMS groups as compared with the DM group. Hepatic mitochondria and microsomal carbonyl values were reduced by the single and combined supplementations of the test ingredients. Hepatic HMG-CoA reductase activities were increased in the all supplementation groups as compared with the DM group. Hepatic total lipid and triglyceride contents were increased but cholesterol contents reduced in the supplemented groups. The effects on the enzyme activities, peroxide or its products and lipid contents were most remarkable in the FMS group. In conclusion, mulberry fruit, mulberry leaves and silkworm powder have the favorable effects on antioxidative system and lipid metabolism in the diabetic liver and the mulberry fruit, leaves and silkworm powder with equal ratio exert the synergistic effect expectedly to prevent diabetic complications.