During diabetes, structural and functional changes in the alimentary tract are known to take place resulting in an increased absorption of intestinal glucose and alterations in the activities of brush-border disaccharidases. To elucidate the effect of administrating polysaccharide from Gynura divaricata (PGD) on disaccharidase activities, the specific activities of intestinal disaccharidases, namely sucrase, maltase and lactase, were measured in streptozotocin-induced diabetic rats. Normal control and diabetic rats were treated by oral administration with PGD. Specific activities of intestinal disaccharidases were increased significantly during diabetes, and amelioration of the activities of sucrase and maltase during diabetes was clearly visible by the treatment with PGD. However, the increased activity of lactase during diabetes mellitus was remarkably alleviated by the administration of PGD only in the duodenum. Meanwhile, oral sucrose tolerance tests demonstrated that PGD alleviated the hyperglycaemia during diabetes mellitus, resulting from the amelioration in the activities of intestinal disaccharidases. The present investigation suggests that PGD exerted an anti-diabetic effect partly via inhibiting the increased intestinal disaccharidase activities of diabetic rats. This beneficial influence of administration of PGD on intestinal disaccharidases clearly indicates their helpful role in the management of diabetes.Key words: Diabetes: Disaccharidases: Polysaccharides: Gynura divaricata: Hypoglycaemic mechanisms: IntestineThe rapid increase in the prevalence of diabetes mellitus is becoming a serious threat to public health all over the world. By the year 2030, diabetes mellitus is expected to affect almost 5 % of the world's population -an estimated 366 million individuals (1) . Diabetes imposes a considerable burden in terms of premature mortality, morbidity and healthcare costs. Life expectancy for individuals with diabetes is estimated to be up to 10 years shorter than for individuals without diabetes (2) . Diabetes mellitus is a metabolic disorder characterised by the presence of hyperglycaemia and relative or absolute insulin deficiencies. A prolonged uncontrolled hyperglycaemic state leads to complications of diabetes, such as vision loss, renal failure, nerve damage and cardiovascular system disease (3) . The prevention and control of complications associated with diabetes have become one of the key issues in biomedical research. Current management of diabetes relies mainly on the reduction of dietary carbohydrate intake and the use of hypoglycaemic agents to lower the level of circulating glucose. Limiting and/or delaying intestinal carbohydrate absorption would help to correct plasma glucose concentrations and reduce diabetic complications (4) . It has been observed that there is an increased glucose absorption in the small intestine (5) , which may be attributed to increased intestinal disaccharidase activities. Disaccharidases are essential for the terminal absorption of carbohydrate dige...
To search for nano-drug preparations with high efficiency in tumor treatment, we evaluated the drug-loading capacity and cell-uptake toxicity of three kinds of nanoparticles (NPs). Pullulan was grafted with ethylenediamine and hydrophobic groups to form hydrophobic cholesterol-modified amino-pullulan (CHAP) conjugates. Fourier transform infrared spectroscopy and nuclear magnetic resonance were used to identify the CHAP structure and calculate the degree of substitution of the cholesterol group. We compared three types of NPs with close cholesterol hydrophobic properties: CHAP, cholesterol-modified pullulan (CHP), and cholesterol-modified carboxylethylpullulan (CHCP), with the degree of substitution of cholesterol of 2.92%, 3.11%, and 3.46%, respectively. As compared with the two other NPs, CHAP NPs were larger, 263.9 nm, and had a positive surface charge of 7.22 mV by dynamic light-scattering measurement. CHAP NPs showed low drug-loading capacity, 12.3%, and encapsulation efficiency of 70.8%, which depended on NP hydrophobicity and was affected by surface charge. The drug release amounts of all NPs increased in the acid media, with CHAP NPs showing drug-release sensitivity with acid change. Cytotoxicity of HeLa cells was highest with mitoxantrone-loaded CHAP NPs on MTT assay. CHAP NPs may have potential as a high-efficiency drug carrier for tumor treatment.
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