conophylline and Diabetes-Mellitus--Type-2

Increasing metabolic syndromes including type-2 diabetes mellitus, obesity, and steatohepatitis are serious problems in most countries in the world. Neurodegenerative diseases such as Alzheimer, Parkinson's, and Huntington's diseases are increasing in many countries. However, therapy for these diseases is not sufficient yet. Thus, effective chemotherapy for these diseases is being expected. Conophylline is an alkaloid isolated from the leaves of Ervatamia microphylla and related plants. It was found to induce beta-cell differentiation in the precursor pancreatic cells. Oral administration of this compound ameliorated type-2 diabetes mellitus model in mice and rats. Later, fibrosis of the pancreatic islets was found to be greatly reduced by conophylline in the pancreatic islets. It also inhibited chemically induced liver cirrhosis. Further study indicated that conophylline inhibited non-alcoholic steatohepatitis in the model mice. On the one hand, loss of autophagy often causes protein aggregation to give neural cell death. Conophylline was found to activate autophagy in cultured neural cells. Activation of autophagy ameliorated cellular models of Parkinson's and Huntington's diseases. Thus, conophylline is likely to be useful for the development of chemotherapy for metabolic and neurodegenerative diseases.

Topics: Animals; Autophagy; Cell Differentiation; Diabetes Mellitus, Type 2; Disease Models, Animal; Fibrosis; Humans; Islets of Langerhans; Metabolic Syndrome; Mice; Molecular Targeted Therapy; Neurodegenerative Diseases; Non-alcoholic Fatty Liver Disease; Phytotherapy; Plant Leaves; Tabernaemontana; Vinca Alkaloids

Conophylline, a vinca alkaloid from Ervatamia microphylla, is known to induce the differentiation of pancreatic precursor cells to insulin-producing cells. In the present research we examined the antidiabetic effects of this alkaloid in vivo by oral administration. Crude conophylline preparations were prepared from the leaves of Tabernaemontana divaricata collected in Okinawa Prefecture, Japan. Conophylline was orally absorbed and showed an increase in its plasma level in both normal and streptozotocin-induced diabetic Sprague-Dawley rats. The plasma conophylline concentration reached its maximum from 1.5 to 3h after a single oral administration and gradually decreased in 24h. The alkaloid decreased the blood glucose level and increased the plasma insulin level in streptozotocin-induced diabetic rats after repetitive administration for 15 days. Fasting blood glucose levels in rats treated orally with conophylline at 0.11 and 0.46 mg/kg/day were 411+/-47 and 381+/-65 mg/dl, respectively; whereas the glucose level of the control rats was 435+/-46 mg/dl. Conophylline also decreased the fasting blood glucose level in Goto-Kakizaki rats in a dose-dependent manner after repetitive administration for 42 days. These results suggest that the extract from conophylline-containing leaves may be useful as a functional food for the treatment of type 2 diabetes mellitus.

Topics: Administration, Oral; Animals; Blood Glucose; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Dose-Response Relationship, Drug; Hypoglycemic Agents; Insulin; Japan; Male; Plant Extracts; Plant Leaves; Rats; Rats, Sprague-Dawley; Streptozocin; Tabernaemontana; Vinca Alkaloids