Mechanistic studies on the antidiabetic activity of a polysaccharide-rich extract of Radix Ophiopogonis.

To study the hypoglycemic mechanisms of a polysaccharide-rich extract of Radix Ophiopogonis, the influences of the extract on activity of NIT-1 insulinoma cells damaged by streptozotocin (STZ), activity of α-glucosidase, glucose absorption into intestinal brush border membrane vesicles, gluconeogenesis by H4IIE hepatoma cells and glucose uptake by 3T3-L1 adipocytes were investigated. The results show that the extract improved the activity of NIT-1 cells damaged by STZ, inhibited glucose absorption into intestinal brush border membrane vesicles and reduced the activity of α-glucosidase. However, gluconeogenesis in H4IIE cells and glucose uptake in 3T3-L1 adipocytes did not change significantly in the presence of the extract. These results suggest that the hypoglycemic mechanisms of the polysaccharide-rich extract of Radix Ophiopogonis are caused by protection in pancreatic islet cells and the inhibition of carbohydrate digestion and absorption. This is possibly the first report on the underlying mechanisms responsible for the antidiabetic effect of Radix Ophiopogonis.