Abstract:
BACKGROUND: Some Ficus species have been used in traditional African medicine in the treatment of diabetes. The
antidiabetic potential of certain species has been confirmed in vivo but the mechanism of activity remains uncertain.
The aim was to investigate the hypoglycaemic potential of ten Ficus species focussing on glucose uptake, insulin
secretion and the possible mechanism of hypoglycaemic activity.
METHODS: The dried and ground leaves of ten Ficus species were extracted with acetone. The dried acetone extract
was reconstituted with DMSO to a concentration of 100 mg/ml which was then serially diluted and used to assay for
glucose uptake in muscle, fat and liver cells, and insulin secretion in pancreatic cells.
RESULTS: Only the F. lutea extract was able to modulate glucose metabolism. In comparison to insulin in the primary
muscle cells, the glucose uptake ability of the extract was 33% as effective. In the hepatoma cell line, the extract was as
effective as metformin in decreasing extracellular glucose concentration by approximately 20%. In the pancreatic
insulin secretory assay, the extract was 4 times greater in its secretory activity than commercial glibenclamide. With
F. lutea extract significantly increasing glucose uptake in the primary muscle cells, primary fat cells, C2C12 muscle and
H-4-II-E liver cells, the extract may act by increasing the activity of cell surface glucose transporters. When the 3T3-L1
pre-adipocytes were compared to the primary muscle, primary fat and C2C12 cells, the differences in the former’s ability
to transport glucose into the cell may be due to the absence of the GLUT4 transporter, which on activation via the insulin
receptor decreases extracellular glucose concentrations. Because the pre-adipocytes failed to show any active increase in
glucose uptake, the present effect has to be linked to the absence of the GLUT4 transporter.
CONCLUSION: Only F. lutea possessed substantial in vitro activity related to glucose metabolism. Based on the effect
produced in the various cell types, F. lutea also appears to be a partial agonist/antagonist of the insulin cell membrane
receptor. While the clinical effectiveness of F. lutea is not known, this plant species does possess the ability to modify
glucose metabolism.
