Abstract
Retama raetam (
RR) fruits are used in Saudi traditional medicine for the treatment of diabetes. Current study aimed at evaluating the potential and mechanisms of the antidiabetic activity of the
RR methanolic extract in streptozotocin-induced diabetic rats. Oral LD
50 of the extract was found to be 1995
mg/kg. The extract was administered once orally to STZ-diabetic rats at three dose levels; 100, 250 or 500
mg/kg/day for 4 consecutive weeks.
RR extract at 250 or 500
mg/kg significantly lowered blood glucose levels at the 3rd and 1st week of treatment, respectively. Meanwhile, oral glucose tolerance test indicated that the same two doses significantly lowered glucose levels at 30 and 60
min after glucose challenge. Administration of
RR extract at 500
mg/kg/day for 4 consecutive weeks significantly increased serum insulin level.
In vitro studies indicated that the extract significantly inhibits glucose absorption by rat isolated intestine. The extract neither altered glucose uptake by rat isolated psoas muscle nor the activity of hepatic microsomal glucose-6-phosphatase. In conclusion, the methanolic extract of
RR improves STZ-induced diabetes in rats. This can be attributed, at least partly, to stimulating pancreatic insulin release and reducing intestinal glucose absorption.