Abstract:
Green beans (Phaseolus vulgaris L.) are consumed as pods or mature seeds (common
beans). The pods were extracted with 95% ethanol and processed to prepare non-
polar and polar fractions. Comparing the antihyperglycemic activity of both fractions,
non-polar fraction (NPF, 200 mg kg−1 day−1) lowered blood glucose in streptozotocin
diabetic rats by 65% compared to 57% for the polar fraction at the same dose. When
NPF treatment was combined with injection of mesenchymal stem cells (MSC) a 4.4-
fold increase in serum insulin and a 73.6% reduction in blood glucose were observed
compared to untreated control. Additionally, a significant decrease in malondialde-
hyde (76.2%), nitric oxide (68.2%), cholesterol (76.1%), and triglycerides (69.5%) and
a 1.75-fold increase in HDL concentrations were observed in the group treated with
this combination compared to diabetic animals. Interestingly, NPF increased homing
of MSC in pancreas potentiating their antidiabetic activity. Finally, 26 compounds
were identified in NPF using LC/MS analysis and four were isolated in pure form. The
isolated compounds namely calotroproceryl acetate, fridelin, calotroproceryl A, and
stigmasterol showed good inhibitory activity against pancreatic lipase with IC50 at
1.93, 1.07, 1.34 and 1.44–1 μg/ml, respectively. Additionally, these compounds inhib-
ited α-amylase, albeit at higher concentration, with IC50 at 248, 212, 254, and 155 μg/
ml for calotroproceryl acetate, fridelin, calotroproceryl A, and stigmasterol, respec-
tively. Our results suggest that green beans extract can potentiate effect of MSC in
diabetes directly due to its own antidiabetic effect and indirectly by increasing MSC
homing in pancreatic tissues.
Practical applications
It has been suggested in this study that green beans can improve hyperglycemia, oxi-
dative balance in diabetes, so green beans can be promoted as a healthy nutrient for
diabetic patients. Green beans also can enhance homing and differentiation of mesn-
chymal stem cells in the pancreas for future stem cell therapy of type I diabetes.
