Methyl jasmolate treated buckwheat sprout powder enhances glucose metabolism by potentiating hepatic insulin signaling in estrogen-deficient rats.

OBJECTIVES

Methyl jasmolate (MeJA)-treated vegetables produce higher concentrations of various bioactive compounds. We investigated whether long-term oral consumption of MeJA-treated and untreated buckwheat sprout powder improves energy, glucose, lipid, and bone metabolism induced by estrogen deficiency in ovariectomized (OVX) rats fed high-fat diets, and explored the mechanisms involved.

METHODS

OVX rats were divided into four groups and fed high-fat diets supplemented with 3% dextrin (OVX-control), buckwheat sprout powder (BWS), or MeJA-treated buckwheat sprout powder (MJ-BWS) for 12 wk. Sham rats without estrogen deficiency had a control diet as a normal-control.

RESULTS

MeJA-treatment increased total polyphenols and flavonoids by about 1.6 fold and isoorientin, orientin, rutin, and vitexin were elevated by about 18% in buckwheat. After 12 wk, OVX rats exhibited increased weight gain, fat mass, skin temperature, hyperglycemia, and decreased bone mineral density (BMD) compared to sham rats. BWS prevented the increase of skin temperature and decrease of femur BMD, but did not improve energy glucose homeostasis as much as MJ-BWS. MJ-BWS prevented increases in body weight and fat mass. Energy expenditure was lowest in OVX-control, followed by BWS, MJ-BWS, and normal-control. Furthermore, MJ-BWS exhibited greater improvements in glucose and insulin tolerance than OVX-control and BWS. Phosphorylation of hepatic Akt and AMPK was potentiated, in ascending order of OVX-control, BWS, MJ-BWS, and normal-control, whereas PEPCK expression was decreased.

CONCLUSIONS

MJ-BWS prevented and ameliorated the disturbances in energy and glucose metabolism in estrogen-deficient animals better than BWS. Therefore, besides flavonoids in BWS, other components such as phytoalexins produced in MJ-BWS during MeJA-treatment might play a crucial role in the improvement.