Anti-diabetic effects of red rose flowers in streptozotocin-induced diabetic mice

Diabetes mellitus is a common chronic metabolic disease that is of increasing concern, because it frequently leads to complications such as cardiovascular diseases and cancer. Plants have been studied as a potential source for anti-diabetics to supplement dietary modifications, insulin, and other medications. The components of green tea polyphenols can be changed by processes such as browning. This processing method was applied to the red rose flower to determine whether the processed or non-processed rose flower has an anti-diabetic effect on the streptozotocin-induced diabetic mouse. Aqueous extracts of processed and non-processed rose flowers were analyzed using liquid chromatography/mass spectrometry. The results show that the polyphenol content decreased with browning. The hemoglobin A1c level, an indicator of long-term diabetes, in diabetic mice after administration of extracts of browned rose flowers for 24 and 48 h were lower than those after administration of extracts of non-browned rose flowers. Moreover, the activity of aspartate transaminase, which is often high in diabetic patients, was low in all groups treated with rose flowers, whether they were non-browned or browned. Taken together, these results indicate that extracts from red rose flowers have long-term anti-diabetic effects, and that this effect is independent of the level of polyphenols in the extract.