Oroxin A from Oroxylum indicum prevents the progression from prediabetes to diabetes in streptozotocin and high-fat diet induced mice

Background: Oroxylum indicum (L.) Kurz (Bignoniaceae) has been widely used for the treatment of respiratory infections and gastrointestinal disorders. Our previous study showed that an ethanol-water O. indicum seed extract (OISE), when combined with acarbose, reduced the risk of diabetes by 75% and effectively prevented the associated complications. Oroxin A, a major component of OISE, can activate PPARγ and inhibit α-glucosidase and it represents a promising candidate for diabetes intervention.

Purpose: The aim of this study is to investigate the effect of oroxin A from O. indicum on the progression of prediabetes to diabetes and the underlying mechanisms in streptozotocin and high-fat-diet induced prediabetic mice.

Methods: Oroxin A was purified from OISE and its PPARγ transcriptional activation was determined in vitro and in vivo. The prediabetic mice were established by high-fat diet and streptozotocin, which was followed by treatment with oroxin A. The effect of oroxin A was determined by analysis of the lipid profiles, oxidative stress, hepatic function and histology. The mechanism of oroxin A was also investigated.

Results: Oroxin A is a compound with low toxicity that has reduced the relative risk of progression from prediabetes to diabetes by 66.7% without inducing weight gain or hepatotoxicity. Oroxin A also improved the complications of prediabetes, such as lipid metabolism dysfunction and liver injury. Results of mechanism studies suggested that oroxin A is a partial PPARγ Agonist that can activate PPARγ transcriptional activation in vitro and in vivo. Oroxin A also exhibited an inhibitory activity against α-glucosidase and an antioxidant capacity.

Conclusion: Oroxin A prevents the progression from prediabetes to diabetes through a multi-pathway intervention mechanism.