Chemical composition and anti-hyperglycaemic effects of triterpenoid enriched Eugenia jambolana Lam. berry extract

In our investigation of the anti-hyperglycaemic constituents of Eugenia jambolana L. (lamun), one new triterpenoid, 2-O-cis-p-coumaroyl maslinic acid, along with thirteen known triterpenoids were isolated from the fruit ethyl acetate extract. The structures of compounds 1-14 were elucidated on the basis of mass spectrometry and nuclear magnetic resonance analyses. Animal studies demonstrated that the triterpenoid-enriched Jamun fruit extract (TJFE) decreased blood glucose content in C57BL/6 mice (P < 0.05) upon sucrose loading challenge, improved the glucose tolerance in mice administrated with TJFE for 2 weeks via oral gavage (100 mg/kg body weight), and increased Akt phosphorylation levels and Glut4 protein levels in skeletal muscle. Additionally, TJFE administration inhibited hepatic gluconeogenesis through suppressing the gluconeogenic gene expression of Pgcl alpha, Pepck, and G6Pase. The current study advances scientific knowledge of Jamun constituents and suggests that triterpenoids may play an important role in the anti-diabetic properties attributed to this edible purple berry. (C) 2016 Elsevier Ltd. All rights reserved.