Abstract:

Objective: To study the hypoglycemic activity of avicularin and guaijaverin in guava leaves. Methods: Reversedphase
high performance liquid chromatography (RP-HPLC) was used to determine the content of avicularin and guaijaverin
in guava leaves in different months of the year. The fat cell model was established to evaluate hypoglycemic activity of
the ethanol extract of guava leaves, avicularin and guaijaverin respectively. Western blotting was used to analyze GLUT4
expression on the fat cell membrane. Free fatty acids as another index were also determined using a fatty acid kit. Results:
The contents of guaijaverin and avicularin in guava leaves showed great difference in different months, and guava leaves
had higher contents and hypoglycemic activity both between June and September. The guava leaf extract, guajava and
avicularin could all significantly promote GLUT4 protein expression on the fat cell membrane and significantly inhibit the
release of free fatty acids. Conclusion: Guaijaverin and avicularin are the major bioactive components in guava leaves with
hypoglycemic activity and inhibitory capacity against free fatty acid release.

Key words: guava leaves, guaijaverin, avicularin, hypoglycemic activity, glucose transporter 4 (GLUT4), free fatty acid