New phloroglucinol derivatives with protein tyrosine phosphatase 1B (PTP1B) inhibitory activities from Syzygium austroyunnanense.

Five new phloroglucinol derivatives (1-5) together with one known analogue (6) were isolated from the leaves of Syzygium austroyunnanense which is an edible folk medicine used for the treatment of diabetes. The new structures were elucidated as austroyunones A - E (1-5) by means of the extensive spectroscopic analyses including high-resolution electrospray ionization mass spectrometry (HRESIMS) and 1D and 2D nuclear magnetic resonance (NMR). Compounds 4-6 showed obvious protein tyrosine phosphatase 1B (PTP1B) inhibitory activity. This discovery of new phloroglucinols and their bioactivities provided a scientific basis for the application of S. austroyunnanense as an edible and medicinal plant.