Abstract: Protein tyrosine phosphatase 1B plays an importance role in the negative regulation of insulin signaling,and thus considered as an attractive therapeutic target for diabetes.Bioassay guided fractionation of the hexane soluble extract of the seeds of Betula platyphylla Suk afforded seven protein tyrosine phosphatase 1B (PTP1B) inhibitory Lupane-triterpenoids 1-7.Isolated compounds (1-7) were identified as lupenone (1), lupeol (2), betulinic acid (3), betulinaldehyde (4), betulini (5), glochidonol (6 ) and lup-20/29-ene-1β/3β-diol (7).Compounds 1-7 inhibited PTP1B activity in a dose dependent manner,displaying IC₅₀ values of 5.6 ± 0.3 μmol/L,4.1 ± 0.2 μmol/L,7.2 ± 0.3 μmol/L,12.6 ± 0.4 μmol/L,11.6 ± 0.3 μmol/L,9.6 ± 0.4 μmol/L and 13.6 ± 0.5 μmol/L, respectively.

Key words: Lupane-triterpenoids, diabetes, protein tyrosine phosphatase1B, Betula platyphylla Suk