Flavans and diphenylpropanes with PTP1B inhibition from Broussonetia kazinoki

Abstract Three new ( 1a/1b and 2b ) and five known flavans ( 2a , 6a/6b , 7 , and 8 ), one new flavan glycoside ( 3 ), and two new ( 4 and 5 ) and six known 1,3-diphenylpropanes ( 9 – 14 ) were isolated from the twigs of Broussonetia kazinoki . Compounds 1 , 2 , and 6 are scalemic mixtures, and were resolved by chiral HPLC to provide 1a / 1b , 2a / 2b , and 6a / 6b . The structures of these compounds were elucidated by extensive spectroscopic methods, including NMR, MS, and ECD analyses. Compounds 1 , 2 , 5 , 8 , 9 , 11 , and 12 showed in vitro inhibition of protein tyrosine phosphatase 1B (PTP1B).