supported by grants from the National Key Research and Development Program of China(Nos.2018YFA0903200 and 2018YFA0903201);the National Natural Science Foundation of China(No.31761143016);Chang Jiang Scholars Program(GAO Hao,2017)from the Ministry of Education of China;National High-level Personnel of Special Support Program(No.2017RA2259);Guangdong Special Support Program(No.2016TX03R280);Young Elite Scientists Sponsorship Program by China Association of Chinese Medicine(No.QNRC2-B06);Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(GAO Hao,2014);Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Y036);K.C.Wong Education Foundation(GAO Hao,2016)
A pair of new tirucallane triterpenoid epimers,picraquassins M and N(1 and 2),were isolated from the stems of Picrasma quassioides(D.Don)Benn.Their structures were determined based on comprehensive spectroscopic and X...