Picrajavanicins H-M, new quassinoids from Picrasma javanica collected in Myanmar and their antiproliferative activities

Six new tetracyclic quassinoids, picrajavanicins H-M, along with two known analogues were isolated from the CHCl₃ soluble extract of Picrasma javanica bark collected in Myanmar. The structures of these compounds were elucidated using spectroscopic techniques, including 1D and 2D NMR. The absolute configuration at C-4 of picrajavanicin L was determined to be R by the modified Mosher method. In contrast, the absolute structures of picrajavanicin H and picrasin A were determined by the X-ray diffraction analyses. The antiproliferative activities of the isolated compounds were evaluated against a panel of five different human cancer cell lines. All isolates exhibited potent and selective antiproliferative activities against human pancreatic cancer PANC-1 cells, with IC₅₀ values ranging from 3.25 to 17.41 μM. Crown.