Antineoplastic agents. 489. Isolation and structures of meliastatins 1-5 and related euphane triterpenes from the tree Melia dubia

The bark of the giant neem tree Melia dubia was found to contain 11 euphane-type Triterpenes. Five new compounds, meliastatins 1-5 (1-5), proved to inhibit growth of the P388 lymphocytic leukemia cell line (ED(50) 1.7-5.6 microg/mL). Four of the Others, the previously known methyl kulonate (8), kulinone (9), 16-hydroxybutyrospermol (10), and kulactone (11), were also found to inhibit (ED(50) 2.5-6.2 microg/mL) the P388 Cancer cell line. In addition, two new euphane Triterpenes were isolated and named dubione A (6) and dubione B (7). Structures for each of the 11 euphane Triterpenes were established by spectral techniques that included HRMS and 2D NMR.