Polyacetylenes from the Roots of Polyalthia debilis

Six new linear polyacetylenic C25 and C27 acetogenins (1-6), named debilisones A-F, have been isolated from a methanol extract of roots of Polyalthia debilis. Structures of these compounds were determined by spectroscopic techniques. The absolute configuration at C-17 of 2 was assigned by the modified Mosher's method. Compounds 2, 3, and 5 exhibited moderate antimycobacterial activity against Mycobacterium tuberculosis with MIC values of 25.0, 12.5, and 25.0 mu g/mL, respectively.