Five new annonaceous acetogenins, calamistrins C-G (1-5), were isolated fro
m an ethanolic extract of the roots of Uvaria calamistrata. Compounds 1-3 w
ere mono-THF ring acetogenins; compounds 4 and 5 were bis-THF acetogenins,
with the THF rings from C-18 to C-25. The absolute configurations of 3, 4,
and 5 as well as the partial absolute configurations of 1 and 2 were determ
ined by C-13 NMR spectroscopy and advanced Mosher methodology.