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Three new diarylheptanoids, (4Z,6E)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)hepta-4,6-dien-3-one, letestuianin A (1), (4Z,6E)-5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-4,6-dien-3-one, letestuianin B (2), and 1,7-bis(4-hydroxyphenyl)heptan-3,5-dione, letestuianin C (3), as well as the known (4Z,6E)-5-hydroxy-1,7-bis(4-hydroxyphenyl)hepta-4,6-dien-3-one (5) were isolated from Aframomum letestuianum. The known flavonoids 3-acetoxy-5,7,4'-trihydroxyflavanone, 3-acetoxy-7-methoxy-5,4'-dihydroxyflavanone, 7-methoxy-3,5,4'-trihydroxyflavone, and 3,3',4',5,7-pentahydroxyflavan were also obtained from this plant. Their structures were determined using a combination of 1D and 2D NMR techniques. The four diarylheptanoids were tested for growth inhibitory activity in vitro versus bloodstream forms of African trypanosomes. IC(50) values in the range of 1-3 microg/mL were found for compounds 3 and 5.

In addition to the two known compounds neotautenol [2] and erythrinassinate B [4], two new compounds, an isoflavanone named sigmoidin J [1] and a coumestan derivative named sigmoidin K [3], have been isolated and characterized from the root bark of the Cameroonian medicinal plant Erythrina sigmoidea. Their structures have been established as 7, 4'-dihydroxy-2',5'-dimethoxy-6'(gamma, gamma-dimethylally)isoflavanone [1] and 3,9-dihydroxy-2,10-(gamma, gamma dimethylallyl) coumestan [3], respectively, by spectroscopic techniques and from chemical evidence.