A new Dieis-Alder-type adduct flavonoid from Dorstenia barteri

A new Dieis-Alder-type adduct, dorstenone (1), was isolated from Dorstenia barteri together with three known fiavonoids, 4,2',4'-trihydoxy-3'- prenylchalcone; 4,2',4'-trihydoxy-3,3'-diprenylchalcone; and 5,7,4'- trihydoxy-8-prenylflavone. The structure of 1 was elucidated using a combination of highfield NMR techniques, particularly, gradient-enhanced HMQC and HMBC

Diterpenoids from Neoboutonia glabrescens (Euphorbiaceae)

Glabrescin, a daphnane diterpenoid, neoboutonin, a degraded diterpenoid with a novel skeleton, and neoglabrescins A and B, two rhamnofolane derivatives, have been isolated from the stem bark of Neoboutonia glabrescens Prain (Euphorbiaceae), together with the known tigliane derivative, baliospermin, and the known daphnane, montanin. Other constituents include squalene, 3-acetylaleuritolic acid, oleanolic acid and sitosterol, and the phenolic compounds 9-methoxy-1,7-dimethylphenanthrene and 2,3,8-tri-O-methylellagic acid. The structures were assigned on the basis of spectral studies and comparison with published literature data. The structures of neoglabrescins A and B were derived for their acetylated derivatives and, in the case of neoglabrescin A, confirmed by X-ray crystallographic analysis

Geranylated flavonoids from Dorstenia poinsettifolia

Two new geranylated flavonoids, poinsettifolins A and B, were isolated from the extracts of the herb Dorstenia poinsettifolia, and the structures were determined with NMR spectroscopy and mass spectrometry. In addition, the flavone 5,7,4-trihydroxy-8-prenylflavone (licoflavone C), the chalcones 4,2',4'-trihydroxy-3'-prenylchalcone (isobavachalcone) and isobavachromene, the triterpene butyrospermol, and the carotenoid lutein were isolated

Diarylheptanoids from Myrica arborea

Investigations of the stem and root bark of Myrica arborea (Myricaceae) have yielded two novel diarylheptanoids, myricarborin and 11-O-β-D-xylopyranosylmyricanol along with the known myricanol and 5-O-β-D-glucopyranosylmyricanol. The structures of the novel compounds were determined by spectroscopic methods. (C) 2000 Elsevier Science Ltd

Trypanocidal diarylheptanoids from Aframomum letestuianum K. Schum (Zingiberaceae).

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. IC50 values in the range of 1-3 g/mL were found for compounds 3 and 5

Three labdane diterpenoids from Aframomum sceptrum (Zingiberaceae)

Three labdane diterpenoids, 8β,17-epoxy-3β,7β-dihydroxy-12(E)-labden-16,15-olide (1), methyl 8β,17-epoxy-3β,7β,15-trihydroxy-12(E)-labden- 16-oate (2) and 3β,7β,8β,12ζ,17-pentahydroxylabdan-16,15-olide (3) have been isolated from the seeds of Afromomum sceptrum K. Schum (Zingiberaceae) and their structures assigned on the basis of their spectroscopic properties. Nerolidol, and the known flavonoids 3-acetoxy-4′,5,7-trihydroxyflavanone, and 3,4′,5,7-tetrahydroxyflavanone were also obtained