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

Urea derivatives from Pentadiplandra brazzeana

Four urea derivatives were isolated from the roots of Pentadiplandra brazzeana, and their structures were elucidated by spectroscopic techniques. N-Benzyl-N'-(4-methoxybenzyl)urea (1) is a new compound, although N,N'-di-(4- methoxybenzyl)urea (2), N,N'-dibenzylurea (3), and p-methoxythiobenzaldehyde (4) are reported from a natural source for the first time

New friedelane triterpenes from Lepidobotrys staudtii

Three new dihydroxy-3-friedelanone triterpenes were isolated from the leaves and the stem bark of the Cameroonian medicinal plant Lepidobotrys staudtii. Structure elucidation by spectroscopic techniques showed that they are 2α,29-dihydroxy-3-friedelanone (1a), 2β,21α-dihydroxy-3-friedelanone (2a) and 6β,21α-dihydroxy-3-friedelanone (3). In addition, the known monohydroxy-3-friedelanones 4, 5, 6 and 7 were obtained

Two labdane diterpenoids and a seco-tetranortriterpenoid from Turreanthus africanus

Seeds of Turreanthus africanus afforded two labdane (1, 2) diterpenoids and a limonoid (3). Their structures were elucidated by extensive NMR spectroscopy and mass spectrometry. Examination of the methylene chloride soluble portion of the acetone extract of the seeds of Turreanthus africanus yielded two labdane diterpenoids 12,15-epoxylabda-8(17),12,14-trien-16-al (1) and 16-acetoxy-12(R),15-epoxy-15β-hydroxylabda-8(17),13(16)-diene (2) and a limonoid, 17-epi 12-dehydroxyheudebolin (3). Structures elucidation was based on the analysis of spectroscopic data

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

Vernoguinosterol and vernoguinoside, trypanocidal stigmastane derivatives from Vernonia guineensis (Asteraceae)

Two bitter stigmastane derivatives, vernoguinosterol (1) and vernoguinoside (2), have been isolated from the stem bark of Vernonia guineensis and their structures eludicated using spectroscopic methods. The new compounds exhibit trypanocidal activity

A norbislabdane and other labdanes from Aframomum sulcatum

Extracts of the seeds of Aframomum sulcatum (Oliv. & Hanb) K. Schum (Zingiberaceae) yielded a novel norbislabdane derivative, sulcanal (1) and the new labdane (12E)-8β,17-epoxy-11-hydroxy-12-labden-15,16-dial-11,15-hemiacetal (2) (as a 1:1 C-15 epimeric mixture), along with known labdane diterpenes

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

Anti-plasmodial sesquiterpenoids from the African Reneilmia cincinnata

A new isodaucane sesquiterpenoid, 6,7,10-trihydoxyisodaucane, was isolated from the fruits of Reneilmia cincinnata, together with the known sesquiterpenoids oplodiol, oplopanone, 5E,10(14)-germacradien-1β,4β-diol, 1(10)E,5E-germacradien-4α-ol and eudesman-1,4,7-triol. A large amount of 5- hydroxy-3,7,4'-trimethoxyflavone was also isolated. Their structures were established by NMR techniques using 1D and 2D experiments. Three of the known sesquiterpenoids exhibited noteworthy anti-plasmodial activity against Plasmodium falciparum strains