Khayanolides from African mahogany Khaya senegalensis (Meliaceae): A revision

Five khayanolides (1-O-acetylkhayanolide B 1, khayanolide B 2, khayanolide E 3, 1-O-deacetylkhayanolide E 4, 6-dehydroxylkhayanolide E 5) were isolated from the stem bark of African mahogany Khaya senegalensis (Meliaceae). Their structures and absolute configurations were determined through extensive spectroscopic analyses including MS, NMR, and single-crystal X-ray diffraction experiments. The results established that two previously reported khayanolides, 1α-acetoxy-2β,3α,6,8α,14β-pentahydroxy-[4.2.1^10,30.1^1,4]-tricyclomeliac-7-oate 6 and 1α,2β,3α,6,8α,14β-hexahydroxy-[4.2.1^10,30.1^1,4]-tricyclomeliac-7-oate 7, were, in fact, 1-O-acetylkhayanolide B 1 and khayanolide B 2, and that the two reported phragmalin derivatives, methyl 1α-acetoxy-6,8α,14β,30β-tetrahydroxy-3-oxo-[3.3.1^10,2.1^1,4]-tricyclomeliac-7-oate 8 and methyl 1α,6,8α,14β,30β-pentahydroxy-3-oxo-[3.3.1^10,2.1^1,4]-tricyclomeliac-7-oate 9, were, in fact, khayanolide E 3 and 1-O-deacetylkhayanolide E 4, respectively. Based on the results from this study and consideration of the biogenetic pathway, the methyl 6-hydroxyangolensate in African mahogany K. senegalensis should have a C-6 S configuration while methyl 6-hydroxyangolensate in genuine mahogany Swietenia species should have a C-6 R configuration.     

Two labdane diterpenoids and a seco-tetranortriterpenoid from Turreanthus africanus

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-15beta-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.     

大叶桃花心木根的化学成分研究

为了解大叶桃花心木(Swietenia macrophylla King)的化学成分,从其根的乙醇提取物中共分离得到13个化合物,经理化性质和波谱分析,分别鉴定为1,5-dihydroxyxanthone(1)、1,6-dihydroxy-5-methoxyxanthone(2)、euxanthone(3)、1,2-dimethoxyxanthone(4)、(+)儿茶素(5)、(+)sesamin(6)、bis-(2-ethylhexyl)phthalate(7)、3-oxotirucalla-7,24-dien-21-oic acid(8)、(20S)-3β-acetoxy-24-methylenedam-maran-20-ol(9)、cycloeucalenol(10)、β-谷甾醇(11)、7-deacetoxy-7-oxogedunin(12)和7-deacetoxy-7α-hydroxygedunin(13),其中化合物1~4、6~10和13为首次从桃花心木属植物中分离得到,且化合物4对乙酰胆碱酯酶具有一定的抑制活性。     

Thaixylomolins D–F,new limonoids from the Thai true mangrove,Xylocarpus moluccensis

Three new limonoids, named thaixylomolins D–F (1–3), were obtained from the seeds of a Thai true mangrove, Xylocarpus moluccensis. The structures of these compounds were identified by extensive NMR and HR-ESIMS/MS investigations. They are further additions to the small group of phragmalins with a C-30 carbonyl moiety, among which thaixylomolins D–E (1–2) contain a Δ^8,14 double bond, whereas thaixylomolin F (3) possesses conjugated Δ^8,9 and Δ^14,15 double bonds.