Cloning of casbene and neocembrene synthases from Euphorbiaceae plants and expression in Saccharomyces cerevisiae

Trigoflavidols A (1) and B (2), tetranorditerpenoid dimers possessing a rearrangement skeleton with a spiroketal core moiety, and trigoflavidol C (3), a hexanorditerpenoid, have been isolated from Trigonostemon flavidus along with two known compounds. Compounds 1 and 2 showed moderate antimicrobial activities (MIC values: 3.12-6.25 mu g/mL) against Staphylococcus aureus, 8#MRSA, and 82#MRSA, and 1, 2, and 5 showed weak activities (IC50 values: 3.75-28.99 mu M) against various human tumor cell lines.

Trigoflavidols A–C, Degraded Diterpenoids with Antimicrobial Activity, from Trigonostemon flavidus

Drug resistance to human infectious diseases caused by pathogens lead to premature deaths through out the world. Plants are sources for wide variety of drugs used for treating various diseases. Systematic screening of medicinal plants for the search of new antimicrobial drug candidates that can inhibit the growth of pathogens or kill with no toxicity to host is being continued by many laboratories. Here we review the phytochemical investigations and biological activities of Meliaceae. The mahogany (Meliaceae) is family of timber trees with rich source for limonoids. So far, amongst the different members of Meliaceae, Azadirachta indica and Melia dubia have been identified as the potential plant systems possessing a vast array of biologically active compounds which are chemically diverse and structurally complex. Despite biological activities on different taxa of Meliaceae have been carried out, the information of antibacterial and antifungal activity is a meager with exception to Azadirachta indica. Together we provide new insights of Meliaceae members demonstrating as a potential source as antimicrobial agents using in vitro studies.

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Phytochemicals and antimicrobial potentials of mahogany family

Publisher Summary This chapter reviews papers that were published in 2006 on the reactions and syntheses of furans, benzofurans, and their derivatives. Like 2005, many new naturally occurring molecules containing tetrahydrofuran and dihydrofuran rings were identified in 2006. Several examples reported in 2006 demonstrate that 2-substituted furans underwent spirocyclization at the 2-position. The reaction of a furan tethered at the 2-position to an iminium ion gave a spiro-2,5-dihydrofuran derivative as the sole diastereoisomer. This spirocyclization that proceeded irrespective of the length of the carbon linker was employed to construct the ABC tricyclic core of manzamine A. Spirocyclization was also the reaction pathway under radical conditions if furan was tethered to a radical precursor at the 2-position. When furans were tethered to silyl enol ethers at the 2-position, spiroannulation also occurred at the 2-position under electrochemical conditions. Furan that was loaded on a soluble dendritic polyglycerol support could be efficiently oxidized electrochemically to a 2,5-dihydro-2,5-dimethoxyfuran, which served as an intermediate in the synthesis of a pyrrole library.

Chapter 5.3 Five-membered ring systems: Furans and benzofurans

Eight new triterpenoids, prototiamins A-G (1-6, 9) and seco-tiaminic acid A (10), were isolated along with four known compounds from the bark of Entandrophragma congoense. Their structures were elucidated by means of HRMS and different NMR techniques and chemical transformations. Assignments of relative and absolute configurations for the new compounds were achieved using NOESY experiments and by chemical modification including the advanced Mosher's method. Additionally, the structure and relative configuration of compound 3 were confirmed by single-crystal X-ray diffraction analysis. Compounds 1, 3, and 5 displayed significant in vitro antiplasmodial activity against the erythrocytic stages of chloroquine-sensitive Plasmodium falciparum strain NF54. Prototiamin C (3) was the most potent of the compounds isolated, with an IC50 value of 0.44 μM. All compounds tested showed low cytotoxicity for the L6 rat skeletal myoblast cell line.

Antiplasmodial and Cytotoxic Triterpenoids from the Bark of the Cameroonian Medicinal Plant Entandrophragma congoënse.

Diterpenoids from Neoboutonia glabrescens (Euphorbiaceae).

Key Word Index-Enrundrophragma cylindrictuq Meliaceae; stem bark; squalene triterpenoids; sapele; sapelenin. AhstracG-The methylene chloride extract of the stem bark of E~~a~~phr~~ cyii~r~~ gave three new acyclic triterpenoids, the squalene derivatives sapelenins A, B and C. The planar structures of these compounds were determined on the basis of spectroscopic properties and chemical transformations.

Sapelenins a, b and c, acyclic triterpenoids from the stem barkof entandrophragmacylindrzcum

Sapelenins A, B and C, acyclic triterpenoids from the stem bark of Entandrophragma cylindricum

A novel acyclic triterpenoid, sapelenin D (1) was isolated from the stem bark of Entandrophragma cylindricum. Its full structure including absolute configuration was determined from spectroscopic data and by chemical transformation.

David Ngnokam

Papers

Diterpenoids from Neoboutonia glabrescens (Euphorbiaceae).

Sapelenins a, b and c, acyclic triterpenoids from the stem barkof entandrophragmacylindrzcum

Sapelenins A, B and C, acyclic triterpenoids from the stem bark of Entandrophragma cylindricum

Sapelenin D, a New Acyclic Triterpenoid from the Stem Bark of Entandrophragma cylindricum

(+)-7′,7′-Dimethyl-5-hydroxy-2R,3S-trans-pubeschin from Entandrophragma cylindricum