Three new bidesmosidic saponins (1-3) and a new ursane triterpenoid, 2α,3β,11α,23-tetrahydroxyurs-12-en-28-oic acid (4), along with seven known compounds, were isolated from a methanolic extract of the leaves of Symplocos lancifolia. The bidesmosidic saponins were found to possess the same sugar unit part, composed of two β-d-glucose moieties and one α-l-rhamnose moiety, linked to maslinic acid, arjunolic acid, and asiatic acid, respectively. Their structures were elucidated by interpretation of their 1D and 2D NMR spectra and completed by analysis of the HRESIMS data. The antibacterial activity of the isolated triterpenoids was evaluated against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa, and several showed activity against Gram-positive bacteria.

Depuis des millenaires, l'homme profite des ressources de la nature pour se soigner, en particulier dans le domaine des maladies cancereuses, ou 60 % des medicaments utilises proviennent des plantes (taxol, vinblastine, podophyllotoxine, combretastatines...), des invertebres marins (aracytine, dolastatines, ecteinascidines...) ou des micro-organismes (daunomycine, epothilones...). La biodiversite unique du patrimoine vivant est ainsi une source sans pareil de decouvertes pouvant enrichir la therapeutique.

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Two new epimeric tricyclic alkaloids, myrioxazines A and B were isolated from the leaves of Myrioneuron nutans and their structures elucidated by spectral analysis (mass spectrometry and 2D NMR). Absolute configurations were determined by total asymmetric synthesis.

Three new compounds, prepromalabaricone B (1) and two dimeric acylphenols, giganteones A (2) and B (3) were isolated from EtOAc extract of the fruits of Myristica gigantea (Myristicaceae), together with known promalabaricone C (4), malabaricones A–C (5–7) and maingayone (8). The structures were determined by mass and 2D NMR spectral analysis, and the enzymatic synthesis of giganteones A and B was performed from malabaricone C. Both 2 and 3 possess significant cytotoxic activity in vitro against human nasopharynx KB cells.

Total synthesis of two cytotoxic natural products, nelumol A (1) and nelumal A (2), were carried out by two different paths. 4-O-Benzyl substitute analogues 26 and 27, as well as the 4-O-(2-methyl-butenyl) derivatives 29 and 30 were also synthesized for a SAR investigation. 1 and 2 were also measured on different tumor cell line.

Two alkaloids, furomegistine I (1) and furomegistine II (2), were isolated from the bark of Sarcomelicope megistophylla. Their structures have been elucidated on the basis of MS and NMR data. Both belong to the category of furanopyridine alkaloids and should be considered as oxidation products of a furo[2,3-b]quinoline precursor. The two alkaloids exhibited moderate cytotoxic activity.

Two new alkaloids, megistosarcimine and megistosarconine, were isolated from the aerial parts of Sarcomelicope megistophylla. Their structures have been elucidated on the basis of their spectral data and molecular modeling.

The leaves of Comptonella microcarpa have yielded one alkaloid, dictamnine, and four known polyoxygenated flavonoids, meliternatin, 3,5,8-trimethoxy-6,7-3',4'-dimethylenedioxyflavone, 7-(3-methylbut-2-enyloxy)-3,5,8-trimethoxy-3', 4'-methylenedioxyflavone (3), 7-hydroxy-3,5,8-trimethoxy-3', 4'methylenedioxyflavone. In addition, two new flavonoids were found whose structures were established on the basis of their spectral data as 7-hydroxy-3,5,6,8-tetramethoxy-3',4'-methylenedioxyflavone (1) and 7-(3-methylbut-2-enyloxy)-3,5,6,8-tetramethoxy-3', 4'-methylenedioxyflavone (2).

Chemical investigation of the methanolic fraction of Lepisanthes rubiginosa bark has led to the isolation and characterisation of a new tetrasaccharide derivative of farnesol named rubiginoside along with known triterpenoid saponins.

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) (CAS Reg. No. 481-42-5) was isolated from the bark of Diospyros olen (Ebenaceae) via an antibiotic guided biological assay using the bacterium Pseudomonas solanacearum. D. olen bark, collected in New Caledonia, was extracted with dichloromethane and components separated by flash chromatography on silica.[...]

Six new triterpenoid saponins, maelaxins A-F (1-6), were isolated from a n-BuOH extract of the leaves of Maesa laxiflora. They possess 22-O-angeloyl-camelliagenin A, 16-O-acetyl, 22-O-angeloyl-camelliagenin A, or 22-O-(2Z)-hexenoyl-camelliagenin A as the aglycon. The pentasaccharide moiety linked to C-3 of the aglycon consists of D-glucuronic acid, L-rhamnose, D-glucose, and/or D-galactose. Their structures were elucidated by extensive NMR experiments including 1H-1H (COSY, 2D HOHAHA, NOESY) and 1H-13C (HMQC and HMBC) spectroscopy and chemical evidence.

Starting from the discoveries of navelbine and taxotere, two potent analogs of natural antitumour compounds, the search of new antitumour drugs has continued at Gif-sur-Yvette, by associating classical cytotoxicity assays with other mechanism involved in the cell replication pathway. The tubulin-microtubules system, an easy and efficient method, is one of the targets used in finding new antimitotic drugs. Through various research programmes in tropical countries and in the framework of the long-term cooperation between the University of Malaya and CNRS, a number of molecules have been shown to possess activity on tubulin. Among them, rhazinilam, isolated from a Malaysian Kopsia, K. singapurensis Ridley, Apocynaceae. It has specific activity on microtubules. Studies of structure-activity relationships guided by the tubulin-test have led to a better knowledge of the properties of rhazinlam and to the design of analogs. Cytotoxic prenylxanthones have also been isolated from Vietnaamese Garcinia, G. nigrolineata (Clausiaceae). Nigrolineatin and its analogues possess anti-oncogene activity on FPTase. Other xanthone derivatives like xanthochymol were isolated from a Malaysian Garcinia, G. pyrifera and were found to possess activity on tubulin. Structure-activity relationships studies on these series have been done. Key Words: Antimitotic properties, Tubulin, Kopsia singapurensis, rhazinilam, Garcinia species, xanthones Nig. J. Nat Prod. And Med. Vol.3 1999: 9-14

Three new monoterpene indole alkaloids, 16-hydroxymethyl-pleiocarpamine 2, 16-epi-deacetylakuammiline 4 and 14 alpha-hydroxycondylocarpine 8, have been isolated from the stem bark of Kopsia deverrei (Apocynaceae). The proposed structures were assigned after detailed analysis of their H-1 and C-13 NMR spectra and by chemical correlation.

Two novel alkaloids, 1-oxo-1,2-dihydro-12-demethyl-12-hydroxyacronycine (1) and 2,3-dicarbomethoxy-1-methyl-4(1H)-quinolinone (3) have been isolated from the leaves of Sarcomelicope dogniensis. The biogenesis of this latter most probably involves oxidation of the A aromatic ring of a 1,2,3,4-tetra-O-subtituted acridone, such as melicopidine.