Antiplasmodial activity of New Caledonia and Vanuatu traditional medicines.

CONTEXT: With the emergence of strains multiresistant to antimalarial drugs, the search for new active molecules remains a priority. Ethnopharmacology appears to be a good method of selection in such investigations. OBJECTIVE: The aim of this research work is to select plants used in Melanesian traditional medicine, in New Caledonia and Vanuatu, which should be a promising source for the isolation of new antimalarial drugs. MATERIALS AND METHODS: Forty-seven plant extracts belonging to 12 families, traditionally used by the Melanesian people or belonging to an antimalarial known genus, were screened in vitro for antimalarial activity on Plasmodium falciparum chloroquine (CQ)-resistant (FcB1) and CQ-sensitive (HB3) strains. They were also tested for their inhibitory effects on a protein kinase (Pfnek) and their cytotoxicity on human breast adenocarcinoma (MCF7) cells. RESULTS: Among all extracts, four displayed strong in vitro activities against P. falciparum: Gardenia urvillei Montrouzier, Scleria polycarpa Boeckeler, Terminalia catappa L. and Acronychia laevis J.R. & J.G. Forster, the latter being also toxic on MCF7 cells. Except for the extracts of S. polycarpa, all others that were active on P. falciparum, also possess an inhibitory effect on Pfnek. DISCUSSION AND CONCLUSION: These results confirm that ethnopharmacology is an excellent approach for such investigations. The two countries considered clearly present advantages in the field. Indeed, local populations keep their traditional knowledge alive, and their flora is exceptionally rich. In New Caledonia, the high endemicity rate (74%) ranks the island as one of the world's biodiversity hotspots. As a consequence, chances to discover new active natural compounds are also high.

Chemical investigations of essential oils from endemic Cupressaceae trees from New Caledonia.

The volatile components obtained by hydrodistillation of leaves of C. neocaledonica Dummer, C. sulcata (Parlatore) Schlechter and N. pancheri (Carrière) de Laubenfels from New Caledonia were investigated for the first time by a combination of GC and GC-MS analysis, and compared with the heartwood oil compositions of the three species. The essential oils from C. sulcata and C. neocaledonica leaves contain a majority of monoterpenes while the leaf oil of N. pancheri is characterized by a high level of sesquiterpenoids. On the basis of the sesquiterpenoid composition of the wood- and leaf oils, N. pancheri is closely related to both New Caledonian Callitris spp. However, C. sulcata and C. neocaledonica oils remain distinct from N. pancheri and the Australian Callitris oils by the presence of compounds biosynthetically related to the bisabolyl cation, mainly barbatenes and thujopsene.

Chemical composition and antimicrobial activity of the essential oils from New Caledonian Citrus macroptera and Citrus hystrix.

The essential oils from the leaves of Citrus macroptera and C. hystrix, collected in New Caledonia, have been analyzed by gas chromatography/mass spectrometry (GC/MS) and evaluated for their antimicrobial activity. A total of 35 and 38 constituents were identified, representing 99.1 and 89.0% of the essential oils, respectively. Both essential oils were rich in monoterpenes (96.1 and 87.0%, resp.), with beta-pinene as major component (33.3 and 10.9%, resp.), and poor in limonene (2.4 and 4.7%, resp.). Other main components of C. macroptera oil were alpha-pinene (25.3%), p-cimene (17.6%), (E)-beta-ocimene (6.7%), and sabinene (4.8%). The essential oil of C. hystrix was characterized by high contents of terpinen-4-ol (13.0%), alpha-terpineol (7.6%), 1,8-cineole (6.4%), and citronellol (6.0%). The antimicrobial activity was evaluated against five bacteria and five fungi strains. Both oils were inactive against bacteria. However, the C. macroptera leaf oil exhibited a pronounced activity against Trichophyton mentagrophytes var. interdigitale, with a minimal-inhibitory concentration (MIC) of 12.5 microg/ml.

Antiparasitic activity of some New Caledonian medicinal plants.

Twenty-nine extracts of 18 medicinal plants used in New Caledonia by traditional healers to treat inflammation, fever and in cicatrizing remedies were evaluated in vitro against several parasites (Leishmania donovani, Trypanosoma brucei brucei, Trichomonas vaginalis and Caenorhabditis elegans). Among the selected plants, Scaevola balansae and Premna serratifolia L. were the most active against Leishmania donovani with IC(50) values between 5 and 10microg/ml. The almond and aril extracts from Myristica fatua had an IC(50) value of 0.5-5microg/ml against Trypanosoma brucei brucei. Only Scaevola balansae extract presented a weak activity against Trichomonas vaginalis. The almond extract from Myristica fatua presented significant activity against Caenorhabditis elegans (IC(50) value of 6.6+/-1.2microg/ml).

Bioassay-guided isolation of antifungal alkaloids from Melochia odorata.

An alkaloidal extract of the leaves of Melochia odorata exhibited antifungal activity against Candida albicans, Cryptococcus neoformans and Saccharomyces cerevisiae using a TLC bioautographic method. Bioassay-guided fractionation of this extract using separation by normal and reverse high-performance liquid chromatography (HPLC) resulted in the isolation of two active compounds identified as frangulanine, a cyclic peptide alkaloid, and waltherione-A, a quinolinone alkaloid.

seco-Cycloartane triterpenes from Gardenia aubryi.

Three new 3,4-seco-cycloartanes, secaubryenol (1), secaubrytriol (2), and secaubryolide (3), were isolated from an exudate collected on the aerial parts of Gardenia aubryi, in addition to the known (24S)-cycloartane-24,25-diol-3-one, coccinetane A, herbacetin 3,8-dimethyl ether, hibiscetin 3,8,3',4'-tetramethyl ether, and conyzatin. The structures of 1 and 2 were established by mass spectrometry and NMR experiments, while the relative configuration of 2 was defined unequivocally using X-ray crystallography. The in vitro cytotoxic activity of compounds 1-3 was evaluated against four human solid tumor cell lines.

Hepatic injury due to traditional aqueous extracts of kava root in New Caledonia.

Traditional aqueous kava extracts were the most probable cause of hepatitis in two patients presenting with markedly elevated transaminases and hyperbilirubinaemia. A consequent survey of 27 heavy kava drinkers in New Caledonia showed elevated gamma glutamyl transferase in 23/27 and minimally elevated transaminases in 8/27. We conclude that not only commercially available, but also traditionally prepared kava extracts may rarely cause liver injury. The increased activity of gamma glutamyl transferase in heavy kava consumers in the presence of normal or minimally elevated transaminases is probably not a sign of liver injury, but rather reflects an induction of CYP450 enzymes.