Liva Harinantenaina

MARCHANTIOPHYTA (LIVERWORTS) : RICH SOURCES OF MACROCYCLIC BIS(BIBENZYLS)

The Marchantiophyta (liverworts) produce which show interesting biological activity such as antimicrobial, antifungal, antiobesity and muscle relaxing activity etc. and are of very valuable for the chemosystematic and evolutional study of the Marchantiophyta and pteridophytes. The isolation, identification, structural elucidation and total synthesis of these characteristic natural products and their biological activity are reviewed.

Antiproliferative and Antiplasmodial Dimeric Phloroglucinols from Mallotus oppositifolius from the Madagascar Dry Forest 1

Bioassay-guided fractionation of an ethanol extract of the leaves and inflorescence of Mallotus oppositifolius collected in Madagascar led to the isolation of the two new bioactive dimeric phloroglucinols mallotojaponins B (1) and C (2), together with the known mallotophenone (3). The structures of the new compounds were determined on the basis of spectroscopic evidence, including their 1D- and 2D-NMR spectra, mass spectrometry, and an X-ray crystal structure. Compounds 1 and 2 showed potent antimalarial activity against chloroquine-resistant Plasmodium falciparum, with IC50 values of 0.75 ± 0.30 and 0.14 ± 0.04 μM, while 3 was inactive in this assay. Compounds 1-3 also displayed strong antiproliferative activity against the A2780 human ovarian cancer cell line (IC50 1.10 ± 0.05, 1.3 ± 0.1 and 6.3 ± 0.4 μM, respectively).

Four Diphenylpropanes and a Cycloheptadibenzofuran from Bussea sakalava from the Madagascar Dry Forest

Investigation of the endemic Malagasy plant Bussea sakalava for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the four new diphenylpropanes 1-4 and the new cycloheptadibenzofuran 5; compound 5 has a previously unreported natural product skeleton. The structure elucidation of these compounds was based on the analysis of their 1D and 2D NMR and mass spectroscopic data. Compounds 1-5 were tested for antiproliferative activity against the A2780 human ovarian cancer cell line.

Antiproliferative Homoisoflavonoids and Bufatrienolides from Urginea depressa

Investigation of the South African plant Urginea depressa Baker (Asparagaceae Juss.) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the six new homoisoflavonoids urgineanins A-F (1-6), the two known bufatrienolides 7 and 9, and the new bufatrienolides urginins B and C (8 and 10). Structures were elucidated based on analysis of their 1D and 2D NMR spectra, electronic circular dichroism, and mass spectrometric data. Five of the six new homoisoflavonoids had good antiproliferative activity against the A2780 ovarian cancer, A2058 melanoma, and H522-T1 human non-small-cell lung cancer cells, and urgineanin A (1) had submicromolar activity against all three cell lines. The four bufatrienolides 7-10 had strong antiproliferative activity against the same cell line, with IC50 values of 24.1, 11.2, 111, and 40.6 nM, respectively.

Antiproliferative acetogenins from a Uvaria sp. from the Madagascar dry forest.

Investigation of the endemic Madagascan plant Uvaria sp. for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of two new acetogenins. The structures of these two compounds were elucidated on the basis of analysis of their 1D and 2D NMR spectra, circular dichroism, and mass spectrometric data, together with chemical modification. The two acetogenins display weak antiproliferative activity against the A2780 ovarian cancer, the A2058 melanoma, and the H522 lung cancer cell lines.

Secondary Metabolites of Cinnamosma madagascariensis and Their α-Glucosidase Inhibitory Properties

Two new drimane-type sesquiterpenes, cinnamadin (1) and cinnamodial 11alpha,12beta-dimethyl acetal (2), together with pereniporin B (3), ugandensolide (4), polygodial (5), capsicodendrin, cinnamodial (6), sitosterol, stigmasterol, lignoceric acid, cinnamosmolide (7), D-mannitol, and delta-tocotrienol were isolated from Cinnamosma madagascariensis. The structures of the new compounds were determined by physical, chemical, and spectroscopic evidence. Compound 7 and D-mannitol were isolated in high yield (5% and 1.36%, respectively). Evaluation of the alpha-glucosidase inhibitory properties of the isolated metabolites demonstrated that compounds 1 and 4 show moderate effects, while cinnamodial (6) exhibited the most potent activity. The chemosystematics of Cinnamosma species are also discussed.

An endogenous bile acid and dietary sucrose from skin secretions of alkaloid-sequestering poison frogs.

The skins of Madagascar poison frogs (Mantella) and certain Neotropical poison frogs (Epipedobates, Dendrobates) secrete the new bile acid tauromantellic acid (1), which was found in both wild-caught and captive-born frogs. This is the first molecule of endogenous origin detected in skin secretions from these taxa. Sucrose was also detected in secretions from wild-caught Mantella but not in captive-born frogs, suggesting a dietary origin.

An Acetylated Eudesmane Glucoside from Apodytes dimidiata Growing in Madagascar

A new eudesmane glucoside has been isolated from the aerial part of Apodytes dimidiata, an Icacinaceous plant widely used in the Southern African countries for its molluscicidal activities. The structure of the new compound was determined by spectroscopic methods. The chemosystematics of the genus belonging to the family Icacinaceae is discussed.