Cytotoxic diterpenoids from Podocarpus madagascariensis from the Madagascar rainforest.

Bioassay-directed fractionation of an extract of the root and bark of Podocarpus madagascariensis resulted in the isolation of a new totarol diterpenoid (1) in addition to the three known cytotoxic diterpenoids 19-hydroxytotarol (2), totaradiol (3), and 4beta-carboxy-19-nor-totarol (4). The structure of the new compound 1 was established as methyl-13-hydroxy-14-isopropyl-9(11),12,14(8)-podocarpatriene-19-oate on the basis of 1D and 2D NMR spectroscopic interpretation and methylation of 4. All the compounds exhibited cytotoxic activity against the A2780 ovarian cancer cell line.

Cytotoxic diterpenes from Cassipourea madagascariensis from the Madagascar rainforest.

Bioassay-directed fractionation of ethanol extracts of the roots and leaves of the plant Cassipourea madagascariensis resulted in the isolation of the two new terpenoids cassipourol (1) and cassipouryl acetate (2) in addition to the three known compounds, 3beta,30-dihydroxylup-20(29)-ene (3), 30-hydroxylup-20(29)-en-3-one (4), and combretol (5). The structures of the two new compounds were established on the basis of 1D and 2D NMR spectroscopic data and chemical conversion. All the isolated compounds were tested against the A2780 human ovarian cancer cell line; the two diterpenes (1 and 2) showed moderate cytotoxic activity, while the three known compounds (3-5) were weakly active.

New cytotoxic coumarins and prenylated benzophenone derivatives from the bark of Ochrocarpos punctatus from the Madagascar rainforest.

Bioassay-guided fractionation of a CH2Cl2-MeOH extract of the bark of Ochrocarpos punctatus resulted in the isolation of seven new coumarins, ochrocarpins A-G (1-7), three new benzophenone derivatives, ochrocarpinones A-C (8-10), and five known coumarins, mammea A/AC cyclo F (11), mammea A/AD cyclo D (12), mammea A/AB cyclo F (13), mammea A/AA cyclo F (14), mammea A/AB cyclo D (15), and 15,16-dihydro-16-hydroperoxyplukenetione (16). The structures of compounds 1-10 were established on the basis of extensive 1D and 2D NMR spectroscopic data interpretation. All compounds exhibited cytotoxicity against the A2780 ovarian cancer cell line.

A new ursane triterpene from Monochaetum vulcanicum that inhibits DNA polymerase beta lyase.

Bioassay-directed fractionation of a butanone extract of Monochaetum vulcanicum resulted in the isolation of a new triterpene (1) and four known compounds, ursolic acid (2), 2alpha-hydroxyursolic acid (3), 3-(p-coumaroyl)ursolic acid (4), and beta-sitosteryl-beta-d-galactoside (5). The structure of the new compound 1 was established as 3beta-acetoxy-2alpha-hydroxyurs-12-en-28-oic acid on the basis of extensive 1D and 2D NMR spectroscopic interpretation and chemical derivatization. Compounds 1-3 and 5 exhibited polymerase beta lyase activity.

New cytotoxic oleanane saponins from the infructescences of Polyscias amplifolia from the Madagascar rainforest.

Bioassay-guided fractionation of an ethanolic extract of the infructescences of Polyscias amplifolia resulted in the isolation of two new oleanolic acid saponins, polyfoliolides A (1) and B (2), in addition to the two known saponins 3-O-beta-D-galactopyranosyloleanolic acid (3) and 3-O-beta-D-galactopyranosyl-(1-->4)-beta-D-galactopyranosyloleanolic acid (4). The structures of the two new compounds were established as 3-O-beta- D-galactopyranosyl-(1-->4)-beta-D-xylopyranosyloleanolic acid (1) and 3-O-beta-D-galactopyranosyl-(1-->4)-alpha-L-arabinopyranosyloleanolic acid (2) on the basis of extensive 1D and 2D NMR spectroscopic data interpretation and chemical conversions. All the isolated compounds showed weak cytotoxicity against A2780 human ovarian cancer cell line, with IC50 values in the range 6.7 to 10.8 microg/mL.

New lupane triterpenoids from Solidago canadensis that inhibit the lyase activity of DNA polymerase beta.

Bioassay-directed fractionation of a methyl ethyl ketone extract of Solidago canadensis L. (Asteraceae), using an assay to detect the lyase activity of DNA polymerase beta, resulted in the isolation of the four new lupane triterpenoids 1-4 and the seven known compounds lupeol, lupeyl acetate, ursolic acid, cycloartenol, cycloartenyl palmitate, alpha-amyrin acetate, and stigmasterol. The structures of the new compounds were established as 3beta-(3R-acetoxyhexadecanoyloxy)-lup-20(29)-ene (1), 3beta-(3-ketohexadecanoyloxy)-lup-20(29)-ene (2), 3beta-(3R-acetoxyhexadecanoyloxy)-29-nor-lupan-20-one (3), and 3beta-(3-hetohexadecanoyloxy)-29-nor-lupan-20-one (4), respectively, on the basis of extensive 1D and 2D NMR spectroscopic interpretation and chemical modification studies. All 11 compounds were inhibitory to the lyase activity of DNA polymerase beta.

New cytotoxic terpenoids from the wood of Vepris punctata from the Madagascar Rainforest.

Continuation of the chemical examination of the cytotoxic constituents of the wood of Vepris punctata resulted in the isolation of the two new terpenoids 1 and 2 and eight known compounds, glechomanolide (3), isogermafurenolide, (E,E)-germacra-1(10),4,7(11)-triene, alpha-amyrin, lupeol, lupeyl acetate, taraxerol, and 3-epi-taraxerol, in addition to the alkaloids reported reported previously. The structures of the two new compounds were established on the basis of 1D and 2D NMR spectroscopic data interpretation and chemical modifications. All the isolated compounds were tested against the A2780 human ovarian cancer cell line; the four sequiterpenoids showed moderate cytotoxic activity, while the six triterpenoids were inactive.

New cytotoxic bis 5-alkylresorcinol derivatives from the leaves of Oncostemon bojerianum from the Madagascar rainforest.

Bioassay-directed fractionation of a CH(2)Cl(2)-MeOH extract of the leaves of Oncostemon bojerianum resulted in the isolation of eight new 5-alkylresorcinols, named oncostemonols A-H (1-8), and two known derivatives, (8'Z)-1,3-dihydroxy-5-[16'-(3' ',5' '-dihydroxyphenyl)-8'-hexadecen-1'-yl]benzene (9) and (8'Z)-1,3-dihydroxy-5-[14'-(3' ',5' '-dihydroxyphenyl)-8'-tetradecen-1'-yl]benzene (10). The structures of the new compounds 1-8 were elucidated on the basis of extensive 1D and 2D NMR spectroscopic interpretation and chemical derivatization. All the compounds exhibited cytotoxic activity against the A2780 ovarian cancer cell line.

Two new triterpene esters from the twigs of Brachylaena ramiflora from the Madagascar rainforest.

Bioassay-guided fractionation of a CH(2)Cl(2)/MeOH extract of the small twigs of Brachylaena ramiflora var. ramiflora resulted in the isolation of the two new triterpene esters 1 and 2 and five known triterpenoids, alpha-amyrin palmitate (3), beta-amyrin palmitate (4), beta-amyrin acetate (5), lupeyl acetate (6), and lupeol (7). The structures of the two new compounds were established as kairatenyl palmitate (1) and hopenyl palmitate (2) on the basis of 1D and 2D NMR spectroscopic data interpretation and chemical conversions. All the isolated compounds showed weak cytotoxicity against the A2780 human ovarian cancer cell line.

New eudesmane derivatives from Melampodium camphoratum from the Suriname rainforest.

Bioassay-guided fractionation of an EtOAc extract of the leaves of Melampodium camphoratum using an assay for inhibitors of the degradation of hemin resulted in the isolation of six new eudesmane sesquiterpenes (1-6) and the known 6-epi-beta-verbesinol coumarate (7). The structures of compounds 1-6 were established as 6alpha-(4'-O-methyl-7'E-coumaryloxy)eudesm-4(14)-ene (1), 6alpha-({4'-O-stearyl}-7'E-coumaryloxy)eudesm-4(14)-ene (2), 6alpha-({4'-O-palmityl}-7'E-coumaryloxy)eudesm-4(14)-ene (3), 6alpha-({4'-O-[9' 'Z-hexadecenoyl]}-7'E-coumaryloxy)eudesm-4(14)-ene (4), 6alpha-(7'Z-coumaryloxy)eudesm-4(14)-ene (5), and 6alpha-({4'-acetoxy}-7'Z-coumaryloxy)eudesm-4(14)-ene (6). Compounds 1-4 showed weak activity in the hemin degradation assay, while compounds 5-7 were inactive.