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The two new lignans 3α-O-(β-D-glucopyranosyl)desoxypodophyllotoxin (1) and 4-O-(β-D-glucopyranosyl)dehydropodophyllotoxin (2) were isolated from Cleistanthus boivinianus, together with the known lignans deoxypicropodophyllotoxin (3), (±)-β-apopicropodophyllin (4), (-)-desoxypodophyllotoxin (5), (-)-yatein (6), and β-peltatin-5-O-β-D-glucopyranoside (7). The structures of all compounds were characterized by spectroscopic techniques. Compounds 1, 4, and 5 showed potent antiproliferative activities against the A2780 ovarian cancer cell line, with IC50 values of 33.0 ± 3.6, 63.1 ± 6.7, and 230 ± 1 nM, respectively. Compounds 2 and 7 showed only modest A2780 activities, with IC50 values of 2.1 ± 0.3 and 4.9 ± 0.1 μM, respectively, while compounds 3 and 6 had IC50 values of >10 μM. Compound 1 also had potent antiproliferative activity against the HCT-116 human colon carcinoma cell line, with an IC50 value of 20.5 nM, and compound 4 exhibited modest antiproliferative activity against the A2058 human caucasian metastatic melanoma and MES-SA human uterine sarcoma cell lines, with IC50 values of 4.6 and 4.0 μM, respectively.

Antiproliferative bioassay-guided fractionation of the ethanol extract of the stems of Anisocycla grandidieri led to the isolation of the known alkaloids stebisimine (1), (+)-1,2-dehydrotelobine (2), (+)-2'-norcocsuline (3) and puetogaline B (4). Herein, we report the full NMR assignments of all compounds and the X-ray crystallography of single crystals of compounds 1 and 3. Compounds 2 and 3 showed moderate antiproliferative activity against the A2780 human ovarian cancer cell line with IC50 values of 4.1 ± 0.3 and 2.7 ± 0.3 μM, respectively, and they also displayed selective activity toward the H460 (large cell lung cancer), MCF-7 (breast ductal carcinoma), and UACC-257 (melanoma) cell lines., (Copyright © 2013 John Wiley & Sons, Ltd.)

Investigation of the endemic Madagascan plant Nematostylis anthophylla (Rubiaceae) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the known triterpene saponin randianin (1), and the two new bioactive triterpene saponins 2"-O-acetylrandianin (2) and 6"-O-acetylrandianin (3). The structures of the two new compounds were elucidated based on analysis of their 1D- and 2D-NMR spectra, and mass spectrometric data. The three isolated triterpene saponins displayed moderate but selective antiproliferative activities, with IC(50) values of 1.2, 1.7, and 2.2 μM, respectively, against the A2780 ovarian cancer, but only weak inhibitions of the proliferation of A2058 melanoma and the H522 lung cancer cell lines., (Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.)

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.

Investigation of the endemic Madagascar plant Leptadenia madagascariensis Decne. (Apocynaceae) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of the four new cardenolides 1-4. The structure elucidations of these compounds were based on analyzes of their 1D and 2D NMR spectra and mass spectrometric data. The cardenolides were strongly antiproliferative to the A2780 ovarian cancer cell line, with IC(50) values of 0.18, 0.21, 0.17, and 0.29μM line, and to the H460 human lung cancer cell line, with IC(50) values of 0.16, 0.68, 0.37, and 0.48μM, respectively., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Bioassay-guided fractionation of an ethanol extract of the roots of the endemic Malagasy plant Pongamiopsis pervilleana led to the isolation of the three new compounds (2'R)-4'-hydroxyemoroidocarpan (1), pongavilleanine (3), and epipervilline (4) together with two known compounds, identified as emoroidocarpan (2) and rotenolone (5). The structures of all compounds were determined by physical, chemical, and spectroscopic evidence. The stereochemistry at C-2' of the previously reported compound emoroidocarpan was determined to be R by the observation of a negative Cotton effect at 474 nm in the CD spectrum of its osmate ester derivative. Compounds 2-5 displayed moderate antiproliferative activity against the A2780 human ovarian cancer cell line, and rotenolone also showed micromolar antiproliferative activity toward the breast cancer BT-549, prostate cancer DU 145, NSCLC NCI-H460, and colon cancer HCC-2998 cell lines.

Fractionation of an ethanol extract of a Madagascar collection of the leaves and fruit of Cassipourea lanceolata Tul. led to the isolation of three euphane triterpenoids 1-3. The (1)H and (13)C NMR spectra of all compounds were fully assigned using a combination of 2D NMR experiments, including COSY, TOCSY, HSQC (HMQC), HMBC and ROESY sequences. The three compounds showed weak antiproliferative activities against the A2780 human ovarian cancer cell line, with IC(50) values of 25, 25 and 32 microM, respectively., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Bioassay-guided fractionation of an EtOH extract obtained from the roots of the Madagascan plant Dodonaea viscosa led to the isolation of two new antiproliferative oleanane-type triterpenoid saponins, dodoneasides A and B (1 and 2). The structures of these two new compounds were elucidated using 1D and 2D NMR experiments and mass spectrometry. Compounds 1 and 2 showed antiproliferative activity against the A2780 human ovarian cancer cell line with IC(50) values of 0.79 and 0.70 muM, respectively.

Bioassay-guided fractionation of an ethanol extract of a Madagascar collection of Elaeodendron alluaudianum led to the isolation of two new cardenolide glycosides (1 and 2). The (1)H and (13)C NMR spectra of both compounds were fully assigned using a combination of 2D NMR experiments, including (1)H-(1)H COSY, HSQC, HMBC, and ROESY sequences. Both compounds 1 and 2 were tested against the A2780 human ovarian cancer cell line and the U937 human histiocytic lymphoma cell line assays, and showed significant antiproliferative activity with IC(50) values of 0.12 and 0.07 microM against the A2780 human ovarian cancer cell line, and 0.15 and 0.08 microM against the U937 human histiocytic lymphoma cell line, respectively.

Bioassay-guided fractionation of an ethanol extract of a Malleastrum sp. afforded three new limonoids, malleastrones A-C ( 1- 3), respectively. Each limonoid contained a rare tetranortriterpenoid skeleton. Structure elucidation of the isolates was carried out by analysis of one- and two-dimensional NMR and X-ray diffraction data. The novel isolates 1 and 2 were tested for antiproliferative activity against a panel of cancer cell lines and exhibited IC 50 values ranging from 0.19 to 0.63 microM.

Bioassay-guided fractionation of an ethanol extract of Artabotrys madagascariensis led to the isolation of the new compound artabotrene (1), two butenolides (2 and 3), and the tetracyclic triterpene polycarpol (4). Structure elucidation was determined on the basis of one and two-dimensional NMR, and absolute configuration of compounds 2-4 was verified by analysis of CD and optical rotation spectra. Two of the isolates, melodorinol (2) and acetylmelodorinol (3), were found to display antiproliferative activity against five different tumour cell lines with IC50 values ranging from 2.4 to 12 microM.

Bioassay-guided fractionation of an ethanol extract obtained from the Madagascar plant Elaeodendron sp. led to the isolation of two new cardenolides, elaeodendrosides T and U (1 and 2). The structures of the new compounds were elucidated using 1D and 2D NMR experiments and mass spectrometry. Compounds 1, 3, 4, and 5 showed significant antiproliferative activity against A2780 human ovarian cancer cells with IC50 values of 0.085, 0.019, 0.19, and 0.10 microM, respectively, while compounds 2 and 6 were less active.

Bioassay-guided fractionation of an EtOH extract obtained from the roots of the Madagascan plant Albizia gummifera led to the isolation of three new cytotoxic oleanane-type triterpenoid saponins, gummiferaosides A-C (1-3). The structures of these new compounds were elucidated using 1D and 2D NMR experiments and mass spectrometry. Compounds 1-3 showed cytotoxicity against the A2780 human ovarian cancer cell line with IC50 values of 0.8, 1.5, and 0.6 microg/mL, respectively.