Bioassay-guided fractionation of an extract of the fruit of Macaranga alnifolia from Madagascar led to the isolation of four new prenylated stilbenes, schweinfurthins E-H (1-4), and one new geranylated dihydroflavonol, alnifoliol (5). The known prenylated stilbene, vedelianin (6), and the known geranylated flavonoids, bonanniol A (7), diplacol (8), bonannione A (9) and diplacone (10), were also isolated. All ten compounds were tested for antiproliferative activity in the A2780 human ovarian cancer cell line assay. Vedelianin (IC 50 = 0.13 µM) exhibited the greatest activity among all isolates, while schweinfurthin E (IC 50 = 0.26 µM) was the most potent of the new compounds.The genus Macaranga is a large genus of the Euphorbiaceae family. Observation of Macaranga plants in their natural environment has revealed that they produce thread-like wax crystals on their ste ms, which make the slippery surfaces impassable for all insects except a species of ants known as "wax runners". Chemical analysis has indicated that terpenoids make up a majority of the wax bloom content that helps maintain this symbiotic relationship between plant and insect. 2 One of the more commonly studied species of this genus is M. tanarius, noted for its diterpenoid 3,4 and flavonoid 5-7 content. Work has also been performed on the isolation and characterization of terpenes from M. carolinensis ,8 flavonoids from M. conifera 9 and M. denticulate ,10 chromenoflavones from M. indica , 11 clerodane diterpenes from M. monandra , 12 bergenin derivatives and polyphenols from M. peltata , 13 , 14 prenylflavones from M. pleiostemona , 15 a geranyl flavanone from M. schweinfurthii ,16 tannins from M. sinensis ,17 a rotenoid and other compounds from M. triloba , 18 and a geranylflavonol from M. vedeliana. 19 No phytochemical studies have been previously reported for M. alnifolia.

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.

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 μM, respectively.In our continuing search for bioactive molecules from the Madagascar rainforests as part of an International Cooperative Biodiversity Group (ICBG) program, we obtained an extract of the roots of Dodonaea viscosa (L.) Jacq. (Sapindaceae). This extract, designated MG 3397, showed reproducible cytotoxicity to the A2780 ovarian cancer cell line, with an IC 50 value of 6.0 μg/ mL. The extract was selected for bioassay-guided fractionation based on this activity. Previous work on Dodonaea viscosa revealed the presence of flavonoids, 2 fatty acids, 3 and cyanolipids. 4 Some ent-clerodane diterpenoids were obtained from D. boroniaefolia. 5 A southern Brazilian outbreak of acute hepatic insufficiency in which 14 dairy animals died after consumption of Dodonaea viscosa has been reported. 6 In this paper, we report the isolation, structure elucidation, and antiproliferative activity of two new triterpenoid saponins (1 and 2) obtained from the roots of Dodonaea viscosa.Liquid-liquid partitioning of a portion of an EtOH extract of the roots of Dodonaea viscosa into hexane, CH 2 Cl 2 and aqueous MeOH fractions indicated that the CH 2 Cl 2 fraction (326.5 mg) was the most active fraction, with an IC 50 value of 1.0 μg/mL. Purification of the CH 2 Cl 2 fraction using a C 18 open column, followed by preparative C 18 HPLC, led to the isolation of antiproliferative compounds 1 and 2.* To whom correspondence should be addressed. Tel: (540) Table 1). 8 The identity of these signals confirmed the structure of compound 1 as shown. 10 Compound 2 was also obtained as a white amorphous solid. Comparison of the NMR data (Table 1) of 1 and 2 in CD 3 OD indicated that there was no substituent at the C-15 position of 2 and that the angeloyl group at the C-21 position of 1 was replaced by an epoxyangeloyl group in 2. The NMR spectra indicated that the other parts of 2 were identical to those of 1. The NMR data of the aglycone and the two substitutents at both the C-21 and C-22 positions of 2 were compatible with those of 22-angeloyl-21-epoxyangeloylbarringtogenol. 11 Therefore, the structure of 2 was determined as shown.Compounds 1 and 2 are oleanane-type triterpenoid saponins with a double bond at the 12-position, an OH group at the 16-position, and substituents at the 3-, 21-, and 28-positions, like gummiferaosides A-C. 12 The triterpenoid sapogenin portion of 1 and 2 is similar to 3β,15α, 21β,22α,28-pentahydroxy-16α-angeloyloxy-12-oleanene isolated from Dodonaea viscosa. 13Cao et al.