Metabolic Profiling of Inga Species with Antitumor Activity.

This work evaluated the metabolic profiling of Inga species with antitumor potential. In addition, we described the antigenotoxicity of polyphenols isolated from I. laurina and a proteomic approach using HepG2 cells after treatment with these metabolites. The in vitro cytotoxic activity against HepG2, HT-29 and T98G cancer cell lines was investigated. The assessment of genotoxic damage was carried out through the comet assay. The ethanolic extract from I. laurina seeds was subjected to bioassay-guided fractionation and the most active fractions were characterized. One bioactive fraction with high cytotoxicity against HT-29 human colon cancer cells (IC50 = 4.0 µg mL-1) was found, and it was characterized as a mixture of p-hydroxybenzoic acid and 4-vinyl-phenol. The I. edulis fruit peel (IC50 = 18.6 µg mL-1) and I. laurina seed (IC50 = 15.2 µg mL-1) extracts had cytotoxic activity against the cell line T98G, and its chemical composition showed a variety of phenolic acids. The chemical composition of this species indicated a wide variety of aromatic acids, flavonoids, tannins, and carotenoids. The high concentration (ranging from 5% to 30%) of these polyphenols in the bioactive extract may be responsible for the antitumor potential. Regarding the proteomic approach, we detected proteins directly related to the elimination of ROS, DNA repair, expression of tumor proteins, and apoptosis.

Terpenoids, Flavonoids and Acetogenins from Some Malagasy Plants.

Humulanes, drimanes, ent-kaurane, lupane, cycloartane, flavanone, flavones and quinol derivatives were isolated from Malagasy Cussonia vantsilana, Helichrysum gymnocephalum, Phyllarthron madagascariense, Gomphocarpus fructicosus, Cinnamosma sp. and C. fragrans, and their structures elucidated by using extensive NMR analysis. A mixture of a few flavones and/or lupane triterpene showed antimicrobial activity against Mycobacterium smegmatis and Pseudomonas aeruginosa.

3,4-seco-24-homo-28-nor-Cycloartane and drimane-type sesquiterpenes and their lactams from the EtOAc-soluble fraction of a leaf extract of Cinnamosma fragrans and their biological activity.

From the EtOAc-soluble fraction of a MeOH extract of leaves of Cinnamosma fragrans, seven new compounds, including 3,4-seco-24-homo-28-nor-cycloartane, drimane-type sesquiterpenes and their lactams, and two known compounds were isolated. Their structures were elucidated by extensive analyses of spectroscopic data. The cytotoxicity, anti-multidrug resistance activity, and anti-Leishmania activity of a cycloartane derivative and drimane-type sesquiterpene derivatives were assayed. The cycloartane derivative showed strong cytotoxicity, and some drimanes and drimane lactam showed moderate anti-multidrug resistance and anti-Leishmania activity.

Isolation of antiplasmodial anthraquinones from Kniphofia ensifolia, and synthesis and structure-activity relationships of related compounds.

Bioassay-guided separation of the South African plant Kniphofia ensifolia for antiplasmodial activity led to the isolation of two new anthraquinones, named kniphofiones A and B (3 and 4), together with three known bioactive anthraquinone monomers (1, 2 and 5), and four known bisanthraquinones (6-9). The structures of the two new compounds were elucidated based on analyses of their 1D and 2D NMR spectra and mass spectrometric data. The dimeric compounds 6 and 7 displayed the strongest antiplasmodial activity among all the isolated compounds, with IC50 values of 0.4 ± 0.1 and 0.2 ± 0.1 µM, respectively. The two new compounds displayed modest activities, with IC50 values of 26 ± 4 and 9 ± 1 µM, respectively. Due to the synthetic accessibility of the new compounds and the increased activity shown by the dimeric compounds, a structure-activity relationship study was conducted. As a result, one analogue of kniphofione B (4), the caffeic acid derivative of aloe-emodin, was found to have the highest activity among all the aloe-emodin derivatives, with an IC50 value of 1.3 ± 0.2 µM.

A new bioactive diterpene glycoside from Molinaea retusa from the Madagascar dry forest.

In a continuing collaboration in a search for new antiproliferative compounds in Madagascar as part of an International Cooperative Biodiversity Group (ICBG), an ethanol extract of Molinaea retusa Radlk. (Sapindaceae) was investigated on the basis of its moderate antiproliferative activity against the A2780 human ovarian cancer cell line (IC50 16 microg/mL). One new compound, 2", 3", 4", 6'-de-O-acetylcupacinoside (1, IC50 15.4 microM) and two known compounds, cupacinoside (2, IC50 9.5 microM) and 6-de-O-acetylcupacinoside (3, IC50 10.9 microM), were isolated by bioassay-directed fractionation using liquid-liquid partitioning, column chromatography, and HPLC. Compounds 2 and 3 also had moderate antiplasmodial activities, with IC50 values of 4.0 and 6.4 microM, respectively, against Plasmodium falciparum, Dd2 strain. The structures were determined using spectroscopic methods.

Bioactive compounds from Stuhlmannia moavi from the Madagascar dry forest.

Bioassay-directed fractionation of the leaf and root extracts of the antiproliferative Madagascar plant Stuhlmannia moavi afforded 6-acetyl-5,8-dihydroxy-2-methoxy-7-methyl-1,4-naphthoquinone (stuhlmoavin, 1) as the most active compound, with an IC50 value of 8.1 µM against the A2780 human ovarian cancer cell line, as well as the known homoisoflavonoid bonducellin (2) and the stilbenoids 3,4,5'-trihydroxy-3'-methoxy-trans-stilbene (3), piceatannol (4), resveratrol (5), rhapontigenin (6), and isorhapontigenin (7). The structure elucidation of all compounds was based on NMR and mass spectroscopic data, and the structure of 1 was confirmed by a single crystal X-ray analysis. Compounds 2-5 showed weak A2780 activities, with IC50 values of 10.6, 54.0, 41.0, and 74.0 µM, respectively. Compounds 1-3 also showed weak antimalarial activity against Plasmodium falciparum with IC50 values of 23, 26, and 27 µM, respectively.

Structure elucidation of antiproliferative bisbenzylisoquinoline alkaloids from Anisocycla grandidieri from the Madagascar dry forest.

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.

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 homoscalarane sesterterpenes from two Madagascan sponges.

Dereplication of the antiproliferative ethyl acetate fraction of the Madagascan sponge Carteriospongia sp. led to the detection and isolation of the two known homoscalarane-type sesterterpenes 1 and 2. Investigation of a similar sponge containing closely related compounds afforded the four new antiproliferative homoscalarane sesterterpenes (3 and 5-7). The structures of all isolated compounds were elucidated by spectroscopic methods, including UV, IR and 1D and 2D NMR. Compounds 1, 3 and 5 displayed submicromolar antiproliferative activity against the A2780 ovarian cell line with IC50 values of 0.65, 0.26 and 0.28 µM, respectively, while compounds 6 and 7 showed moderate activity (4.5 and 8.7 µM, respectively). Compounds 3 and 5 also displayed anti-proliferative activity against the H522-T1 non-small cell lung and A2058 human melanoma cancer cell lines.

Eight new diterpenoids and two new nor-diterpenoids from the stems of Croton cascarilloides.

From the stems of Croton cascarilloides, eight new diterpenoids, named crotocascarins A-H (1-8), having a crotofolane skeleton were isolated along with two new nor-diterpenoids (9 and 10), named crotocascarins α and ß, derived through rearrangement of the crotofolane skeleton. The structures of these compounds were elucidated by means of extensive one- and two-dimensional NMR spectroscopic analyses. The absolute structures of the diterpene moiety were determined by application of the circular dichroism (CD) rule for the γ-lactone ring. The relative structures of the two crotofolanes (1 and 2) and one rearranged compound (9) were confirmed by X-ray crystallographic analyses. Compounds 1, 2 and 9 possessed 2-methylbutyric acid in their molecules, the absolute configuration of which was found to be 2S by comparison of its HPLC behavior with that of an authentic sample. Therefore, the absolute structures of these crotocascarins (1, 2 and 9) were unambiguously determined. The absolute structures of crotofolanes are reported for the first time in this paper.

Two antiproliferative triterpene saponins from Nematostylis anthophylla from the highlands of Central Madagascar.

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.

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).

C-Glycosyl flavonoids and coloratane-type sesquiterpene glucosides from the water-soluble fraction of a leaf extract of a Malagasy endemic plant, Cinnamosma fragrans (Canellaceae).

Leaves of Cinnamosma fragrans were extracted with MeOH, and the concentrated MeOH extract was partitioned with EtOAc and H2O. From the H2O-soluble fraction, three new flavonol C-glycosides and two coloratane glucosides were isolated, along with nine known compounds. On extensive spectroscopic analysis, C-glycosylation was found to have occurred on the B-ring.

Isolation and synthesis of two antiproliferative calamenene-type sesquiterpenoids from Sterculia tavia from the Madagascar rain forest.

Investigation of the endemic Madagascan plant Sterculia taiva Baill. (Malvaceae) for antiproliferative activity against the A2780 ovarian cancer cell line led to the isolation of two new bioactive calamenene-type sesquiterpenoids, named tavinin A (2) and epi-tavinin A (3) together with the known sesquiterpenoid mansonone G (1). The structures of the two new compounds were elucidated based on analysis of their 1D and 2D NMR spectra and mass spectrometric data, and were confirmed by de novo synthesis. The three isolated sesquiterpenoids (1-3) had modest antiproliferative activities against the A2780 ovarian cancer cell line, with IC(50) values of 10.2, 5.5 and 6.7 µM, respectively.

Distribution of drimane sesquiterpenoids and tocopherols in liverworts, ferns and higher plants: Polygonaceae, Canellaceae and Winteraceae species.

The liverwort, Porella vernicosa complex produces a very hot tasting polygodial, a drimane-type sesquiterpene dialdehyde. The same compound has been isolated from two ferns, Thelypteris hispidula and Blechnum fluviatile, as well as from the higher plants Polygonum hydropiper, P. hydropiper f. purpurascens (Polygonaceae), Cinnamosma, Caspicodendron, Canella and Warburgia species (Canellaceae), and Pseudowintera colorata, Tasmannia lanceolata, Drimys and Zygogynum species (Winteraceae). In addition, the liverworts and higher plants which elaborate polygodial and its related pungent drimane dials contain a small amount of alpha-tocopherol, gamma-tocopherol or delta-tocotrienol. The present paper gives the results of a comparative study on the drimane-type sesquiterpenoids in some liverworts, ferns and higher plants, and the role of tocopherols in these plant groups.

Two antiproliferative saponins of Tarenna grevei from the Madagascar dry forest [1].

Antiproliferative bioassay-guided fractionation of the ethanol extract of the endemic Malagasy Rubiaceous plant Tarenna grevei led to the isolation of two new antiproliferative oxygenated oleanane triterpene saponins. The structures of the two active compounds were elucidated as 23-hydroxylongispinogenin 3-O-beta-D-glucopyranoside (1) and longispinogenin 3-O-beta-D-glucopyranosyl (1 --> 2)-beta-D-glucopyranoside (3) by analyses of their spectral data including 1D- and 2D-NMR spectroscopy and chemical evidence. Compounds 1 and 3 displayed moderate antiproliferative activity against the A2780 ovarian cancer cell line with IC50 values of 7.6 and 4 microM, respectively.

Glucosylated sesquiterpene alcohols from Fraxinus griffithii.

Phytochemical investigation of the leaves of Fraxinus griffithii has led to the isolation of two new glucosylated acyclic sesquiterpene alcohols, griffithosides D (1) and E (2), along with iridoid and secoiridoid glycosides. The molecular structures of these compounds were elucidated using NMR, MS and other spectroscopic techniques, as well as comparison with literature data. The isolated compounds were tested for radical-scavenging activity and cytotoxicity against A549 human lung adenocarcinoma cells and Leishmania major parasites.

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.

Entadosides A-D, triterpene saponins and a glucoside of the sulphur-containing amide from the kernel nuts of Entada phaseoloides (L.) Merrill.

From a MeOH extract of kernel nuts of Entada phaseoloides (L.) Merrill, one new and one known sulphur-containing glucoside were isolated. From the 1-BuOH-soluble fraction of a H(2)O extract, four new triterpene saponins containing N-acetylglucosamine in their sugar chains were isolated. The antiproliferative activities of the triterpene saponins were assayed.

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.