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Two new minor silvestrol analogues [2'''-episilvestrol (1) and 2''',5'''-diepisilvestrol (2)], together with a new 21-norbaccharane-type triterpene (3), two new 3,4-secodammarane triterpenes (4 and 5), and a new eudesmane sesquiterpene (6), as well as nine known compounds, were isolated from a large-scale re-collection of the CHCl(3)-soluble extract of the stem bark of Aglaia foveolata obtained in Kalimantan, Indonesia. The structures of the new compounds were established by interpretation of their spectroscopic data. All of the isolates were tested for cytotoxicity against HT-29 cells. The new silvestrol analogues, 1 and 2, were considerably less active as cytotoxic agents than silvestrol (7) and episilvestrol (5'''-episilvestrol) (8) against this cell line, showing the importance of the configuration at C-2''' in mediating such activity within this compound class. Several of the compounds isolated were also evaluated in a NF-κB (p65) inhibition assay.

Four new prenylated flavonoids (1-4), a new stilbenoid (5), and nine known compounds were isolated from the twigs of Artocarpus rigida, collected in Indonesia. The structures of the new compounds were determined by analysis of their spectroscopic data, and the absolute configuration at C-12 of 1 and 2 and the known compounds artonin O (6), artobiloxanthone (7), and cycloartobiloxanthone (8) was determined from their CD and NMR spectroscopic data. Several of the compounds obtained were cytotoxic toward HT-29 human colon cancer cells, with the most potent being compound 2 and the known compounds 6 and 8. Of the substances obtained, compounds 1 and 7 were the most active in the NF-kappaB p50 and p65 assay, respectively.

Bioactivity-guided fractionation of the stem bark of Mitrephora glabra yielded nine compounds, comprising three ent-kaurenoids (1-3), five polyacetylenic acids/esters (4-8), and one aporphine alkaloid, liriodenine (9). The structures of the six new compounds (1-3, 5, 7, and 8) were determined by spectroscopic data interpretation. All compounds were evaluated for their inhibitory activities against a panel of cancer cell lines and a battery of microorganisms.

Bioassay-guided fractionation of a chloroform-soluble extract of Garcinia mangostana stem bark, using the HT-29 human colon cancer cell line and an enzyme-based ELISA NF-kappaB assay, led to the isolation of a new xanthone, 11-hydroxy-3-O-methyl-1-isomangostin (1). The structure of 1 was elucidated by spectroscopic data analysis. In addition, 10 other known compounds, 11-hydroxy-1-isomangostin (2), 11alpha-mangostanin (3), 3-isomangostin (4), alpha-mangostin (5), beta-mangostin (6), garcinone D (7), 9-hydroxycalabaxanthone (8), 8-deoxygartanin (9), gartanin (10), and cratoxyxanthone (11), were isolated. Compounds 4-8 exhibited cytotoxicity against the HT-29 cell line with ED50 values of 4.9, 1.7, 1.7, 2.3, and 9.1 microM, respectively. In an ELISA NF-kappaB assay, compounds 5-7, 9, and 10 inhibited p65 activation with IC50 values of 15.9, 12.1, 3.2, 11.3, and 19.0 microM, respectively, and 6 showed p50 inhibitory activity with an IC50 value of 7.5 microM. Alpha-mangostin (5) was further tested in an in vivo hollow fiber assay, using HT-29, LNCaP, and MCF-7 cells, but it was found to be inactive at the highest dose tested (20 mg/kg).

Activity-guided fractionation of hexanes- and CHCl 3-soluble extracts of Amomum aculeatum leaves, collected in Indonesia, led to the isolation of three new dioxadispiroketal-type ( 3- 5) and two new oxaspiroketal-type ( 6 and 7) derivatives. Nine semisynthetic derivatives ( 1a- 1h and 2a) of the parent compounds, aculeatins A ( 1) and B ( 2), were prepared. All isolates and semisynthetic compounds were tested against a small panel of human cell lines. Of these, aculeatin A ( 1; ED 50 0.2-1.0 microM) was found to be among the most cytotoxic of the compounds tested and was further evaluated in an in vivo hollow fiber assay; it was found to be active against MCF-7 (human breast cancer) cells implanted intraperitoneally at doses of 6.25, 12.5, 25, and 50 mg/kg. However, when 1 was tested using P388 lymphocytic leukemia and human A2780 ovarian carcinoma in vivo models, it was deemed to be inactive at the doses used.

Two new cyclopenta[b]benzofurans, aglaroxin A 1-O-acetate (2) and 3'-methoxyaglaroxin A 1-O-acetate (3), a new benzo[b]oxepine, 19,20-dehydroedulisone A (4), and five new cyclopenta[bc]benzopyrans, edulirin A (5), edulirin A 10-O-acetate (6), 19,20-dehydroedulirin A (7), isoedulirin A (8), and edulirin B (9), were isolated from the bark of Aglaia edulis, along with one known cyclopenta[b]benzofuran, aglaroxin A (1). Additionally, four new amides, aglamides A-D (10-13), as well as three known compounds, aglalactone, scopoletin, and 5-hydroxy-3,6,7,4'-tetramethoxyflavone, were isolated from the leaves and/or twigs of this species. The structures of the new compounds (2-13) were elucidated by interpretation of their spectroscopic data. All isolates obtained in this study were evaluated for cytotoxicity against both several human cancer cell lines (Lu1, LNCaP, and MCF-7) and a nontumorigenic (HUVEC) cell line. Among these isolates, the cyclopenta[b]benzofurans (1-3) exhibited potent in vitro cytotoxic activity (ED50 range 0.001 to 0.8 microg/mL). Aglaroxin A 1-O-acetate (2) was further evaluated in the in vivo P388 lymphocytic leukemia model, by intraperitoneal injection, but found to be inactive in this model.

Activity-guided fractionation of a chloroform-soluble extract of the leaves of Ormosia sumatrana, using a proteasome inhibition assay, led to the isolation of a new A-type proanthocyanidin derivative, 3'-O-cinnamoylprocyanidin A-2 (1), and a new cerebroside, sumatranoside (2). The structures of these two isolates were determined as epicatechin-(2 beta-->O-->7',4 beta-->8')-epicatechin-3'-O-cinnamate (1) and 1-O-(beta-d-glucopyranosyl)-(2S,3S,4R)-2N-[(2'R)-2'-hydroxy-tetracosanoyl]-9Z-octadecene-1,3,4-triol (2), respectively, by spectroscopic and chemical methods. Sumatranoside (2) exhibited proteasome inhibitory activity with an IC(50) value of 30 microM.

Bioactivity-directed fractionation of extracts of two Diospyros maritima bark samples from Indonesia,one collected at sea level in a beach forest in Java and the other collected at a slight elevation away from the sea shore on the island of Lombok, yielded a diverse set of secondary metabolites. The naphthoquinone plumbagin (1), although found in extracts of both specimens, constituted a much larger percentage of the former sample, which also yielded a series of plumbagin dimers, maritinone (2), chitranone (3), and zeylanone (4). The latter sample yielded a new naphthoquinone derivative, (4S)-shinanolone (5), and a new natural product coumarin, 7,8-dimethoxy-6-hydroxycoumarin (6), along with three other analogues of plumbagin, 2-methoxy-7-methyljuglone (7), 3-methoxy-7-methyljuglone (8), and 7-methyljuglone (9). The structures of compounds 5 and 6 were elaborated by physical, spectral, and chemical methods. All of the isolates were evaluated in both cytotoxicity and antimicrobial assays, and structure-activity relationships of these naphthoquinones are proposed. Plumbagin (1) and maritinone (2) were evaluated also for in vivo antitumor activity in the hollow fiber assay, but both were found to be inactive.

Activity-guided fractionation of the bark of Nephelium maingayi, collected in Indonesia, led to the isolation of six new saponins (1-6). The aglycon of 4 was determined to be a new compound, 7alpha-methoxyerythrodiol, and those of 1-3 and of 5 and 6 were identified as erythrodiol and maniladiol (16beta-hydroxyamyrin), respectively. The structures of 1-6 were determined on the basis of spectral data interpretation, and the absolute configurations of their component monosaccharides were determined as their thiazolidine derivatives after acid hydrolysis. Of the isolates, only compounds 1 and 5 showed very weak cytotoxic activity against a panel of human tumor cell lines.

Activity-guided fractionation of the petroleum ether and ethyl acetate extracts of the stem bark of Pongamia pinnata, using cultured Hepa 1c1c7 mouse hepatoma cells to evaluate quinone reductase (QR) inducing activity, led to the isolation of four new flavanone derivatives (1-4), one new flavone (5), one new chalcone (6), and 13 known compounds of the flavonoid, terpenoid, and fatty acid types. The structures of 1-6 were characterized on the basis of the interpretation of their spectroscopic data. The absolute stereochemistry of compounds 1-4 was determined from their CD data and by Mosher ester determination. All isolates obtained were evaluated in the quinone reductase induction assay.

Bioassay-guided fractionation of the chloroform-soluble extract of the leaves of Vitex negundo led to the isolation of the known flavone vitexicarpin (1), which exhibited broad cytotoxicity in a human cancer cell line panel. In an attempt to increase the cytotoxic potency of 1, a series of acylation reactions was performed on this compound to obtain its methylated (2), acetylated (3), and six new acylated (4-9) derivatives. Compound 9, the previously unreported 5,3'-dihexanoyloxy-3,6,7,4'-tetramethoxyflavone, showed comparative cytotoxic potency to compound 1 and was selected for further evaluation. However, this compound was found to be inactive when evaluated in the in vivo hollow fiber assay with Lu1, KB, and LNCaP cells at the highest dose (40 mg/kg/body weight) tested, and in the in vivo P-388 leukemia model (135 mg/kg), using the ip administration route.

Activity-guided fractionation of an ethyl acetate extract of the twigs of Hernandia ovigera, using a soft agar assay with JB6 murine epidermal cells, led to the isolation of two new naturally occurring aryltetralin lignans, (7R,8S,7'R,8'R)-(+)-7'-acetyl-5'-methoxypicropodophyllin (1) and (7R,8S,7'R,8'R)-(+)-7'-acetylpicropodophyllin (2), of which 2 was previously identified as a synthetic product, along with eight known compounds, epiyangambin (3), caruilignan C, diasesartemin, (+)-epimagnolin A, N-methylcorydaldine, (-)-5'-methoxyyatein, (+)-syringaresinol dimethyl ether, and (-)-yatein. The structures and stereochemistry of 1 and 2 were determined using spectroscopic methods. Compounds 2 and 3 exhibited significant inhibition of the transformation of murine epidermal JB6 cells, with IC50 values of 0.15 and 0.4 microg/mL, respectively, while the other isolates were regarded as inactive (IC50 >4 microg/mL).

The hollow fiber test has been developed for the preliminary in vivo assessment of cancer chemotherapeutic efficacy of selected natural products. Using this model, we have established growth conditions for HL-60, HUVEC, Ishikawa, KB, KB-V1, LNCaP, Lu1, MCF-7, Mel2, P-388, and SW626 cells implanted at the intraperitoneal (i.p.) and subcutaneous (s.c.) compartments of athymic mice. Five cytotoxic natural product isolates (2-6) were tested in this model, along with paclitaxel (taxol) (1). Among the compounds tested, dioscin (2) and 13-methoxy-15-oxozoapatlin (3) were found to be active, indicating their potential to function as cancer chemotherapeutic agents. On the other hand, ochraceolide A (4), alpha-lapachone (5), and 2-(1-hydroxyethyl)naphtha[2,3-b]furan-4,9-quinone (6), all of which were significantly cytotoxic to cultured mammalian cells, did not mediate significant responses with the hollow fiber model. In further xenograft studies using KB cells implanted at the subcutaneous site, compound 3 mediated a statistically significant response which was consistent with the response observed at the subcutaneous compartment in the hollow fiber tests. In sum, these studies illustrate the usefulness of the hollow fiber model in natural product drug discovery programs. Preliminary indications of potential therapeutic efficacy can be provided quickly at relatively low expense. Agents capable of mediating a response at the subcutaneous site would appear to warrant greatest attention.

Six new xanthones, cratoxyarborenones A-F (1-6), were isolated from the leaves, twigs, and/or stem bark of Cratoxylum sumatranum along with the known compound, vismione B (9), as active constituents by bioassay-directed fractionation using the KB human cancer cell line cytotoxicity assay. In addition, two novel anthraquinobenzophenones, cratoxyarborequinones A (7) and B (8), and two known compounds, 2,4,6-trihydroxybenzophenone 4-O-geranyl ether and delta-tocotrienol, were obtained as inactive constituents.

Fractionation of an ethyl acetate-soluble extract of the bark of Artocarpus dadah has led to the isolation of three new prenylated stilbenoid derivatives, 3-(gamma,gamma-dimethylallyl)resveratrol (1), 5-(gamma,gamma-dimethylallyl)oxyresveratrol (2), 3-(2,3-dihydroxy-3-methylbutyl)resveratrol (3), and a new benzofuran derivative, 3-(gamma,gamma-dimethylpropenyl)moracin M (4), along with six known compounds, oxyresveratrol, (+)-catechin, afzelechin-3-O-alpha-L-rhamnopyranoside, (-)-epiafzelechin, dihydromorin, and epiafzelechin-(4beta-->8)-epicatechin. From an ethyl acetate-soluble extract of the twigs of the same plant were isolated compound 4 and two new neolignan derivatives, dadahols A (5) and B (6), as well as 10 known compounds, oxyresveratrol, (+)-catechin, afzelechin-3-O-alpha-L-rhamnopyranoside, resveratrol, steppogenin, moracin M, isogemichalcone B, gemichalcone B, norartocarpetin, and engeletin. The structures of compounds 1-6 were determined using spectroscopic and chemical methods. Isolates were evaluated for their inhibitory effects against both cyclooxygenase-1 (COX-1) and -2 (COX-2) and in a mouse mammary organ culture assay.