beta-Secretase (BACE-1) inhibitory effect of biflavonoids.

Here, we describe amentoflavone-type biflavonoids, which were isolated from natural sources and were found to inhibit beta-secretase (BACE-1). The structure-activity relationship was studied, and compounds 1-8, 10, 17, and 18 showed BACE-1 inhibitory activity. Among these compounds, 2,3-dihydroamentoflavone 17 and 2,3-dihydro-6-methylginkgetin 18 exhibited potent inhibitory effects with IC(50) values of 0.75 and 0.35 microM, respectively.

Phenolic compounds from Cryptocarya konishii: their cytotoxic and tyrosine kinase inhibitory properties.

Two chalcone derivatives, 2'-hydroxychalcone (1) and desmethylinfectocaryone (2), together with five known phenolic compounds infectocaryone (3), cryptocaryone (4), kurzichalcolactone A (5), pinocembrin (6) and trans-N-feruloyltyramine (7), were isolated from the methanol extract of the wood of Cryptocarya konishii. The structures of the new compounds were determined based on the analysis of spectroscopic data, including UV, IR, 1D and 2D NMR, and mass spectra. Evaluation of the cytotoxic and tyrosine kinase inhibitory activities of compounds 1-7 showed that compounds 2-4 strongly inhibited the growth of murine leukemia P-388 cells, whereas compound 4 significantly inhibited the enzyme.

A 2-arylbenzofuran derivative from Hopea mengarawan.

A new 2-arylbenzofuran derivative (diptoindonesin G) (1), along with nine known oligostilbenes, have been isolated and identified from the acetone extract of the tree bark of Hopea mengarawan. The structures of these compounds were determined based on spectroscopic data, including 2D NMR and HREIMS spectra. On cytotoxic evaluation of the isolated compounds against murin leukemia P-388 cells, compound 1 was the strongest in inhibiting the growth of the cells.

A modified oligostilbenoid, diptoindonesin C, from Shorea pinanga Scheff.

A new oligostilbenoid, diptoindonesin C, has been isolated from the tree bark of Shorea pinanga Scheff., along with the two known oligostilbenoids gnetin H and hopeaphenol, and a known coumarin scopoletin. The new oligostilbenoid was moderately active against brine shrimps Artemia salina.

Isoprenylated flavanones and dihydrochalcones from Macaranga trichocarpa.

Two isoprenylated flavanones, macatrichocarpins A and B, and two isoprenylated dihydrochalcones, macatrichocarpins C and D, have been isolated and identified from the acetone extract of the leaves of Macaranga trichocarpa. The structures of these compounds were determined based on spectroscopic data, including UV, IR, 1D and 2D NMR spectroscopic and HREIMS data. This is the first report of the presence of dihydrochalcone derivatives in the genus Macaranga.

Phenolic constituents from the wood of Morus australis with cytotoxic activity.

A new methylated flavonol, 5,7,2',4'-tetrahydroxy-3-methoxyflavone (1), had been isolated from the methanol extract of the wood of Morus australis, along with nine known compounds, kuwanon C (2), morusin (3), morachalcone A (4), oxyresveratrol (5), 4'-(2-methyl-2-buten-4-yl)oxyresveratrol (6), moracins M (7) and C (8), alboctalol (9), and macrourin B (10). The structures of these compounds were determined based on spectral evidence, including UV, IR, NMR, and mass spectra. Cytotoxic properties of compounds 1-10 were evaluated against murine leukemia P-388 cells. The prenylated stilbene 6 and 2-arylbenzofuran 8, and morusin (3) were found to have strong cytotoxic effects with IC50 values of 6.9, 8.7, and 10.1 microM, respectively.

Oligostilbenoids from Shorea gibbosa and their cytotoxic properties against P-388 cells.

A new oligostilbenoid derivative, diptoindonesin F (1), along with five known oligostilbenoids, (-)-ampelopsin A (2), (-)-alpha-viniferin (3), ampelopsin E (4), (-)-vaticanol B (5), and (-)-hemsleyanol D (6), were isolated from the methanol extract of the tree bark of Shorea gibbosa. The structure of the new compound was determined based on the analysis of spectroscopic data, including UV, IR, NMR 1-D and 2-D, and mass spectra. Cytotoxic properties of the isolated oligostilbenoids were evaluated against murine leukemia P-388 cells with the result that compounds 2 and 4 showed the highest cytotoxicity.

Cytotoxic resveratrol oligomers from the tree bark of Dipterocarpus hasseltii.

A new resveratrol tetramer, named diptoindonesin E, was isolated from the acetone extract of the tree bark of Dipterocarpus hasseltii, together with five known resveratrol oligomers (-)-epsilon-viniferin, laevifonol, (-)-alpha-viniferin, vaticanol B, (-)-hopeaphenol, and a coumarin, scopoletin. The structures of these compounds were determined from spectroscopic evidence. Cytotoxicity test of the isolated compounds showed that hopeaphenol strongly inhibited murine leukemia P-388 cells.

Cytotoxic chalcones and flavanones from the tree bark of Cryptocarya costata.

A new flavanone, 7-hydroxy-5,6-dimethoxyflavanone (1), together with three other flavonoids, didymocarpin (2), 2',4'-dihydroxy-5',6'-dimethoxychalcone (3), and isodidymocarpin (4), had been isolated from the methanol extract of the tree bark of Cryptocarya costata. The structures of these compounds were determined based on spectral evidence, including UV, IR, 1-D and 2-D NMR, and mass spectra. Cytotoxic properties of compounds 1-4 were evaluated against murine leukemia P-388 cells. The chalcones 3 and 4 were found to have substantial cytotoxicity with IC50 of 5.7 and 11.1 microM, respectively.

Prenylated flavonoids and related compounds of the Indonesian Artocarpus (Moraceae).

Several species of the genus Artocarpus (Moraceae) have been investigated in our laboratories during the last decade. Over 60 phenolic constituents have been discovered and characterized, including 27 new compounds from 13 Indonesian taxa of Artocarpus, namely A. champeden, A. lanceifolius, A. teysmanii, A. scortechinii, A. rotunda, A. maingayi, A. kemando, A. bracteata, A. altilis, A. fretessi, A. gomezianus, A. reticulatus and A. glaucus. The principal and the most pronounced features of these phenolic constituents are the assembly of an isoprenyl substituent at C-3 of a flavone skeleton by closure of an ether bridge or a carbon-carbon linkage with the B ring of the skeleton, which may further rearrange into xanthone to produce various classes of natural products. The structures of the new and unusual natural products are presented. Many of the metabolites also exhibit cytotoxic effect against murine leukemia P388 cells.

Cytotoxic properties of oligostilbenoids from the tree barks of Hopea dryobalanoides.

A new modified stilbene dimer, diptoindonesin D (1), was isolated from the acetone extract of the tree bark of Hopea dryobalanoides, together with seven known compounds, parviflorol (2), (-)-balanocarpol (3), heimiol A (4), hopeafuran (5), (+)-alpha-viniferin (6), vaticanol B (7) and (-)-hopeaphenol (8). Cytotoxic properties of compounds 1-8 were evaluated against murine leukemia P-388 cells. Compound 8 was found to be the most active with IC50 of 5.7 microM.

Molecular diversity of Artocarpus champeden (Moraceae): a species endemic to Indonesia.

A summary of results obtained in the study of natural products isolated from a Moraceae species Artocarpus champeden is presented. The various classes of 3-prenylflavonoids isolated and the biogenetical correlation between the metabolites are discussed. Some of the flavonoids exhibited strong cytotoxicity against murine leukemia P388 cell lines, suggesting that flavonoids derived from moraceous plants represent a plausible unexplored resource of novel antitumor leads.

Two new cytotoxic isoprenylated flavones, artoindonesianins U and V, from the heartwood of Artocarpus champeden.

Two new isoprenylated flavones, artoindonesianins U (1) and V (2), have been isolated from the heartwood of Artocarpus champeden together with three known isoprenylated flavonoids, 5'-hydroxycudraflavone A, cyclocommunin and artonin B. The structures of the new flavones were elucidated on the basis of spectroscopic evidence. Both compounds 1 and 2 showed strong cytotoxic activity against P-388 cell lines.

Artoindonesianins X and Y, two isoprenylated 2-arylbenzofurans, from Artocarpus fretessi (Moraceae).

Two isoprenylated 2-arylbenzofurans, artoindonesianins X and Y (1-2), together with seven known flavonoids, have been isolated from the roots and tree bark of Artocarpus fretessi. Their structures were established on the basis of spectral analysis. Compounds 1 and 2 showed moderate activity against the brine shrimp Artemia salina.

Two oligostilbenes, cis- and trans-diptoindonesin B, from Dryobalanops oblongifolia.

Two oligostilbenes, cis- and trans-diptoindonesin B, have been isolated from the tree bark of Dryobalanops oblongifolia (Dipterocarpaceae). The structures and relative configurations of both compounds were determined on the basis of spectroscopic evidence, including 2D-NMR spectroscopic analysis.

Artoindonesianins Q-T, four isoprenylated flavones from Artocarpus champeden Spreng. (Moraceae).

Four isoprenylated flavones, artoindonesianins Q-T, were isolated from the heartwood of Artocarpus champeden Roxb. The structures of these compounds were elucidated on the basis of their spectroscopic data.

Diptoindonesin A, a new C-glucoside of epsilon-viniferin from Shorea seminis (Dipterocarpaceae).

A new C-glucoside of epsilon-viniferin, named diptoindonesin A (1), was isolated from the ethyl acetate extract of the tree bark of Shorea seminis, together with the known stilbene oligomers (-)-ampelopsin A (2), (-)-alpha-viniferin (3), and (-)-hopeaphenol (4). The structure of 1 was determined from spectroscopic evidence.