Euis H. Hakim

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.

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.

Artoindonesianin P, a new prenylated flavone with cytotoxic activity from Artocarpus lanceifolius

A new prenylated flavone, named artoindonesianin P (1), was isolated from the tree bark of Artocarpus lanceifolius, together with three known related compounds, artobiloxanthone (2), cycloartobiloxanthone (3) and artonol B (4). The structure of artoindonesianin P 1 was determined on the basis of spectral evidence (MS, 1H and 13C NMR) and by comparison with known related compounds. Compounds 1-4 exhibited significant cytotoxicity against murine P388 leukemia cells.

Artoindonesianin L, a new prenylated flavone with cytotoxic activity from Artocarpus rotunda.

A new prenylated flavone, named artoindonesianin L (1), was isolated from Artocarpus rotunda (Hout) Panzer (Moraceae). Its structure was elucidated as on the basis of spectroscopic evidence. Along with this new compound, four known phenolic compounds were also isolated from this plant and identified as artonins M (2) and E (3), cycloartobiloxanthone (4) and artonin O (5). All these compounds showed significant cytotoxicity against murine P388 leukemia cells.

Diptoindonesin A, a new C-glucoside of ε-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.

Artoindonesianins N and O, new prenylated stilbene and prenylated arylbenzofuran derivatives from Artocarpus gomezianus

A new prenylated stilbene, named artoindonesianin N (1) and a new prenylated arylbenzofuran, named artoindonesianin O (2), were isolated from Artocarpus gomezianus Wall. ex Trec. (Moraceae). Their structures were elucidated as 1 and 2 on the basis of spectroscopic evidence. Along with these new compounds, a known phenolic compound was also isolated from this plant and identified as oxyresveratrol (3).

β-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.

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.

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), (−)-α-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.