Antiplasmodial dimeric chalcone derivatives from the roots of Uvaria siamensis.

Four dimeric chalcone derivatives, 8″,9″-dihydrowelwitschin H, uvarins A-C, a naphthalene derivative, 2-hydroxy-3-methoxy-6-(4'- hydroxyphenyl)naphthalene, and the known dimeric chalcones, dependensin and welwitschin E, flavonoids, a cyclohexane oxide derivative, an aromatic aldehyde were isolated from the roots of Uvaria siamensis (Annonaceae). The structures of the compounds were elucidated by spectroscopic analysis, as well as by comparison with literature data. The isolated compounds with a sufficient amount for biological assays were evaluated for their antimalarial, antimycobacterial, and cytotoxic activities.

A new cerebroside and the cytotoxic constituents isolated from Xylaria allantoidea SWUF76.

A new cerebroside, namely allantoside (1), and 10 known compounds (2-11) were isolated from Xylaria allantoidea SWUF76. The structure of compound 1 was determined by comprehensive spectroscopic analysis including 1D and 2D nuclear magnetic resonance (NMR) as well as high-resolution electron ionisation mass spectrometry (HREIMS) and electrospray ionisation mass spectrometry (ESIMS). Compounds 1, 4, 5, 6, 7, 8 and 11 were evaluated for cytotoxic activities against cancer cell lines (Hela, HT29, HCT116 and MCF-7) and normal Vero cell lines by MTT assay.

Antibacterial dihydrobenzopyran and xanthone derivatives from Garcinia cowa stem barks.

Two new compounds, garciniacowol (1) and garciniacowone (2) along with 15 knowncompounds were isolated from the stem barks of Garcinia cowa. Their structures weredetermined by intensive spectroscopic methods. The structure of 1 was a symmetrical dimericdihydrobenzopyran derivative, whereas the framework of 2 was a triprenyl caged-xanthoneprecursor.

Two new C-benzylated dihydrochalcone derivatives from the leaves of Melodorum siamensis.

Two new C-benzylated dihydrochalcone derivatives, 4,2',4'-trihydroxy-6'-methoxy-3'(2''-hydroxybenzyl)dihydrochalcone (1) and 2',4'-dihydroxy-4,6'-dimethoxy-3'(2''-hydroxybenzyl)dihydrochalcone (2), along with six known flavonoid derivatives (3-8), a known dihydrochalcone dimer (9), three known aromatic esters (10-12), and one known aromatic amide (13), were isolated from the leaves of Melodorum siamensis. The structures of the compounds were elucidated by spectroscopic analysis, mainly 1D and 2D NMR techniques (1H, 13C, COSY, HMQC, and HMBC), as well as by comparison with literature data. The isolated compounds with a sufficient amount for biological assays were evaluated for their antimalarial, antimycobactirial, and cytotoxic activities.

Rearranged benzophenones and prenylated xanthones from Garcinia propinqua twigs.

The first phytochemical investigation of Garcinia propinqua has led to the isolation and identification of three new compounds, including two rearranged benzophenones, doitunggarcinones A (1) and B (2), and a xanthone, doitunggarcinone C (3), together with seven known compounds (4-10). The structures of 1-3 were elucidated on the basis of spectroscopic methods, including UV, IR, NMR, and MS. The antibacterial activity of the 10 isolates was evaluated against Escherichia coli TISTR 780, Salmonella typhimurium TISTR 292, Staphylococcus aureus TISTR 1466, and methicillin-resistant Staphylococcus aureus (MRSA) SK1.

8-O-Acetyl-8-epi-9-de-oxygoniopypyrone.

7-oxo-3-phenyl-2,6-dioxabicyclo-[3.3.1]nonan-4-yl acetate), C(15)H(16)O(5), is a styryllactone derivative which was isolated from Goniothalamus macrophyllus.

Anthraquinones from the roots of Prismatomeris malayana.

A novel anthraquinone, 1,3-dihydroxy-5,6-dimethoxy-2-methoxymethyl-9,10-anthraquinone (9) and a new natural product, 2-hydroxymethyl-1-methoxy-9,10-anthraquinone (8) were isolated from the roots of Prismatomeris malayana together with seven known anthraquinones, tectoquinone (1), 1-hydroxy-2-methyl-9,10-anthraquinone (2), rubiadin (3), rubiadin-1-methyl ether (4), 1,3-dihydroxy-5,6-dimethoxy-2-methyl-9,10-anthraquinone (5), nordamnacanthal (6), and damnacanthal (7). Their structures were determined on the basis of spectroscopic data. Some of the anthraquinones were tested for anticancer, antifungal, and antimalarial activities.

Cyanogenic and non-cyanogenic glycosides from Manihot esculenta.

In addition to lotaustralin and linamarin, a novel cyanogenic glycoside, 2-((6-O-(beta-D-apiofuranosyl)-beta-D-glucopyranosyl)oxy)-2-met hylbutanenitrile , two novel non-cyanogenic glycosides, (2S)-((6-O-(beta-D-apiofuranosyl)-beta-D- glucopyranosyl)oxy)butane and 2-((6-O-(beta-D-apiofuranosyl)-beta-D-glucopyranosyl)oxy)propane, and a simple non-cyanogenic glycoside, ethyl beta-D-glucopyranoside, were isolated from an ethanolic extract of the fresh root cortex of Manihot esculenta. From a methanolic extract of the fresh leaves of this species lotaustralin and linamarin, and two flavonoid glycosides, kaempferol-3-O-rutinoside and quercetin-3-O-rutinoside were isolated.