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. Compounds 6 and 7 exhibited anticancer activity after 24 h of treatment. Compound 7 showed significant cytotoxicity against Hela (IC50 = 2.24 µg/mL), HT29 (IC50 = 2.51 µg/mL), HCT116 (IC50 = 3.50 µg/mL) and MCF-7 (IC50 = 3.77 µg/mL) and Vero (IC50:3.65 µg/mL) cells. Compound 6 showed slight cytotoxicity against all tested cancer cell lines.

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. The dimeric chalcones 8″,9″-dihydrowelwitschin H, uvarins B and C, dependensin and welwitschin E showed strong antiplasmodial activity with IC50 values of 3.10, 3.02, 3.09, 4.21 and 3.99 µg/mL, respectively. A possible biosynthesis pathway of the dimeric chalcones is discussed.

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. Compounds 1, 2, and 13 exhibited strong cytotoxicity against human tumor cell lines KB and NCI-H187, with IC50 values in the range of 0.66-7.16 µg/mL.

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.

THE TITLE COMPOUND (SYSTEMATIC NAME: 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. The mol-ecule has two fused rings consisting of a tetra-hydro-2H-pyran and a lactone ring, with the benzene ring and the acetyl group attached to the tetra-hydro-2H-pyran ring. The tetra-hydro-2H-pyran ring is in a standard chair conformation, whereas the lactone ring is in an envelope conformation. In the crystal, mol-ecules are linked by weak C-H⋯O inter-actions into sheets parallel to the ac plane. Weak C-H⋯π inter-actions are also observed.

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. The antibacterial activities against Escherichia coli TISTR 780, Salmonellatyphimurium TISTR 292, Staphylococcus aureus TISTR 1466, and methicillin-resistant S. aureus(MRSA) SK1 of the isolated compounds were also evaluated. Compounds 2 and 9 exhibitedgood antibacterial activity against MRSA SK1 with the same minimum inhibitory concentration(MIC) value of 2 µg/mL. Moreover, compound 2 also showed good antibacterial activityagainst S. aureus with an MIC value of 2 µg/mL.

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.