A new antibacterial tirucallane from Walsura trichostemon roots.

Phytochemical investigation of the roots of Walsura trichostemon, a Thai medicinal plant, provided a new tirucallane, 3-epimesendanin S 12-acetate (1), together with four known compounds, 3-epimesendanin S (2), meliasenin G (3), ß-sitosterol (4) and ß-sitosterol glucoside (5). Their structures were characterized by intensive spectroscopy including 1 D and 2 D NMR, UV, IR and MS spectrometric analysis. The isolated compounds were evaluated for antibacterial and acetylcholinesterase inhibitory activities. Compounds 1-2 showed antibacterial activity against Bacillus cereus and Bacillus subtilis with MIC values ranging from 16-128 µg/mL. In addition, compound 3 was active against Pseudomonas aeruginosa and Escherichia coli with MIC values of 64 and 128 µg/mL, respectively.

A new cytotoxic plumbagin derivative from roots of Diospyros undulata.

A new plumbagin derivative, 3-(5-oxohexyl)plumbagin (1), together with six known benzoquinone derivatives (2-7), four known triterpenoids (8-11) and coniferyl aldehyde (12) were isolated from Diospyros undulata roots. Their structures were elucidated by intensive spectroscopy including 1 D and 2 D NMR, UV, IR and MS spectrometric analysis. Compound 1 exhibited strong cytotoxicity against three cancer cell lines as lung cancer (NCI-H187), breast cancer (MCF-7), and oral cancer (KB) with IC50 values of 7.16, 12.85 and 28.67 µM, respectively. Moreover, it did not showed cytotoxicity to Vero cells. In addition, the antimicrobial activity of compound 1 was moderate that kill only S. aureus with MBC of 250 µg/mL while other compounds especially compound 4 showed a broader activity that kill all tested bacteria.

Phytochemical investigation and acetylcholinesterase inhibitory activity of bark of Hymenodictyon orixense.

The chemical investigation of the methanol extract of Hymenodictyon orixense bark, a Thai medicinal herb, provided five compounds. Their structures were identified on the basis of 1D NMR and MS data, as well as by comparison of the data with published values, as an iridoid glycoside: loganin (1), four coumarins: scopoletin (2), scopolin (3), hymexelsin (4) and scopoletin 7-O-ß-D-xylopyranosyl-(1→6)-ß-D-glucopyranoside (5). Compounds 1-5 showed acetylcholinesterase (AChE) inhibitory activity in the range of 13.92-34.18% at a concentration of 100 µg/mL. In addition, compounds 1 and 5 are reported for the first time from this genus.

A 2H-tetrahydropyran derivative and bioactive constituents from the bark of Goniothalamus elegants Ast.

A new 2H-tetrahydropyran derivative, 6-epi-goniothalesdiol A (1), together with nine known styryllactones (2-10) and five known aristolactams (11-15) were isolated from the bark of Goniothalamus elegants Ast. The structures were elucidated by spectroscopic methods. The isolated compounds were evaluated for their cytotoxicity toward the KB, MCF7 and NCI-H187 cell lines as well as antimalarial and antimycobacterial activities. Compounds 4 and 10 showed strong activity against all three human cancer cell lines with IC50 values in the range of 0.538 to 4.25 µg/ml, while compounds 2, 4, 10 and 14 showed potent cytotoxicity against NCI-H187 with IC50 values in the range of 0.072 to 2.17 µg/ml. In addition, compounds 4, 6, 7, 9, 10 and 13 showed strong antiplasmodial activity with IC50 in the range of 2.28 to 5.89 µg/ml.