Cytotoxic Sesterterpenes from Thai Marine Sponge Hyrtios erectus.

Four sesterterpenes, erectusolides B, C, D, and seco-manoalide-25-methyl ether, two 2-furanone derivatives, erectusfuranones A and B, together with thirteen known sesterterpenes, (6Z)-neomanoalide-24-acetate, two diastereomers of 24-O-methylmanoalide, luffariolide B, manoalide, (6E)- and (6Z)-neomanoalide, seco-manoalide, scalarafuran, 12-acetylscalarolide, 12-epi-O-deacetyl-19-deoxyscalarin, 12-epi-scalarin, and 12-O-deacetyl-12-epi-scalarin, three indole alkaloids, 5-hydroxy-1H-indole-3-carbaldehyde, hyrtiosine A, and variabine B, and one norterpene, cavernosine were isolated from the marine sponge Hyrtios erectus. Their structures were determined by means of spectroscopic methods and the absolute configurations of the asymmetric centers were determined using the modified Mosher's method. The cytotoxic activities for the isolated compounds have been reported.

Cytotoxic Steroidal Glycosides from the Whole Plant of Calamus acanthophyllus.

A new steroidal glycoside, callaphylloside (1), together with seven known glycosides (2-8), was isolated from the whole plant of Calamus acanthophyllus. The structure of the new compound was elucidated by spectral data analyses and chemical transformations. Compounds 5 and 8 exhibited strong cytotoxic activity against four cancer cell lines (0.7 ≤ IC50 ≤ 3.4 µM). Evaluation of the structure-activity relationship among steroidal glycosides revealed that the structure of spirostanol with an α-L-rhamnopyranosyl linked to C-2 of the inner glucopyranosyl residue both play a critical role in the effects of these compounds on the cancer cell lines.

Phukettosides A-E, mono- and bis-iridoid glycosides, from the leaves of Morinda umbellata L.

Four undescribed bis-iridoid glycosides, named phukettosides A-D, and one iridoid glycoside, referred to as phukettoside E, were isolated and fully characterized from the leaves of Morinda umbellata L. Phytochemical analysis also revealed the presence of eight known compounds. The structures were determined through extensive analysis of 1D and 2D-NMR spectroscopic and HRMS spectral data, and the absolute configurations of the isolates were deduced through ECD calculations. Biogenetic pathways for the bis-iridoid glycosides, phukettosides A-C, through intermolecular Diels-Alder type reactions, were proposed. The isolated compounds, with the exception of phukettosides B and D, were evaluated against a panel of cancer cell lines (MOLT-3, HuCCA-1, A549, HeLa, HepG2, and MDA-MB-231) and a non-cancerous cell line (MRC-5) for their cytotoxicity. None of the isolates had significant cytotoxic effects on the tested cell lines.

Acetogenins from the stems of Uvaria micrantha showing antiproliferative effects on HepG2 liver cancer cells.

Five mono-tetrahydrofuran acetogenins: uvamicranins A-E and three known mono-tetrahydrofuran acetogenins; reticulatacin, calamistrin A, and uvarigrin, were isolated from the stems of Uvaria micrantha (Annonaceae). Their structures were elucidated by 2D NMR and high-resolution mass spectral analysis. The absolute configurations of uvamicranins A and B were determined by modified Mosher's method. Evaluation of antiproliferative activity of the isolated compounds showed that they were more potent towards the human hepatocellular carcinoma cell line HepG2, compared to the five other tested cell lines. Among the tested compounds, uvamicranin B (UvB) and uvarigrin (Uv) possessed strong antiproliferative activity with IC50 values of 2.89 ± 0.71 µM and 0.37 ± 0.06 µM, respectively. The antiproliferative mechanism of UvB and Uv, was investigated in HepG2 cell line showing that both compounds marginally induced apoptotic cell death, but exhibited cytostatic effect through induction of cell cycle arrest at the G2/M phase.

Polyoxygenated ursane and oleanane triterpenes from Siphonodon celastrineus.

Twenty polyoxygenated triterpenes, including nineteen ursanes and one oleanane, were characterized from the stem material of Siphonodon celastrineus (Celastraceae) through the application of spectroscopic techniques and chemical transformation. Three of the ursane-type triterpenoids possessed the rare 13,27-cyclopropane ring skeleton.

Lupane, friedelane, oleanane, and ursane triterpenes from the stem of Siphonodon celastrineus Griff.

Twenty-one triterpenes consisting of a lupane derivative, two friedelanes, an oleanane derivative, and 17 ursane-type triterpenoids, together with three known triterpenes, three sterols, a fatty acid, a sesquiterpene alkaloid, and a glycerol derivative, were isolated from the stem of Siphonodon celastrineus. Their structures were characterized by various spectroscopic techniques, as well as comparison with literature data. Twenty-seven metabolites of these were evaluated for cytotoxic activity against six human cancer cell lines. The biosynthetic formation of a 1,4-dioxane bridge is also discussed.

5-formylfurfuryl esters from Duabanga grandiflora.

5-Formylfurfuryl esters, duabanganals A-D, together with sixteen known compounds, a known 5-formylfurfuryl ester, latifolinal, eight pentacyclic triterpenes, a benzofuran derivative, an ellagic acid derivative, vanillin, ß-sitosterol, ß-sitosterol glucoside, 3-hydroxy-4-methoxycinnamaldehyde, and 5-formylfurfurol, were isolated from the stem bark of Duabanga grandiflora. The structures of these compounds were elucidated on the basis of spectroscopic analysis. Several of these metabolites were evaluated for cytotoxic activities against six cancer cell lines.

Mammea coumarins from the flowers of Mammea siamensis.

Four new mammea coumarins, mammea E/BA cyclo D (1), mammea E/BC cyclo D (2), mammea E/BD cyclo D (3), and mammea E/AC cyclo D (4), were isolated from the flowers of Mammea siamensis, along with six known coumarins. Extensive 1D and 2D NMR experiments and other spectroscopic studies, as well as chemical transformations, were employed to determine the structures of 1-4.