Bioassay-guided fractionation of a cytotoxic EtOAc extract of Aspergillus flavipes occurring in the rhizosphere of Ericameria laricifolia resulted in the isolation of three new cytochalasans, namely, aspochalasins I (1), J (2), and K (3), and four known cytochalasans, aspochalasins C (4), D (5), and E (6) and TMC-169 (7). The structures of compounds 1-3 were established on the basis of extensive 1D and 2D NMR spectroscopic analysis. All compounds exhibited weak to moderate cytotoxicity against NCI-H460, MCF-7, and SF-268 cancer cell lines, but none showed significant selectivity.
Antiangiogenic activity has been identified in an aqueous EtOH extract of Rabdosia rubescens, a component of the dietary supplement PC SPES. Bioassay-guided fractionation using a novel in vitro human endothelial cell-based assay for angiogenesis afforded the diterpenoids ponicidin (1) and oridonin (2), with significant antiangiogenic activity at subcytotoxic concentrations, suggesting that these constituents may strongly contribute to the demonstrated clinical efficacy of PC SPES as a treatment for advanced prostate cancer.
Two new chlorocyclopropane macrolides, phorbasides A and B, have been characterized from the sponge Phorbas sp. that previously yielded phorboxazoles A and B. We describe the assignment of the absolute configuration of the trans-chlorocyclopropane ring that exploits a CD Cotton effect arising from hyperconjugation to the ene-yne chromophore. Phorbasides and callipeltoside A share the same macrolide configurations but, unexpectedly, opposite cyclopropane configurations.
Three new styryl-lactones 8-acetylgoniofufurone(1), 7-acetylgonio-pypyrone(3), and 5-acetylgoniopypyrone(4), along with ten known compounds, goniofufurone(2), goniopypyrone(5), goniothalamin, goniothalenol, (+)-isoaltholactone, goniodiol, 7-acetylgoniodiol, goniotriol, 8-acetylgoniotriol, 9-deoxygoniopypyrone were isolated from the rhizomes of Goniothalamus griffithii Hook f. et. Thoms. Their structures were elucidated by IR, MS, NMR spectra and chemical evidence. All compounds showed cytotoxic activities against human cancer cell lines.
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