New potent anti-Candida dimeric acylphloroglucinols from H. mexicanum
Through bioassay-guided isolation, five new dimeric acylphloroglucinols, named uliginosin C, uliginosin D, 3'prenyl uliginosin B, 3'prenyl uliginosin C and 3'prenyl uliginosin D together with one known dimeric acylphloroglucinol, uliginosin B, and the terpenoids cembrene and isocembrene have been isolated from the lipophilic extract of Hypericum mexicanum. Their structures were elucidated by a combination of spectrometric and spectroscopic analyses including LC-MS and NMR. The isolated compounds showed strong in vitro anti-Candida activity and reduced or absent cytotoxicity against human cell lines. A chemogenomic screen of 3'prenyl uliginosin B revealed possible target genes that are important for cell cycle regulation and cytoskeleton assembly.