Specialized metabolites of the United States lichen Niebla homalea and their antiproliferative activities.

Three undescribed stictanes, nieblastictanes A-C, two flavicanes, nieblaflavicanes A and B, together with three already reported stictanes, along with the known compounds (+)-usnic acid, sekikaic acid, divaricatic acid, and divaricatinic acid methyl ester were isolated from an ethyl acetate extract of the western North American lichen Niebla homalea. The structures of the new and known compounds were established by spectroscopic methods including nuclear magnetic resonance spectroscopy, mass spectrometry and electronic circular dichroism. Among the compounds isolated, usnic acid exhibited moderately potent antiproliferative activities against the A2780 ovarian (IC 3.

Tumor suppressor p53 independent apoptosis in HT-29 cells by auransterol from Penicillium aurantiacobrunneum.

Colorectal cancer is the third leading cause of cancer related-death in the United States. Search for new alternatives to treat this type of cancer is necessary. In a previous report, auransterol from Penicillium aurantiacobrunneum showed cytotoxicity in HT-29 cancer cells.

α-Pyrone and Sterol Constituents of , a Fungal Associate of the Lichen .

Four new metabolites, 4--citreoviridin (), auransterol (), and two analogues ( and ) of paxisterol (), together with two known metabolites (15*,20*)-dihydroxyepisterol () and (), were isolated from cultures of the fungal associate, , of the lichen , endemic to California and Baja California. The structures of all compounds were determined by comprehensive spectroscopic and spectrometric methods, as well as single-crystal X-ray diffraction for the determination of the absolute configuration of . Compound showed selective cytotoxicity toward MCF-7 breast and A2780 ovarian cells with IC values of 4.