Anicequol

A novel inhibitor for anchorage-independent growth of tumor cells was isolated from the culture broth of a fungal strain. The producing strain TP-F0213 was identified as Penicillium aurantiogriseum Dierckx based on the taxonomic study. The compound designated anicequol was obtained by solvent extraction, HP-20 and silica gel chromatographies and recrystallization. The planar structure was elucidated by NMR analysis to be 16-acetoxy-3,7,11-trihydroxyergost-22-en-6-one. The absolute configuration was determined by the X-ray analysis of 3,7-bis-p-bromobenzoyl derivative. The carbon skeleton of anicequol has the same absolute configuration as ergostane and the configurations of substituents are 3beta, 5alpha, 7beta, 11beta, 16beta and 24S. Anicequol inhibited the anchorage-independent growth of human colon cancer DLD-1 cells with the IC50 of 1.2 microM whereas the IC50 against anchorage-dependent growth was 40 microM.

Fifteen compounds, including six quinone/hydroquinone meroterpenoids, purpurogemutantin (1), macrophorin A (2), 4'-oxomacrophorin (3), 7-deacetoxyyanuthone A (4), 2,3-hydro-deacetoxyyanuthone A (5), 22-deacetylyanuthone A (6), anicequol (7), three roquefortine derivatives, roquefortine C (8), (16S)-hydroxyroquefortine C (9), (16R)-hydroxyroquefortine C (10), dihydroresorcylide (11), nectriapyrone (12), together with three fatty acid derivatives, methyl linoleate (13), phospholipase A2 (14), methyl elaidate (15), were isolated from the sponge-derived fungus Gliomastix sp. ZSDS1-F7 isolated from the sponge Phakellia fusca Thiele collected in the Yongxing island of Xisha. Their structures were elucidated mainly by extensive NMR spectroscopic and mass spectrometric analyses. Among these compounds, compounds 1-3 and 5-7 showed significant in vitro cytotoxicities against the K562, MCF-7, Hela, DU145, U937, H1975, SGC-7901, A549, MOLT-4 and HL60 cell lines, with IC50 values ranging from 0.19 to 35.4 μM. And compounds 2-4 exhibited antitubercular activity with IC50 values of 22.1, 2.44 and 17.5 μM, respectively. Furthermore, compound 7 had anti-enterovirus 71 activity with MIC value of 17.8 μM. To the best of our knowledge, this is the first report to product two quinone/hydroquinone meroterpenoids skeletons (linear skeleton and drimane skeleton) from the same fungal strain.

Anchorage-independent growth is evidence of the malignant transformation of cells. We previously reported the characterization of anicequol, a novel inhibitor of the anchorage-independent growth of tumor cells, and here we show that the effects of 25-hydroxycholesterol (25-HC) on colon cancer cells were very similar to those of anicequol. By analyzing the effects of inhibitors and performing RNA interference experiments, we found that p38 mitogen-activated protein kinase (p38MAPK) was involved in anicequol- and 25-HC-induced anoikis in DLD-1 cells. In addition, Rho-associated, coiled-coil containing protein kinase (ROCK) was also associated with anoikis induced by anicequol or 25-HC. Taken together, our findings suggest that activation of the p38MAPK and ROCK pathways might provide a new therapeutic strategy against cancer, and raise the possibility that tumor metastasis is influenced by 25-HC under physiological conditions.