The in vitro anticancer activity of the crude extract of the sponge-associated fungus Eurotium cristatum and its secondary metabolites

Abstract

Background: Marine natural products has captivated many researchers over the years and there is always a need for sources of diverse and pharmacologically active leads in the area of anticancer drugs. Materials and Methods: The ethyl acetate extract of the fungus Eurotium cristatum (ECE), isolated from the marine sponge Mycale sp., furnished 2-(2’, 3-epoxy-1’,3’-heptadienyl)-6-hydroxy-5-(3-methyl-2-butenyl) benzaldehyde (1), 1,8-dihydroxy-6-methoxy-3-methyl-9,10-anthracenedione (physcion, 2), and the dioxopiperazine alkaloid echinulin (3). The structures of the compounds were established by Nuclear Magnetic Resonance (NMR) spectral analysis (1H, 13C, DEPT, COSY, HSQC, and HMBC). The ECE and its metabolites were evaluated for their growth inhibitory activity on the following three human tumor cell lines: breast adenocarcinoma (MCF-7), non-small lung cancer (NCI-H460), and melanoma (A375-C5). Results: The results showed that the ECE was active in all the three cell lines, with the values of GI50 = 44.3 ± 1.2, 45.5 ± 7.5, and 71.3 ± 2.1 μg/ml for MCF-7, NCI-H460, and A375-C5, respectively. Compound 1 also exhibited moderate growth inhibitory activity against all the three cell lines (GI50 = 58.3 ± 1.2, 46.0 ± 5.5, and 116.7 ± 7.2 μM for MCF-7, NCI-H460, and A375-C5, respectively), whereas compound 3 showed only weak inhibition against MCF-7 (GI50 = 109.7 ± 0.3 μM) and NCI-H460 (GI50 = 96.7 ± 1.5 μM) but was inactive against A375-C5 (GI50 >150 μM). On the contrary, compound 2 was inactive in all the three cell lines at the highest concentration tested (150 μM). Furthermore, ECE was investigated for its effect on the cell cycle in the NCI-H460 cells. Analysis of the cell cycle profile showed that ECE was able to cause a slight cell arrest in the G1 phase, with a corresponding decrease of cells in the S and G2/M phases. Conclusion: The secondary metabolites isolated [Compound 1] from the crude ethyl acetate extract of the culture of the marine fungus E. cristatum were found as the most potent compound regarding cell growth inhibition.