A Lipoaminopeptaibol Secreted by Alkalophilic Fungus Emericellopsis alkalina Demonstrates a Strong Cytotoxic Effect against Tumor Cell Lines ^†

Abstract

Soil fungi are known to produce and secrete antibiotics with a strong antimicrobial effect towards eukaryotic organisms. In many occasions, these compounds belong to peptides that are products of non-ribosomal biosynthesis and are called peptaibols. Many peptaibols are cytotoxic and some of them suppress tumor cell lines much better than normal cells by inducing calcium-mediated apoptosis. The main antimicrobial lipoaminopeptaibol—emericellipsin A—isolated from the fungus Emericellopsis alkalina strain VKPM F-1428, which demonstrates promising antifungal activity against different fungal taxons,has been found to exhibit selective cytotoxic activity against HepG2 and Hela cell lines (EC₅₀ 2.8 and 0.5 μM, respectively) in MTT assays in vitro. This result corresponds to the standard antitumor antibiotic doxorubicin, which has an EC₅₀ value of 440 nM. In a fibroblast toxicity test, emericellipsin A exhibited less cytotoxic activity than doxorubicin (EC₅₀ 14 and 0.34 μM, respectively). Therefore, it is less toxic to normal cells than doxirubicin (~40 times), but it yields a more potent cytotoxic effect on tumor cell lines. That is why emericellipsin A can be considered for future more detailed investigations to be an effective antitumor substance.