Cytotoxic activity of aquatic fungus Pseudohalonectria lignicola on two different human cell lines

Abstract

Water covers nearly three-quarters of the earth's surface and host a diversity of unexplored microbes. Considerable researches have been done to expose the bioactive potential of free living and symbiotic marine and fresh water microorganisms, many of them have proved to be potent producers of bioactive secondary metabolites. Beside bacteria and algae, fungi represent a comprehensive and promising source of novel anticancer, antibacterial, anti-inflammatory, antiviral and cytotoxic agents. Therefore the limnetic fungus Pseudohalonectria lignicola, first described by Minoura and Muroi in 1978, was investigated in more detail. Previous experiments exhibited antibiotic, antifungal and nematicidal properties of P. lignicola. All studies about this fungus were done on a isolated P. lignicola strain from Baltic Sea. In search of new characteristics of this strain we generated 10 HPLC fractions from the methanolic extract and determined cell viability by treatment of human bladder cancer cell line 5637 and nontumorigenic human HaCaT keratinocytes using MTT assay. Fraction 4, 5 and 6 showed strong cytotoxic effects with IC50 values of 18.7 µg/ml, 17.9 µg/ml and 17.3 µg/ml on 5637 cell line. Fraction 3 and 6 were also cytotoxic for HaCaT cells. Isolation and structure elucidation of active fractions and pure substances are currently underway. The natural substance nectriapyrone has already been identified. Our generated fungus P. lignicola shows both antibacterial and cytotoxic effects that is why it could be a promising candidate for cancer treatment or for usage as antibiotic agent.