Epigenetic Tailoring for the Production of Anti-Infective Cytosporones from the Marine Fungus Leucostoma persoonii

Recent genomic studies have demonstrated that fungi can possess gene clusters encoding for the production of previously unobserved secondary metabolites. Activation of these attenuated or silenced genes to obtain either improved titers of known compounds or new ones altogether has been a subject of considerable interest. In our efforts to discover new chemotypes that are effective against infectious diseases, including malaria and methicillin-resistant Staphylococcus aureus (MRSA), we have isolated a strain of marine fungus, Leucostoma persoonii, that produces bioactive cytosporones. Epigenetic modifiers employed to activate secondary metabolite genes resulted in enhanced production of known cytosporones B (1, 360%), C (2, 580%) and E (3, 890%), as well as the production of the previously undescribed cytosporone R (4). Cytosporone E was the most bioactive, displaying an IC90 of 13 µM toward Plasmodium falciparum, with A549 cytotoxicity IC90 of 437 µM, representing a 90% inhibition therapeutic index (TI90 = IC90 A459/IC90 P. falciparum) of 33. In addition, cytosporone E was active against MRSA with a minimal inhibitory concentration (MIC) of 72 µM and inhibition of MRSA biofilm at roughly half that value (minimum biofilm eradication counts, MBEC90, was found to be 39 µM)

Epigenetic Regulation in Endophytic Fungi Acquired from Mangrove Trees

Gene regulation gives the cell control over structure and function. Epigenetics is an upcoming concept which studies chemical changes DNA without actually changing the genotype. Direct DNA cytosine methylation is associated with strong silencing of gene clusters in fungi. Studies show that a variety of new compounds can be acquired from fungi once those silent bio-synthetic pathways are active. To study the effects of Azacitidine, fungal samples were isolated and cultured from Floridian mangroves collected in Everglades City, Florida. We hypothesized that if we expose our three samples to Azacitidine, it would activate previously silent bio-synthetic pathways thus producing diverse array of secondary metabolites when compared to the unmodified controls. LCMS data confirmed our hypothesis. Results of the modified samples had different peaks when compared to the unmodified controls