The Potential of Marine Microbes, Flora and Fauna in Drug Discovery

• Main Author: Thomas, Santana Alexa Lavonia
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: Digital Commons @ University of South Florida 2019
• Subjects: Endophytic fungi; epigenetics; keikipukalide; bathyptilone; enbepenone; scotianone; Ntera-2; octocoral; Antarctica; Chemistry; Antarctic; The Antarctic; Antarc*
• Online Access: https://digitalcommons.usf.edu/etd/8418; https://digitalcommons.usf.edu/context/etd/article/9615/viewcontent/Thomas_usf_0206D_15416.pdf

Natural products are chemical compounds synthesized by a living organism. These compounds have been utilized by humans from ancient times to the present for their pharmacological and biological activities. Terrestrial organisms are considered a lucrative source of bioactive compounds and chemical diversity. Within the past 60 years, the marine environment has presented its potential as a validated source for structural diversity and biologically active compounds. Technology has given access from shallow waters down to the abyssal plane for exploration and investigation of the inhabitants. Marine organisms have displayed their benefits in the pharmaceutical industry with the approval of several marine-derived drugs active against various diseases. This dissertation presents the potential of marine microbes, flora, and fauna specifically fungal endophytes, red alga and corals in drug discovery. Chapter 2 describes the isolation of secondary metabolites from endophytic fungi by manipulation of their epigenome. As a continuation of a screening project, prioritization of the extracts of the fungal endophytes was necessary for further chemical investigation based on the significant biological activity against two free-living amoebas; Naegleria fowleri and Acanthamoeba sp. Bioassay-guided isolation and mass-directed fractionation were the two methods utilized in the isolation of compounds — several known mycotoxins isolated with known biological activities against the amoeba. With repetition of isolating known compounds, mass-directed fractionation facilitated the pursuit of new compounds from bioactive extracts. A new compound was successfully isolated and is currently awaiting biological activity against N. fowleri. Chapter 3 demonstrates the ecological importance of secondary metabolites from the Antarctic red alga, Delisea pulchra. A suite of polyhalogenated polyketides was isolated and described. Five of the metabolites were previously described in the literature isolated from Delisea sp. and a new natural product ...