Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2013

Psammaplysin F: Novel marine natural product target gram-positive cell division (#222)

Md Amirul Islam 1 , Deborah M Ramsey 1 , Lynne Turnbull 2 , Rohan A Davis 3 , Cynthia B Whitchurch 2 , Shelli R McAlpine 1
  1. School of Chemistry, University of New South Wales, Sydney, NSW, Australia
  2. The ithree Institute, University of Technology, Sydney, NSW, Australia
  3. Eskitis Institute, Griffith University, Brisbane, QLD, Australia
Described is the antimicrobial activity of alkaloid psammaplysins, which are marine natural products. A compound library collected from natural sources in Australia was screened for antimicrobial activity against a panel of Gram-positive and Gram-negative bacteria. Two natural products psammaplysins F (1) and H (2), inhibited the growth of different Gram-positive strains by 80% or more. The activity of these compounds, isolated from marine sponge Pseudoceratina is related to the amine at position C20, where substitution to a urea group reduced the antibacterial activity by 3-fold (psammaplysin G [3]). The MIC values for (1) and (2) were 42-45 µM against penicillin-resistant S. aureus, and between 40-80 µM against two strains of methicillin-resistant S.aureus (MRSA). Morphological evaluation of treated S. aureus using 3D-structured illumination microscopy indicates that psammaplysin F (1) inhibits equal partitioning of DNA into each daughter cell. Indeed, this is the first report of an alkaloid psammaplysin that targets prokaryotic cell division.