The anti-biofilm potential of lead cyclic peptides (15c and 16c) was determined against bacterial strains MRSA (ATCC BAA-1556) (Figure ) and E. coli (ATCC BAA-2452) (Figure ), as well as fungal strains A. fumigatus (Af 293) (Figure ) and C. albicans ), at MIC and 2×MIC. The ability of test compounds (lead cyclic peptides and standard antibiotics) to inhibit biofilm was determined by conducting an XTT assay, and the results were represented as the percent reduction in the biofilm mass relative to non-treated cells.