Novel peptide compounds and pharmaceutical compositions thereof are disclosed that have a formula represented by the following formula (I) wherein L1, L2, L3, Z, R1, R2, R4 and R5 are as described herein. The compounds demonstrate antimicrobial activity and may be prepared as pharmaceutical compositions and used for the prevention and treatment of a variety of conditions in mammals including humans where microbial invasion is involved. The present peptides are particularly valuable as their effect is rapid, broad in spectrum and mostly indifferent to resistance provided by standard antibiotics.