Cyclic Peptide Natural Product Inspired Inhibitors of the Free-Living Amoeba Balamuthia mandrillaris

Area of Science:

• Microbiology
• Infectious Diseases
• Drug Discovery

Background:

• Balamuthia mandrillaris causes severe central nervous system infections (Balamuthia amoebic encephalitis) with high mortality.
• Current treatments for Balamuthia infections are ineffective and have severe side effects.
• Cyclic peptides are known antimicrobials but their anti-amoebic potential is largely unexplored.

Purpose of the Study:

• To investigate the efficacy of Synthetic Natural Product Inspired Cyclic Peptides (SNaPP) against Balamuthia mandrillaris.
• To identify novel cyclic peptides with anti-amoebic activity and assess their safety profile.

Main Methods:

• Screening of approximately 500 bacterial biosynthetic gene clusters to identify SNaPP library.
• Evaluating the inhibitory effects of identified cyclic peptides on Balamuthia mandrillaris trophozoites.
• Assessing hemolytic and cytotoxic effects of active peptides on human red blood cells and carcinoma cells.

Main Results:

• Several cyclic peptides from the SNaPP library demonstrated significant inhibition of Balamuthia mandrillaris trophozoites.
• Five cyclic peptides showed potent activity with IC50 values less than or equal to 5 μM.
• The identified active peptides exhibited minimal to no hemolytic or cytotoxic effects on human cells.

Conclusions:

• Cyclic peptides represent a promising new class of compounds for developing treatments against Balamuthia mandrillaris infections.
• This research provides the first evidence of anti-Balamuthia activity for cyclic peptides, opening new therapeutic avenues.
• The identified peptides offer a potential starting point for novel drug development against Balamuthia amoebic encephalitis.