PT  - JOURNAL ARTICLE
AU  - Stephan Brinkmann
AU  - Sandra Semmler
AU  - Christian Kersten
AU  - Maria A. Patras
AU  - Michael Kurz
AU  - Natalie Fuchs
AU  - Stefan J. Hammerschmidt
AU  - Jennifer Legac
AU  - Peter E. Hammann
AU  - Andreas Vilcinskas
AU  - Philip. J. Rosenthal
AU  - Tanja Schirmeister
AU  - Armin Bauer
AU  - Till F. Schäberle
TI  - Identification, Characterization and Synthesis of Natural Parasitic Cysteine Protease Inhibitors – More Potent Falcitidin Analogs
AID  - 10.1101/2021.10.30.466580
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.10.30.466580
4099  - http://biorxiv.org/content/early/2021/10/30/2021.10.30.466580.short
4100  - http://biorxiv.org/content/early/2021/10/30/2021.10.30.466580.full
AB  - Protease inhibitors represent a promising therapeutic option for the treatment of parasitic diseases such as malaria and human African trypanosomiasis. Falcitidin was the first member of a new class of inhibitors of falcipain-2, a cysteine protease of the malaria parasite Plasmodium falciparum. Using a metabolomics dataset of 25 Chitinophaga strains for molecular networking enabled identification of over 30 natural analogs of falcitidin. Based on MS/MS spectra, they vary in their amino acid chain length, sequence, acyl residue, and C-terminal functionalization; therefore, they were grouped into the four falcitidin peptide families A-D. The isolation, characterization and absolute structure elucidation of two falcitidin-related pentapeptide aldehyde analogs by extensive MS/MS spectrometry and NMR spectroscopy in combination with advanced Marfey’s analysis was in agreement with the in silico analysis of the corresponding biosynthetic gene cluster. Total synthesis of chosen pentapeptide analogs followed by in vitro testing against a panel of proteases revealed selective parasitic cysteine protease inhibition and additionally low-micromolar inhibition of α-chymotrypsin. The pentapeptides investigated here showed superior inhibitory activity compared to falcitidin.Competing Interest StatementThe authors have declared no competing interest.