1. Studies on the membrane interactions of the cyclotides kalata B1 and kalata B6 on model membrane systems by surface plasmon resonance
Hiroshi Kamimori, Kristopher Hall, David J Craik, Marie-Isabel Aguilar Anal Biochem. 2005 Feb 1;337(1):149-53. doi: 10.1016/j.ab.2004.10.028.
In this study we have demonstrated the interactions of kalata B1 and its naturally occurring analogue kalata B6 with five model lipid membranes and have analyzed the binding kinetics using surface plasmon resonance. Two kalata peptides showed a higher affinity for the phosphatidylethanolamine-containing membranes, indicating that the peptides would bind selectively to bacterial membranes. Also we have optimized the procedure for the immobilization of five liposome mixtures and have shown that the procedure provides reproducible levels of immobilized liposomes and could be used to screen the selective binding of putative antimicrobial peptides to model mammalian or microbial phospholipid membranes.
2. Anthelmintic activity of cyclotides: In vitro studies with canine and human hookworms
Michelle L Colgrave, Andrew C Kotze, Steven Kopp, James S McCarthy, Glen T Coleman, David J Craik Acta Trop. 2009 Feb;109(2):163-6. doi: 10.1016/j.actatropica.2008.11.003. Epub 2008 Nov 18.
Hookworm infection is a leading cause of maternal and child morbidity in countries of the tropics and subtropics, as well as being an important parasite in companion-animal medicine. The cyclotides are a novel family of cyclic cystine knot containing peptides from plants that have been shown to possess anthelmintic activity against Haemonchus contortus and Trichostrongylus colubriformis, two important gastrointestinal nematodes of sheep. In the current study we demonstrated the in vitro effects of three representative cyclotides, kalata B1, kalata B6 and cycloviolacin O14, on the viability of larval and adult life stages of the dog hookworm Ancylostoma caninum, and larvae of the human hookworm Necator americanus. The cyclotides showed significant anthelmintic activity towards both hookworm species. The different cyclotides showed similar patterns of relative activity as that seen previously with the livestock nematode species. This study demonstrates that cyclotides have promising activity in vitro against important parasites of companion animals and humans.
