Parasitology



Assessment of the anthelmintic effect of natural plant cysteine proteinases against the gastrointestinal nematode, Heligmosomoides polygyrus, in vitro


G. STEPEK a1, D. J. BUTTLE a2, I. R. DUCE a1, A. LOWE a1 and J. M. BEHNKE a1c1
a1 School of Biology, University Park, University of Nottingham, Nottingham NG7 2RD, UK
a2 Division of Genomic Medicine, University of Sheffield, Sheffield S10 2TH, UK

Article author query
stepek g   [PubMed][Google Scholar] 
buttle dj   [PubMed][Google Scholar] 
duce ir   [PubMed][Google Scholar] 
lowe a   [PubMed][Google Scholar] 
behnke jm   [PubMed][Google Scholar] 

Abstract

We examined the mechanism of action and compared the anthelmintic efficacy of cysteine proteinases from papaya, pineapple, fig, kiwi fruit and Egyptian milkweed in vitro using the rodent gastrointestinal nematode Heligmosomoides polygyrus. Within a 2 h incubation period, all the cysteine proteinases, with the exception of the kiwi fruit extract, caused marked damage to the cuticle of H. polygyrus adult male and female worms, reflected in the loss of surface cuticular layers. Efficacy was comparable for both sexes of worms, was dependent on the presence of cysteine and was completely inhibited by the cysteine proteinase inhibitor, E-64. LD50 values indicated that the purified proteinases were more efficacious than the proteinases in the crude latex, with purified ficin, papain, chymopapain, Egyptian milkweed latex extract and pineapple fruit extract, containing fruit bromelain, having the most potent effect. The mechanism of action of these plant enzymes (i.e. an attack on the protective cuticle of the worm) suggests that resistance would be slow to develop in the field. The efficacy and mode of action make plant cysteine proteinases potential candidates for a novel class of anthelmintics urgently required for the treatment of humans and domestic livestock.

(Received April 30 2004)
(Revised June 10 2004)
(Accepted June 10 2004)


Key Words: plant cysteine proteinases; gastrointestinal nematodes; anthelmintic; Heligmosomoides polygyrus.

Correspondence:
c1 School of Biology, University Park, University of Nottingham, Nottingham NG7 2RD, UK. Tel: +44 115 951 3208. Fax: +44 115 951 3251. E-mail: jerzy.behnke@nottingham.ac.uk


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