the inhibitory properties of and mode of action of plant essential oils ...

(Naganuma et al. 1985). Due to the phototoxic nature of lemon oil, no more than a
2% solution can be applied externally to the skin (Tisserand & Balacs 1995).
1:4 Parasites investigated
Three parasites covering 2 different phyla were used in this study to investigate the
antiparasitical actions of 12 plant essential oils (Appendix 1) and 11 soft fruit
extracts (Appendix 2). The parasites investigated represent 3 organisms from the
World Health Organisations (WHO) neglected diseases initiative which was
organised to provide improvements to the health and quality of life for people
affected by diseases with expensive and/or lengthy treatment regimens. As these
diseases predominantly afflict the very poor, there is no adequate incentive for
research and development by pharmaceutical companies (WHO 2003; Savioli,
Thompson and Smith 2006). The parasites investigated are shown in Table 1.3 and
further described in the text.
Table 1.3 Parasites used in experiments.
PHYLUM FAMILY NAME DISEASE
Sarcomastigophora Trypanosomatidae Trypanosoma cruzi American
trypanosomiasis
Sarcomastigophora Hexamitidae Giardia duodenalis Giardiasis
Apicomplexa Cryptosporidiidae Cryptosporidium
parvum
Cryptosporidiosis
1:5 Giardia duodenalis
The flagellated protozoan parasite G. duodenalis was first observed by Antony van
Leeuwenhoek in 1681 by investigation of his diarrhoeic stools. G. duodenalis (syn.
G. lamblia and G. intestinalis) is a simple binucleated, unicellular organism having a
world wide distribution (Ortega & Adam 1997). It is estimated that 280 million
humans are infected every year and is the most common intestinal infection in the
developed world (Lane & Lloyd 2002; Olson, Ceri and Morck 2000). In developing
countries in Asia, Africa and Latin America, an estimated 200 million people have
symptomatic giardiasis with 500,000 new cases reported each year (Lane & Lloyd
18