Tavassoli et al.: Novel in Vitro Efficiency of Chitosan Biomolecule … Fig. 2: Effect of different concentrations of chitosan on the mortality rate of T. gallinae trophozoites. Con- trol was samples containing medium without chitosan Discussion In this study, we preliminary demonstrated that low molecular weight chitosan was promising in creating new anti-protozoal ef- fective agent in vitro against T. gallinae. Although the exact mechanism of antiproto- zoal activity of chitosan is not fully eluci- dated, but nevertheless, ability to induce morphological changes in the cell parasite, in part, may be a possible mechanism. Only a few attempts have been made to determine antiparasitic properties of chitosan. In one of them (11) investigated the effects of chitosan microspheres cross linked with glutaralde- hyde and containing beta-cyclodextrin (b CD) on the survival of Philasterides dicentrarchi, a protozoan ciliate, in 7d cul- tures. When used alone in assays, chitosan (10 μgml-1) showed no activity, whereas, both microspheres without b CD and micro- spheres containing b CD led to a marked and significant (P < 0.01) decline in P. dicentrarchi survival, at both microsphere concentrations tested (10 and 50 μ g ml–1). The decline obtained with b CD-containing microspheres was significantly greater than other treatments. They proposed that glutaraldehyde, which used as a cross link- Available at: http://ijpa.tums.ac.ir ing agent, had a strong antiparasitic activity. More recently, relative impacts of chitosan, alum, and FeCl3 coagulation on the removal of Cryptosporidium parvum oocysts were investigated previously (10). At all doses investigated, chitosan coagulation resulted in excellent turbidity and particle reductions by filtration. Nonetheless, chitosan coagulation at doses of 0.1, 0.5, and 1.0 mg L-1 did not result in appreciable improvements in C. parvum oocyst removal and complete coagu- lation failure. The functional properties of chitosan are likely to differ based on the preparation me- thods used to convert chitin to chitosan and influenced by intrinsic and extrinsic factors such as the type of chitosan (e.g. plain or derivative), molecular weight, degree of dea- cetylation, and environmental conditions (6). For example, it has been proposed that low molecular weight chitosans (of less than 10 kDa) have greater antimicrobial activity (15). Therefore, there is a need to study the effi- ciency of different types of chitosan deriva- tives on T. gallinae in vitro and in bird mod- el alone and/or with combination with other agents. 95