Table 2.

In vitro activity of chitosan formulations against intracellular Leishmania amastigotes at two pH values.

Compound	Properties	Medium pH = 7.5 *				Medium pH = 6.5 *
		L. major **		L. mexicana **		L. major **		L. mexicana **
		EC50 µg/mL	EC90 µg/mL	EC50 µg/mL	EC90 µg/mL	EC50 µg/mL	EC90 µg/mL	EC50 µg/mL	EC90 µg/mL
Amphotericin B (AmB solution)	Purity ≥ 95%, MW 924.1	0.09 ± 0.003	0.5 ± 0.04	0.3 ± 0.003	0.7 ± 0.02	0.09 ± 0.003	0.5 ± 0.02	0.5 ± 0.04	0.6 ± 0.04
AmBisome®	Liposomal AmB, Size = 70–80 nm	1.2 ± 0.07	8 ± 0.3	1.8 ± 0.08	12 ± 1	1.3 ± 0.08	7 ± 0.1	1.8 ± 0.07	13 ± 1
HMW chitosan	MW = 310–375 KDa	105 ± 7	1192 ± 58	123 ± 5	2206 ± 5	10 ± 0.3	127 ± 5	16 ± 0.7	165 ± 27
CH-TPP nanoparticles	Size = 67 ± 7 nm, Zeta potential = 28.5 ± 1.9 mV	162 ± 10	828 ± 43	177 ± 7	4020 ± 352	13 ± 0.5	122 ± 19	21 ± 0.9	284 ± 10
AmB-CH-TPP nanoparticles	Size = 69 ± 8 nm, Zeta potential = 25.5 ± 1 mV	0.14 ± 0.09	1 ± 0.09	0.5 ± 0.01	1.8 ± 0.1	0.06 ± 0.003	0.5 ± 0.08	0.3 ± 0.01	1.8 ± 0.02
CH-Dex nanoparticles	Size = 170 ± 9 nm, Zeta potential = −12.9 ± 3 mV	No activity up to 486
AmB-CH-DEX nanoparticles	Size = 174 ± 8 nm, Zeta potential = −11 ± 1 mV	0.16 ± 0.008	1.4 ± 0.02	0.5 ± 0.01	1.8 ± 0.05	0.16 ± 0.007	0.9 ± 0.04	0.4 ± 0.01	1.8 ± 0.05
TPP	MW = 367.864 g/mol	No activity up to 486
dextran sulphate	MW = 40 KDa	No activity up to 486

Experiments were conducted in quadruplicate cultures, data expressed as mean +/− SD (experiment was reproduced further two times with confirmed similar data not shown). * Statistically significant differences were found for the EC₅₀ values of chitosan or CH-TPP at pH = 6.5 and pH = 7.5 (p < 0.05 by using t-test). ** L. major amastigotes were significantly more susceptible to AmB solution and AmB-loaded chitosan nanoparticles than L. mexicana (p < 0.05 by using an extra sum-of-squares F test). AmB solution, AmB-CH-TPP and AmB-CH-Dex had a similar anti-leishmanial activity.