Table 1. In vitro activities of chromene-based chalcones 25–29 and 30–34 against the promastigote form of L. major.

Compound	R	% inhibition at the concentration of 10a μM
		Day 1	Day 2	Day 3	IC50b (μM)
25	H	0.0	18.8	93	30 ± 0.06
26	2-Cl	100	100	100	5 ± 0.14
27	3-Cl	100	100	100	0.8 ± 0.26
28	4-Cl	100	100	100	0.7 ± 0.3
29	2,4-Cl2	98.1	100	100	0.75± 0.23
30	H	0.0	12.8	62.8	45 ± 0.15
31	2-Cl	0.0	0.0	1.0	>50
32	3-Cl	0.0	0.0	75.2	45 ± 0.22
33	4-Cl	0.0	0.0	5.4	>50
34	2,4-Cl2	4.3	4.3	8.4	>50
Glucantime					81.97 ± 3.85c

^aThe growth inhibitory effect of compounds on Leishmania parasite for three consecutive days.

^bThe values represent mean ± SD,

^cIC₅₀ in mM.