Table 5.

The cytotoxic activity of tested lactones against L929 cell lines.

Lactone	Concentration [$\mathsf{\mu }$g/mL]						5% DMSO	${\mathit{IC}}_{50}$ [$\mathsf{\mu }$M]
	50	20	10	5	0.5	0.1
5a	1 ± 0.01	5 ± 0.06	8 ± 0.07	10 ± 0.03	15 ± 0.02	17 ± 0.09	79 ± 0.07	0.0058
5b	1 ± 0.03	4 ± 0.02	7 ± 0.06	12 ± 0.05	18 ± 0.15	20 ± 0.08		0.0071
5c	2 ± 0.12	4 ± 0.06	10 ± 0.03	14 ± 0.09	21 ± 0.15	26 ± 0.03		0.0078
6a	2 ± 0.09	6 ± 0.03	7 ± 0.07	9 ± 0.15	11 ± 0.08	15 ± 0.03		0.0083
6b	2 ± 0.05	4 ± 0.15	16 ± 0.03	25 ± 0.02	27 ± 0.12	32 ± 0.07		0.0041
6c	2 ± 0.02	4 ± 0.08	9 ± 0.05	18 ± 0.12	22 ± 0.05	24 ± 0.03		0.0047
7a	1 ± 0.12	2 ± 0.03	6 ± 0.07	12 ± 0.02	18 ± 0.12	25 ± 0.02		0.0043
7b	2 ± 0.09	5 ± 0.15	10 ± 0.05	13 ± 0.12	18 ± 0.08	25 ± 0.03		0.0048
7c	1 ± 0.03	5 ± 0.05	11 ± 0.08	17 ± 0.02	21 ± 0.08	27 ± 0.08		0.0066
8a	1 ± 0.15	4 ± 0.02	7 ± 0.06	14 ± 0.03	19 ± 0.03	23 ± 0.03		0.0044
8b	1 ± 0.02	4 ± 0.08	8 ± 0.05	15 ± 0.03	17 ± 0.08	24 ± 0.03		0.0055
8c	1 ± 0.05	5 ± 0.02	11 ± 0.03	15 ± 0.03	20 ± 0.08	25 ± 0.03		0.0044
9b	1 ± 0.12	4 ± 0.15	11 ± 0.06	13 ± 0.07	18 ± 0.03	23 ± 0.03		0.0044
9c	1 ± 0.05	3 ± 0.09	6 ± 0.03	9 ± 0.06	12 ± 0.08	15 ± 0.03		0.0068
10b	1 ± 0.02	5 ± 0.06	7 ± 0.15	15 ± 0.08	20 ± 0.03	25 ± 0.08		0.0040
10c	2 ± 0.05	2 ± 0.15	6 ± 0.09	12 ± 0.07	18 ± 0.03	22 ± 0.05		0.0041
12a	2 ± 0.06	3 ± 0.03	8 ± 0.06	10 ± 0.02	15 ± 0.05	19 ± 0.15		0.0062
13a	1 ± 0.07	5 ± 0.12	6 ± 0.06	9 ± 0.03	12 ± 0.02	16 ± 0.09		0.0081

The cytotoxicity was assessed by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) reduction assay. The cell viability was calculated for four experiments including three repeats for each compound. Complete RPMI-1640 medium was used as a positive control (Control +) of cell viability (100% viable cells) and 0.03% H${}_2$O${}_2$ as a negative control (Control −) of cell viability (100% dead inactive cells). All values were expressed as the mean percentage of viable cells ± SD. The differences between positive control and treated with tested compounds were evaluated by non-parametric Mann–Whitney U test. Statistical significance: p < 0.05. Dimethyl sulfoxide (DMSO) was used as a solvent; $I{C}_{50}$, half maximal inhibitory concentration.