Table 1.

Cytotoxicity of the compounds Quercetin (Q) and Quercetin penta-acetate (Q5) against the healthy cell line MRC-5 (human lung fibroblasts) and different cancer cell lines: HepG2 (human hepatocellular carcinoma), HL-60 (human promyelocytic leukemia) and C6 (rat glioma).

	Tested Compounds (IC50 µM)
	Quercetin (Q)	Q5	Doxorrubicin
Cancer cells
IC50 (µM) a HL-60	51.3 (±0.4)	33.6 (±2.6)	0.2 (±0.0)
IC50 (µM) b HepG2	>80	53.9 (±11.3)	0.1 (±0.0)
Non-cancer cells
CC50 MRC-5	>80	>80	0.9 (±0.0)

^a Determined in HL-60 incubated with compounds for 72 h; ^b determined in HepG2 incubated with compounds for 72 h. Values represented as the mean ± SD and were calculated using three independent experiments. CC₅₀ = 50% cytotoxic concentration. IC₅₀ = 50% inhibitory concentration.