Table 5. Reversal Effect of quercetin and rutin on the cytotoxicity of paclitaxel to KB 3-1, KB Ch^R 8-5 cell lines.

The concentration of flavonoid required for 50% inhibition (IC₅₀ values) for cell survival were calculated from the killing curves shown in Figure 5. Mean values (±SEM) are from four independent experiments, each performed in triplicate. ^bFR: fold-resistance was calculated by dividing the IC₅₀ value for paclitaxel of KB 3-1 and KB CH^R 8-5 cells in the absence or presence of quercetin and rutin by IC₅₀ value for paclitaxel of KB 3-1 cells.

Compound	KB 3-1		KB ChR 8-5
	IC50 ± SEMα (μM)	FRb	IC50 ± SEMα (μM)	FRb
Paclitaxel	0.04 ± 0.01	[1.0]	2 ± 0.20	[50.0]
+1 μM Quercetin	0.04 ± 0.01	[1.0]	1.26 ± 0.05	[31.5]
+ 5 μM Quercetin	0.03 ± 0.01	[1.3]	0.88 ± 0.01	[22.0]
+ 10 μM Quercetin	0.03 ± 0.01	[1.0]	0.37 ± 0.01	[9.25]
+1 μM Rutin	0.04 ± 0.01	[1.0]	1.96 ± 0.05	[49.5]
+ 5 μM Rutin	0.03 ± 0.01	[1.3]	0.68 ± 0.01	[22.6]
+ 10 μM Rutin	0.03 ± 0.01	[1.0]	0.47 ± 0.01	[15.6]

FR, Fold-resistance

a -mean ± SEM, n = number of experiments