Table 4.

In vitro kinase inhibition activity assessment of 19a, 16b, and 22b, against EGFR and HER2.

Compound No.	Protein Kinase Inhibition IC50 (µM) ± SEM
	EGFR	HER2
19a	0.081 ± 0.003 **	0.059 ± 0.002
16b	0.062 ± 0.002 ****	0.045 ± 0.010
22b	0.074 ± 0.002 ****	0.033 ± 0.015
Lapatinib	0.130 ± 0.002	0.037 ± 0.016
Erlotinib	0.038 ± 0.002	0.052 ± 0.004

IC₅₀ values ± SD of three independent experiments. (Significance determined by unpaired sample t-test where, ** indicates p < 0.01, and **** indicates p < 0.0001 levels of significance).