Table 5.

The in vitro antioxidant activity of spirooxindoles (6a–p) in DPPH˙ scavenging assay.

Compound	R	Ar	IC50 (µg/mL)a
6a	H	C6H5–	29.76 ± 1.82
6b	H	4–CH3–C6H4–	113.45 ± 5.59
6c	H	4–OCH3–C6H4–	43.04 ± 2.39
6d	H	4–Cl–C6H4–	33.43 ± 1.24
6e	Cl	C6H5–	36.03 ± 1.37
6f	Cl	4–CH3–C6H4–	40.31 ± 2.61
6g	Cl	4–OCH3–C6H4–	97.47 ± 5.62
6h	Cl	4–Cl–C6H4–	46.29 ± 2.18
6i	Br	C6H5–	36.38 ± 2.71
6j	Br	4–CH3–C6H4–	43.42 ± 3.04
6k	Br	4–OCH3–C6H4–	69.25 ± 4.25
6l	Br	4–Cl–C6H4–	41.36 ± 2.17
6m	OCH3	C6H5–	28.07 ± 1.63
6n	OCH3	4–CH3–C6H4–	46.29 ± 2.52
6o	OCH3	4–OCH3–C6H4–	58.82 ± 3.14
6p	OCH3	4–Cl–C6H4–	55.05 ± 3.41
Ascorbic acid	–	–	45.89 ± 2.39

^aIC₅₀ values are the mean ± SD of three separate experiments.