TABLE 1.

Softness, electrophilicity, and IC₅₀ values for quinone and α,β-unsaturated carbonyl derivatives

Softness (σ) and electrophilicity (ω) for the selected compounds were calculated as described under Materials and Methods. The respective IC₅₀ values represent in vitro electrophile concentrations that produce 50% thiol loss and reflect the relative electrophilic potency of each chemical.

Electrophile	σ	ω	IC50
	× 10–3 ev–1	ev	μM
NAPQI	500	6.83	9.1
pBQ	524	7.78	11.6
tBQ	505	7.20	17.5
HNE	393	3.78	ND
Acrolein	379	3.57	52.5
Acrylamide	346	2.62	436,515

tBQ, 2-tert-butyl-1,4-benzoquinone