Pyridoxylamine reactivity kinetics as an amine based nucleophile for screening electrophilic dermal sensitizers.
Chipinda-I; Mbiya-W; Adigun-RA; Morakinyo-MK; Law-BF; Simoyi-RH; Siegel-PD
Toxicology 2014 Jan; 315:102-109
Chemical allergens bind directly, or after metabolic or abiotic activation, to endogenous proteins to become allergenic. Assessment of this initial binding has been suggested as a target for developmentof assays to screen chemicals for their allergenic potential. Recently we reported a nitrobenzenethiol(NBT) based method for screening thiol reactive skin sensitizers, however, amine selective sensitizers are not detected by this assay. In the present study we describe an amine (pyridoxylamine (PDA))based kinetic assay to complement the NBT assay for identification of amine-selective and non-selective skin sensitizers. UV-Vis spectrophotometry and fluorescence were used to measure PDA reactivity for 57 chemicals including anhydrides, aldehydes, and quinones where reaction rates ranged from 116 to6.2 × 10-6M-1s-1for extreme to weak sensitizers, respectively. No reactivity towards PDA was observed with the thiol-selective sensitizers, non-sensitizers and prohaptens. The PDA rate constants correlated significantly with their respective murine local lymph node assay (LLNA) threshold EC3 values (R2= 0.76).The use of PDA serves as a simple, inexpensive amine based method that shows promise as a preliminary screening tool for electrophilic, amine-selective skin sensitizers.
Allergens; Chemical-composition; Metabolic-activation; Proteins; Skin; Sensitization; Bioassays;
Author Keywords: Skin sensitization; Reactivity assay; Pyridoxylamine; Local lymph node assay
Paul Siegel, CDC/NIOSH, 1095 Willowdale Road, Morgantown, WV26505-2888
Healthcare and Social Assistance; Services