Inhibition Properties of Arylsulfatase and β-Glucuronidase by Hydrogen Peroxide, Hypochlorite, and Peracetic Acid.

Arylsulfatase and β-glucuronidase are two important enzymes in humans, which play an important role in the dynamic equilibrium of steroidal estrogens. This work probably for the first time reported that hydrogen peroxide (H2O2), hypochlorite, and peracetic acid (PAA) could effectively inhibit the activities of arylsulfatase and/or β-glucuronidase. The 50% of inhibitions (IC50) of H2O2, hypochlorite, and PAA on arylsulfatase were found to be 142.90 ± 9.00, 91.83 ± 10.01, and 43.46 ± 2.92 μM, respectively. The corresponding IC50 values of hypochlorite and PAA on β-glucuronidase were 704.90 ± 41.40 and 23.26 ± 0.82 μM, whereas H2O2 showed no inhibition on β-glucuronidase. The inhibitions of arylsulfatase and/or β-glucuronidase by these three chemicals were pH-dependent. It was further revealed that the inhibitions of hypochlorite on both arylsulfatase and β-glucuronidase were irreversible. On the contrary, the inhibitions by H2O2 and PAA were reversible. In addition, the inhibition by H2O2 was competitive and that by PAA was noncompetitive. In general, H2O2 and hypochlorite can be endogenously produced in humans, which suggested that the two compounds are potential endocrine disruption compounds (EDCs) as they can cause endocrine disruption via the inhibition of arylsulfatase and β-glucuronidase. This work further indicated that any agent that can induce the production of H2O2 or hypochlorite in humans is a potential EDC, which explains why some EDCs with very weak or no estrogenic potency can cause endocrine disruption, which is confirmed in epidemiological studies.