What are brightening agents or tyrosinase inhibitors?

1) Substances that brighten the skin by inhibiting the enzyme tyrosinase
2) Substances that darken the skin by activating the enzyme tyrosinase
3) Substances that brighten the skin by activating the enzyme tyrosinase
4) Substances that darken the skin by inhibiting the enzyme tyrosinase

Brightening agents or tyrosinase inhibitors are used to lighten the skin by inhibiting tyrosinase, an enzyme that participates in melanin production, leading to reduced melanin synthesis.

Explanation:

Brightening agents or tyrosinase inhibitors are substances that brighten the skin by inhibiting the enzyme tyrosinase. Tyrosinase is involved in the production of melanin, the pigment that gives color to the skin, hair, and eyes. When tyrosinase's activity is reduced, the result is a decrease in melanin synthesis, leading to a lighter skin tone.

An inhibitor is a molecule which interferes with the function of an enzyme by either slowing or stopping the chemical reaction. Enzyme inhibitors work by binding to a specific portion of the enzyme, thus preventing the substrate from reacting at the active site. This can either be reversible or irreversible, with some inhibitors being classified as competitive or noncompetitive.

Therefore, the correct answer to the question is: 1) Substances that brighten the skin by inhibiting the enzyme tyrosinase.