About hydroquinonebenzenediol derivative, depigmenting agent.mechanism of action of hydroquinonehydroquinone decreases the formation of melanin in the skin. it inhibits tyrosinase and other melanin forming enzymes and thus decreases the formation and increases the degradation of melanosomes.indications for hydroquinone1. melasma 2. freckles 3. hyperpigmention 4. lentigo