Melatonin-d7 is the deuterated form of melatonin. Melatonin is a hormone produced by the pineal gland that activates melatonin receptors. It plays a role in sleep and possesses significant antioxidant and anti-inflammatory properties. As a novel selective ATF-6 inhibitor, melatonin induces apoptosis in human liver cancer cells by downregulating COX-2. Additionally, melatonin mitigates palmitic acid-induced apoptosis in mouse granulosa cells through endoplasmic reticulum stress.