What are Insulin-epinephrine-melatonin-and-glucagon called?

The Word you're reaching for is "hormones". All of these substances are natural hormones, but they are a mixed bag otherwise. Insulin and glucagon are polypeptide, or protein-based, hormones, and they both regulate aspects of glucose (blood sugar) metabolism. Melatonin and epinephrine (adrenaline) are both small-molecule hormones that regulate sleep-wake (circadian) cycles and the "fight or flight" response, respectively. Both melatonin and epinephrine have non-hormone functions in the body as well. Melatonin is an antioxidant, while epinephrine is an important neurotransmitter.