Now what a great gift that would be! Alas, you cannot produce the actual formula for your depressive friends, but you can give them the symbol in silver to wear as an anti-gloom talisman.
This lovely necklace looks just like an abstract modernist design. But only nature could've produced these shapes, as it's really the molecular structure for serotonin. You know what serotonin is: the body's equivalent of happy juice, swimming through the bloodstream like a sweet syrup of contentment. And trust me, your crabby friends know what serotonin is, too; mostly, they don't have enough of it.
The necklace is made, fittingly enough, by a company called Made with Molecules. And you can find it at www.supermarkethq.com. It's a reminder that a good mood is just a few molecules away.