What is the ruling in Islamic law regarding the circulation, sale, and purchase of the substance glutathione, which is used for health and cosmetic purposes, and does the ruling differ based on the purpose of its use?

There is no harm in using and promoting the aforementioned material, whether its purpose is for bodily benefit or its effect on the skin, as long as its use does not involve harm greater than its benefit. The default ruling for things is permissibility unless there is evidence to suggest prohibition.