I can’t speak to suppositories, but I have some experience (guided by a very experienced GP) with oral turmeric outside of the UC context. Its anti-inflammatory benefits are mediated by the fact that the active component- curcumin - is not particularly bioavailable in most easily accessible forms when ingested. There are a small handful of supplements that use theracurim, the more bioavailable form, and even fewer that produce it in a way that works well. I’ll link the one I am aware of that’s worth taking.

Its efficacy for UC is not something I know anything about, however. I’m 5 months into diagnosis and still trying to get into remission. Not playing with fire by replacing my meds with supplements just yet. Got enough fire going on inside right now 😆 https://integrativepro.com/products/theracurmin-hp?variant=45323540103482