Glutamine

Quoted from Wikipedia, not yet written up by hand. Its infobox gives no timings, so this shows only what the article text says it turns into.

1. hoursfrom the article text

   What else it turns into

   “Although glutamine is metabolized to glutamate and ammonia, both of which have neurological effects, their concentrations are not increased much, and no adverse neurological effects were detected.” ¹