The iboga effects were studied scientifically back in like the 60s and then added as a schedule 1 narcotic making researching it nearly impossible. But you can read all about it by typing that same query into a search engine, that is assuming the search engine will bother to give you what you are asking for.

Yes, many plants hit opiate receptors sideways. Kratom hits the kappa's, but will break through to the deltas in large doses, (a very unpleasant effect with kratom,) while the aphrodesiac Yohimbe, also from equatorial africa, hits some of the side receptors. Then there is what's it called, another one too from africa. Salvia Divinorum as well. That is a very short list, I think some of the solanaceaes even have a side hit on receptors but I might be wrong on that one.