Sorry about the link, that was what I got from google scholar. I uploaded a copy.
I have a feeling you're correct, that it's probably a trace constituent of these plants and soy sauce.
Still it's always interesting to know what small signal molecules are around and what our body apparently tolerates.
Codonopsis has been part of an adoptogen stack I've been taking that I feel is potentiating psychedelics somehow.
Just a hunch to look at the adaptogens, I believe Rhodiola has some minor MAOI activity.
Here's a snippet from the paper:
Quote:The pharmacological activity of [perlolyrine], which is a B-carboline substituted at C-1, will be examined elsewhere
with respect to that of gingseng, as it is known that substitution at the C-3 position is essential to produce activity toward the benzodiazepine and GABA receptors(4).