I think you mean 6-methoxy-2-methyl-1,2,3,4-tetrahydro-β-carboline.
That’s found in Virola theiodora.
According to one source on Erowid, the most alkaloids ever found in the bark was 0.25% and that consisted of:
52% N,N-dimethyltryptamine
43% 5-methoxy-N,N-dimethyltryptamine
4% 6-methoxy-2-methyl-1,2,3,4-tetrahydro-β-carboline
1% N-methyltryptamine
One report only obtained 0.017% alkaloids. That’s much more common. That mirrors SWIM’s results more accurately. So 100 grams of bark would only contain about from 17 mg up to 250 mg of alkaloids. 250 mg is a lot from 100 grams. SWIM never had bark that was that good. Most of his was 0.006% or less alkaloids and not at all worth extracting.
Remember, it’s the resin, not the bark that is high in alkaloids. But that's fresh resin, the kind that pours right out of the bark when you cut it, not the dry hard stuff sold on-line. According to the natives, the resin is only active for a short time unless processes right away.