[interroboink]

I don't know anything about the tea you refer to, but "the chemical is similar" is not a great signal, IMO. You can even have the exact same chemical with different chirality having dramatically different effects on the body (eg: l- and d- methamphetamine, and plenty of others).

Not saying it has 0 relevance, but I wouldn't take it to mean much on its own. It's like people being scared of mercury dental fillings because "it has mercury in it, which is poisonous." That doesn't follow.

[civilitty]

Knee-jerk reactions like that aren't helpful with biological compounds. In this case they're both benzophenanchridine/isoquinoline alkaloids with the same functional groups: a methylenedioxy bridge and at least one methoxy group.

L- and D-methamphetamine are a rather unique case because their enantiomeric forms have different effects on the central and peripheral nervous systems. They're much more different from each other structurally than berberine is from sanguinarine.