anyone ever used this? shouldn't that be way more potent than making a tea with some herb? How much of it would one have to consume to produce a decent maoi effect?

Essential oils are usually the result of a steam distillation of the plant material, so the question is are harmala alkaloids steam volitile? If not then the oil is worthless.

wouldn't harmalas boil off into vapor when you brew ayahuasca if they were volitile?

Not necessarily even if they had a low bp, eg you can heat up MeI (bp <40) in ethanol to the high 70's and the MeI won't boil off, I'm not sure of the exact term (something to do with vapor pressure?) but i just know it doesn't happen. The melting point of harmine is 321C, and 232C for harmaline, so they won't boil in a double boiler (at 100C) and definitely won't boil off in solution. Steam distillation involves steam being generated outside the vessel and piped through the plant material then condensed, so its different to boiling aya which generates a small amount of steam in situ but is very inefficient and wouldn't be expected to carry steam volatile species anywhere.

thanks, that might explain why it didn't work at all when eating it. I was hoping one could just rub it on the skin, but I guess there is nothing in it

essential oil will contains totally different classes of compounds than beta carbolines..it would contains almost terpenes and maybe some different other substances,usually and tipically EO are just terpenes mix