Was your solution crystal clear after filtration? If not then there might be stuff suspended in solution and not really dissolved, they might coagulate under some conditions like adding salt or basifying and float or sink. I don't know what it could be but if it doesn't behave like alkaloids then it's not alkaloids and you can discard it, you can wash it with water or something to retrieve any alkaloids that got carried with it.
I notice something similar in rue extractions, there is stuff that make the tea cloudy and once based they coagulate and sink like harmalas and the tea becomes crystal clear, but when the solution is acidified again they stay coagulated but refuse to dissolve and so it's easy to let them settle and discard them, i am curious about what they are as i am curious to what the stuff you got might be.
I isolated mine and cleaned it but i don't know how to test it further. It's also what makes rue tea hard to filter by simple gravity filtration.
"Is this the end of our adventure? Nothing has an end. We came in search of the secret of immortality, to be like gods, and here we are... mortals, more human than ever. If we have not obtained immortality, at least we have obtained reality. We began in a fairytale and we came to life! But is this life reality? We are images, dreams, photographs. We must not stay here! Prisoners! We shall break the illusion. This is Maya. Goodbye to the holy mountain. Real life awaits us." ~ Alejandro Jodorowsky