So do I throw away the liquid that comes from the lysed cells? Or should I save it and evaporate it? Will there be mescaline/alkaloids in it?

If you freeze pieces of cactus, there shouldn't be liquid. If there is, sure, brew it up.

Kk thanks, yeah a bunch of liquid came out of the cactus after I thawed it.
It's like this picture:

that sticky stuff looks potently familiar, but to be sure, invite my friends over for an assay-party!

I always just toss frozen bits of cacti in a boiling pot of water, so I have never encountered that. It definitely has some goods.