Yes. A biochemist can give you a better procedure but this should work.

Completely grind the material so as to rupture all the cells - there is a specialized peice of glassware to do this, though you would need to use a mortar and pestal first.

Filter (the soxhlet extractor could be used instead - ask a biochemist which would be better) and wash with water (3 volumes), then MeOH (1 volume; you need to remove then water) then with heptane (3 volumes) - the residue on the filter will be cellose and can be discarded.

Combine all the filtrates then acidify to pH 3-4 (?). Mix throughly then seperate the layers. Extract the heptane layer twice more with acidic water (pH 3-4). Extract the aqueous layer with heptanes twice. Alkaloids are basic (and often poisonous) so they should be in acidic water. The heptane layers will contain organic acids, proteins and fats.

Combine all the acidic water layers and basify to pH 13-14 then extract with heptanes trice. If you're lucky all the remaining proteins have been denatured and can be filtered from the heptanes. The heptane layers contain all the basic organic compounds - not just the alkaloids.

Concentrate/dry the combined heptanes with a rotoary evaporator then weigh the produces.