For example, for several years, I did ethnobotanical study in South America, researching native uses for coca leaf, which most of us know only as the source of the isolated, problematic, addictive drug cocaine. For Andean Indians, whole coca leaf is the number one medicinal plant. They use it to treat gastrointestinal disturbances; specifically, for both diarrhea and constipation. From the perspective of Western pharmacology, this makes no sense. Cocaine stimulates the gut, it increases bowel activity, so obviously it would be a good treatment for constipation, but what could it do for diarrhea except make it worse?
However, if you look carefully at the coca leaf's molecular array, you find 14 bioactive alkaloids, with cocaine in the greatest amount. While cocaine acts as a gut stimulant, other coca alkaloids can have precisely the opposite action, they inhibit gut activity.
This means that when you take the whole mixture into the body, the potential is there for the action to go in either direction. What decides it? The state of the body, which is a function of which receptors in the gut's tissues are available for binding. During my time in Andean Indian communities, I collected many reports about whole coca's paradoxical, normalizing effect on bowel function, and experienced it firsthand, as well.