Synthetic cannabinoids
They have been designed to be similar to THC , the natural cannabinoid with the strongest binding affinity to the CB1 receptor , which is linked to the psychoactive effects or "high" of marijuana . 
<triplet> THC <subj> cannabinoid <obj> subclass of <subj> CB1 receptor <obj> physically interacts with <triplet> CB1 receptor <subj> THC <obj> physically interacts with <triplet> marijuana <subj> THC <obj> has part <subj> cannabinoid <obj> has parts of the class