Fentacyamine was a chemical compound. Several plants or fungi on earth contained fentacyamine, which gave them hallucinogenic properties.
While trying to discover the cure for the gate plague, Steven Johnson, Carol Smithson, and Oscar Shelton realized that sallowroot (a drug that had been protecting Sophie Donitz from succumbing) contained fentacyamine. This allowed Micah Landon to synthesize a cure for Sophie to bring to Vurna when she returned through the Einstein-Rosen Bridge. (Next of Kin)