Rapamycin is a macrolide isolated from a fermentation broth of Streptomyces hygroscopicus, a bacterium discovered on Easter island in 1972. This peptide plays a central role in mediating the beneficial effects of dietary restriction on healthy aging. Rapamycin initially began as an FDA-approved immunosuppressant for renal transplant patients. At higher doses, it has been shown to improve immunity, reduce agerelated conditions and prolong the lifespan (animal studies).