The original isolation of rapamycin from a soil bacterium found on Easter Island, discovered first as an antifungal compound decades before its mTOR-inhibiting mechanism was known.
| Evidence tier | D Mechanistic / in vitro / review |
| Study type | 5 - Mechanistic / In Vitro |
| Model system | Streptomyces hygroscopicus (soil bacterium) |
| Journal | Journal of Antibiotics |
| Year | 1975 |
| Peer reviewed | Yes |
| Source | DOI 10.7164/antibiotics.28.721 · PMID 1102508 |
A streptomycete was isolated from an Easter Island soil sample and found to inhibit Candida albicans, Microsporum gypseum and Trichophyton granulosum. The antibiotic-producing microorganism was characterized and identified as Streptomyces hygroscopicus. The antifungal principle was extracted with organic solvent from the mycelium, isolated in crystalline form and named rapamycin. Rapamycin is mainly active against Candida albicans; minimum inhibitory concentration against ten strains ranged from 0.02 to 0.2 mug/ml. Its apparent activity against Microsporum gypseum and Trichophyton granulosum is lower because of its instability in culture media on prolonged incubation required by these fungi. No activity was observed against gram-positive and gram-negative bacteria. Acute toxicity in mice is low.
| Intervention | Rapamycin (natural product isolation) |
| Target | Antifungal principle (later FKBP/TOR) |
| Model | Streptomyces hygroscopicus (soil bacterium) |
| Effect | Original isolation and characterization of rapamycin as an antifungal antibiotic from Easter Island soil |