[{"from": "human", "value": "Could you give me a brief overview of this molecule? [C][N][C][=N][C][=Branch2][Ring1][C][=C][Ring1][Branch1][S][C][=N][C][=N][C][=C][Ring1][=Branch1][N][C][=N][Ring1][Branch1][N+1][=Branch1][C][=O][O-1]"}, {"from": "gpt", "value": "The molecule is a purine analogue and prodrug of mercaptopurine that is used as an immunosuppressive agent in organ transplantation to prevent rejection and in autoimmune diseases as a corticosteroid sparing agent. Azathioprine is associated with minor, usually transient and asymptomatic elevations in serum aminotransferase levels during therapy and with rare instances of acute, cholestatic liver injury and, with long term use, noncirrhotic portal hypertension as a result of nodular regenerative hyperplasia or sinusoidal obstruction syndrome."}]