[{"from": "human", "value": "Describe this molecule. [C][C][C][C][C][C][C][Branch1][=C][C][Ring1][=Branch1][C][C][C][Ring1][=Branch2][Branch1][Ring1][C][#C][O][C][C][C][=C][C][=Branch1][C][=O][C][C][C][Ring2][Ring1][C][Ring1][#Branch1]"}, {"from": "gpt", "value": "The molecule is synthetic steroidal progestin that is used in combination with ethinyl estradiol for oral contraception. Norgestrel is composed of a racemic mixture of two stereoisomers, dextronorgestrel and levonorgestrel.  However, only the levorotary enantiomer ([levonorgestrel]) is biologically active."}]