You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Isolation and structure determination of new siderophore tsukubachelin B from Streptomyces sp. TM-74. The new siderophore tsukubachelin B (1) was isolated from the iron-deficient culture medium of the newly isolated strain Streptomyces sp. TM-74. The chemical structure of tsukubachelin B (1) was established via interpretation of 2D nuclear magnetic resonance and electrospray ionization-mass spectroscopic data. The structure of tsukubachelin B (1) comprises 6 mol of amino acids, including 2 mol of serine and 1 mol each of ornithine, N-α-methyl-N-δ-hydroxy-N-δ-formylornithine, N-α-methyl-N-δ-hydroxyornithine, and cyclic N-hydroxyornithine.
{"Chemical": ["cyclic N-hydroxyornithine", "amino acids", "serine", "tsukubachelin B", "iron", "ornithine", "N-\u03b1-methyl-N-\u03b4-hydroxyornithine", "N-\u03b1-methyl-N-\u03b4-hydroxy-N-\u03b4-formylornithine"]}