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:

Chemical composition and antioxidant activity of the essential oil of Tabernaemontana catharinensis A. DC. leaves. The essential oils obtained by hydrodistillation from the leaves of Tabernaemontana catharinensis had their composition analysed by GC-MS. A total of 18 substances were identified, consisting of a complex mixture of sesquiterpenes (83.52%), monoterpenes (5.46%) and triterpenes (4.56%). The main components in the oil were β-caryophyllene (56.87%), α-cadinol (12.52%), 8S,13-cedran-diol (5.41%), α-terpineol (3.99%), β-eudesmol (2.54%), caryophyllene oxide (2.51%) and ethyl iso-allocholate (2.03%) along with β-cubebene, γ-cadinene, cubenol, 1,8-cineol, o-cymene, curcumenol, spathulenol, friedeline and β-sitosterol as minor constituents. An antioxidant property was tested with the oil obtained by means of 1,1-diphenyl-2-picrylhydrazyl assay; the oil presented interesting radical scavenging activity. To the best of our knowledge, this is the first study of the composition and antioxidant activity of essential oil from the T. catharinensis collected from Brazil.
{"Chemical": ["1,1-diphenyl-2-picrylhydrazyl", "caryophyllene oxide", "\u03b2-cubebene", "\u03b2-caryophyllene", "sesquiterpenes", "curcumenol", "\u03b1-cadinol", "\u03b3-cadinene", "8S,13-cedran-diol", "o-cymene", "monoterpenes", "ethyl iso-allocholate", "friedeline", "\u03b2-eudesmol", "\u03b1-terpineol", "cubenol", "triterpenes", "1,8-cineol", "\u03b2-sitosterol", "spathulenol"]}