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:

Design, synthesis and antithrombotic evaluation of novel dabigatran prodrugs containing methyl ferulate. A novel series of prodrugs containing dabigatran and methyl (E)-3-(4-hydroxy-2-methoxyphenyl)propenoate (methyl ferulate) were synthesized. All of them reveal the effect of thrombin-induced anti-platelet aggregation in vitro. In addition, in vivo experiment shows that one of the target compounds, X-2 (ED50=3.7 ± 1.0 μmol/kg) possesses a more potent activity for inhibiting venous thrombosis than that of dabigatran etexilate (ED50=7.8 ± 1.5 μmol/kg).
{"Chemical": ["methyl ferulate", "methyl (E)-3-(4-hydroxy-2-methoxyphenyl)propenoate", "dabigatran etexilate", "dabigatran"]}