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:

2-Arylpyrazolo[4,3-d]pyrimidin-7-amino derivatives as new potent and selective human A3 Adenosine receptor antagonists. Molecular modeling studies and pharmacological evaluation. On the basis of our previously reported 2-arylpyrazolo[4,3-d]pyrimidin-7-ones, a set of 2-arylpyrazolo[4,3-d]pyrimidin-7-amines were designed as new human (h) A3 adenosine receptor (AR) antagonists. Lipophilic groups with different steric bulk were introduced at the 5-position of the bicyclic scaffold (R5 = Me, Ph, CH2Ph), and different acyl and carbamoyl moieties (R7) were appended on the 7-amino group, as well as a para-methoxy group inserted on the 2-phenyl ring. The presence of acyl groups turned out to be of paramount importance for an efficient and selective binding at the hA3 AR. In fact, most of the 7-acylamino derivatives showed low nanomolar affinity (Ki = 2.5-45 nM) and high selectivity toward this receptor. A few selected pyrazolo[4,3-d]pyrimidin-7-amides were effective in counteracting oxaliplatin-induced apoptosis in rat astrocyte cell cultures, an in vitro model of neurotoxicity. Through an in silico receptor-driven approach the obtained binding data were rationalized and the molecular bases of the observed hA3 AR affinity and hA3 versus hA2A AR selectivity were explained.
{"Chemical": ["Ph", "oxaliplatin", "2-arylpyrazolo[4,3-d]pyrimidin-7-ones", "acyl", "carbamoyl", "2-phenyl", "Adenosine", "2-Arylpyrazolo[4,3-d]pyrimidin-7-amino", "7-amino", "CH2Ph", "para-methoxy", "7-acylamino", "2-arylpyrazolo[4,3-d]pyrimidin-7-amines", "adenosine", "pyrazolo[4,3-d]pyrimidin-7-amides", "Me"]}