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 anticancer activity of N(3),N(11)-bis(2-hydroxyethyl)-14-aryl-14H-dibenzo[a,j]xanthenes-3,11-dicarboxamide. A series of novel N(3),N(11)-bis(2-hydroxyethyl)-14-aryl-14H-dibenzo[a,j]xanthenes-3,11-dicarboxamide, three N(3),N(11)-bis(2-hydroxyethyl)-14-aryl-14H-dibenzo[a,j]xanthene-3,11-dimethanamine derivatives and their intermediates 14-aryl-14H-dibenzo[a,j]xanthenes-3,11-dicarboxylic acid, were synthesized, and the structures of which were characterized by (1)H-NMR, (13)C-NMR, high resolution (HR)-MS, and IR spectra. The antitumor activities of these molecules were evaluated on five cancer cell lines. The results of in vitro assay against human hepatocellular carcinoma cell lines (SK-HEP-1 and HepG2 and SMMC-7721 cells), acute promyelocytic leukemia NB4 cells and uterine cervix cancer HeLa cells, show several compounds to be endowed with cytotoxicity in micromolar to submicromolar range. The carboxamide derivatives 6c and 6e exhibitted good inhibition on NB4 cancer cells, and the IC(50) values of which were 0.82 µM and 0.96 µM, respectively, much lower than 5.01 µM of the positive control As(2)O(3). Flow cytometric analysis results revealed that compounds 6e and 6f may induce tumor cell apoptosis.
{"Chemical": ["(13)C", "N(3),N(11)-bis(2-hydroxyethyl)-14-aryl-14H-dibenzo[a,j]xanthenes-3,11-dicarboxamide", "As(2)O(3)", "(1)H", "carboxamide", "N(3),N(11)-bis(2-hydroxyethyl)-14-aryl-14H-dibenzo[a,j]xanthene-3,11-dimethanamine", "14-aryl-14H-dibenzo[a,j]xanthenes-3,11-dicarboxylic acid"]}