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:

Reduction of helical content by insertion of a disulfide bond leads to an antimicrobial peptide with decreased hemolytic activity. CAPs off to the S-S bond: Application of a strategy involving the introduction of intramolecular disulfide bonds to amphipathic cationic antimicrobial peptides (CAPs) led to decreased α-helicity and hydrophobicity. The mutant peptides were observed to have significantly increased (250-fold) minimum hemolytic concentrations while maintaining MIC values against E. coli, affording more therapeutically selective CAPs.
{"Chemical": ["disulfide", "S-S"]}