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:

The conjugation of microcystin-RR by human recombinant GSTs and hepatic cytosol. Many cyanobacterial species can produce cyanotoxins, among which mycrocistins (MC) are a group of ≈100 congeners of hepatotoxic cyclic heptapeptides. MC-RR differs from MC-LR, the most studied congener only for one residue (arginine vs leucine), resulting in a ten-fold difference in the acute toxicity in mice. Although humans may be exposed to MC through several routes and kinetics appeared to be the major factor affecting congener-specific toxicity, little is known on MC metabolism. The accepted pathway for MC detoxication is GSH conjugation: here the MC-RR conjugation with GSH catalyzed by 5 recombinant human GSTs and human liver cytosol (HLC) has been characterized and appeared to be more efficient than MC-LR conjugation. The catalytic efficiency score is T1-1>A1-1≈P1-1>M1-1>A3-3 (0.161-0.056pmol GSMC-RR (μgproteinminμM)(-1)). In HLC the spontaneous reaction is favored vs the enzymatic one (ratio 3:1) at physiological GSH content. However, at low MC-RR concentrations, representative of repeated oral exposure, and low GSH content (down to 0.05mM), possibly associated to exposure to drugs or in patients affected by several pathologies, the relevance of the enzymatic reaction progressively increases, providing the predominant contribution to MC-RR detoxication.
{"Chemical": ["cyclic heptapeptides", "GSH", "mycrocistins", "leucine", "arginine", "MC-RR", "microcystin-RR", "MC-LR"]}