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:

Discovery and optimization of potent broad-spectrum arenavirus inhibitors derived from benzimidazole. A chemically diverse library of about 400,000 small molecules was screened for antiviral activity against lentiviral pseudotypes with the Lassa virus envelope glycoprotein (LASV GP) gene incorporated. High-throughput screening resulted in discovery of a hit compound (ST-37) possessing a benzimidazole core which led to a potent compound series. Herein, we report SAR studies which involved structural modifications to the phenyl rings and methylamino linker portion attached to the benzimidazole core. Many analogs in this study possessed single digit nanomolar potency against LASV pseudotypes. Compounds in this benzimidazole series also exhibited nanomolar antiviral activity against pseudotypes generated from other arenavirus envelopes indicating the potential for development of a broad-spectrum inhibitor. Ultimately, lead compound ST-193 was identified and later found to be efficacious in a lethal LASV guinea pig model showing superior protection compared to ribavirin treatment.
{"Chemical": ["ST-193", "phenyl", "methylamino", "benzimidazole", "ST-37"]}