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Updated: Jun 14, 2026

A Microplate Assay to Assess Chemical Effects on RBL-2H3 Mast Cell Degranulation: Effects of Triclosan without Use of an Organic Solvent
Published on: November 1, 2013
(E,Z)-3-(3',5'-Dimethoxy-4'-hydroxy-benzylidene)-2-indolinone blocks mast cell degranulation
S Kiefer1, A C Mertz, A Koryakina
1Institute of Pharmaceutical Biology, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland.
Abstract:
(E,Z)-3-(3',5'-Dimethoxy-4'-hydroxy-benzylidene)-2-indolinone (indolinone) is an alkaloid that has been identified as a pharmacologically active compound in extracts of the traditional anti-inflammatory herb Isatis tinctoria. Indolinone has been shown to inhibit compound 48/80-induced mast cell degranulation in vitro. Application of indolinone to bone marrow derived mast cells showed that it was uniformly distributed in the cytoplasm and that cellular uptake was terminated within minutes. Pre-treatment of IgE-sensitized mast cells with 100nM indolinone rendered them insensitive against FcvarepsilonRI-receptor dependent degranulation. However, upstream signalling induced by antigen such as activation of PI3-K and MAPK remained unaffected. We conclude that indolinone blocks mast cell degranulation at the level of granule exocitosis with an IC(50) of 54nm.
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