Chalcone-flavanone enzyme complex. Molecular model of the complex formed by the chalcone isomerase (CHI) enzyme (blue and yellow) with the flavanone molecule naringenin. The molecule of naringenin is at upper centre (green [carbon] and red [oxygen]). The surrounding structure is the CHI enzyme, with its secondary structure (blue alpha helices and yellow beta sheets). In vascular plants, CHI-catalysed conversion of chalcones to chiral (S)-flavanones is a key step in the production of plant flavonoids. Naringenin, found in grapefruits, has been studied for its antioxidant, anti-inflammatory, and immunological effects.