Isolation and characterization of a novel oxyphenisatin analogue, 4-Chloro-oxyphenisatin diisobutyrate, from a jelly candy purported to possess weight-loss properties

A novel oxyphenisatin analogue was identified in a type of jelly candy during routine inspections of food products marketed for weight-loss purposes. Through analysis utilizing ultra-high-performance quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-HRMS), the fragment ions at m/z 258 and 195 observed in the MS/MS experiments were found to be consistent with those of 4-Chloro-oxyphenisatin diacetate. It was inferred that the unknown compound is likely a derivative of 4-Chloro-oxyphenisatin diacetate. The candy was separated and purified by column chromatography, and the purified compound was determined to be 96.4 % by high-performance liquid chromatography (HPLC). Subsequently, the structure was confirmed through nuclear magnetic resonance (NMR) spectroscopy. Based on the data, it was concluded that the structure of the unknown compound involved the substitution of two symmetrical acetyl groups in the 4-chloro-oxyphenisatin diacetate molecule with two isobutyl groups. Ultimately, the novel oxyphenisatin analogue was identified as (5-chloro-2-oxoindolin-3,3-ylidene) bis (4,1-phenylbutan-2-yl) diisobutyrate and designated as 4-Chloro-oxyphenisatin diisobutyrate. Finally, a quantitative analysis of the novel unknown compound in the jelly candy revealed a concentration of 6 mg per pellet. Based on the recommended daily consumption of one pellet, as indicated on the product packaging, the level of illegal additives may lead to diarrhoea and consequently poses a risk to human health. To the best of our knowledge, this represents the first report on the identification of 4-Chloro-oxyphenisatin diisobutyrate.