A stability-indicating method by LC-UV for analysis of 7-epi-clusianone extracted from Garcinia brasiliensis fruits and a novel prenylated benzophenone from the oxidation of this molecular marker

Abstract

The potential of 7-epi-clusianone (7-EPI), a natural prenylated benzophenone extracted from fruits of Garcinia brasiliensis, as a drug candidate with antimicrobial, antileishmanial, and anti-inflammatory activities has been reported. In this study, we developed a stability-indicating method by LC-UV for determination of 7-EPI isolated from fractionated extracts of Garcinia brasiliensis fruits. Under forced degradation conditions (acid and alkaline media, oxidative stress, and thermal stability), 7-EPI showed one degradation product which was detected under oxidative conditions using hydrogen peroxide. The chemical structure of the oxidative degradation product was elucidated after characterization studies using high-resolution mass spectrometry, heteronuclear multiple bond correlation (HMBC), and ATR-FTIR. The results indicated a Baeyer–Villiger rearrangement, where one oxygen atom was incorporated and stabilized by resonance between two carbonyl moieties in the 7-EPI structure. In this way, a stability-indicating method for 7-EPI analysis was developed and validated. The structure of the oxidative degradation product was elucidated and its degradation pathway was proposed. From this, a novel prenylated benzophenone was identified and denoted as 7-epi-oxi-clusianone, a compound with the potential to be exploited as a drug candidate or a sunscreen agent.