Determination of benzophenones in lipophilic extract of Brazilian red propolis, nanotechnology-based product and porcine skin and mucosa: Analytical and bioanalytical assays.

Lipophilic compounds of Brazilian Red Propolis (BRP) have received increasing attention due to some interesting findings regarding their biological activities. This study was first aimed at evaluating the chemical composition of BRP n-hexane extract (HEXred) by UPLC-MS-PDA. Chemical investigation mainly resulted in the identification of polyprenylated benzophenones (PPBs) in this extract, named oblongifolin A, guttiferone E, and/or xanthochymol. After that, an isocratic HPLC-UV method was validated for the determination of total content of PPBs (at 260 nm) expressed as garcinol, a commercially available guttiferone E diastereoisomer. The method showed to be specific, precise, accurate, and linear (0.1-10 µg/mL) for the determination of PPBs in HEXred, BRP-loaded nanoemulsions, as well as, in porcine skin and mucosa samples after permeation/retention studies. The matrix effect was determined for all complex matrices, demonstrating low effect during the analysis. The stability-indicating method was verified by submitting HEXred to acidic, alkaline, oxidative, and thermal stress conditions. No interference of degradation products was detected during analysis. Therefore, the proposed analytical and bioanalytical methods proved to be simple and reliable for the determination of PPBs in the presence of different matrices.