UHPLC-DAD-ESI-MSn profiling and predictive modeling of polyphenols in Ceratonia siliqua flowers with cosmetic applications

Abstract

This study explored the valorisation of carob (Ceratonia siliqua) flowers by optimizing the extraction of antioxidant compounds using Response Surface Methodology (RSM) with a Box Behnken Design (BBD). To the best of our knowledge, this represents the first report on carob flower polyphenols optimized with BBD model. Three variables were investigated: solvent concentration (50–80%), agitation speed (100–200 rpm), and extraction time (30–60 min). The optimized conditions were established at 80% ethanol, 200 rpm, and 50.96 min, resulting in a high global desirability score of 0.97. Under these optimal conditions, the experimental yields were 120.23 ± 1.16 mg GAE/g for total phenolic compounds (TPC), 26.44 ± 0.76 QE/g for flavonoids, 30.65 ± 0.85 mg TAE/g for tannins, and 17.77 ± 1.22 QE/g for flavanols. The data reported that all models developed exhibited good agreement between predicted and experimental values (R² = 0.8681–0.9997) and were statistically significant (F-values ranging from 0.000 to 0.032). The results of optimized extract were charachterized using Ultra High Performance Liquid Chromatography coupled with Diode Array Detection and Electrospray Ionisation Mass Spectrometry (UHPLC-DAD-ESI-MSⁿ), revealing gallic acid and apigenin derivative as the most abundant compounds. Furthermore, the extracts demonstrated strong antioxidant and antidiabetic activities. Finally, five cosmetic body lotions were formulated using the optimized extract. Sensory evaluation revealed that formulation F3 received the highest overall score, indicating good consumer acceptability in terms of odor, spread ability, and skin feel.