Supercritical, ultrasound and conventional extracts from carob (Ceratonia siliqua L.) biomass: Effect on the phenolic profile and antiproliferative activity

Abstract

A new approach to the extraction of bioactive phenolic compounds from carob kibbles has been proposed. Carob pulp kibbles, a by-product of the carob bean gum production, were subject to supercritical fluid extraction (SFE) and to ultrasound assisted (UAE) and conventional solid–liquid extractions with two different solvent systems (100% H2O and 70% acetone), in order to obtain phenolic rich extracts with biological activities. These extracts were characterized for total phenolics content, antioxidant activity and their phenolic profile was qualitatively evaluated by HPLC-DAD. Chromatographic profile of SFE extract showed a diversity of phenolic compounds while ultrasound and conventional extracts contained mainly gallic acid. The highest phenolics concentration and antioxidant capacity was also found in the SFE extract. Preliminary screening of the extracts antiproliferative activity on rat N1E-115 neuroblastoma cells, and on human HeLa cervical and MCF-7 breast cancer cell lines revealed that carob SFE extract exhibited a much higher antiproliferative effect in the studied tumor cells, indicating its greater potential as a source of natural antitumor compounds. Supercritical fluid extraction revealed to be a more selective and efficient method of extraction. Thus, the potential association of two environmentally clean processes (UAE and SFE) for obtaining polyphenols from carob kibbles will enable bioactive compounds within an integrated and sustainable recovery process. Also, the solid residue after extractions could be used as dietary fiber.