Extraction and identification by high resolution mass spectrometry of bioactive substances in different extracts obtained from pomegranate peel.

This work proposes a method to separate proteins and polyphenols in a food byproduct with high bioactive properties and demonstrate by high performance liquid chromatography tandem mass spectrometry its efficiency. Bioactive substances were extracted using high intensity focused ultrasounds. Resulting extract (SR) was submitted to a step for the purification of proteins and to obtain a protein isolate (PI). Both extracts (SR and PI) were digested using two different enzymes (alcalase and thermolysin). Antioxidant, hypocholesterolemic, and antihypertensive properties of hydrolysates were explored. High antioxidant capacity, mainly due to the presence of polyphenols, was observed in SR and its hydrolysates. Hydrolysates obtained from PI using the alcalase enzyme showed simultaneously a high capacity to inhibit cholesterol esterase and to reduce micellar cholesterol solubility. Hydrolysate obtained from PI using the thermolysin enzyme showed a high antihypertensive capacity. Peptides and polyphenols in hydrolysates were identified by RP-HPLC-ESI-Q-TOF. Hydrolysates obtained from PI showed a high amount of peptides and a negligible amount of polyphenols while polyphenols were mainly present in hydrolysates from SR.