Degradation of β-casomorphin-7 through in vitro gastrointestinal and jejunal brush border membrane digestion

摘要

This work aimed to study the opioid peptideβ-casomorphin-7 (BCM7) degradation or stabilityduring digestion using human gastrointestinal (GI)juices and porcine jejunal brush border membrane(BBM) peptidases. Synthetic BCM7 was subjected toin vitro digestion by GI fluids obtained from humanvolunteers for 180 min, and to downstream degradationwith porcine BBM vesicles. The BCM7 was sampledat 4 time points over 24 h after BBM addition. Thedigests were profiled by HPLC-electrospray ionizationmass spectrometry (ESI/MS) to monitor BCM7during GI digestion, and intact BCM7 through BBMdigestion was quantified by reverse-phase (RP)-HPLC.We found that BCM7 was partly digested with humanGI enzymes, as 3 proteolytic fragments in addition tof(60–66) YPFPGPI were detected: f(62–66) FPGPI,f(60–65) YPFPGP and f(61–66) PFPGPI. The RPHPLCanalysis revealed that 42% of the initial peptidewas degraded after only 2 h of BBM digestion, and asmuch as 79% was degraded after 4-h digestion withsupplementation of BBM. In conclusion, this studyshowed that most of BCM7 was degraded during GIand BBM digestion, although a small amount (5%)was still detected after 24-h digestion. It remains tobe studied whether the small amount of intact BCM7detected after in vitro digestion is transported via activetransceptors in the human intestinal epithelial cellsand enters blood circulation.