Table 5.

Mechanisms of action of anti-inflammatory peptides isolated from various food sources.

Dietary protein source	Enzyme used to produce peptides	Peptide sequence or molecular weight	Object	Dose & duration	Activity/mechanisms of action	Reference
Soy bean	—	150–500 Da	Pigs with DSS-induced colitis	250 mg/kg BW for 5 d	Peptides decreased TNF and IL-6 levels and inhibited IFN-γ, IL-1β, and TNF expression	[141]
Soy bean	—	VPY	Caco-2 cells and mouse of DSS-induced colitis mice	0.1, 1, 2, and 4 mM for 2 h and 10 and 100 mg/kg BW for 14 d	VPY inhibited IL-8 secretion and reduced the expressions of TNF-α, IL-6, IL-1β, IFN-γ, and IL-17	[108]
Salmon	—	<1000 Da	DSS-induced colitis in rats	3.5% in diet for 29 d	Peptides reduced inflammation by reducing IL-6 and IL-1β expressions	[142]
Egg shell membrane	Alcalase and protease S	—	TNF-α induced Caco-2 cells and DSS-treated colitis mice	0.001, 0.01, 0.5, and 0.1 mg/mL for 2 h	Peptides inhibited IL-8 secretion and decreased TNF-α and IL-6 levels	[143]
Milk casein	Bacterial food-grade enzyme	<5000 Da	TNF-α-induced Caco-2 cells and ex vivo porcine colonic tissue system	0.01, 0.02, 0.05, 0.1, 0.5, 1, 2.5, and 5 mg/mL for 24 h	Peptides reduced IL-8 by 66–68% and reduced IL-1α/β, IL-8, TGF-β, and IL-10 expression	[107]
Rat collagen	Pepsin	—	DSS-induced colitis in mice	100 mg/kg BW from days 6 to 15	Peptides reduced IL-1β and IL-6 expression	[144]
Egg white	Pepsin and pancreatin	—	TNF-α-induced inflammation in Caco-2 cells and DSS-induced colitis mice	0.05, 0.1, 0.5, 1, and 2.5 mg/mL for 2 h	Peptides inhibited IL-8 secretion and decreased expression of TNF-α, IL-6, IL-1β, IFN-γ, and IL-17 and enhanced IL-10 expression and decreased the expression of TNF-α, IL-6, IL-1β, IFN-γ, and IL-17	[145]
Egg white ovotransferrin	Pepsin and trypsin	CR, FL, HC, LL, and MK	TNF-α-induced Caco-2 cells	0.05, 0.1, 0.5, 1, 2.5, and 5 mg/mL for 2 h	Peptides decreased expression of TNF-α, IL-8, IL-6, IL-1β, and IL-12, and enhanced IL-10 expression. CR and HC attenuated intestinal inflammation by inhibiting NF-κB and MAPK pathways	[103]
Milk whey	Pronase	IPAV	TNF-α induced Caco-2 cells	2.5 and 5 mg/mL for 1 h	IPAV showed anti-inflammatory effect by inhibiting IL-8 expression and suppressing phosphorylation of p65, ERK1/2, p38, JNK1/2, and Syk signaling	[102]
Egg white	—	DEDTQAMPFR, MLGATSL, SLSFASR, and MSYSAGF	DSS-induced colitis mice	50 or 150 mg/kg/day for 14 d	Peptides inhibited the local production of TNF-α and IL-6 and reduced the expression of TNF-α, IL-6, IL-17, IL-1β, IFN-γ, and MCP-1	[111]
Common bean (Phaseolus vulga L.) milk and yogurts	Pepsin and pancreatin	γ-E-S-(Me)C, γ-EL, and LLV	TNF-α-induced Caco-2 cells	0.5 mg/mL for 2 h	Peptides inhibited TNF-α-induced IL-8 production via inhibiting activation of NF-κB and MAPK pathways	[113]
Egg white	Pancreatin	DEDTQAMPFR, DEDTQAMPF, MLGATSL, and MSYSAGF	TNF-α-induced Caco-2 cells	0.1, 0.25, or 0.5 mg/mL for 2 h	Peptides downregulated the expression of IL-8, IL-1β, IL-6, TNF-α, and IL-12 and upregulated IL-10 expression via inhibiting NF-κB and MAPK pathways	[110]
Crucian carp	Pancreatin	<1500 Da	IEC-6 cells and DSS-induced colitis mice	0, 50, 100, or 150 μg/mL for 20 h and 50 mg/kg BW for 15 days	Peptides reduced IL-1β, IL-6, and TNF-α levels via inhibiting the NF-κB pathway	[106]
Soy bean	B. subtilis BS12	<3000 Da	Intestinal porcine epithelial cells-J2	50 μg/mL for 2 h	Soy peptides reduced the expression of IL-6, IL-1β, and IL-8 and decreased Escherichia coli K88-induced inflammation	[4]
Corn	Alcalase and pancreatin	—	TNF-α-induced Caco-2 cells and colitis mice	500, 1500, and 2500 μg/mL for 6 h and 100 and 300 mg/kg/d for 14 days	Peptides reduced inflammation via inhibiting IL-8 secretion and iNOS and COX-2 expression and downregulating TNF-α and IL-6 expression	[109]

DSS: dextran sodium sulfate; ERK: extracellular signal-regulated kinases; IL: interleukin; TNF-α: tumor necrosis factor alpha; MAPK: mitogen-activated protein kinase; NF-κB: nuclear factor-κB; JNK: c-Jun N-terminal kinase.