Bioactivity of Polyphenols: Preventive and Adjuvant Strategies toward Reducing Inflammatory Bowel Diseases—Promises, Perspectives, and Pitfalls

Table 5

In vitro trials suggesting health benefits of polyphenols with respect to IBD—an overview.

Aspects studied	Dosing and time	Effects found	Mechanism proposed and critics	Reference
Effect of phytolens (water-soluble extract of PP antioxidants from nonsoy legumes) on colonic (T84) & murine macrophage (RAW 264.7) cells	Phytolens (10–100 M/mL) exposed to T84 & RAW 264.7 cells, 4 h & 12 h of exposure	Phytolens sign. attenuated apoptosis in T84 cells induced by ONOO^−. Phytolens did not directly affect T84 cell viability or induce apoptosis after 4 h or overnight exposure. RAW 264.7 cells exposed to phytolens displayed decreased cell viability & increased apoptosis	Potential beneficial effects of phytolens on inflammation via attenuating induced apoptosis	[106]
PP standards effects of Caco-2 cells	Chrysin, ellagic acid, genistein, & EGCG (all 50 M) for 28 h	Chrysin & ellagic acid inhibited NF-B activity & genistein & resveratrol increased it. Mixed effects on IL-8 secretion	Anti- & proinflammatory aspects of PP	[107]
Effect of PP metabolites 3,4-dihydroxyphenyl-acetic acid (ES) & 3-(3,4-dihydroxy-phenyl)-propionic acid (PS) on LT97 colon cells	Cells incubated with ES (0–18 M) & PS (0–90 M), metabolites of quercetin & chlorogenic acid/caffeic acid, respectively, up to 72 h	PP metabolites did not affect cell number but sign. upregulated GSTT2 expression & decreased COX-2	Intestinal metabolites showed anti-inflammatory properties	[108]
Effect of red wine PP extract (from Lenoir grapes) on human colon-derived CCD-18 Co myofibroblasts cells	0–100 g/mL GAE, for 24 h	Red wine extract decreased mRNA expression of NF-B, ICAM-1, VCAM-1, & PECAM-1, in a dose dependent manner	miR-126, a target region within the 3′-UTR of VCAM-1 mRNA, was increased at 100 g/mL	[109]
Effect of PP-rich grape seed (GS) & grape marc (GM) on Caco-2 cells	24 h with up to 2 mg/mL	Decreased mRNA levels of NF-κB target genes IL-1, IL-8, MCP-1 & CXCL1 in Caco-2 cells. Unchanged mRNA levels of Nrf-2 target genes GPX-2, NQO1, CYP1A1 & UGT1A1	2 mg/mL ethanolic extracts dose-dependently reduced NF-κB transactivation. No effect of ethanolic extracts was observed on Nrf-2	[110]
Effect of apple peel PP on Caco-2/15 cells	250 g/mL apple peel PP for 24 h	Apple peel PP prevented Fe/ascorbate-mediated lipid peroxidation & counteracted LPS-mediated inflammation by downregulating cytokines (TNF-, IL-6) & PGE2	Downregulation of COX-2 & NF-κB. Also induction of Nrf-2	[111]
Effect of red wine extract (RWE) (rich in catechin B1 & malvidin-3-glucoside) on HT-29 colon cells	100–600 g/mL RWE extract (144 mg/g PP) for 24 h	RWE suppressed IκB degradation & IL-8 production dose-dependently. It also inhibited increase of NO from iNOS & of protein tyrosine nitration (biomarker of nitrosative stress)	RWE reduced NF-κB activation; COX-2 & iNOS	[69]
Effect of catechin, theaflavin, malvidin, cyanidin & apigenin on human Int-407 cells treated with ketoprofen	25 M (malvidin, cyanidin & apigenin) or 100 M (catechin & theaflavin) for 5 h	Catechin sign. decreased levels of lipid peroxidation & ROS (MDA, DCF) & increased activity of intracellular antioxidant enzymes GPx, Gred, total sulfhydryl groups (TSH)	ROS reduction of PP. WB analysis revealed that catechin stimulated a time-dependent increase in Nrf-2 & total HO-1 protein expression	[96]
Effect of cyanidin-3-glucoside on HT-29 colon cells	25 M cyanidin-3-glucoside, up to 24 h	Improved NO, PGE2 & IL-8 production	Improved iNOS & COX-2 expressions. No effect on NF-κB or p38 MAPK, but STAT1	[112]
Effect of blueberry anthocyanin-rich extract on Caco-2 cells	Up to 100 g/mL up to 48 h	Reduced IL-1β levels in Caco-2 cells	Reduced activation of NF-κB. 50 & 100 g mL^−1 effective	[113]
Effect of resveratrol on HT-29 colon cells	25 M resveratrol, up to 24 h	Decreasing levels of activated; STAT1 in nucleus. Also reduction of cytokine-stimulated activation of SAPK/JNK pathway	Downregulation of JAK-STAT pathway, though not counteracting cytokine-triggered negative feedback mechanism of STAT1 through p38 MAPK	[114]
Plum & cabbage digesta: triple culture cell model: Caco-2/HT-29-MTX with THP-1	18 h of incubation following digestion	Reduction of IL-8 secretion by plum varieties	Influences via NF-κB & Nrf-2	[67]

See footnote of Table 3.