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 μM/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 μM) for 28 h	Chrysin & ellagic acid inhibited NF-κB 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 μM) & PS (0–90 μM), 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 μg/mL GAE, for 24 h	Red wine extract decreased mRNA expression of NF-κB, 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 μg/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-1β, 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 μg/mL apple peel PP for 24 h	Apple peel PP prevented Fe/ascorbate-mediated lipid peroxidation & counteracted LPS-mediated inflammation by downregulating cytokines (TNF-α, 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 μg/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 μM (malvidin, cyanidin & apigenin) or 100 μM (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 μM 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 μg/mL up to 48 h	Reduced IL-1β levels in Caco-2 cells	Reduced activation of NF-κB. 50 & 100 μg mL−1 effective	[113]
Effect of resveratrol on HT-29 colon cells	25 μM 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.