Table 5.

Polyphenol metabolites and functions.

Polyphenols	Subclasses	Metabolites	Bacterial Catabolism	Metabolites Functions	Ref
Flavonols	Quercetin	3,4-DHPAA 3-HPAA 4-HPAA	Clostridium orbiscidens Eubacterium oxidoreducens Eubacterium ramulus Enterococcus casseliflavus	Oxygen radical scavenging (all the metabolites), SOD- like activities (3,4 DHPAA), ↑glutathione S-transferase (3,4 DHPAA), ↑Nrf2-AhR (3,4 DHPAA) ↓Proinflammatory cytokines (3,4 DHPAA) ↑Glucose induced-insulin secretion (3,4 DHPAA) ↑Function and survival of pancreatic β-cells (3,4 DHPAA) Protective effect against OxS induced-endothelial dysfunction (3,4 DHPAA)	[132,208,209,210,211,212,213,214,215,216,217,218,219,220]
Flavones	Apigenin	Phloretin 3-HPPA 4-HPPA 4-HCA	Clostridium orbiscindens	↓Oxygen radical scavenging (3-HPPA) ↓Proinflammatory cytokines (3-HPPA) ↑Glucose induced-insulin secretion (3-HPPA) ↑Function and survival of pancreatic β-cells (3-HPPA) Protective effect against OxS induced-endothelial dysfunction (3-HPPA)	[132,208,209,212,213,214,215,221]
Flavanones	Naringenin	3,4-DHPPA 3-HPPA 4-HPPA	Clostridium strains Eubacterium ramulus	↓Oxygen radical scavenging (3-HPPA) ↓Proinflammatory; 3,4 DHPPA) ↑Glucose induced-insulin secretion (3-HPPA) Protective effect against OxS induced-endothelial dysfunction (3-HPPA)	[34,60,209,212,213,214,215,217,222,223]
Isoflavones	Daidzein	(S)-Equol O-DMA	Bacteroides ovatus, Streptococcus intermedius, Ruminococcus productus, Eggerthella sp.Julong 732, Enterococcus faecium EPI1, Lactobacillus mucosae EPI2, Finegoldia magna EPI3 Clostridium spp. HGHA136	Stimulation of cellular antioxidant systems ↑Catalase and SOD activity Anti-atherogenic effect	[224,225,226]
Flavan-3-ols	Monomers (catechins, epicatechins) and proanthocyanidins	3-HPPA 3,4-DHPPA 3′,4′-DHPVL 3,4-DHPVA 3′-HPVL 3′,4′,5′-THPVL 3′,5′-DHPVL	Clostridium coccoides, Bifidobacterium spp. Eggerthella lenta Flavonifractor plautii	↓Oxygen radical scavenging (3-HPPA) ↓ROS generation (3′-HPVL, 3′,4′-DHPVL) ↓NF-κB transcriptional activity ↓NO synthesis (3′,4′,5′-THPVL; 3′,4′-DHPVL) ↓iNOS expression (3′,4′-DHPVL) Maintenance of endothelial homeostasis and functions (3′,4′-DHPVL): ↓Endothelial adhesion (3′,4′-DHPVL) ↓VCAM1 and MCP1 (3′,4′-DHPVL) ↓Systolic blood pressure (3′,4′,5′-THPVL; 3′,5′-DHPVL)	[87,92,109,131,227,228,229,230,231,232,233,234,235,236]
Anthocyanins	Cyanidin Peonidin Pelargonidin Malvidin Delphinidin	Protocatechuic acid Vanillic acid 4-Hydroxybenzoic acid Syringic acid Gallic acid	Lactobacillus plantarum, Lactobacillus casei Lactobacillus acidophilus LA-5 Bifidobacterium lactis BB-12	Antidiabetic activities due to their antioxidant capacity ↓DNA damages, ↓ROS production ↑Cellular glutathione level, ↑glucose uptake by HepG2 and human skeletal cells, ↑glycogen production by HepG2 cells, ↑Mitochondria homeostasis	[237,238,239,240,241,242]
Hydroxycinnamic acids	Chlorogenic acids	3-HPPA 3,4-DHPPA Caffeic acid	Escherichia coli, Bifidobacterium lactis, Lactobacillus gasseri	↓Oxygen radical scavenging(3-HPPA) ↓Proinflammatory cytokines (3-HPPA; 3,4 DHPPA) Antidiabetic activities due to its antioxidant capacity (caffeic acid): ↑Cellular glutathione level ↓DNA damages ↓Cytotoxicity, ↓ROS production ↑Glucose consumption ↑Glycogen production	[209,212,214,215,243,244]
Hydrolyzables tannins	Ellagitannins	Ellagic acid Urolithin A Urolithin B	Butyrivibrio spp.	↓Intracellular ROS accumulation (Urolithin A) ↓Cellular injury by ROS ↓Proinflammatory mediators (Ellagic acid and Urolithin A) ↓NADPH oxidase activation (Urolithin A) ↓PGE2 production (Urolithin A and B) ↓mPGES-1 and COX-2 expression (Urolithin A and B) ↓Proteins glycation (Urolithin A and B) ↓Triglycerides accumulation (Ellagic acid and Urolithin A) ↓Expression of adipogenic protein and gene (Urolithin A) ↑Fatty acid β-oxidation (Urolithin A) Alleviation of myocardial ischemia/reperfusion injury (Urolithin A)	[245,246,247,248,249,250,251,252,253,254,255,256,257]
Lignans	Secoisolariciresinol	Enterodiol Enterolactone	Bacteroides distasonis, Bacteroides fragilis, Bacteroides ovatus, Clostridium cocleatum, Butyribacterium methylotrophicum, Eubacterium callanderi, Eubacterium limosum, Peptostreptococcus productus, Clostridium scindens, Eggerthella lenta	Antioxidant capacity OH-scavenging activity Immunomodulatory effects in human cells ↓NF-κB transcriptional activity ↓Proinflammatory cytokines expression	[258,259,260,261]
Stilbenes	Trans-resveratrol	DHR 3,4′-dihydroxy-trans-stilbene 3,4′-dihydroxybibenzyl (lunularin)	Slackia equolifaciens Adlercreutzia equolifaciens	Antioxidant activity Free radical scavenging (DHR) ↓NO production (DHR)	[262,263,264]

3,4-DHPPA, 3,4-dihydroxyphenylpropionic acid; 3-HPPA, 3-hydroxyphenylpropionic acid; 4-HPPA, 4-hydroxyphenylpropionic acid; 4-HCA, 4-hydroxycinnamic acid; 3,4-DHPAA, 3,4-dihydroxyphenylacetic acid; 3-HPAA, hydroxyphenylacetic acid; 4-HPAA,4-hydroxyphenylacetic acid. O-DMA, O-demethylangolensin, 3,4-DHPVA, 3,4-dihydroxyphenyl-γ-valeric acid; 3′,4′,5′-THPVL, 3′,4′,5′-trihydroxyphenyl-γ valerolactone; 3′,4′-DHPVL, 3′,4′-dihydroxyphenyl-γ-valerolactone; 3′,5′-DHPVL, 3′,5′-Dihydroxyphenyl-γ-valerolactone 3′,-HPVL, 3′-hydroxyphenyl-γ-valerolactone; DHR, dihydroresveratrol, NO: nitric oxide; ↑: increase; ↓: decrease.