Table 1.

Metabolites evolved from colonic fermentation of different non-extractable polyphenols (NEPP).

Food Source	Polyphenol	Metabolites	Model	Species	Effect	Reference
Triphala extract(mixture of Terminalia chebula, Terminalia bellerica, and Phyllanthus emblica.	Flavonoids, hydrolysable tannin, condensed tannin	Analysed (not mentioned specifically)	In vitro fermentation	Human faecal microbiota of obese female adults	No significant changes found in microbial population. Significant changes in metabolite profile and tyrosine, phenyl alanine and tryptophan biosynthesis.	(Kwandee et al., 2023)
Hawthorn (Crataegus pinnatifida)	Procyanidin	Not analysed	In vivo administration	Mice model	Upragulate growth of Akkermansia, Bacteroides and Adlercreutzia, and decreased Lactobacillus, Bifidobacterium, Blautia, Lachnospiraceae and Subdoligranulum Reduced insulin resistance, oxidative stress	(Han et al., 2022)
peanut skin	Type A procyanidins	Not tested	In vivo administration	Balb/c mice model	Reverse the ulcerative colitis by improving gut barrier and modu;ating inflammatory cytokines Increase growth of Oscillibacter and Roseburia Decrease growth of Bacteroides, Helicobacter, Parabacteroides, Escherichia-Shigella, and Enterobacter	(Huang et al., 2022)
Grape seed extract	Proanthocyanidin polyphenol extract	Not tested	In vivo administration	Mice model	GSPE normalized the colonic Firmicutes/Bacteroidetes ratios, reversed the relative abundance of Weissella, Faecalibaculum, Bacteroides, Akkermansia and Ruminococcus 1 induced by HFD reduced HFD-induced insulin resistance and increased levels of adiponectin and leptin	(Du et al., 2021)
Pomegranate juice	Hydrolysable tannin	Not mentioned	In vivo fermentation	Insulin resistance mice model	Reduced glucose and lipid metabolic disorder, liver injury and insulin resistance; decreased the Firmicutes/Bacteroides ratio, reduced Coprococcus and Anaerotruncus, and increased Rikenellaceae and liver tumor necrosis factor-alpha and interleukin-1β levels, supressed liver IKKβ and NF-κB phosphorylation; and upragulated liver autophagy-related proteins LC3-II, P62, and Beclin1.	(Cao et al., 2021)
Quebracho wood extract Chestnut wood extract\ Tara pods extract	profisetinidin condensed tannin hydrolysable ellagitannins hydrolysable gallotannins)	Not tested	In vitro digestion and fermentation	Human gut microbiata	Increase of genus Akkermansia, Lachnospiraceae and Ruminococcaceae sp.	(Molino et al., 2021)
Grape seed	proanthocyanidins	Not analysed	In vivo administration	Mice model	Reduced colitis associated inflammation	(Sheng et al., 2020)
Grape seed	Proanthocyanidin extract	Proanthocyanidin polymers	In vivo administration	Rat model	Reduced firmicutes/Bacteroidetes ratio Reduced weight gain, food intake, induced entero hormone secretion.	(Casanova-Martí et al., 2018b)
Grape seed extract	Flavan 3-ol polymers, proanthocyanidins	Not tested	In vivo administration	Overiectomised mice model	Improved Firmicutes:bacteroidetes ratio Prevented menoposal weight gain	(Jin et al., 2018)
–	Pure procyanidins	Not tested	In vivo administration	Mice model	Reduced high fat diet induced obesity Improved Firmicutes to bacteroidetes ratio Increased energy expenditure Improved lipid profile	(Zheng et al., 2018)
Pomegranate extract	Ellagitannin and ellagic acid	Urolithin and ellagic acid	In vitro and in vivo incubation	Human subjects	Increased ellagic acid release from ellaigitannin and increased bioavailability	(González-Sarrías et al., 2015)
Cranberry juice	Oligomeric proanthocyanidins	Hydroxyphenyl propionic acid and hydroxyphenyl acetic acid derivatives	In vivo fermentation	Human subject	Increased detectable bioavalability of proanthocyanidin A2 in the plasma	(McKay et al., 2015)
Strawberry, fresh berries and processed puree	Ellagitanins and ellagic acid	Urolithins	In vivo fermentation	Human subjects	both samples were found to be efficiently metabolised by human gut microbiota	(Truchado et al., 2012)
Grapes	Proanthocyanidin	Valerolactones, phenylvaleric acids, phenylpropionic acids, phenylacetic acids, benzoic acid, cinnamic acids	In vivo fermentation	Rat model	Rich source of henolics in the gut and the NEPA and its metabolites remain bioavailable fr 24 h after ingestion	(Mateos-Martín et al., 2012)
Green tea	Flavan 3-ols and proanthocyanidins	Pyrocatechol, pyrogallol, 4-hydroxybenzoic acid, 4-hydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylacetic acid, hippuric acid, 3-(3-hydroxyphenyl)-3-hydroxypropionic acid, (-)-5-(3′,4′,5′ -trihydroxyphenyl)-γ-valerolactone	In vivo fermentation	Human subject	Reported absorption of flavan 3- ol metabolites in the circulatory system,	(Roowi et al., 2010)
Grape seed	Procyanidin dimer	2-(3,4-dihydroxyphenyl)acetic acid and 5-(3,4-dihydroxyphenyl)-γ-valerolactone., 3-hydroxyphenylacetic acid, 4-hydroxyphenylacetic acid, 3-hydroxyphenylpropionic acid, phenylvaleric acids, monohydroxylatedphenylvalerolactone, and 1-(3′,4′-dihydroxyphenyl)- 3-(2′′,4′′,6′′-trihydroxyphenyl)propan-2-ol	In vitro fermentation	Human faecal microbiota	Procyanidins are metabolised slowly by gut micribiome instead of reapid depolymerisation to flavan 3-ols	(Appeldoorn et al., 2009)
Almond skin extract	Oligomeric proanthocyanidin type A	Hydroxyphenylvalerolactones Hydroxyphenylpropionic acids Hydroxyphenylacetic acids Hydroxycinnamic acids Hydroxybenzoic acids Hydroxyhippuric acids	In vivo fermentation	Human subject	Microbial metabolism increased the bioavilability of proanthocyanidin metabolites	(Urpi-Sarda et al., 2009)
Pomegranate extract	Ellagitannin	Urolithins	In vivo fermentation	Human subjects	Urplithins (proanthocyanidin metabolites) remain in circulation much longer and exerts healt benefits	(Seeram et al., 2006)
Strawberry,raspberry, walnuts,oak aged red wines	Ellagitannins and ellagic acid	Urolithins	In vivo fermentation	Human subjects	Increased microbial metabolites absorption in the blood confirms colonic microbial catabolism	(Cerdá, Tomás-Barberán, et al., 2005)
Walnut extract	Ellagic acid, Ellagitannin	Urolithins	In vitro fermentation	Human faeces	Microbial metabolism of ellaigitannin depends on inter-individual differences of colonic microbial profile	(Cerdá, Periago, et al., 2005)
Grape seed extract	Oligomeric proanthocyanidins	3-Hydroxyphenylpropionic Acid, 3-Hydroxyphenylacetic Acid, 4-Hydroxyphenylacetic Acid, and 4-O-Methylgallic Acid	In vivo fermentation	Human subject	Gradual increase in 3hydroxypropionic acid excretion indicateslong duration resorption of colonic microbial metabolites of proanthocyanidins	(Ward et al., 2004)
Chocolate	Oligomeric proanthocyanidins	3,4-Dihydroxyphenylpropionic acid, m-hydroxyphenylpropionic acid, ferulic acid, 3,4-dihydroxyphenylacetic acid, m-hydroxyphenylacetic acid, phenylacetic acid, vanillic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, p-hydroxyhippuric acid, hippuric acid.	In vivo fermentation	Human subject	Increased urinary excretion of proanthocyanidin metabolites authenticates involvement of the same in exerting antioxidant and other biological effects	(Rios et al., 2003)
Willow tree shoot (similar to apple and grape seed)	14C labelled PCA	2- (p-hydroxyphenyl)acetic acid, 2-(p-hydroxyphenyl)- propionic acid and their m-hydroxy isomers 2-(m-hydroxyphenyl) acetic acid and2- (m-hydroxyphenyl) propionic acid, 5-(m-hydroxyphenyl)valeric acid and phenylpropionic acid	In vitro incubation	Human faecal microbiota	Confirms release of low molecular weight metabolites of polymeric polyphenols similar to monomeric flavanols	(Déprez et al., 2000)