Tannins in Fruits and Vegetables: Chemistry and Biological Functions

In vitro gastrointestinal digestion impact on stability, bioaccessibility and antioxidant activity of polyphenols from wild and commercial blackberries (Rubus spp.)

“…[7][8][9] In blackberries, different hydroxycinnamic and hydroxybenzoic acids are present in free forms, but they are mainly found as blocks of polymeric polyphenols, such as proanthocyanidins and hydrolysable tannins. 10 In contrast, flavonoid derivatives, which have a characteristic C6-C3-C6 (A, B and C rings) carbon skeleton, exhibit several patterns of hydroxylation, acylation, glycosylation and methoxylation of the main structure of each phenolic compound. 9 Also, these substituents may be found in phenolic acid derivatives and polymers, and may explain their biological importance, which is seriously compromised during digestion.…”

Anti-inflammatory Potential of Edible Ornamental Flowers Grown in Containers Due to High Anthocyanin Content

“…The conversion of cinamic acid to anthocyanins requires a series of reactions: the first reaction is catalyzed by cinnamate 4-hydroxylase to form a coumaric acid and by 4-hydroxy-cynnamoyl CoA ligase to create 4-Coumaroyl CoA, which is a direct precursor to kaempferol. After four steps of enzymatic reaction from 4-Coumaroyl CoA the leucoanthocyanidins are formed [11]. By the catalysis of anthocyanin synthase (ANS), the colorless leucoanthocyanidins (flavan-3,4-diols) are oxidized to the coloured anthocyanidins [9].…”

“…The antioxidant capacity of consumed products can be measured using chemical, in vitro methods generally performed on extracts. The literature mentions nearly 20 methods [9,11,13], but in general, if there are many methods, none of them is perfect. In addition, we must remember that the indicators give us a picture of the potential of the product, but they will not answer the question of how many substances will be absorbed and what impact they will have on the body.…”

“…The biological activity of isolated anthocyanins and anthocyanidins, or foods rich in anthocyanins, can be manifested in: prevention of cardiovascular disease [42], influence on cholesterol distribution, protection of endothelial cells from CD40-induced proinflammatory signaling [43], anticancer, antitumor and antimutagenic activity [44], beneficial effects in diabetes [45], protective effect against oxidative liver damage [46], protective effect on gastric inflammation and damage [47], antimicrobial and antiviral activity [48,49], slowing down neuronal and behavioural aging [50] and protection from some neurodegenerative diseases such as Alzheimer's disease [51]. Anthocyanins and anthocyanidins also effectively induce insulin secretion when tested in pancreatic cell lines Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 19 October 2021 [11]. The effectiveness of insulin secretion depends on the number of hydroxyl groups in the B-ring of their structures [45].…”

Potential Adverse Effects of Alteration of Phytochemical Accumulation in Fruits and Vegetables

“…Aromatic amino acids enter secondary metabolite biosynthesis via the Shikimate pathway. The Shikimate pathway leads to the production of simple compounds such as gallic acid and p-coumaric acid that are precursors to complex products like tannins and nitrogen-containing phytochemicals [5]. Acetyl-CoA, an end-product of carbohydrate metabolism, leads to the biosynthesis of terpenes and steroids through the Acetate-Mevalonate pathway [6].…”