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Apple polyphenols (AP) have strong antioxidant and anti-inflammatory properties. We examined the effects of AP on the progression of osteoarthritis (OA) AP was administered to surgically-induced OA model rats for 4 or 8 weeks. This treatment suppressed inflammation and oxidative stress in the synovium, resulting in a decrease in the OA severity score, and the expression of tumor necrosis factor (TNF)-α and matrix metalloproteinase (MMP)-13 in the synovium. It was suggested that long-term administration of AP may be effective for the treatment of OA. In addition, superoxide dismutase (SOD) activity was enhanced in serum samples by AP. AP or its constituent procyanidin B2 (PC) were added to HIG-82 synoviocytes. The results showed that AP enhanced cell proliferation and hyaluronan production. This indicates that AP may improve synovial conditions in OA and suppress OA progression. These effects may be attributed to the antioxidant and anti-inflammatory properties of AP. • Apple polyphenols (AP) have strong antioxidant and anti-inflammatory properties. • The effects of AP on the progression of osteoarthritis (OA) is studied. • AP suppresses inflammation and oxidative stress in the synovium. • Administration of AP may be effective to treat OA. • Superoxide dismutase (SOD) activity in serum was enhanced by AP. [ABSTRACT FROM AUTHOR]

Apple (Malus domestica) polyphenols are strong antioxidants. However, the functional properties of apple polyphenols are limited due to their considerable low digestibility. Therefore, in this study, the effects of fermentation of apple pulp by Lactobacillus acidophilus on its total polyphenol content and antioxidant activity were assessed using metabolomics. The results showed that the total polyphenol content and antioxidant activity of apple pulp fermented with L. acidophilus zrx02 were significantly higher than those in the unfermented apple pulp. Six different significantly changed metabolites, including caffeic acid, hypericin, p -coumaric acid, p -hydroxybenzoic acid, ferulic acid, and eugenic acid, were selected using ultra-performance liquid chromatography-tandem mass spectrometry and a metabolomics analysis. A cluster analysis revealed that one group contained caffeic acid, while the other one contained ferulic acid, p -hydroxybenzoic acid, p -coumaric acid, hypericin, and syringic acid. Ten metabolic pathways with significant differences were screened using the hypergeometric method. Overall, the results suggest that after fermentation by L. acidophilus zrx02, apple polyphenols can be biotransformed into small molecules that are easily digested and absorbed, and they have improved antioxidant activity. It is a raw material source of antioxidant-rich active substances that merits full utilization. • The strain has been patented. • We have independent intellectual property rights. • Fermentation can biotransform apple polyphenols into small molecules. • The digestibility and antioxidant activity of the apple polyphenols were improved. [ABSTRACT FROM AUTHOR]

Polyphenol-gelatin binary complex and polyphenol-gelatin-pectin ternary complex were synthesized. The differences in antioxidant activity between the binary complex and ternary complex were evaluated by using ABTS, DPPH, and reducing power assays. The differences in structural characterization between the binary complex and ternary complex were investigated by scanning electron microscopy (SEM), nuclear magnetic resonance (1H and 13C NMR), and Fourier transform infrared (FT-IR) spectroscopy. The reducing power assays of the ternary complex was greater than that of the binary complex. The maximum of ABTS•+ scavenging activity of the binary complex and the ternary complex was 98.1% and 99.3%, respectively, and the maximum DPPH• scavenging activity was 84.7% and 87.6%, respectively. The results of structural characterization showed that they were very similar in structure. Both complexes are mainly composed of hydrogen bonds and hydrophobic interactions, but the ternary complex is more tightly bound. In addition, the surface is smoother, and the gap is smaller. ► Ternary and binary complexes have excellent antioxidant properties. ► The addition of pectin increased the amount of hydroxyl groups, which improved antioxidant capacity. ► Due to the polyhydroxy structure, apple polyphenols can bind to gelatin and pectin tightly. ► Polyphenols can be used as natural and harmless cross-linking agents for macromolecules. [ABSTRACT FROM AUTHOR]

The effects of polyphenols on the chromatic characteristics of thermal processed apple slices during the Maillard reaction is unknown. Changes in the chromatic values (CIE L* , a* , b*) of the d -fructose/ l -lysine solution containing the apple polyphenol compounds chlorogenic acid, (+)-catechin, (−)-epicatechin and phlorizin on exposure to different temperatures, pH and incubation times were investigated. The results showed that (+)-catechin/(−)-epicatechin and phlorizin elevated the redness value (a*) and retarded 5-hydroxymethyl furfural (5-HMF) formation in d -fructose/ l -lysine solution at 90 °C and pH 4.0. Chlorogenic acid, on the other hand, boosted the yellowness (b*) value and accelerated 5-HMF formation. Browning was mainly observed in fructose/ l -lysine solutions after addition of catechin, the products of which were identified by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Five compounds (C 21 H 23 NO 8 , C 21 H 28 N 2 O 8 , C 21 H 26 O 12 , C 27 H 37 N 3 O 10, and C 27 H 40 N 2 O 14) were observed and their formation pathways were proposed. This demonstrates that catechin reacts with lysine, fructose or both at the para position of its B ring to form red-colored adducts, while simultaneously inhibiting 5-HMF formation. These results provide insights to explain and control browning in apple products. • Different polyphenols impact on fructose-lysine Maillard reaction and differ its color value. • Temperature, pH, and time affect the color of Maillard solution in presence of polyphenols. • Five catechin adducts that contribute to higher a* value in Maillard system were identified. • Catechin adducts formation was mainly based on the covalent conjugation on its B ring. [ABSTRACT FROM AUTHOR]