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Summary: In the current study, polyphenols were extracted from chestnut (Castanea sativa) shells (CSS) by two eco‐friendly techniques, namely microwave‐assisted extraction (MAE) and ultrasound‐assisted extraction (UAE). The bioaccessibility, phenolic composition and bioactivity of CSS extracts were explored upon in vitro gastrointestinal digestion considering a future nutraceutical use. The phenolic and flavonoid concentrations, bioaccessibility and antioxidant/antiradical properties of both extracts decreased during digestion. The bioaccessibility was 25% and 26%, respectively, for UAE and MAE extracts. The phenolic profile demonstrated that gallic acid, caftaric acid and catechin were the most bioaccessible compounds for both extraction techniques. The CSS extracts unveiled notable radicals scavenging efficiency, particularly against HOCl (18.32–75.44% inhibition) and ONOO− (16.78–86.11% inhibition), as well as hypoglycaemic (6.95–17.99% α‐amylase inhibition) and neuroprotective (16.44–54.66% AChE inhibition) properties upon digestion. Considering the undigested extracts, the UAE extract revealed better results than the MAE extract. Oppositely, among digested fractions the MAE digests disclosed the most promising outcomes. The remarkable contribution of phenolic compounds to the bioactivity of CSS extracts after in vitro digestion was proved by heatmap correlations, indicating that their pro‐healthy properties were modified after gastrointestinal digestion, being ascribed to the distinct phenolic composition. This study evaluates, for the first time, the impact of in vitro gastrointestinal digestion on the bioaccessibility and bioactivity of phenolics‐rich CSS extracts prepared by UAE and MAE. [ABSTRACT FROM AUTHOR]

Chestnut (Castanea sativa) shells (CSs), an undervalued agro-industrial biowaste, have arisen as a source of bioactive compounds with promising health-promoting effects. This study attempted, for the first time, to develop a functional food, namely cookies, using a CS extract obtained by an eco-friendly technology (subcritical water extraction). The cookies were characterized regarding their nutritional composition, total phenolic and flavonoid contents (TPC and TFC, respectively), antioxidant/antiradical activities, phenolic profile, and sensory evaluation. The results demonstrated that the CS-extract-enriched cookies were mainly composed of carbohydrates (53.92% on dry weight (dw)), fat (32.62% dw), and fiber (5.15% dw). The phenolic profile outlined by HPLC-PDA revealed the presence of phenolic acids, flavonoids, and hydrolysable tannins, attesting to the high TPC and TFC. The in vitro antioxidant/antiradical effects proved the bioactivity of the functional cookies, while the sensory evaluation unveiled excellent scores on all attributes (≥6.25). The heatmap diagram corroborated strong correlations between the TPC and antioxidant/antiradical properties, predicting that the appreciated sensory attributes were closely correlated with high carbohydrates and phenolic compounds. This study encourages the sustainable recovery of antioxidants from CSs and their further employment as an active nutraceutical ingredient in functional cookies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chestnut shells extract induced in-vivo antioxidant effects in rats. • Metabolic profiling by LC-ESI-TQ-Orbitrap-MS was done for chestnut shell. • 52 phenolic compounds and metabolites were identified in blood serum. • Potential mild hypolipidemic and hypoglycemic effects were determined. • Histological analysis revealed no structural changes or toxicity signs. Chestnut (Castanea sativa) shells (CSS) are a source of bioactive compounds with well demonstrated in-vitro antioxidant properties. Nevertheless, no in-vivo studies have already evaluated this effect. This study evaluated the effects of the oral daily administration of an eco-friendly CSS extract (50 and 100 mg/kg per body weight (b.w.)) to rats regarding in-vivo antioxidant activity, glucose and lipids levels, and metabolomic profiling of polyphenols by LC-ESI-LTQ-Orbitrap-MS. The results demonstrated the in-vivo antioxidant properties in the animals liver, kidney and blood serum, as well as protective effects against hemolysis and rising of blood glucose and lipids levels. New insights on metabolomic profiling of polyphenols proved their absorption and further biotransformation by phase I (hydrogenation and hydroxylation) and II reactions (glucuronidation, methylation and sulfation). This is the first study that attempted to validate a novel nutraceutical ingredient extracted from CSS by in-vivo assays, corroborating the outcomes screened by in-vitro assays. [ABSTRACT FROM AUTHOR]

• Optimization of chestnut shells extraction using response surface methodology. • Subcritical water extraction is a clean method for antioxidants extraction. • Optimum extraction conditions: temperature 220 °C and extraction time 30 min. • Caffeoylquinic acid isomers were the main phenolic compounds. The objective of this study was to evaluate the optimal Subcritical Water Extraction (SWE) conditions of antioxidants and polyphenols from chestnut shells using Response Surface Methodology (RSM). A central composite design (CCD) was conducted to analyse the time (6–30 min) and temperature (51–249 °C) effects in antioxidant activity (ABTS, DPPH and FRAP) and Total Phenolic Compounds (TPC). TPC ranged from 315.21 to 496.80 mg gallic acid equivalents (GAE)/g DW; the DPPH from 549.23 to 1125.68 mg Trolox equivalents (TE)/g DW; ABTS varied between 631.16 and 965.45 mg ascorbic acid equivalents (AAE)/g DW and FRAP from 2793.95 to 11393.97 mg ferrous sulphate equivalents (FSE)/g DW. The optimal extraction conditions were 30 min/220 °C, revealing excelling scavenging efficiencies against HOCl (IC 50 = 0.79 µg/mL) and O 2 − (IC 50 = 12.92 µg/mL) without toxicity on intestinal cells (0.1 µg/mL). The phenolic composition revealed high amounts of pyrogallol and protocatechuic acid. SWE can be a useful extraction technique for the recovery of polyphenolics from chestnut shells. [ABSTRACT FROM AUTHOR]

Chestnut processing industry generates large amounts of by-products, including leaves, burs and shells that are a source of bioactive compounds. The purpose of this study was to establish an ultrasound-assisted extraction (UAE) of phenolic and antioxidant compounds from industrial chestnut shells. A central composite design (CCD) was conducted to analyze the effects of time (4–46 min) and temperature (34–76 °C) in the antioxidant activity (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP)) and total phenolic compounds (TPC) of chestnut shells extracts. The optimal extraction conditions were obtained at 70 °C for 40 min. The optimal extract was characterized regarding phenolic profile, radical scavenging capacity, and effects on intestinal and dermal cell lines. The optimal extract revealed high amounts of ellagic acid (40.4 µg/mg dw), followed by caffeic acid derivative (15.4 µg/mg dw) and epigallocatechin (15.3 µg/mg dw). Indeed, the extract exhibited the highest scavenging efficiencies against NO● (IC50 = 0.1 µg/mL) and HOCl (IC50 = 0.7 µg/mL) and did not conducted to a decrease on HaCaT and HFF-1 viability up to 100 μg/mL. Oppositely, a decrease on Caco-2 and HT29-MTX viability was observed. This study suggests that UAE could be a sustainable option to valorize chestnut shells as raw material for different industries. [ABSTRACT FROM AUTHOR]