For the first time, the characterization of antioxidant activity and phenolic profile of apple tree (Malus domestica) bark, core and roots was carried out. Phenolic compounds were extracted from the Belgium apple tree wood residues collected at two seasons, namely summer 2015 and winter 2016, using conventional (CE) and microwave-assisted extraction (MAE) techniques. For each extraction technique, the influence of the most important operational parameters, namely solvent composition, extraction time and temperature, on the total phenolic and flavonoid content, and antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH-RSA) and ferric reducing activity power (FRAP) assays were optimized. The phenolic profile from the obtained extracts was also characterized by high-performance liquid chromatography with photodiode array detection (HPLC-PDA). Optimum conditions were: 20 mL ethanol:water 60:40 v/v, 20 min, 100 °C, sample weight 0.1 g for MAE and 20 mL ethanol:water 50:50 v/v, 2 h, 55 °C, sample weight 0.5 g for CE. Root extracts obtained by MAE (the most efficient technique) presented the highest phenolic (47.7 ± 0.9 mg gallic acid equivalents/g dry weight) and flavonoid (17.1 ± 0.8 mg epicatechin equivalents/g dry weight) content, and antioxidant activity (28.4 ± 2.0 mg trolox equivalents/g dry weight and 36.1 ± 2.7 mg ascorbic acid equivalents/g dry weight for DPPH-RSA and FRAP assays, respectively), followed by bark and core wood extracts. HPLC-PDA analysis revealed that phloridzin was the main contributor to the phenolic composition representing 52%-87% of the total amount of phenolic compounds quantified, while phenolic acids represents less than 10%. This study reveals the potential of apple tree wood residues valorization through the recovery of phenolic compounds for food, pharmaceutical and cosmetic applications.

Hop‐derived sesquiterpenoid‐type oxidation products have been associated with a spicy or herbal hoppy beer character. However, the flavour threshold values of hitherto identified oxygenated sesquiterpenes are generally much higher than their estimated levels in beer. By applying two‐step supercritical fluid extraction of hop pellets using carbon dioxide, followed by chromatographic purification of the enriched sesquiterpenoid fraction, highly specific varietal hop oil essences containing all main oxygenated sesquiterpenes were obtained. Post‐fermentation addition (at ppb levels) of these purified sesquiterpenoid essences from various European aroma hops led to distinctive spicy or herbal flavour notes, reminiscent of typical ‘noble’ hop aroma. It is concluded that a spicy hop flavour impression in beer depends significantly on minor constituents of the natural sesquiterpenoid hop oil fraction.

Background Macrophages play a dual role in neuroinflammatory disorders such as multiple sclerosis (MS). They are involved in lesion onset and progression but can also promote the resolution of inflammation and repair of damaged tissue. In this study, we investigate if and how phloretin, a flavonoid abundantly present in apples and strawberries, lowers the inflammatory phenotype of macrophages and suppresses neuroinflammation. Methods Transcriptional changes in mouse bone marrow-derived macrophages upon phloretin exposure were assessed by bulk RNA sequencing. Underlying pathways related to inflammation, oxidative stress response and autophagy were validated by quantitative PCR, fluorescent and absorbance assays, nuclear factor erythroid 2–related factor 2 (Nrf2) knockout mice, western blot, and immunofluorescence. The experimental autoimmune encephalomyelitis (EAE) model was used to study the impact of phloretin on neuroinflammation in vivo and confirm underlying mechanisms. Results We show that phloretin reduces the inflammatory phenotype of macrophages and markedly suppresses neuroinflammation in EAE. Phloretin mediates its effect by activating the Nrf2 signaling pathway. Nrf2 activation was attributed to 5′ AMP-activated protein kinase (AMPK)-dependent activation of autophagy and subsequent kelch-like ECH-associated protein 1 (Keap1) degradation. Conclusions This study opens future perspectives for phloretin as a therapeutic strategy for neuroinflammatory disorders such as MS. Trial registration Not applicable.

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This study describes the possibilities of valorising a waste stream that originates from apple wood by mapping the reducing capacity and phenolic profile from extracts derived from apple tree (Malus domestica). This study evaluated the efficiency of warm solvent extraction (WSE) and ultrasound-assisted extraction (UAE) techniques for extracting antioxidant phenolic compounds from the bark and core wood of an apple tree cultivated in the northeastern part of Belgium. Furthermore, the influence of the pre-treatment technique, namely, fresh, oven-dried, and freeze-dried samples, respectively, on the yield of polyphenols was studied. Fresh bark extract obtained by UAE-the most efficient extraction technique-employing acetone 60% v/v contains the highest levels of phenolic compounds as well as the highest antioxidant activity. High-performance liquid chromatographic analysis shows that phloridzin is the major compound of the identified polyphenol markers present in bark and core wood extracts. Based on the obtained results, it may be possible to produce a polyphenolic extract from apple wood at an industrial scale without extensive costs or altering the antioxidant properties. This study reveals the potential of apple tree wood residues valorisation through the recovery of phenolic compounds for food, pharmaceutical, and cosmetic applications.