Polyphenols are antioxidant ingredients in apples and are related to human health because of their free radical scavenging activities. The polyphenolic profiles of old and new apple cultivars (n = 15) were analysed using high-performance liquid chromatography (HPLC) with diode array detection (DAD). The in vitro antioxidant capacity was determined by total phenolic content (TPC) assay, hydrophilic trolox equivalent antioxidant capacity (H-TEAC) assay and hydrophilic oxygen radical absorbance (H-ORAC) assay. Twenty polyphenolic compounds were identified in all investigated apples by HPLC analysis. Quercetin glycosides (203 ± 108 mg/100 g) were the main polyphenols in the peel and phenolic acids (10 ± 5 mg/100 g) in the flesh. The calculated relative contribution of single compounds indicated flavonols (peel) and vitamin C (flesh) as the major contributors to the antioxidant capacity, in all cultivars investigated. The polyphenolic content (HPLC data) of the flesh differed significantly between old (29 ± 7 mg/100 g) and new (13 ± 4 mg/100 g) cultivars, and the antioxidant capacity of old apple cultivars was up to 30% stronger compared to new ones.

N-acetylcysteine (NAC) is a frequently prescribed drug and known for its metal chelating capability. However, to date it is not well characterized whether NAC intake affects the homeostasis of essential trace elements. As a precursor of glutathione (GSH), NAC also has the potential to modulate the cellular redox homeostasis. Thus, we aimed to analyze effects of acute and chronic NAC treatment on the homeostasis of copper (Cu) and zinc (Zn) and on the activity of the redox-sensitive transcription factor Nrf2. Cells were exposed to 1 mM NAC and were co-treated with 50 μM Cu or Zn. We showed that NAC treatment reduced the cellular concentration of Zn and Cu. In addition, NAC inhibited the Zn-induced Nrf2 activation and limited the concomitant upregulation of cellular GSH concentrations. In contrast, mice chronically received NAC via drinking water (1 g NAC/100 mL). Cu and Zn concentrations were decreased in liver and spleen. In the duodenum, NQO1, TXNRD, and SOD activities were upregulated by NAC. All of them can be induced by Nrf2, thus indicating a putative Nrf2 activation. Overall, NAC modulates the homeostasis of Cu and Zn both in vitro and in vivo and accordingly affects the cellular redox balance.

Physiological selenium (Se) levels counteract excessive inflammation, with selenoproteins shaping the immunoregulatory cytokine and lipid mediator profile. How exactly differentiation of monocytes into macrophages influences the expression of the selenoproteome in concert with the Se supply remains obscure. THP-1 monocytes were differentiated with phorbol 12-myristate 13-acetate (PMA) into macrophages and (i) the expression of selenoproteins, (ii) differentiation markers, (iii) the activity of NF-κB and NRF2, as well as (iv) lipid mediator profiles were analyzed. Se and differentiation affected the expression of selenoproteins in a heterogeneous manner. GPX4 expression was substantially decreased during differentiation, whereas GPX1 was not affected. Moreover, Se increased the expression of selenoproteins H and F, which was further enhanced by differentiation for selenoprotein F and diminished for selenoprotein H. Notably, LPS-induced expression of NF-κB target genes was facilitated by Se, as was the release of COX- and LOX-derived lipid mediators and substrates required for lipid mediator biosynthesis. This included TXB₂, TXB₃, 15-HETE, and 12-HEPE, as well as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Our results indicate that Se enables macrophages to accurately adjust redox-dependent signaling and thereby modulate downstream lipid mediator profiles.