Molecular Mechanisms of Nemorosone-Induced Ferroptosis in Cancer Cells.

Ferroptosis is an iron-dependent cell death-driven by excessive peroxidation of polyunsaturated fatty acids (PUFAs) of membranes. A growing body of evidence suggests the induction of ferroptosis as a cutting-edge strategy in cancer treatment research. Despite the essential role of mitochondria in cellular metabolism, bioenergetics, and cell death, their function in ferroptosis is still poorly understood. Recently, mitochondria were elucidated as an important component in cysteine-deprivation-induced (CDI) ferroptosis, which provides novel targets in the search for new ferroptosis-inducing compounds (FINs). Here, we identified the natural mitochondrial uncoupler nemorosone as a ferroptosis inducer in cancer cells. Interestingly, nemorosone triggers ferroptosis by a double-edged mechanism. In addition to decreasing the glutathione (GSH) levels by blocking the System xc cystine/glutamate antiporter (SLC7A11), nemorosone increases the intracellular labile Fe2+ pool via heme oxygenase-1 (HMOX1) induction. Interestingly, a structural variant of nemorosone (O-methylated nemorosone), having lost the capacity to uncouple mitochondrial respiration, does not trigger cell death anymore, suggesting that the mitochondrial bioenergetic disruption via mitochondrial uncoupling is necessary for nemorosone-induced ferroptosis. Our results open novel opportunities for cancer cell killing by mitochondrial uncoupling-induced ferroptosis.

Sweet Biotechnology: Enzymatic Production and Digestibility Screening of Novel Kojibiose and Nigerose Analogues.

In view of the global pandemic of obesity and related metabolic diseases, there is an increased interest in alternative carbohydrates with promising physiochemical and health-related properties as a potential replacement for traditional sugars. However, our current knowledge is limited to only a small selection of carbohydrates, whereas the majority of alternative rare carbohydrates and especially their properties remain to be investigated. Unraveling their potential properties, like digestibility and glycemic content, could unlock their use in industrial applications. Here, we describe the enzymatic production and in vitro digestibility of three novel glycosides, namely, two kojibiose analogues (i.e., d-Glcp-α-1,2-d-Gal and d-Glcp-α-1,2-d-Rib) and one nigerose analogue (i.e., d-Glcp-α-1,3-l-Ara). These novel sugars were discovered after an intensive acceptor screening with a sucrose phosphorylase originating from Bifidobacterium adolescentis (BaSP). Optimization and upscaling of this process led to roughly 100 g of these disaccharides. Digestibility, absorption, and caloric potential were assessed using brush border enzymes of rat origin and human intestinal Caco-2 cells. The rare disaccharides showed a reduced digestibility and a limited impact on energy metabolism, which was structure-dependent and even more pronounced for the three novel disaccharides in comparison to their respective glucobioses, translating to a low-caloric potential for these novel rare disaccharides.

Synthesis, trehalase hydrolytic resistance and inhibition properties of 4- and 6-substituted trehalose derivatives.

Although trehalose has recently gained interest because of its pharmaceutical potential, its clinical use is hampered due to its low bioavailability. Hence, hydrolysis-resistant trehalose analogues retaining biological activity could be of interest. In this study, 34 4- and 6-O-substituted trehalose derivatives were synthesised using an ether- or carbamate-type linkage. Their hydrolysis susceptibility and inhibitory properties were determined against two trehalases, i.e. porcine kidney and Mycobacterium smegmatis. With the exception of three weakly hydrolysable 6-O-alkyl derivatives, the compounds generally showed to be completely resistant. Moreover, a number of derivatives was shown to be an inhibitor of one or both of these trehalases. For the strongest inhibitors of porcine kidney trehalase IC50 values of around 10 mM could be determined, whereas several compounds displayed sub-mM IC50 against M. smegmatis trehalase. Dockings studies were performed to explain the observed influence of the substitution pattern on the inhibitory activity towards porcine kidney trehalase.

Rational design of an improved transglucosylase for production of the rare sugar nigerose.

The sucrose phosphorylase from Bifidobacterium adolescentis (BaSP) can be used as a transglucosylase for the production of rare sugars. We designed variants of BaSP for the efficient synthesis of nigerose from sucrose and glucose, thereby adding to the inventory of rare sugars that can conveniently be produced from bulk sugars.

Daucane esters from laserwort (Laserpitium latifolium L.) inhibit cytokine and chemokine production in human lung epithelial cells.

BACKGROUND: Laserwort, Laserpitium latifolium L. (Apiaceae), is a European medicinal plant. Its roots and rhizomes were traditionally used as a general tonic and to treat inflammatory and infective diseases. PURPOSE: The anti-inflammatory potential of daucane esters, isolated from underground parts extract of L. latifolium and specific structural features that contribute to their activity were investigated. In addition, we studied their interference with the transactivation capacity of the Glucocorticoid Receptor when added together with a classic glucocorticoid (GC), dexamethasone (DEX). This particular property may be relevant in combination strategies, attempting to circumvent diabetogenic side effects of glucocorticoids upon long-term anti-inflammatory treatments. MATERIALS AND METHODS: Nine L. latifolium daucane esters were isolated and elucidated as derivatives of desoxodehydrolaserpitin, laserpitin and a novel 2ß-esterified laserpitinol analogue. Of all compounds effects on NF-κB- and AP-1-driven pro-inflammatory pathways were assessed using TNF- or PMA-induced reporter gene analysis in A549 cells. Daucanes with a strong and concentration-dependent inhibition of both NF-κB and AP-1, were tested for a potential effect on DEX-stimulated GR-driven Glucocorticoid Response Element (GRE) reporter gene activity. In addition, GRE-driven anti-inflammatory mRNA expression was determined (GILZ and DUSP1). Also anti-inflammatory properties were validated by monitoring effects on CCL-2, IL-6, IL-1ß mRNA expression levels (qPCR) and on CCL-2 chemokine production (ELISA). RESULTS: Daucanes featuring an ester moiety and/or a hydroxy group at positions 2ß, 6α and 10α and especially the novel 2ß-esterified laserpitinol derivative that, in comparison to other isolated compounds, features an additional 9α-hydroxy group, demonstrated suppression of both NF-κB- and AP-1-dependent pro-inflammatory pathways. Remarkably, those entities competitively and concentration-dependently repressed GR-driven GRE-dependent reporter gene activities. The most active compounds inhibited CCL-2 protein excretion and compound 4 downregulated genes coding for IL-1ß and IL-6 induced upon TNF treatment in A549. In absence of TNF, compound 4 upregulated the GRE-mediated anti-inflammatory gene GILZ, but not DUSP1. CONCLUSIONS: Daucane esters are novel anti-inflammatory agents that may, in combination with GCs, potentially improve therapeutic benefit. These results contribute to the ongoing search for novel anti-inflammatory agents as safer alternatives to, or with, GCs.