Rotational constriction of curcuminoids impacts 5-lipoxygenase and mPGES-1 inhibition and evokes a lipid mediator class switch in macrophages

Oxylipin profiling for clinical research: Current status and future perspectives

Oxylipins are potent lipid mediators with increasing interest in clinical research. They are usually measured in systemic circulation and can provide a wealth of information regarding key biological processes such as inflammation, vascular tone, or blood coagulation. Although procedures still require harmonization to generate comparable oxylipin datasets, performing comprehensive profiling of circulating oxylipins in large studies is feasible and no longer restricted by technical barriers. However, it is essential to improve and facilitate the biological interpretation of complex oxylipin profiles to truly leverage their potential in clinical research. This requires regular updating of our knowledge about the metabolism and the mode of action of oxylipins, and consideration of all factors that may influence circulating oxylipin profiles independently of the studied disease or condition. This review aims to provide the readers with updated and necessary information regarding oxylipin metabolism, their different forms in systemic circulation, the current limitations in deducing oxylipin cellular effects from in vitro bioactivity studies, the biological and technical confounding factors needed to consider for a proper interpretation of oxylipin profiles.

Novel thiazolopyridine derivatives of diflapolin as dual sEH/FLAP inhibitors with improved solubility

Inflammatory responses are orchestrated by a plethora of lipid mediators, and perturbations of their biosynthesis or degradation hinder resolution and lead to uncontrolled inflammation, which contributes to diverse pathologies. Small molecules that induce a switch from pro-inflammatory to anti-inflammatory lipid mediators are considered valuable for the treatment of chronic inflammatory diseases. Commonly used non-steroidal anti-inflammatory drugs (NSAIDs) are afflicted with side effects caused by the inhibition of beneficial prostanoid formation and redirection of arachidonic acid (AA) into alternative pathways. Multi-target inhibitors like diflapolin, the first dual inhibitor of soluble epoxide hydrolase (sEH) and 5-lipoxygenase-activating protein (FLAP), promise improved efficacy and safety but are confronted by poor solubility and bioavailability. Four series of derivatives bearing isomeric thiazolopyridines as bioisosteric replacement of the benzothiazole core and two series additionally containing mono- or diaza-isosteres of the phenylene spacer were designed and synthesized to improve solubility. The combination of thiazolo[5,4-b]pyridine, a pyridinylen spacer and a 3,5-Cl2-substituted terminal phenyl ring (46a) enhances solubility and FLAP antagonism, while preserving sEH inhibition. Moreover, the thiazolo[4,5-c]pyridine derivative 41b, although being a less potent sEH/FLAP inhibitor, additionally decreases thromboxane production in activated human peripheral blood mononuclear cells. We conclude that the introduction of nitrogen, depending on the position, not only enhances solubility and FLAP antagonism (46a), but also represents a valid strategy to expand the scope of application towards inhibition of thromboxane biosynthesis.

Formation of lipoxins and resolvins in human leukocytes

Specialized pro-resolving lipid mediators (SPMs) such as lipoxins or resolvins are formed by the consecutive action of 5-lipoxygenase (5-LO, ALOX5) and different types of arachidonic acid 12- or 15-lipoxygenases using arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid as substrate. Lipoxins are trihydroxylated oxylipins which are formed from arachidonic and eicosapentaenoic acid. The latter can also be converted to di- and trihydroxylated resolvins of the E series, whereas docosahexaenoic acid is the substrate for the formation of di- and trihydroxylated resolvins of the D series. Here, we summarize the formation of lipoxins and resolvins in leukocytes. From the data published so far, it becomes evident that FLAP is required for the biosynthesis of most of the lipoxins and resolvins. Even in the presence of FLAP, formation of the trihydroxylated SPMs (lipoxins, RvD1-RvD4, RvE1) in leukocytes is very low or undetectable which is obviously due to the extremely low epoxide formation by 5-LO from oxylipins such as 15-H(p)ETE, 18-H(p)EPE or 17-H(p)DHA. As a result, only the dihydroxylated oxylipins (5 S,15S-diHETE, 5 S,15S-diHEPE) and resolvins (RvD5, RvE2, RvE4) can be consistently detected using leukocytes as SPM source. However, the reported levels of these dihydroxylated lipid mediators are still much lower than those of the typical pro-inflammatory mediators including the monohydroxylated fatty acid derivatives (e.g. 5-HETE), leukotrienes or cyclooxygenase-derived prostaglandins. Since 5-LO expression is mainly restricted to leukocytes these cells are considered as the main source of SPMs. The low formation of trihydroxylated SPMs in leukocytes, the fact that they are hardly detected in biological samples as well as the lack of functional signaling by their receptors make it highly questionable that trihydroxylated SPMs play a role as endogenous mediators in the resolution of inflammation.

Identification of a Novel Curcumin Derivative Influencing Notch Pathway and DNA Damage as a Potential Therapeutic Agent in T-ALL

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy considered curable by modern clinical management. Nevertheless, the prognosis for T-ALL high-risk cases or patients with relapsed and refractory disease is still dismal. Therefore, there is a keen interest in developing more efficient and less toxic therapeutic approaches. T-ALL pathogenesis is associated with Notch signaling alterations, making this pathway a highly promising target in the fight against T-ALL. Here, by exploring the anti-leukemic capacity of the natural polyphenol curcumin and its derivatives, we found that curcumin exposure impacts T-ALL cell line viability and decreases Notch signaling in a dose- and time-dependent fashion. However, our findings indicated that curcumin-mediated cell outcomes did not depend exclusively on Notch signaling inhibition, but might be mainly related to compound-induced DNA-damage-associated cell death. Furthermore, we identified a novel curcumin-based compound named CD2066, endowed with potentiated anti-proliferative activity in T-ALL compared to the parent molecule curcumin. At nanomolar concentrations, CD2066 antagonized Notch signaling, favored DNA damage, and acted synergistically with the CDK1 inhibitor Ro3306 in T-ALL cells, thus representing a promising novel candidate for developing therapeutic agents against Notch-dependent T-ALL.

Phytochemical Characterization of Cannabis sativa L. Chemotype V Reveals Three New Dihydrophenanthrenoids That Favorably Reprogram Lipid Mediator Biosynthesis in Macrophages

The growing general interest surrounding Cannabis sativa L. has led to a renewal in breeding and resulted in an impressive variability of chemotypical characteristics that required the division of cannabis into different recognized chemotypes. The chemotype V has been overlooked in terms of phytochemical composition due to the almost total absence of cannabinoids, on which biomedical attention is focused. Systematic approaches addressing diverse chemotypes are, however, needed to discriminate and define phytochemical aspects beyond cannabinoids. Such thoroughly characterized chemotypes guarantee blinding in controlled studies by mimicking the sensory properties of hemp and may help to unravel the “entourage effect”. Capitalizing on the ability of cannabis to synthesize a large number of non-cannabinoid phenolic compounds, we here investigated, for the first time, the composition of the Ermo chemotype V and identified new compounds: two dihydrophenanthrenes and the methoxy-dihydrodenbinobin. All three compounds suppress pro-inflammatory leukotriene biosynthesis in activated macrophage subtypes by targeting 5-lipoxygenase, but substantially differ in their capacity to elevate the levels of specialized pro-resolving lipid mediators and their precursors in M2 macrophages. We conclude that the discovered compounds likely contribute to the anti-inflammatory properties of Cannabis sativa L. chemotype V and might promote inflammation resolution by promoting a lipid mediator class switch.