From the organic extracts of two Guam sponges, Rhaphoxya sp. and Suberea sp., determined to have cytotoxic and chemopreventive activities, three new compounds, theonellin isocyanate (1) and ...psammaplysins I and J (5, 6), and six previously reported compounds (2-4, 7-9) were isolated and characterized spectroscopically ((1)H and (13)C NMR, MS, IR, UV, α(D)). The two new metabolites (5 and 6) isolated from the Suberea sp. sponge are rare examples of compounds containing a bromotyramine moiety rather than the more usual dibromo analogue. For the compounds isolated from the Rhaphoxya sp., this is the first report of the known compounds 2-4 being found in a single sponge. For previously reported compounds 2-4 complete unambiguous (1)H and (13)C NMR data are provided.
The high similar look of different types of brown sugar in combination with high price discrepancies make these sugars a potential target of food fraud. We therefore analyzed the different metabolic ...profiles of browned beet sugar, unrefined cane sugar and coconut blossom sugar. The investigation was carried out by 1H NMR and supplementary ULPC-Q-TOF-MS analysis to confirm identified metabolites. In addition to the highly variable metabolic profiles, an unambiguous metabolite was identified for each sugar, which was not detectable in the other sugar types by NMR. Betaine was identified as a marker for browned beet sugar, trans-aconitic acid (TAA) for raw cane sugar and pyroglutamic acid as a unique marker for coconut blossom sugar. Based on the variable metabolic profile, we were also able to demonstrate the potential of a multivariate regression model to estimate the degree of adulteration of coconut blossom sugar. In the second part of our study, we additionally investigated the use of minor metabolites for the detection of added sugars in different foods. Using unrefined cane sugar as an example, we demonstrated the thermal and chemical stability of TAA as a marker metabolite. The results of this study show the high potential use of the different metabolic profiles for the detection of food fraud. In combination with multivariate data analysis even small amounts of admixtures can be detected in different types of sugar.
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•Description of the polar, non volatile metabolome of coconut sugar.•Identification of unambiguous metabolites for differentiation of sugars.•Betaine, Pyrogluatamic Acid and TAA were identified as marker molecules.•Development of a multivariate regression model for admixture estimation.•Use of the identified metabolic profile for detection of food fraud with sugars.
Stemphol (STP) is a novel druggable phytotoxin triggering mixed apoptotic and non-apoptotic necrotic-like cell death in human acute myeloid leukemia (AML). Use of several chemical inhibitors ...highlighted that STP-induced non-canonical programmed cell death was Ca2+-dependent but independent of caspases, poly (ADP-ribose) polymerase-1, cathepsin, or calpains. Similar to thapsigargin, STP led to increased cytosolic Ca2+ levels and computational docking confirmed binding of STP within the thapsigargin binding pocket of the sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA). Moreover, the inositol 1,4,5-trisphosphate receptor is implicated in STP-modulated cytosolic Ca2+ accumulation leading to ER stress and mitochondrial swelling associated with collapsed cristae as observed by electron microscopy. Confocal fluorescent microscopy allowed identifying mitochondrial Ca2+ overload as initiator of STP-induced cell death insensitive to necrostatin-1 or cycloheximide. Finally, we observed that STP-induced necrosis is dependent of mitochondrial permeability transition pore (mPTP) opening. Importantly, the translational immunogenic potential of STP was validated by HMGB1 release of STP-treated AML patient cells. STP reduced colony and in vivo tumor forming potential and impaired the development of AML patient-derived xenografts in zebrafish.
•Stemphol induces cell death by disrupting calcium homeostasis.•Stemphol induces necrosis by mediating mPTP opening.•Stemphol triggers immunogenic cell death markers ER stress and HMGB1 release.•Stemphol impairs development of leukemia patient-derived zebrafish xenografts.
has been reported as a seaweed-associated or marine-derived species with largely unknown secondary metabolites. The combination of bioinformatic analysis and MS- and bioactivity guided separation led ...to the isolation of a new antibiotically active dialkylresorcin from the marine bacterium
. The antibiotic profile of the new dialkylresorcin zobelliphol (1: ) was investigated and compared with related and naturally occurring dialkyresorcins (i.e., stemphol (2: ) and 4-butyl-3,5-dihydroxybenzoic acid (3: )) from the marine-derived fungus
. Bacterial reporter strain assays provided insights into the mode of action of this antibiotic compound class. We identified an interference with bacterial DNA biosynthesis for the dialkylresorcin derivative 1: . In addition, the putative biosynthetic gene cluster corresponding to production of 1: was identified and a biosynthetic hypothesis was deduced.
Monocyte apoptosis is an important determinant of atherothrombosis. Two major mechanisms for apoptosis‐associated thrombogenicity have been described: exposure of negatively charged membrane ...phospholipids and up‐regulation of tissue factor (TF). However, the relative importance of these mechanisms is unclear. Thus, procoagulant functions (thrombin generation) of apoptotic (staurosporine, 2 μM, 24 h) U937 cells versus cell‐derived microparticles (MPs) were studied. In apoptotic U937 cells, a significant increase in TF mRNA (real‐time PCR), surface expression of TF (flow cytometry), and total cellular amount of TF (Western blotting) was observed. Control cells only minimally triggered thrombin generation (endogenous thrombin potential), and apoptotic cells were highly procoagulant. However, addition of negatively charged membranes completely restored the thrombin generation capacity of control U937 cells to the levels of apoptotic cells. MPs (defined as CD45+ particles of subcellular size), derived from apoptotic U937 cells, were highly procoagulant but did not exhibit an increased TF expression or annexin V binding. Taken together, our data support the concept that the membrane environment, independent of TF expression, determines the extent of thrombin formation triggered by apoptosis of monocytic cells. Externalization of negatively charged phospholipids represents the most important mechanisms for whole cells. Additional yet unknown mechanisms appear to be involved in the procoagulant actions of MPs derived from apoptotic monocytes.
Apoptotic monocytes release membrane microparticles which may play a major role in thrombogenicity through a P-selectin glycoprotein ligand (PGSL-1)-mediated mechanism. We have studied systematically ...the regulation of PSGL-1 expression and function in apoptotic monocytic cells.
PSGL-1 expression (flow cytometry, immunofluorescence microscopy, immunoblot) was virtually abolished in apoptotic monocytes by proteolytic shedding. This was accompanied by a complete loss of PSGL-1-mediated platelet-leukocyte (flow cytometry) and leukocyte-endothelial cell (parallel plate flow chamber) interactions. Systematic screening of protease inhibitors combined with knock-out and siRNA experiments characterized the PSGL-1-cleaving enzyme as an N-ethylmaleimide-inhibitable metalloproteinase of the ADAM family.
Downmodulation of PGSL-1 in apoptotic monocytes may prevent ectopic cell clearance in the peripheral vasculature to reduce local inflammatory and proliferative responses. Depletion of PSGL-1 expression on apoptotic microparticles may also act as a molecular switch to modulate their thrombogenic activity.
Circulating tissue factor (TF) is an important determinant of coronary thrombosis. Among other cell types, such as monocytes, vascular smooth muscle cells (SMCs) are capable of releasing TF. When ...studied under static conditions, SMCs do release TF, but this process is slow and, thus, cannot explain the elevated levels of circulating TF, as observed in patients with acute coronary syndromes. The present study demonstrates that cultured human mammary artery SMCs very rapidly (minutes) release active, microparticle-bound TF when exposed to flow conditions. There was a clear log-linear correlation between the shear rate (range 10 s(-1) to 1500 s(-1)) and the procoagulant activity of SMC perfusates. Flow-dependent release of TF was transient (10 minutes) and did not measurably reduce cell surface TF content. Interestingly, a time-dependent (t(1/2) 30 minutes) re-exposure of releasable TF was detected after a no-flow period. These data demonstrate that SMCs may become a pathophysiologically relevant source of TF that can be rapidly released into the circulation in situations in which endothelial damage occurs and SMCs come into a close contact with the flowing blood.
The clinical course of patients with polycythaemia vera (PV) and essential thrombocythaemia (ET) is frequently complicated by arterial thrombotic events. The pathogenesis is not clearly understood ...but attributed to abnormalities in platelet function. An increase in platelet thromboxane formation has been described in the majority of asymptomatic patients with thrombocythaemia, probably reflecting spontaneous platelet activation in vivo. In the present study we prospectively investigated whether an increase in platelet thromboxane formation actually precedes arterial microvascular thrombosis. In addition, we studied the effect of selective inhibition of platelet thromboxane formation on clinical outcome by reinstitution of low‐dose aspirin (50 mg/d). Six ET patients and one PV patient participated in this study. Within 10 d after withdrawal of aspirin, three patients developed arterial microvascular thrombosis of extremities (erythromelalgia), which was preceded by a 3–30‐fold increase in urinary thromboxane excretion as compared with patients who remained asymptomatic. The increased urinary thromboxane excretion and clinical signs could be inhibited by a platelet‐specific aspirin regimen of 50 mg/d without affecting vascular cyclooxygenase, indicating that platelets were the main source of the increased thromboxane generation. These data suggest that in symptomatic patients an enhanced formation of thromboxane by platelets, reflecting platelet activation in vivo, precedes the development of arterial microvascular thrombosis. These data provide a rationale for using low‐dose aspirin as an antithrombotic agent in thrombocythaemia.
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