An LC/MS/MS method for quantitation of chemopreventive sphingadienes in food products and biological samples

Targeted sphingolipidomics indicates increased C22-C24:16 ratios of virtually all assayed classes in liver, kidney, and plasma of fumonisin-fed chickens

The biological properties of sphinganine-(d18:0)-, sphingosine-(d18:1)-, deoxysphinganine-(m18: 0)-, deoxysphingosine-(m18:1)-, deoxymethylsphinganine-(m17:0)-, deoxymethylsphingosine-(m17:1)-, sphingadienine-(d18:2)-, and phytosphingosine-(t18:0)-sphingolipids have been reported to vary, but little is known about the effects of fumonisins, which are mycotoxins that inhibit ceramide synthase, on sphingolipids other than those containing d18:0 and d18:1. Thirty chickens divided into three groups received a control diet or a diet containing 14.6 mg FB1 + FB2/kg for 14 and 21 days. No effects on health or performance were observed, while the effects on sphingoid bases, ceramides, sphingomyelins, and glycosylceramides in liver, kidney, and plasma varied. The t18:0 forms were generally unaffected by fumonisins, while numerous effects were found for m18:0, m18:1, d18:2, and the corresponding ceramides, and these effects appeared to be similar to those observed for d18:0-, and d18:1-ceramides. Partial least square discriminant analysis showed that d18:1- and d18:0-sphingolipids are important variables for explaining the partitioning of chickens into different groups according to fumonisins feeding, while m17:1-, m18:0-, m18:1-, d18:2-, and t18:0-sphingolipids are not. Interestingly, the C22-C24:C16 ratios measured for each class of sphingolipid increased in fumonisin-fed chickens in the three assayed matrices, whereas the total amounts of the sphingolipid classes varied. The potential use of C22-C24:C16 ratios as biomarkers requires further study.

Parallel Reaction Monitoring Mass Spectrometry for Rapid and Accurate Identification of β-Lactamases Produced by Enterobacteriaceae

The increasing spread of drug-resistant bacterial strains presents great challenges to clinical antibacterial treatment and public health, particularly with regard to β-lactamase-producing Enterobacteriaceae. A rapid and accurate detection method that can expedite precise clinical diagnostics and rational administration of antibiotics is urgently needed. Targeted proteomics, a technique involving selected reaction monitoring or multiple reaction monitoring, has been developed for detecting specific peptides. In the present study, a rapid single-colony-processing procedure combined with an improved parallel reaction monitoring (PRM) workflow based on HRAM Orbitrap MS was developed to detect carbapenemases (Klebsiella pneumoniae carbapenemase, KPC; imipenemase, IMP; Verona integron-encoded metallo-β-lactamase, VIM; New Delhi metallo-β-lactamase, NDM; and oxacillinase, OXA), extended spectrum β-lactamases (TEM and CTX-M), and AmpC (CMY-2) produced by Enterobacteriaceae. Specific peptides were selected and validated, and their coefficients of variation and stability were evaluated. In total, 188 Enterobacteriaceae strains were screened using the workflow. Fourteen out of total 19 peptides have 100% specificity; three peptides have specificity >95% and two peptides have specificity ranged from 74∼85%. On the sensitivity, only nine peptides have 95∼100% sensitivity. The other 10 peptides have sensitivity ranged from 27∼94%. Thus, a screening method based on peptide groups was developed for the first time. Taken together, this study described a rapid extraction and detection workflow for widespread β-lactamases, including KPC, IMP, VIM, NDM, OXA, CMY, CTX-M, and TEM, using single colonies of Enterobacteriaceae strains. PRM-targeted proteomics was proven to be a promising approach for the detection of drug-resistant enzymes.

The Importance of Reference Materials and Method Validation for Advancing Research on the Health Effects of Dietary Supplements and Other Natural Products

Insufficient assessment of the identity and chemical composition of complex natural products, including botanicals, herbal remedies, and dietary supplements, hinders reproducible research and limits understanding mechanism(s) of action and health outcomes, which in turn impede improvements in clinical practice and advances in public health. This review describes available analytical resources and good methodological practices that support natural product characterization and strengthen the knowledge gained for designing and interpreting safety and efficacy investigations. The practice of validating analytical methods demonstrates that measurements of constituents of interest are reproducible and appropriate for the sample (e.g., plant material, phytochemical extract, and biological specimen). In particular, the utilization of matrix-based reference materials enables researchers to assess the accuracy, precision, and sensitivity of analytical measurements of natural product constituents, including dietary ingredients and their metabolites. Select case studies are presented where the careful application of these resources and practices has enhanced experimental rigor and benefited research on dietary supplement health effects.

The noncanonical chronicles: Emerging roles of sphingolipid structural variants

Sphingolipids (SPs) are structurally diverse and represent one of the most quantitatively abundant classes of lipids in mammalian cells. In addition to their structural roles, many SP species are known to be bioactive mediators of essential cellular processes. Historically, studies have focused on SP species that contain the canonical 18‑carbon, mono-unsaturated sphingoid backbone. However, increasingly sensitive analytical technologies, driven by advances in mass spectrometry, have facilitated the identification of previously under-appreciated, molecularly distinct SP species. Many of these less abundant species contain noncanonical backbones. Interestingly, a growing number of studies have identified clinical associations between these noncanonical SPs and disease, suggesting that there is functional significance to the alteration of SP backbone structure. For example, associations have been found between SP chain length and cardiovascular disease, pain, diabetes, and dementia. This review will provide an overview of the processes that are known to regulate noncanonical SP accumulation, describe the clinical correlations reported for these molecules, and review the experimental evidence for the potential functional implications of their dysregulation. It is likely that further scrutiny of noncanonical SPs may provide new insight into pathophysiological processes, serve as useful biomarkers for disease, and lead to the design of novel therapeutic strategies.

Sphingoid bases of dietary ceramide 2-aminoethylphosphonate, a marine sphingolipid, absorb into lymph in rats

Various functions of dietary sphingolipids have been reported; however, little is known about marine sphingolipids. Ceramide 2-aminoethylphosphonate (CAEP), an abundant sphingolipid in marine mollusks, frequently has a unique triene type of sphingoid base [2-amino-9-methyl-4,8,10-octadecatriene-1,3-diol (d19:3)]. We previously reported that dietary CAEP prepared from the skin of squid was digested in the intestinal mucosa of mice via ceramides to yield free sphingoid bases. How dietary CAEP is then used in the body remains unclear. Here, we investigated the absorption of dietary CAEP using a lipid absorption assay on the lymph collected from rats with thoracic duct cannulation. Our results reveal that sphingoid bases derived from CAEP, including d16:1, d18:1, and d19:3, were detected in the lymph after administration of CAEP. Lymphatic recovery of d19:3 was lower than that of other sphingoid bases. A large fraction of the absorbed sphingoid bases was present as complex sphingolipids, whereas a smaller portion was present in the free form. Fatty acids in ceramide moieties found in the lymph were partially different from dietary CAEP, which indicates that sphingoid bases derived from CAEP could be, at least in part, resynthesized into complex sphingolipids. Future studies should elucidate the metabolism of sphingoid bases derived from CAEP.

Sphingadienes show therapeutic efficacy in neuroblastoma in vitro and in vivo by targeting the AKT signaling pathway

Neuroblastoma is a childhood malignancy that accounts for approximately 15% of childhood cancer deaths. Only 20-35% of children with metastatic neuroblastoma survive with standard therapy. Identification of more effective therapies is essential to improving the outcome of children with high-stage disease. Sphingadienes (SD) are growth-inhibitory sphingolipids found in natural sources including soy. They exhibit chemopreventive activity in mouse models of colon cancer, where they mediate cytotoxicity by inhibiting key pro-carcinogenic signaling pathways. In this study, the effect of SD on neuroblastoma was analyzed. Low micromolar concentrations of SD were cytotoxic to transformed and primary neuroblastoma cells independently of N-Myc amplification status. SD induced both caspase-dependent apoptosis and autophagy in neuroblastoma cells. However, only inhibition of caspase-dependent apoptosis protected neuroblastoma cells from SD-mediated cytotoxicity. SD also inhibited AKT activation in neuroblastoma cells as shown by reduced phosphorylated AKT levels. Pre-treatment with insulin attenuated SD-mediated cytotoxicity in vitro. SD-loaded nanoparticles (NP) administered parenterally to immunodeficient mice carrying neuroblastoma xenografts resulted in cytotoxic levels of SD in the circulation and significantly reduced tumor growth compared to vehicle-treated controls. Analysis of tumor extracts demonstrated reduced AKT activation in tumors of mice treated with SD-NP compared to controls treated with empty NP. Our findings indicate SD are novel potential chemotherapeutic agents that promote neuroblastoma cell death and reduce tumorigenicity in vivo.