Exploring molecular mechanisms underlying changes in lipid fingerprinting of salmon (Salmo salar) during air frying integrating machine learning-guided REIMS and lipidomics analysis.

Lipid oxidation in air-fried seafood poses a risk to human health. However, the effect of a prooxidant environment on lipid oxidation in seafood at different air frying (AF) temperatures remains unknown. An integrated machine learning (ML) - guided REIMS and lipidomics method was applied to explore lipid profiles, lipid oxidation, and lipid metabolic pathways of salmons under different AF temperatures (140, 160, 180, and 200 °C). A significant difference in the lipidomic fingerprinting of air-dried salmon at different temperatures was shown by the main ML methods (neural networks, support vector machines, ensemble learning, and naïve bayes). In total, 773 differential expression metabolites (DEMs) were identified, including glycerophospholipids (GPs), glycerides (GLs), and sphingolipids. A total of 34 DEMs with p values <0.05 and variable importance of projection values >1.0 were analyzed, belonging to linoleic acid metabolism, GL metabolism, and GP metabolism pathways. Correlation network analysis revealed that some characteristic DEMs (phosphatidylcholine, lyso-phosphatidylcholine, triglycerides, fatty acids, and phosphatidylethanolamine) were highly correlated with lipid oxidation. In addition, variations of volatile compounds, color values, texture characteristics, and thiobarbituric acid-reactive substance values were analyzed to corroborate the oxidation characteristics.

Dispersive Solid-Phase Extraction and Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry-A Rapid and Accurate Method for Detecting 10 Macrolide Residues in Aquatic Products.

The amount of macrolide (MAL) residues in aquatic products, including oleandomycin (OLD), erythromycin (ERM), clarithromycin (CLA), azithromycin (AZI), kitasamycin (KIT), josamycin (JOS), spiramycin (SPI), tilmicosin (TIL), tylosin (TYL), and roxithromycin (ROX), was determined using solid-phase extraction and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The residues were extracted with 1% ammonia acetonitrile solution and purified by neutral alumina adsorption. Chromatographic separation was completed on an ACQUITY UPLC BEH C18 column with acetonitrile-0.1% formic acid aqueous solution as the mobile phase, and mass spectrometry detection was performed by multiple reaction monitoring scanning with the positive mode in an electrospray ion source (ESI+). Five isotopically labeled compounds were used as internal standards for quality control purposes. The findings indicated that across the mass concentration span of 1.0-100 µg/L, there was a strong linear correlation (R2 > 0.99) between the concentration and instrumental response for the 10 MALs. The limit of detection of UPLC-MS/MS was 0.25-0.50 µg/kg, and the limit of quantitation was 0.5-1.0 µg/kg. The added recovery of blank matrix samples at standard gradient levels (1.0, 5.0, and 50.0 µg/kg) was 83.1-116.6%, and the intra-day precision and inter-day precisions were 3.7 and 13.8%, respectively. The method is simple and fast, with high accuracy and good repeatability, in line with the requirements for accurate qualitative and quantitative analysis of the residues for 10 MALs in aquatic products.

Structural Characterization and In Vitro Antioxidant Activity of Metallothionein from Oratosquilla oratoria.

We report here the purification of a novel metal-binding protein from Oratosquilla oratoria (O. oratoria MT-1) by gel and ion-exchange chromatography. SDS-PAGE and MALDI-TOF analyses demonstrated that isolated O. oratoria MT-1 was of high purity with a molecular weight of 12.4 kDa. The fluorescence response to SBD-F derivatives revealed that O. oratoria MT-1 contained a large number of sulfhydryl groups, which is a general property of metallothioneins. Zn and Cu metal stoichiometries for O. oratoria MT-1 were 3.97:1 and 0.55:1, respectively. The proportion of cysteine (Cys) residues in the amino acid composition was 32.69%, and aromatic amino acids were absent. The peptide sequence coverage with Macrobrachium rosenbergii calmodulin (accession AOA3S8FSK5) was 60%. Infrared spectroscopy of O. oratoria MT-1 revealed two obvious peaks at absorption frequencies for the amide I band and the amide II band. CD spectra revealed that the secondary structure was mainly composed of random coil (57.6%) and ß-sheet (39.9%). An evaluation of in vitro antioxidant activity revealed that isolated O. oratoria MT-1 has strong reducing activities, exhibiting scavenging rates for DPPH and OH of 77.8% and 75.8%, respectively (IC50 values 0.57 mg/mL and 1.1 mg/mL). O. oratoria MT-1 may be used as a functional additive in cosmetics, health foods, and medical products, as well as a reference material for quantitative analysis of metallothionein in such products.

Synergistic antitumor activity of DHA and JQ1 in colorectal carcinoma.

Colon cancer is still a major disease plaguing humans. In this study, we evaluated the synergistic antitumor effects of the combination of BRD4 inhibitor JQ1 and docosahexaenoic acid (DHA) in colon cancer. We demonstrated that simultaneous exposure to JQ1 and DHA resulted in strong synergistic antiproliferative and proapoptotic effects related to inhibition of expression of c-Myc and activation of NF-κB in colon cancer cell lines. At the same time, the synergetic anticancer effect had been confirmed in vivo. For in vivo experiments, JQ1 and DHA resulted in more significant tumor growth inhibition (53.7%) in a human colon cancer HCT116 xenograft model, comparing with the moderate inhibition in JQ1-treated (31.9%) or DHA-treated groups (20.3%). Because DHA is the predominant component of fish oil, our data suggest that this nontoxic dietary supplement could be administered with BRD4 inhibitor during therapy for CRC, which lay an important foundation for the development of therapeutic regimens for CRC.

Response Surface Methodology for the Optimization of Ultrasound-Assisted Extraction of Tetrodotoxin from the Liver of Takifugu pseudommus.

Tetrodotoxin (TTX) is a marine biotoxin that has high scientific value. However, the lack of efficient TTX extraction and preparation methods has led to a scarcity of TTX samples for clinical application. In this study, TTX from the liver of Takifugu pseudommus was ultrasound-assisted extracted with acidified organic solvents. The extraction process was analyzed and optimized by single factor method and response surface methodology (RSM). The optimal extraction conditions predicted by a response surface model were as follows: liquid:material ratio, 2.8:1; extraction temperature, 60 °C; extraction time, 23.3 min. Under these conditions, the extraction of TTX had a yield of 89.65%, and the results were further verified by experimental extraction, and analyzed by ultra performance liquid chromatography⁻tandem mass spectrometry (UPLC⁻MS/MS). It was found that the extracts of T. pseudommus liver contained TTX and its four analogues at certain proportions (TTX: 10.4%; 5,6,11-trideoxyTTX: 83.3%; 5,11-dideoxyTTX:2.4%; 4,9-anhydro TTX:2.6%; 5-deoxyTTX:1.3%). This study demonstrates a stable and efficient extraction process of TTX from pufferfish liver, which can be helpful for further research and analysis, as well as the utilization of TTX from pufferfish.

[Purification and structural elucidation of exoploysaccharide from a new marine bacterium Lentibacter algarum ZXM100T].

Exopolysaccharide La0.1-1 was extracted from the broth of a marine bacterium Lentibacter algarum ZXM100T isolated from the seawater in the coastal region of Qingdao and purified by Q Sepharose Fast Flow ion-exchange chromatography and Superdex 75 gel-permeation chromatography. Its physiochemical properties and primary structural characters were investigated by chemical analysis together with high performance liquid chromatography (HPLC), high performance gel permeation chromatography (HPGPC) and gas chromatography and mass spectrometry (GC-MS). The results show that the total sugar content of the exoploysaccharide La0.1-1 was about 66% with an average molecular weight at 12.0 kDa. La0.1-1 is mainly composed of Gal, Man, GlcN at the ratio of 1.35:1.1:1.0. Results of GC-MS and NMR demonstrate that the exopolysaccharide La0.1-1 mainly exists with the beta configuration. The primary linkage styles are --> 2)-Manp(1 --> and --> 3)-Galp(1 --> with a small amount of --> 4)-Galp(--> 1 and --> 4)-Manp(1 --> linkages. The linkage mode of GlcN is --> 4)GlcN(1 --> and terminal linkage. The exopolysaccharide has mainly a linear sructure with a few branches linked to 0-6 of --> 2)-Manp(1 --> and 0-4 or 0-6 of --> 3)-Galp(1 -->. 1D-NMR data also revealed that La0.1-1 is substituted by certain acetyl; the acetyl is mainly linked to N-2 of GlcN. The exopolysaccharides of the bacterium of Lentibacter genus is reported for the first time, and an exopolysaccharide with novel structure was obtained, which enriched marine polysaccharide resources.

Determination of marker residue of Olaquindox in fish tissue by ultra performance liquid chromatography-tandem mass spectrometry.

Methyl-3-quinoxaline-2-carboxylic acid (MQCA) is the last major remaining detectable metabolite of Olaquindox in animal tissue. A rapid, sensitive and specific ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the detection and quantification of MQCA in fish tissue using deuterated quinoxaline-2-carboxylic acid (d(4)-QCA) as internal standard. Various parameters affecting sample preparation, LC separation and MS/MS detection were investigated, and the optimal conditions concerned were determined. Fish tissue samples were subject to hydrochloric acid hydrolysis followed by Oasis MAX solid-phase extraction clean-up; analysis was performed using UPLC coupled to electrospray MS/MS. The chromatographic separation was achieved in less than 5 min. The limit of detection and the limit of quantification were 0.1 and 0.25 ng/g, respectively. The average recoveries of MQCA, spiked at levels of 0.25-50.0 ng/g, were from 92.7 to 104.3%. The relative standard deviation values were <6%. The validated method was successfully applied to analyze 60 batch samples collected from the local market.