A Comparative Analysis of the Anti-Tumor Activity of Sixteen Polysaccharide Fractions from Three Large Brown Seaweed, Sargassum horneri, Scytosiphon lomentaria, and Undaria pinnatifida.

Searching for natural products with anti-tumor activity is an important aspect of cancer research. Seaweed polysaccharides from brown seaweed have shown promising anti-tumor activity; however, their structure, composition, and biological activity vary considerably, depending on many factors. In this study, 16 polysaccharide fractions were extracted and purified from three large brown seaweed species (Sargassum horneri, Scytosiphon lomentaria, and Undaria pinnatifida). The chemical composition analysis revealed that the polysaccharide fractions have varying molecular weights ranging from 8.889 to 729.67 kDa, and sulfate contents ranging from 0.50% to 10.77%. Additionally, they exhibit different monosaccharide compositions and secondary structures. Subsequently, their anti-tumor activity was compared against five tumor cell lines (A549, B16, HeLa, HepG2, and SH-SY5Y). The results showed that different fractions exhibited distinct anti-tumor properties against tumor cells. Flow cytometry and cytoplasmic fluorescence staining (Hoechst/AO staining) further confirmed that these effective fractions significantly induce tumor cell apoptosis without cytotoxicity. qRT-RCR results demonstrated that the polysaccharide fractions up-regulated the expression of Caspase-3, Caspase-8, Caspase-9, and Bax while down-regulating the expression of Bcl-2 and CDK-2. This study comprehensively compared the anti-tumor activity of polysaccharide fractions from large brown seaweed, providing valuable insights into the potent combinations of brown seaweed polysaccharides as anti-tumor agents.

Versatile Bilayer Hydrogel for Wound Dressing through PET-RAFT Polymerization.

Multifunctional hydrogel-based wound dressings have been explored for decades due to their huge potential in multifaceted medical intervention to wound healing. However, it is usually not easy to fabricate a single hydrogel with all of the desirable functions at one time. Herein, a bilayer model with an outer layer for hydrogel wound dressing was proposed. The inner layer (Hm-PNn) was a hybrid hydrogel prepared by N-isopropylacrylamide and chitosan-N-2-hydroxypropyl trimethylammonium chloride (HACC), and the outer layer (PVAo-PAmp) was prepared by polyvinyl alcohols and acrylamide. The two hydrogel layers of the bilayer model were covalently connected with excellent interfacial strength by photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization. The outer layer exposed to the ambient environment exhibited good stretchability and toughness, while the inner-layer hydrogel adhered to the skin exhibited excellent softness, antibacterial activity, thermoresponsivity, and biocompatibility. In particular, the inner layer of a hydrogel demonstrated excellent antibacterial capability toward both Staphylococcus aureus as Gram-positive bacteria and Escherichia coli as Gram-negative bacteria. Cell cytotoxicity showed that the cell viability of all Hm-PNn layer hydrogels exceeds 80%, confirming that the hydrogels bear excellent biocompatibility. In vivo experimental results indicated that the Hm-PNn/PVAo-PAmp bilayer hydrogel has a significant effect on the acceleration of wound healing, which was demonstrated in a full-thickness skin defect model showing improved collagen disposition and granulation tissue thickness. With these results, the established multifunctional bilayer hydrogel exhibits potential as an excellent wound dressing for wound healing applications, especially for open and infected traumas.

An aptamer and flower-shaped AuPtRh nanoenzyme-based colorimetric biosensor for the detection of profenofos.

In this work, a simple, sensitive and selective colorimetric method was established for the detection of profenofos. Firstly, novel flower-shaped AuPtRh trimetallic nanospheres were synthesized via a simple one-pot method, and had outstanding peroxidase catalytic activity. AuPtRh nanospheres with a great specific surface area were linked with an aptamer via Au-S and Pt-S bonds to specifically recognize profenofos. A graphene oxide grafted stainless-steel mesh (SSM-GO) was prepared to be a carrier and the aptamer-AuPtRh was nonspecifically adsorbed on the surface of SSM-GO, which was to be the capture probe for the detection of profenofos in real samples. They were characterized and confirmed by transmission electron microscopy, atomic force microscopy, etc. Through the investigation of the catalytic performance on the basis of the Michaelis equation, the Vmax of AuPtRh nanospheres was 22.27 × 10-8 M s-1, and Km was 0.6632 mM, which indicated that the affinity of AuPtRh nanospheres was relatively higher than that of horseradish peroxidase and Au NPs. In the presence of profenofos, the aptamer-AuPtRh would specifically combine with profenofos, which would further detach from SSM-GO. Then, it was introduced into the 3,3',5,5'-tetramethylbenzidine/H2O2 (TMB/H2O2) system to form blue oxTMB. The linear range of this colorimetric biosensor was 1-300 ng L-1 and the limit of detection was 0.725 ng L-1. It also had good recovery and anti-interference ability in real samples, which provided a new strategy for the rapid detection of pesticides.

Cloning and Characterization of Fructose-1,6-Bisphosphate Aldolase from Euphausia superba.

Fructose-1,6-bisphosphate aldolase (EC 4.1.2.13) is a highly conserved enzyme that is involved in glycolysis and gluconeogenesis. In this study, we cloned the fructose-1,6-bisphosphate aldolase gene from Euphausia superba (EsFBA). The full-length cDNA sequence of EsFBA is 1098 bp long and encodes a 365-amino-acid protein. The fructose-1,6-bisphosphate aldolase gene was expressed in Escherichia coli (E. coli). A highly purified protein was obtained using HisTrap HP affinity chromatography and size-exclusion chromatography. The predicted three-dimensional structure of EsFBA showed a 65.66% homology with human aldolase, whereas it had the highest homology (84.38%) with the FBA of Penaeus vannamei. Recombinant EsFBA had the highest activity at 45 °C and pH 7.0 in phosphate buffer. By examining the activity of metal ions and EDTA, we found that the effect of metal ions and EDTA on EsFBA's enzyme activity was not significant, while the presence of borohydride severely reduced the enzymatic activity; thus, EsFBA was confirmed to be a class I aldolase. Furthermore, targeted mutations at positions 34, 147, 188, and 230 confirmed that they are key amino acid residues for EsFBA.

Construction of an electrochemical sensor with graphene aerogel doped with ZrO2 nanoparticles and chitosan for the selective detection of luteolin.

A simple, fast and sensitive method for the detection of luteolin is proposed based on the chitosan/reduced graphene oxide aerogel with dispersed ZrO2 nanoparticles modified glassy carbon electrode (ZrO2/CS/rGOA-GCE) as an electrochemical sensor. The ZrO2/CS/rGOA composite was prepared by one pot synthesis from a mixture of GO, CS and zirconyl chloride octahydrate, and subsequently be freeze-dried. Scanning electron microscope images showed a typical thin, wrinkled and fluctuant morphology of graphene nanosheets and the polymerized CS and ZrO2 nanoparticles deposited on the surface of rGOA. Cyclic voltammetry and differential pulse voltammetry were used to measure the electrochemical response of ZrO2/CS/rGOA composite-based biosensor towards luteolin at the working potential window (-0.8-0.8 V). The improved performance of this biosensor was attributed to efficient electron transfer and large surface area of 3D rGOA, and high specific activity of Zr towards adjacent hydroxyl groups. Under optimized conditions, the analytical performance of this method towards luteolin was investigated with a detection limit of 1 nM and a linear range from 5 nM to 1000 nM.. Finally, the ZrO2/CS/rGOA-GCE electrochemical method coupled with solid phase extraction was used for the detection of luteolin in real samples. Recoveries of  spiked samples with different concentrations were in the range 78.6-103.3% with a relative RSD lower than 12.0%. Graphical abstract Schematic representation of the preparation of the ZrO2 nanoparticles and chitosan doped graphene aerogel modified electrode. The electrode was employed for the detection of luteolin coupled with the solid-phase extraction technique.

A label-free fluorometric aptasensor for adenosine triphosphate (ATP) detection based on aggregation-induced emission probe.

Based on Aggregation-Induced Emission (AIE), the development of a label-free, simple and sensitive fluorometric aptasensor for adenosine triphosphate (ATP) detection is described. With ATP present, the aptamers will combine with ATP and the conformation of the aptamer will switch from a random coil to an antiparallel G-quadruplex, which impedes the digestion by exonuclease I (Exo I). Addition of 4,4 -(1E,1E)-2,2-(anthracene-9,10-diyl) bis (ethene-2,1-diyl) bis (N,N, N-trimethyl-benzenaminium iodide) (DSAI) into the solution will cause aggregation of DSAI on the surface of the aptamer/ATP complex and consequently give rise to strong emission. Additionally, a good linear relationship was observed under optimized conditions between the fluorescence intensities and the logarithm of ATP concentrations (R2 = 0.9908). The established aptamer sensor was highly sensitive and exhibited a low limit of detection of 32.8 nM, with superior specificity for ATP. It was also used in the quantification of ATP levels in human serum samples and demonstrated satisfactory recoveries in the scope of 93.2%-107.6%. The cellular ATP assay results indicated that the developed method can be used for monitoring ATP concentrations in cell extracts without the interference of other substances in the cells. This method offers several advantages such as simplicity, rapidity, low cost and excellent selectivity, which make it hold great potential for the detection of ATP in bioanalytical and biological studies.

Expression, Purification and Characterization of Chondroitinase AC II from Marine Bacterium Arthrobacter sp. CS01.

Chondroitinase (ChSase), a type of glycosaminoglycan (GAG) lyase, can degrade chondroitin sulfate (CS) to unsaturate oligosaccharides, with various functional activities. In this study, ChSase AC II from a newly isolated marine bacterium Arthrobacter sp. CS01 was cloned, expressed in Pichia pastoris X33, purified, and characterized. ChSase AC II, with a molecular weight of approximately 100 kDa and a specific activity of 18.7 U/mg, showed the highest activity at 37 °C and pH 6.5 and maintained stability at a broad range of pH (5⁻7.5) and temperature (below 35 °C). The enzyme activity was increased in the presence of Mn2+ and was strongly inhibited by Hg2+. Moreover, the kinetic parameters of ChSase AC II against CS-A, CS-C, and HA were determined. TLC and ESI-MS analysis of the degradation products indicated that ChSase AC II displayed an exolytic action mode and completely hydrolyzed three substrates into oligosaccharides with low degrees of polymerization (DPs). All these features make ChSase AC II a promising candidate for the full use of GAG to produce oligosaccharides.

Stable isotope labelling by amino acids in cell culture (SILAC) applied to quantitative proteomics of Edwardsiella tarda ATCC 15947 under prolonged cold stress.

Edwardsiella tarda poses a threat to human health and has resulted in enormous economic losses in aquaculture. Low temperatures are usually applied to contain the growth of this microorganism. In this study, stable isotope labelling by amino acids in cell culture (SILAC) was used to conduct comparative proteomic quantitation of E. tarda ATCC 15947 under cold stress for two weeks. We identified 1391 proteins, of which 898 were quantifiable. Of these, 72 proteins were upregulated and 164 were downregulated in response to cold stress. Even though E. tarda ATCC 15947 is not a psychrophile, several key proteins related to DNA synthesis and transcription were significantly upregulated. Additionally, proteins related to haemolytic activities and gluconeogenesis were upregulated, even though E. tarda ATCC 15497 is considered non-virulent in aquaculture. This study therefore delineated the specific proteomic response of this E. tarda ATCC 15947 to prolonged cold stress.

Long-Term Krill Oil Administration Alleviated Early Mild Cognitive Impairment in APP/PS1 Mice.

SCOPE: Alzheimer's disease is an age-dependent neurodegenerative disorder. Mounting studies focus on the improvement of advanced cognitive impairment by dietary nutrients. Krill oil (KO), a rich source of DHA/EPA and astaxanthin, is effective in improving cognitive function. The study mainly investigates the protective effects of long-term KO administration on early cognitive impairment. METHODS AND RESULTS: Results show that 2 months KO administration (50 and 100 mg kg-1 BW) can dramatically promote learning and memory abilities. Mechanism studies demonstrate that KO reduces amyloid ß concentration by regulating the amyloidogenic pathway, inhibits neuro-inflammation via regulating TLR4-NLRP3 signaling pathway, and prevents neuron injure. KO supplementation also enhances gut barrier integrity, reduces serum lipopolysaccharide leakage, and alters the gut microbiota by reducing Helicobacteraceae, Lactobacillaceae proportion, increasing Dubosiella and Akkermansia relative abundance. Particularly, a significant increase of isovaleric acid, propionic acid, and acetic acid levels is observed after KO supplementation. Correlation analysis shows that short-chain fatty acids (SCFAs), gut microbiota, and cognitive function are strongly correlated. CONCLUSIONS: The results reveal that KO relieves early mild cognitive impairment possibly for its role in mediating the gut microbiome-SCFAs-brain axis. Thus, KO may provide potential intervention strategies to prevent cognitive impairment in the early stages through the microbiota-gut-brain axis.

Orally administered selenium-containing α-D-1,6-glucan and α-D-1,6-glucan relief early cognitive deficit in APP/PS1 mice.

Alzheimer's disease (AD) is a complex, progressive and deadly disorder that exhibits various typical pathological characteristics. Till now no effective treatment has been found that can prevent or reverse AD. Here, the effects of 2 months of treatment with α-D-1,6-glucan (CPA) and selenium-containing α-D-1,6-glucan (Se-CPA) on early cognitive dysfunction and neuropathology were explored in the 3-month-old APP/PS1 transgenic mouse. The results of the Morris water maze and open-field test revealed that Se-CPA exerted more significant effects than CPA in improving cognitive function and depressive-like behavior by attenuating the oxidative stress, decreasing serum LPS level, downregulating the inflammation of astrocytes and microglia through inhibiting the activation of NLRP3 inflammasome, mitigating neuronal cells loss and improving synaptic plasticity. Moreover, Se-CPA exerted beneficial effects on reshaping gut microbiome by increasing the microbial α-diversity, enhancing the proportion of beneficial bacteria such as Akkermansia muciniphila and promoting the SCFAs concentration. These findings provide evidence that Se-CPA might be a potentially viable compound for AD prevention.

Saccharina japonica Ethanol Extract Ameliorates Dextran Sulfate Sodium-Induced Colitis via Reshaping Intestinal Microenvironment and Alleviating Inflammatory Response.

Saccharina japonica belongs to brown macro-alga with various potential health benefits; its antioxidant and anti-inflammatory activities indicate the potential to improve inflammatory bowel diseases. Here, the potential anti-colitis effect of Saccharina japonica extract (SJE) was evaluated on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in C57B/L6 mice. The mice were treated with mesalazine (MES) and various doses of SJE by gavage for 14 days. Results showed that both MES and SJE treatment decreased the disease activity index scores, relieving the short colon. SJE increased the occludin and zonula occludens-1 levels, and the beneficial effects were better than MES. MES and SJE exerted similar effects in decreasing inflammatory cytokines and oxidative stress. Moreover, SJE reshaped the intestinal microbiota by increasing α-diversity and reducing plenty of harmful bacteria. Dietary SJE was significant to relieving the reduction in short-chain fatty acids. The results revealed the protective effect of SJE on colitis and potential mechanisms, which is important for the rational use of SJE in UC prevention.

Ink melanin from Sepiapharaonis ameliorates colitis in mice via reducing oxidative stress, andprotecting the intestinal mucosal barrier.

Melanin is the major component from Sepiapharaonis ink (MSI), and its anti-inflammatory and antioxidant activities indicate the potential for improvement of inflammatory bowel diseases. The study aimed to investigate how orally-administered MSI on alleviating the dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) and the potential mechanisms. We found that MSI significantly improved DSS-induced weight loss, colon shortening, hematochezia, DAI score, histopathology, and antioxidant indices (SOD and MDA). Further analysis demonstrated that MSI could significantly down-regulate the expression of pro-inflammatory cytokines (TNF-α, IL-1ß and IFN-γ) and up-regulate the concentration of anti-inflammatory cytokine IL-10 by regulating TLR4/NF-κB and NLRP3/ASC/Caspase-1 signal pathway. Moreover, tight junction proteins in melanin groups were also maintained by ZO-1 and occludin expressions. In addition, MSI also regulated cellular apoptosis by reducing the expression of pro-apoptosis protein Caspase-3. Interestingly, MSI treatments increased the proportion of dominant bacteria (such as Bacteroidetes and Clostridium) and the abundance of community (alpha diversity, ß-diversity, etc.), which significantly balanced microbiota in a dose-dependent manner. In conclusion, oral administration of MSI alleviated DSS-induced colitis by modulating inflammatory cytokines and oxidation stress, maintaining the mucosal barrier, and reverting microbiota changes.

Supplementary selenium in the form of selenylation α-D-1,6-glucan ameliorates dextran sulfate sodium induced colitis in vivo.

The deficiency of selenium has been found in clinical IBD patients and supplementation selenium is recognized as beneficial for colitis treatment. In this study, an organic selenium compound-selenylation α-D-1,6-glucan (sCPA) was prepared, and the effect of sCPA on DSS induced colitis mice was investigated. The results suggested that sCPA prevented the weight loss, colon length shortening, and stool loose of colitis mice. It protected colon mucosal barrier by promoting tight junction protein ZO-1 and Occludin expression. Moreover, sCPA reduced oxidative stress via regulating SOD and MDA levels, and decreased the contents of inflammatory proteins NF-κB and NLRP3 and adjusted TNF-α, IFN-γ, IL-1ß, and IL-10 inflammatory cytokines. Furthermore, sCPA repaired intestinal microbiota composition especially Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria that altered by DSS in colitis mice. Meanwhile, SCFAs produced by gut microbiota were restored by sCPA close to the level in the normal group. In conclusion, these findings indicated that the sCPA might be a potential dietary selenium supplementation for the prevention and treatment of colitis.

Identification of novel paralytic shellfish toxin binding protein via homology modeling and molecular docking.

A paralytic shellfish toxin binding protein (PST-BP) was extracted and purified from the viscera of oyster (Crassostrea hongkongensis) that accumulates paralytic shellfish toxin (PST), and the amino acid sequence of the protein was detected via HPLC-MS-MS. The structure of the PST-BP was built by homology modeling, and the interaction between PST and PST-BP was studied using molecular docking. The results showed that the purity of PST-BP was more than 99.8% after the purification. The PST-BP carried a molecular weight of 33.5 kDa and sequence alignment revealed its high sequence similarities with glyceraldehyde-3-phosphate-dehydrogenase (GAPDH). It has been shown that 99.9% of the amino acid residues in the PST-BP homology model are within a reasonable range, which exceeds the 90% threshold requirement for residuals in high-quality model structures. The molecular docking results revealed that Arg, Asp, Lys, Ala, Ser, Gln, Gly, Trp, Asn, Met, and Pro were identified as the major interacting amino acids residues between PST-BP and PST.

Halophilic bacteria as starter cultures: A new strategy to accelerate fermentation and enhance flavor of shrimp paste.

Retaining the traditional flavor while shortening the fermentation cycle is the current research focus for shrimp paste fermentation technology. The present study investigated the effect of combined use of halophilic bacteria as starters on the sensory and flavor characteristics of rapidly fermented shrimp paste. Sensory evaluation indicated that the starter-inoculated samples had high texture, appearance, and overall quality scores. Headspace gas chromatography-ion mobility spectrometry/mass spectrometry (HS-GC-IMS/MS) identified 95 volatile compounds, the fingerprint profiles of the starter-inoculated samples were similar to those of the traditional sample. Notably, the content of benzaldehyde, phenylethylaldehyde, and 3-methylbutyraldehyde increased significantly in the starter-inoculated samples (p < 0.05), which may provide an intense malt, caramel, and pleasant odor. Although the content of certain flavor substances in the starter-inoculated samples was lower than those of traditional sample, the use significantly reduced the fermentation time and mimicked the flavor profile of traditional shrimp paste to some extent.

α-D-1,6-glucan from Castanea mollissima Blume alleviates dextran sulfate sodium-induced colitis in vivo.

A homogenous α-D-1,6-glucan (CPA) was extracted from Castanea mollissima Blume. The effect of CPA on ameliorating dextran sulfate sodium induced colitis was investigated. CPA repressed TNF-α and IL-1ß level in LPS stimulated RAW264.7 cells. After the intragastric administration of CPA (200 or 400 mg/kg/day), the colon length and body weights of mice with colitis increased and the disease activity index reduced. CPA alleviated colon tissue damage by elevating ZO-1 and occludin protein levels and regulating TNF-α and IL-1ß by inhibiting the protein expression of NLPR3 and NF-κB p65. The abundance of Bacteroidetes and Firmicutes was altered and short-chain fatty acid (SCFA) levels, especially propionic, butyric, and isovaleric acids increased significantly. These results indicated that CPA could alleviate colitis by protecting mucosal barriers, reducing inflammation, and regulating intestinal microbiota and SCFA levels. Thus, CPA can be developed as a functional food for the prevention and treatment of colitis.

Orally administered melanin from Sepiapharaonis ink ameliorates depression-anxiety-like behaviors in DSS-induced colitis by mediating inflammation pathway and regulating apoptosis.

The effects of intestinal inflammation on the brain and behavior have received a lot of attention. Melanin (MSI) from Sepiapharaonis ink as an emerging functional food, it exhibited a significant protective effect on dextran sulfate sodium (DSS) induced colitis in previous study. In present study, C57BL/6J mice were free to drink 2.5% DSS solution to establish the colitis model. During the DSS treatment, mice were orally administrated with MSI once per day (75, 150, and 300 mg/kg, respectively). The results showed that MSI treatment ameliorated the depression and anxiety symptoms of colitis mice. Further mechanism studies indicated that MSI alleviated inflammatory response by adjusting cytokines TNF-α, IL-1ß, IFN-γ, and IL-10, and proteins NLRP3/ASC/caspase-1 inflammasome), inhibited the activation of microglia, restored brain synaptic density, reduced oxidative stress (SOD, MDA) and regulated apoptosis (tunel staining, caspase-3). MSI could modulate depression-anxiety states by targeting inflammation, nerve tissue, oxidative stress and apoptosis. MSI administration could serve as an emerging blue food and nutrition strategy for the prevention of digestive tract inflammation and behavioral disorders.

The complete mitochondrial genome of Sporobolus alterniflorus (loisel.) P.M. Peterson & Saarela (Poaceae) and phylogenetic analysis.

The complete mitochondrial genome of Sporobolus alterniflorus was a circular molecule of 566,328 bp in length and encoded 64 genes, including 35 protein-coding genes, 24 tRNA genes, and 5 rRNA genes. The most common initiated codon was ATG and the most common termination codon was CAT. The overall A + T content was 55.96%. The phylogenomic analysis revealed that Sporobolus alterniflorus have a closest phylogenetic relationship with Sorghum bicolor.

Extraction of Chitin From Shrimp Shell by Successive Two-Step Fermentation of Exiguobacterium profundum and Lactobacillus acidophilus.

As an environmentally friendly and efficient method, successive two-step fermentation has been applied for extracting chitin from shrimp shells. To screen out the microorganisms for fermentation, a protease-producing strain, Exiguobacterium profundum, and a lactic acid-producing strain, Lactobacillus acidophilus, were isolated from the traditional fermented shrimp paste. Chitin was extracted by successive two-step fermentation with these two strains, and 85.9 ± 1.2% of protein and 95 ± 3% of minerals were removed. The recovery and yield of chitin were 47.82 and 16.32%, respectively. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy (SEM) were used to characterize the chitin. The crystallinity index was 54.37%, and the degree of deacetylation was 3.67%, which was lower than that of chitin extracted by the chemical method. These results indicated that successive two-step fermentation using these two bacterial strains could be applied to extract chitin. This work provides a suitable strategy for developing an effective method to extract chitin by microbial fermentation.

Effect of carboxymethyl chitosan on the detoxification and biotransformation of paralytic shellfish toxins in oyster Ostrea rivularis.

Economic bivalve ingested toxic algae causes frequent human poisoning events. To explore new compounds that can accelerate the depuration of toxins in shellfish, we investigated the detoxification of the paralytic shellfish toxins (PSTs) and the biotransformation pathway of PSTs during detoxification by the application of three treatments to a toxic bloom, Alexandrium minutum (A. minutum). The detoxification effect of Platymonas subcordiformis (PS) mixed with carboxymethyl chitosan (CMC) group is significantly better than the starving group in each oyster tissues. The toxicity of viscera which occupied 78.95% of total toxicity reduced to 155 MU/100g after 13 days' depuration experiment. And adding CMC could significantly achieve rapid detoxification and effectively reduce the STX to 0.07 µmol/100 g in viscera. Meanwhile, PSTs underwent biotransformation during the depuration process, which mainly manifested as GTX1/4→GTX2/3→STX, GTX2→dcGTX2. This study explored a new strategy for toxin depuration in shellfish.