Vibriosis in farmed animals is a serious threat to aquaculture worldwide. Using probiotics and anti-Vibrio antimicrobial substances in aquaculture systems can be a means of preventing Vibrio infections. Therefore, we aimed to characterize and compare 16 potential anti-Vibrio probiotics (Vi+) isolated from marine sponges and fish intestines collected from the Vietnam Sea, as well as an anti-Vibrio bacteriocin to fully explore their application potentials. 16S rRNA sequencing confirmed all Vi+ to be Bacillus species with different strain variants across two sample types. An obvious antimicrobial spectrum toward Gram-negative bacteria was observed from intestinal Vi+ compared to sponge-associated Vi+. The reason was the higher gene frequency of two antimicrobial compounds, non-ribosomal peptides (NRPS) and polyketide type-I (PKS-I) from intestinal Vi+ (66.7%) than sponge-associated Vi+ (14.3% and 0%, respectively). Additionally, a three-step procedure was performed to purify an anti-Vibrio bacteriocin produced by B. methylotrophicus NTBD1, including (i) solvent extraction of bacteriocin from cells, (ii) hydrophobic interaction chromatography, and (iii) reverse-phase HPLC. The bacteriocin had a molecular weight of ~2–5 kDa, was sensitive to proteolysis and thermally stable, and showed a broad antimicrobial spectrum, all of which are essential properties for promising feed additives. This study provides necessary information of the potential of probiotic Bacillus species with anti-Vibrio antimicrobial properties to study their further use in sustainable aquaculture.

The new polyketides lopouzanones A and B, as well as the new 1-O-acetyl and 2-O-acetyl derivatives of dendrodochol B, were isolated from the sponge-derived marine fungus Lopadostoma pouzarii strain 168CLC-57.3. Moreover, six known polyketides, gliorosein, balticolid, dendrodolide G, dihydroisocoumarine, (–)-5-methylmellein, and dendrodochol B, were identified. The structures of the isolated compounds were determined by a combination of NMR and ESIMS techniques. The absolute configurations of the lopouzanones A and B were determined using the Mosher’s method. The cytotoxicity of the isolated compounds against human prostate cancer cells PC-3 and normal rat cardiomyocytes H9c2 was investigated. Gliorosein showed weak DPPH radical-scavenging activity and in vitro cardioprotective effects toward rotenone toxicity and CoCl₂-mimic hypoxia.

Objectives: This study aimed to investigate the in vitro and in vivo antibacterial and cytoprotective activities of marine fungal tripeptide derivatives with cinnamic acid moiety asterripeptides A–C (1–3). Methods: The antimicrobial and antibiofilm activities of asterripeptides A–C were tested using the Staphylococcus aureus ATCC 21027 strain. Human HaCaT keratinocytes infected with S. aureus were used for the in vitro investigation of the various aspects of the influence of asterripeptides A–C by lumino- and fluorospectrometry, ELISA, flow cytometry, Western blotting, and microscopy techniques. In the in vivo experiments, mice with burns and scalped S. aureus-infected wounds were used according to ethical committee resolution. Results: Asterripeptides A–C (10 µM) inhibited S. aureus growth and biofilm formation. Asterripeptides A–C increased the viability, proliferation, and migration of S. aureus-infected HaCaT cells and reduced the release of reactive oxygen species (ROS), NO, TNF-α, and IL-18. Asterripeptides A–C protected HaCaT cells against TNF-α-induced inflammation, decreased the transcriptional level of NF-κB in JB6 Cl41 cells, and increased the protein levels of Nrf2 and glutathione synthetase in HaCaT cells. More active asterripeptide C was tested in in vivo burn wounds and S. aureus-infected incised wounds. Asterripeptide C significantly enhanced wound healing, normalized cytokine levels and profiles of peripheral blood samples, and decreased S. aureus contamination of wounds and blood in mice with infected incised wounds. Conclusions: Taken together, these results confirm the dual antibacterial and Nrf2-dependent anti-inflammatory activities of asterripeptides A-C in in vitro and in vivo assays.

This study aims to evaluate the antioxidant and cytoprotective activities of 32 fungal strains isolated from brown seaweeds collected from Nha Trang Bay, Khanh Hoa Province, Central Vietnam. These fungal extracts were screened for antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging assay. In contrast, cytoprotective activity on rat cardiomyocytes H9c2 cell line was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. The results indicated the capacity for free DPPH and ABTS radical scavenging of fungal crude extracts with 31.25% (n = 10) and 81.25% (n = 26), respectively. Among the fungal strains with high antioxidant activity, the three fungal extracts 2104NT-1.3, 2104NT-3.3, and 2104NT-7.7 increased the viability of rotenone-exposed cardiomyocyte cells by 9.9%, 15.2%, and 13.6%, respectively. Three fungal strains with significant antioxidant and cytoprotective activities were identified as Penicillium chermesinum 2104NT-1.3, Aspergillus sp. 2104NT-3.3, and Penicillium sp. 2104NT-7.7 based on sequence analysis of internal transcribed spacer (ITS) region. This study provided the potential fungal strains isolated from Nha Trang Bay for further investigation of antioxidant and cytoprotective compounds.