Search Results (57)

The Red Sea is rich in symbiotic microorganisms that have been identified as sources of bioactive compounds with antimicrobial, antifungal, and antioxidant properties. In this study, we aimed to explore the potential of marine sponge-associated bacteria as sources of antibacterial compounds, emphasizing their significance in combating antibiotic resistance (AMR). The crude extracts of Micrococcus, Bacillus, and Staphylococcus saprophyticus exhibited significant antibacterial activity, with inhibition zones measuring 12 mm and 14 mm against Escherichia coli, Staphylococcus aureus, Candida albicans, and other infectious strains. The DPPH assay showed that the bacterial isolates AN3 and AN6 exhibited notable antioxidant activity at a concentration of 100 mg/mL. To characterize the chemical constituents responsible for the observed bioactivity, a GC–MS analysis was performed on ethyl acetate extracts of the potent strains. The analysis identified a range of antimicrobial compounds, including straight-chain alkanes (e.g., Tetradecane), cyclic structures (e.g., Cyclopropane derivatives), and phenolic compounds, all of which are known to disrupt microbial membranes or interfere with metabolic pathways. The bioprospecting and large-scale production of these compounds are challenging. In conclusion, this study underscores the potential for marine bacteria associated with sponges from the Red Sea to be a source of bioactive compounds with therapeutic relevance. Full article

Malbranchea circinata SDU050, a fungus derived from deep-sea sediment, is a prolific producer of diverse secondary metabolites. Genome sequencing revealed the presence of at least 69 biosynthetic gene clusters (BGCs), including 30 encoding type I polyketide synthases (PKSs). This study reports the isolation and identification of four classes of secondary metabolites from wild-type M. circinata SDU050, alongside five additional metabolite classes, including three novel cytochalasins (7–9), obtained from a mutant strain through the metabolic blockade strategy. Furthermore, bioinformatic analysis of the BGC associated with the isocoumarin sclerin (1) enabled the deduction of its biosynthetic pathway based on gene function predictions. Bioactivity assays demonstrated that sclerin (1) and (−)-mycousnine (10) exhibited weak antibacterial activity against Gram-positive bacteria such as Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Bacillus subtilis. These findings underscore the chemical diversity and biosynthetic potential of M. circinata SDU050 and highlight an effective strategy for exploring marine fungal metabolites. Full article

The structural diversity of marine natural products is considered a potential resource for the pharmaceutical industry. In our study of marine-derived compounds, one bacterium Bacillus licheniformis S-1 was discovered to have the ability to produce bioactive natural products. After a further chemistry investigation, one novel 4-aminopyridinium derivative, 4-(dimethylamino)-1-(2S-((4hydroxybenzoyl)oxy)propyl)pyridin-1-ium (1), along with 15 known cyclic dipeptides (2–16) were isolated from the bacterium B. licheniformis S-1 derived from a shallow sea sediment. The structures of compounds 1–16 were elucidated through comprehensive NMR spectroscopic and specific optical rotation (OR) data analyses. Compound 6 showed antibacterial activity against Pseudomonas fulva with an MIC value of 50 µg/mL. This is the first study to discover a pyridinium derivative and cyclic dipeptides from B. licheniformis. Full article

Two new fusarochromanone derivatives, deacetylfusarochromene (1) and deacetamidofusarochrom-2′,3-diene (2), along with the previously reported metabolites fusarochromanone TDP-2 (3), fusarochromene (4), 2,2-dimethyl-5-amino-6-(2′E-ene-4′-hydroxylbutyryl)-4-chromone (5), fusarochromanone (6), (−)-chrysogine (7), and equisetin (8), were isolated from the marine fungus Fusarium equiseti UBOCC-A-117302. The structures of the compounds were determined by extensive spectrometric (HRMS) and spectroscopic (1D and 2D NMR) analyses, as well as specific rotation. Among them, 2 and 5 showed inhibition of three protein kinases with IC₅₀ values ranging from 1.42 to 25.48 μM. Cytotoxicity and antimicrobial activity of all isolated compounds were also evaluated. Six fusarochromanone derivatives (1–6) exhibited diverse activities against three cell lines, RPE-1, HCT-116, and U2OS (IC₅₀ values ranging from 0.058 to 84.380 μM). Equisetin (8) showed bactericidal activities against Bacillus cereus and Listeria monocytogenes (MBC values of 7.8 and 31.25 µM, respectively), and bacteriostatic activity against Enterococcus faecalis (MIC value of 31.25 µM). Compounds 2 and 4 showed bacteriostatic activities against Listeria monocytogenes (MIC of 125 µM). Full article

A variety of metabolites produced by marine microorganisms are gaining high value for their significant biological properties. Therefore, the search for active secondary metabolites from marine bacteria against pathogenic microorganisms has become essential for alternative and effective strategies. In this study, Halomonas saccharevitans, a marine-derived bacterium, was cultured and fermented on a liquid medium. The ethyl acetate (EtOAc) crude extract was then fractioned yielded five fractions to study their biological effect. Two fractions had significantly higher activity, i.e., absolute n-hexane against Staphylococcus aureus and Pseudomonas aeruginosa and absolute methanol (MeOH) against Escherichia coli and Bacillus subtilis, with promising MIC values. The time–kill kinetics assay for the very susceptible bacteria against active fractions was also examined. The antifungal assay of the active fractions had the highest activity against Aspergillus niger and Candida albicans with the examined variable MFC values. The cytotoxic assay against HepG2 cells showed promising activities, resulting in a 78% inhibition of cell viability. Moreover, the antioxidant activities showed reasonable inhibition values at 21.87 ± 0.85% and 98.25 ± 1.45%, compared to the control. Molecular docking revealed a high affinity between major detected compounds with free binding energies. The active fractions were characterized by the presence of diverse chemically esters, phenolics, essential oils, and other organic compounds detected by GC–MS. In conclusion, H. saccharevitans, derived from the Red Sea, might be useful as an alternative source for the possible production of bioactive substances with a variety of biomedical application. Full article

Two new compounds, macrolactin XY (1) and (5R, 9S, 10S)-5-(hydroxymethyl)-1,3,7-decatriene-9,10-diol (2), together with nine known compounds (3–11) were isolated from the marine Bacillus subtilis sp. 18 by the OSMAC strategy. These compounds were evaluated for antibacterial activity against six tested microorganisms. Compounds 1–5 and 7–10 showed varied antibacterial activity, with the minimum inhibitory concentration (MIC) ranging from 3 to 12 μg/mL. Macrolactin XY (1) was found to possess superior antibacterial activity, especially exhibiting significant effectiveness against Enterococcus faecalis. The antibacterial activity mechanism against E. faecalis was investigated. The mechanism may disrupt bacterial cell membrane integrity and permeability, and also inhibit the expression of genes associated with bacterial energy metabolism, as established by the experiments concerning cell membrane potential, SDS-PAGE electrophoresis, cell membrane integrity, and key gene expressions. This study offers valuable insights and serves as a theoretical foundation for the future development of macrolactins as antibacterial precursors. Full article

Algae are used as safe materials to fabricate novel nanoparticles to treat some diseases. Marine brown alga Sargassum vulgare are used to fabricate silver nanoparticles (Sv/Ag-NPs). The characterization of Sv/Ag-NPs was determined by TEM, EDX, Zeta potential, XRD, and UV spectroscopy. The Sv/Ag-NPs were investigated as antioxidant, anticancer, and antibacterial activities against Gram-positive bacteria Bacillus mojavensis PP400982, Staphylococcus caprae PP401704, Staphylococcus capitis PP402689, and Staphylococcus epidermidis PP403851. The activity of the Sv/Ag-NPs was evaluated as hepatoprotective in vitro in comparison with silymarin. The UV–visible spectrum of Sv/Ag-NPs appeared at 442 nm; the size of Sv/Ag-NPs is in range between 6.90 to 16.97 nm, and spherical in shape. Different concentrations of Sv/Ag-NPs possessed antioxidant, anticancer activities against (HepG-2), colon carcinoma (HCT-116), cervical carcinoma (HeLa), and prostate carcinoma (PC-3) with IC50 50.46, 45.84, 78.42, and 100.39 µg/mL, respectively. The Sv/Ag-NPs induced the cell viability of Hep G2 cells and hepatocytes treated with carbon tetrachloride. The Sv/Ag-NPs exhibited antibacterial activities against Staphylococcus caprae PP401704, Staphylococcus capitis PP402689, and Staphylococcus epidermidis PP403851. This study strongly suggests the silver nanoparticles derived from Sargassum vulgare showed potential hepato-protective effect against carbon tetrachloride-induced liver cells, and could be used as anticancer and antibacterial activities. Full article

The Streptomyces strain G222, isolated from a Vietnamese marine sediment, was confidently identified by 16S rRNA gene sequencing. Its AcOEt crude extract was successfully analyzed using non-targeted LC-MS/MS analysis, and molecular networking, leading to a putative annotation of its chemical diversity thanks to spectral libraries from GNPS and in silico metabolite structure prediction obtained from SIRIUS combined with the bioinformatics tool conCISE (Consensus Annotation Propagation of in silico Elucidations). This dereplication strategy allowed the identification of an interesting cluster of a series of putative cyclic and linear lipopeptides of the lichenysin and surfactin families. Lichenysins (3–7) were isolated from the sub-fraction, which showed significant anti-biofilm activity against Pseudomonas aeruginosa MUC-N1. Their structures were confirmed by detailed 1D and 2D NMR spectroscopy (COSY, HSQC, HMBC, TOCSY, ROESY) recorded in CD₃OH, and their absolute configurations were determined using the modified Marfey’s method. The isolated lichenysins showed anti-biofilm activity at a minimum concentration of 100 µM. When evaluated for antibacterial activity against a panel of Gram-positive and Gram-negative strains, two isolated lichenysins exhibited selective activity against the MRSA strain without affecting its growth curve and without membranotropic activity. This study highlights the power of the MS/MS spectral similarity strategy using computational methods to obtain a cross-validation of the annotated molecules from the complex metabolic profile of a marine sediment-derived Streptomyces extract. This work provides the first report from a Streptomyces strain of combined cyclic and linear lichenysins and surfactins, known to be characteristic compounds of the genus Bacillus. Full article

This study represents a primary investigation centered on screening six marine fungi, Emericellopsis maritima, Engyodontium album, Hypomontagnella monticulosa, Hortaea werneckii, Trichoderma harzianum, and Aspergillus sp.7, associated with the red algae Pterocladiella capillacea, which was collected from Chao-Jin Park in Keelung, Taiwan, as potential immunostimulants for shrimp aquaculture. Recognizing the imperative for novel strategies to combat pathogen resistance arising from the use of antibiotics and vaccines in aquaculture, this study aimed to evaluate the metabolomic profile, antioxidant capabilities, and antibacterial properties of marine fungi. The antibacterial activity of the fungal extract was evaluated against five major aquaculture pathogens: Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Enterobacter aeruginosa, and Vibrio parahaemolyticus. The viability and cytotoxicity of marine fungal extracts were preliminarily evaluated using brine shrimps before assessing cytotoxicity, growth performance, immune efficacy, and disease resistance in white shrimp. The present study demonstrated that total phytochemical analysis correlated with antioxidant activity. Emericellopsis maritima and Trichoderma harzianum exhibited the strongest DPPH antioxidant scavenging activities of half-maximal inhibitory concentration (IC50) 16.5 ± 1.2 and 12.2 ± 2.6, which are comparable to ascorbic acid. LC-HDMSE analysis of the marine fungal extracts identified more than 8000 metabolites mainly classified under the superclass level of organic oxygen compounds, Organoheterocyclic compounds, Phenylpropanoids and polyketides, alkaloid and derivatives, benzenoids, lignans and neolignans, lipid and lipid-like molecules, nucleotides and nucleosides, organic nitrogen compounds, and organic acids and derivatives. Overall, our study significantly contributes to the advancement of sustainable practices by exploring alternative antimicrobial solutions and harnessing the bioactive potential inherent in marine endophytic fungi. In conclusion, our study advances our comprehension of fungal communities and their applications and holds promise for the development of effective and environmentally friendly approaches for enhancing shrimp health and productivity. Full article

Although melanin protects against ultraviolet radiation, its overproduction causes freckles and senile lentigines. Recently, various biological effects of metabolites derived from marine microorganisms have been highlighted due to their potential for biological and pharmacological applications. In this study, we discovered the anti-melanogenic effect of Bacillus sp. APmarine135 and verified the skin-whitening effect. Fractions of APmarine135 showed the melanin synthesis inhibition effect in B16 melanoma cells, and 2,4,6-triphenyl-1-hexene was identified as an active compound. The melanogenic capacity of 2,4,6-triphenyl-1-hexene (1) was investigated by assessing the intracellular melanin content in B16 cells. Treatment with 5 ppm of 2,4,6-triphenyl-1-hexene (1) for 72 h suppressed the α-melanocyte-stimulating hormone (α-MSH)-induced intracellular melanin increase to the same level as in the untreated control group. Additionally, 2,4,6-triphenyl-1-hexene (1) treatment suppressed the activity of tyrosinase, the rate-limiting enzyme for melanogenesis. Moreover, 2,4,6-triphenyl-1-hexene (1) treatment downregulated tyrosinase, Tyrp-1, and Tyrp-2 expression by inhibiting the microphthalmia-associated transcription factor (MITF). Furthermore, 2,4,6-triphenyl-1-hexene (1) treatment decreased the melanin content in the three-dimensional (3D) human-pigmented epidermis model MelanoDerm and exerted skin-whitening effects. Mechanistically, 2,4,6-triphenyl-1-hexene (1) exerted anti-melanogenic effects by suppressing tyrosinase, Tyrp-1, and Tyrp-2 expression and activities via inhibition of the MITF. Collectively, these findings suggest that 2,4,6-triphenyl-1-hexene (1) is a promising anti-melanogenic agent in the cosmetic industry. Full article

Zwitterionic polymer coatings facilitate the formation of hydration layers via electrostatic interactions on their surfaces and have demonstrated efficacy in preventing biofouling. They have emerged as a promising class of marine antifouling materials. However, designing multifunctional, environmentally friendly, and natural products-derived zwitterionic polymer coatings that simultaneously resist biofouling, inhibit protein adhesion, exhibit strong antibacterial properties, and reduce algal adhesion is a significant challenge. This study employed two diisocyanates as crosslinkers and natural urushiol and ethanolamine as raw materials. The coupling reaction of diisocyanates with hydroxyl groups was employed to synthesize urushiol-based precursors. Subsequently, sulfobetaine moieties were introduced into the urushiol-based precursors, developing two environmentally friendly and high-performance zwitterionic-functionalized polyurushiol antifouling coatings, denoted as HUDM-SB and IPUDM-SB. The sulfobetaine-functionalized polyurushiol coating exhibited significantly enhanced hydrophilicity, with the static water contact angle reduced to less than 60°, and demonstrated excellent resistance to protein adhesion. IPUDM-SB exhibited antibacterial efficacy up to 99.9% against common Gram-negative bacteria (E. coli and V. alginolyticus) and Gram-positive bacteria (S. aureus and Bacillus. sp.). HUDM-SB achieved antibacterial efficacy exceeding 95.0% against four bacterial species. Furthermore, the sulfobetaine moieties on the surfaces of the IPUDM-SB and HUDM-SB coatings effectively inhibited the growth and reproduction of algal cells by preventing microalgae adhesion. This zwitterionic-functionalized polyurushiol coating does not contain antifouling agents, making it a green, environmentally friendly, and high-performance biomaterial-based solution for marine antifouling. Full article

Siderophores are low-molecular-weight and high-affinity molecules produced by bacteria under iron-limited conditions. Due to the low iron (III) (Fe⁺³) levels in surface waters in the marine environment, microbes produce a variety of siderophores. In the current study, halophilic bacteria Bacillus taeanensis SMI_1, Enterobacter sp., AABM_9, and Pseudomonas mendocina AMPPS_5 were isolated from marine surface water of Kalinga beach, Bay of Bengal (Visakhapatnam, Andhra Pradesh, India) and were investigated for siderophore production using the Chrome Azurol S (CAS) assay. The effect of various production parameters was also studied. The optimum production of siderophores for SMI_1 was 93.57% siderophore units (SU) (after 48 h of incubation at 30 °C, pH 8, sucrose as carbon source, sodium nitrate as nitrogen source, 0.4% succinic acid), and for AABM_9, it was 87.18 %SU (after 36 h of incubation period at 30 °C, pH 8, in the presence of sucrose, ammonium sulfate, 0.4% succinic acid). The maximum production of siderophores for AMPPS_5 was 91.17 %SU (after 36 h of incubation at 35 °C, pH 8.5, glucose, ammonium sulfate, 0.4% citric acid). The bacterial isolates SMI_1, AABM_9, and AMPPS_5 showed siderophore production at low Fe⁺³ concentrations of 0.10 µM, 0.01 µM, and 0.01 µM, respectively. The SMI_1 (73.09 %SU) and AMPPS_5 (68.26 %SU) isolates showed siderophore production in the presence of Zn⁺² (10 µM), whereas AABM_9 (50.4 %SU) exhibited siderophore production in the presence of Cu⁺² (10 µM). Additionally, these bacterial isolates showed better heavy-metal chelation ability and rapid development in seed germination experiments. Based on these results, the isolates of marine-derived bacteria effectively produced the maximum amount of siderophores, which could be employed in a variety of industrial and environmental applications. Full article

Marine yeasts have versatile applications in the industrial, medical, and environmental fields. However, they have received little attention compared to terrestrial yeasts and filamentous fungi. In this study, a phylogenetic analysis of 11 marine-derived yeasts was conducted using internal transcribed spacers and nuclear large subunit rDNA, and their bioactivities, such as antioxidant, antibacterial, and tyrosinase inhibition activities, were investigated. The 11 marine-derived yeasts were identified to belong to seven species including Geotrichum candidum, Metschnikowia bicuspidata, Papiliotrema fonsecae, Rhodotorula mucilaginosa, Vishniacozyma carnescens, Yamadazyma olivae, and Yarrowia lipolytica, and three strains of these were candidates for new species of the genera Aureobasidium, Rhodotorula, and Vishniacozyma. Most extracts showed antioxidant activity, whereas seven strains exhibited antibacterial activities against Bacillus subtilis. Only Aureobasidium sp. US-Sd3 among the 11 isolates showed tyrosinase inhibition. Metschnikowia bicuspidata BP-Up1 and Yamadazyma olivae K2-6 showed notable radical-scavenging activity, which has not been previously reported. Moreover, Aureobasidium sp. US-Sd3 exhibited the highest antibacterial and tyrosinase inhibitory activities. These results demonstrate the potential of marine-derived yeasts as a source of bioactive compounds for improving industrial applications. Full article

Chitooligosaccharides (COS), a high-value chitosan derivative, have many applications in food, pharmaceuticals, cosmetics and agriculture owing to their unique biological activities. Chitosanase, which catalyzes the hydrolysis of chitosan, can cleave β-1,4 linkages to produce COS. In this study, a chitosanase-producing Bacillus paramycoides BP-N07 was isolated from marine mud samples. The chitosanase enzyme (BpCSN) activity was 2648.66 ± 20.45 U/mL at 52 h and was able to effectively degrade chitosan. The molecular weight of purified BpCSN was approximately 37 kDa. The yield and enzyme activity of BpCSN were 0.41 mg/mL and 8133.17 ± 47.83 U/mg, respectively. The optimum temperature and pH of BpCSN were 50 °C and 6.0, respectively. The results of the high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) of chitosan treated with BpCSN for 3 h showed that it is an endo-chitosanase, and the main degradation products were chitobiose, chitotriose and chitotetraose. BpCSN was used for the preparation of oligosaccharides: 1.0 mg enzyme converted 10.0 g chitosan with 2% acetic acid into oligosaccharides in 3 h at 50 °C. In summary, this paper reports that BpCSN has wide adaptability to temperature and pH and high activity for hydrolyzing chitosan substrates. Thus, BpCSN is a chitosan decomposer that can be used for producing chitooligosaccharides industrially. Full article

Benzoxazine resins are new thermosetting resins with excellent thermal stability, mechanical properties, and a flexible molecular design, demonstrating promise for applications in marine antifouling coatings. However, designing a multifunctional green benzoxazine resin-derived antifouling coating that combines resistance to biological protein adhesion, a high antibacterial rate, and low algal adhesion is still challenging. In this study, a high-performance coating with a low environmental impact was synthesized using urushiol-based benzoxazine containing tertiary amines as the precursor, and a sulfobetaine moiety into the benzoxazine group was introduced. This sulfobetaine-functionalized urushiol-based polybenzoxazine coating (poly(U−ea/sb)) was capable of clearly killing marine biofouling bacteria adhered to the coating surface and significantly resisting protein attachment. poly(U−ea/sb) exhibited an antibacterial rate of 99.99% against common Gram negative bacteria (e.g., Escherichia coli and Vibrio alginolyticus) and Gram positive bacteria (e.g., Staphylococcus aureus and Bacillus sp.), with >99% its algal inhibition activity, and it effectively prevented microbial adherence. Here, a dual-function crosslinkable zwitterionic polymer, which used an “offensive-defensive” tactic to improve the antifouling characteristics of the coating was presented. This simple, economic, and feasible strategy provides new ideas for the development of green marine antifouling coating materials with excellent performance. Full article