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Chemical investigation of Phaeophytan marine macroalga Turbinaria ornata (family Sargassaceae) resulted in the characterization of three 2-furanone analogues, which were characterized as 6, 7-dihydroxy-8-methyl-3-(5′-methyloct-4′-en-1′-yl)-hexahydrocyclooct-1-en-[1, 2-c]furan-11-one (turbinafuranone A), 4-hydroxy-3-isopropyl-7, 8-dimethyl-6-(pentan-2′-acetate)-hexahydrocycloocta-1-en-[1, 2-c]furan-11-one (turbinafuranone B), and 6-acetoxy-8-ethyl-5-methoxy-3-(2′-methylhex-4′-en-1′-yl)-pentahydrocycloocta-1, 7-dien-[1, 2-c]furan-11-one (turbinafuranone C). Inhibitory property of turbinafuranone B against tyrosine phosphatase-1B was significantly greater (IC50 2.42 mM) than standard agent sodium metavanadate (IC50 2.52 mM). Greater electronic properties along with molecular docking experiments corroborated the attenuation property of turbinafuranone B against protein tyrosine phosphatase-1B, by exhibiting minimum binding energy of −11.80 kcal/mol compared to other studied analogues. The results demonstrated that the undescribed turbinafuranone B might be used as prospective natural anti-hyperglycemic lead to alleviate the likelihood of higher postprandial blood glucose levels. [ABSTRACT FROM AUTHOR]

A heterotrophoic Bacillus amyloliquefaciens MTCC12713 isolated from an intertidal macroalga Kappaphycus alverezii displayed promising antibacterial activities against multidrug-resistant bacteria. Genome mining of the bacterium predicted biosynthetic gene clusters coding for antibacterial secondary metabolites. Twenty-one membered macrocyclic lactones, identified as difficidin analogues bearing 6-hydroxy-8-propyl carboxylate, 9-methyl-19-propyl dicarboxylate, 6-methyl-9-propyl dicarboxylate-19-propanone, and (20-acetyl)-6-methyl-9-isopentyl dicarboxylate (compounds 1 through 4) functionalities were purified through bioassay-guided fractionation. The difficidin analogues exhibited bactericidal activities against vancomycin-resistant Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, and other drug-resistant strains, such of Klebsiella pneumonia and Pseudomonas aeruginosa with the minimum inhibitory concentration of about 2–9 × 10−3 μM. A plausible enzyme-catalyzed biosynthetic pathway that is generated through addition of acrylyl initiator unit by repetitive decarboxylative Claisen condensation modules with malonate units was recognized, and their structures were corroborated with gene organization of the dif operon, which could comprehend dif A-O (~ 70 kb). Drug-likeness score for 5-ethoxy-28-methyl-(9-methyl-19-propyl dicarboxylate) difficidin (compound 2, 0.35) was greater than those of other difficidin analogues, which corroborated the potential in vitro antibacterial properties of the former. The present study demonstrated the potential of difficidin analogues for pharmaceutical and biotechnological uses against the bottleneck of emergent drug-resistant pathogens. Key Points: • Difficidins were isolated from marine alga associated Bacillus amyloliquefaciens. • Whole-genome mining of bacterial genome predicted biosynthetic gene clusters. • Greater drug-likeness for difficidin 2 confirmed its potent antibacterial activity. [ABSTRACT FROM AUTHOR]

Sulfated polysaccharides derived from green marine macroalgae are known for their wide range of therapeutic properties, including the mitigation of inflammatory disorders. A sulfated polysaccharide, URP-2, composed of (1 → 4) linked α-rhamnopyranose, β-xylopyranose, and β-glucuropyranose, was isolated from Ulva reticulata (Ulvaceae). URP-2 exhibited significant anti-inflammatory effects by increasing interferon (IFN)-α expression (four to ten-fold) in lipopolysaccharide (LPS)-induced CALU-1 cells in a dose-dependent manner (31.25 to 125 μg mL−1), compared to LPS-induced cells. Additionally, the elevated IFN-γ levels observed in LPS-induced cells were substantially reduced (by five-fold) following treatment with URP-2 at 125 μg mL−1. URP-2, at a concentration of 125 μg mL−1, effectively reduced the elevated levels of interleukin (IL)-1β in LPS-induced cells, decreasing it from approximately 95% to 1.3%. Tumor necrosis factor (TNF)-α level was also reduced from 30% to approximately 1% in LPS induced CALU-1 cells. Structure–activity relationship analyses of URP-2 suggest that its potent anti-inflammatory properties are likely attributed to the presence of sulfate groups and (1 → 4) linkages. Therefore, URP-2 demonstrated promising potential as a natural alternative for the treatment of inflammatory-related disorders.Graphical abstract: Sulfated polysaccharides derived from green marine macroalgae are known for their wide range of therapeutic properties, including the mitigation of inflammatory disorders. A sulfated polysaccharide, URP-2, composed of (1 → 4) linked α-rhamnopyranose, β-xylopyranose, and β-glucuropyranose, was isolated from Ulva reticulata (Ulvaceae). URP-2 exhibited significant anti-inflammatory effects by increasing interferon (IFN)-α expression (four to ten-fold) in lipopolysaccharide (LPS)-induced CALU-1 cells in a dose-dependent manner (31.25 to 125 μg mL−1), compared to LPS-induced cells. Additionally, the elevated IFN-γ levels observed in LPS-induced cells were substantially reduced (by five-fold) following treatment with URP-2 at 125 μg mL−1. URP-2, at a concentration of 125 μg mL−1, effectively reduced the elevated levels of interleukin (IL)-1β in LPS-induced cells, decreasing it from approximately 95% to 1.3%. Tumor necrosis factor (TNF)-α level was also reduced from 30% to approximately 1% in LPS induced CALU-1 cells. Structure–activity relationship analyses of URP-2 suggest that its potent anti-inflammatory properties are likely attributed to the presence of sulfate groups and (1 → 4) linkages. Therefore, URP-2 demonstrated promising potential as a natural alternative for the treatment of inflammatory-related disorders. [ABSTRACT FROM AUTHOR]