Seaweed Protein Hydrolysates and Bioactive Peptides: Extraction, Purification, and Applications.

Seaweeds are industrially exploited for obtaining pigments, polysaccharides, or phenolic compounds with application in diverse fields. Nevertheless, their rich composition in fiber, minerals, and proteins, has pointed them as a useful source of these components. Seaweed proteins are nutritionally valuable and include several specific enzymes, glycoproteins, cell wall-attached proteins, phycobiliproteins, lectins, or peptides. Extraction of seaweed proteins requires the application of disruptive methods due to the heterogeneous cell wall composition of each macroalgae group. Hence, non-protein molecules like phenolics or polysaccharides may also be co-extracted, affecting the extraction yield. Therefore, depending on the macroalgae and target protein characteristics, the sample pretreatment, extraction and purification techniques must be carefully chosen. Traditional methods like solid-liquid or enzyme-assisted extraction (SLE or EAE) have proven successful. However, alternative techniques as ultrasound- or microwave-assisted extraction (UAE or MAE) can be more efficient. To obtain protein hydrolysates, these proteins are subjected to hydrolyzation reactions, whether with proteases or physical or chemical treatments that disrupt the proteins native folding. These hydrolysates and derived peptides are accounted for bioactive properties, like antioxidant, anti-inflammatory, antimicrobial, or antihypertensive activities, which can be applied to different sectors. In this work, current methods and challenges for protein extraction and purification from seaweeds are addressed, focusing on their potential industrial applications in the food, cosmetic, and pharmaceutical industries.

Spectroscopic and theoretical investigation of the potential anti-tumor and anti-microbial agent, 3-(1-((2-hydroxyphenyl)amino)ethylidene)chroman-2,4-dione.

The coumarin-orthoaminophenol derivative was prepared under mild conditions. Based on crystallographic structure, IR and Raman, 1H and 13C NMR spectra the most applicable theoretical method was determined to be B3LYP-D3BJ. The stability and reactivity parameters were calculated, in the framework of NBO, QTAIM and Fukui functions, form the optimized structure. This reactivity was then probed in biological systems. The antimicrobial activity towards four bacteria and three fungi species was examined and activity was proven. In vitro cytotoxic effects, against human epithelial colorectal carcinoma HCT-116 and human healthy lung MRC-5 cell lines, of the investigated substance are also tested. Compound showed significant cytotoxic effects on HCT-116 cells, while on MRC-5 cells showed no cytotoxic effects. The effect of hydroxy group in ortho-position on the overall reactivity of molecule was examined through molecular docking with Glutathione-S-transferases.

Simultaneous production of pullulan and biosorption of metals by Aureobasidium pullulans strain CH-1 on peat hydrolysate.

It was demonstrated that during the growth of Aureobasidium pullulans strain CH-1 on the acid hydrolysate of peat from the Vlasina Lake, the content of metals (Cu, Fe, Zn, Mn, Pb, Cd, Ni and Cr) decreased due to biosorption. The reduction in the metal content was found to be in the range (%): 38.2-62.2, 67.7-97.3, 0.02-62.05, 0.05-23.97, 0.16-4.24, 3.45-51.72, 1.18-35.82, 0.86-44.44, for Cu, Fe, Zn, Mn, Pb, Cd, Ni and Cr, respectively. During this process, the metals were accumulated in the biomass, while pullulan, an extracellular polysaccharide produced by Aureobasidium pullulans strain CH-1, was found not to bind the above-mentioned metals.

Relationships between structure, retention and biological activity of some Schiff base ligands and their complexes.

The lipophilicity of a series of Schiff base ligands and their complexes with nickel(II) and copper(II) has been determined by reversed-phase thin-layer chromatography using binary dioxane-water mobile phase. Chelate ligands were prepared by condensation of diamine and the corresponding beta-diketone. Copper(II) and nickel(II) complexes with chelate ligands containing ethane-1,2-diamine or propane-1,2-diamine as the amine part and pentane-2,4-dione and/or 1-phenylbutane-1,3-dione, pentane-2,4-dione and/or 1,1,1-trifluoropentane-2,4-dione, or 1,1,1-trifluoropentane-2,4-dione and/or 1-phenylbutane-1,3-dione as the beta-diketone part were synthesized. Some of investigated compounds were screened for their in vitro antifungal activity against Sacharomyces cerevisiae and antibacterial activity against Escherichia coli. Chromatographically obtained lipophilicity parameters were correlated both with calculated n-octanol-water partition coefficient C log P and antimicrobial activities. Satisfactory correlations were obtained. Chromatographic data proved to be reliable parameters for describing the lipophilic properties of the investigated compounds. Additionally, the principal components analysis was performed on the data chromatographically obtained. This statistical method was useful for distinguishing compounds and objective comparison of their lipophilicity parameters.

Interesting coordination abilities of antiulcer drug famotidine and antimicrobial activity of drug and its cobalt(III) complex.

Crystal structure of a novel cobalt(III) complex with antiulcer drug famotidine and ethylenediamine was determined. This is the second structure of a transition metal complex with famotidine resolved by a single crystal X-ray analysis, in which famotidine shows different mode of coordination than that observed in the other cases. Drug molecule is coordinated to metal ion as a tetradentate ligand through guanidine N6, thiazole N4, thioether S2 and terminal N3 atom. Two NH(2) groups (N3H(2) and N6H(2)) are deprotonated and drug coordinates as dianion. In the asymmetric unit, one chloride anion and one water molecule were found to complete the complex stoichiometry. The structure of the complex is abundant in atoms, which can be involved in hydrogen bond formation either as hydrogen acceptors or hydrogen donors. Because of that, a great number of hydrogen bonds dominates the crystal packing. Beside the hydrogen bonds, there are two interesting noncovalent interactions: CH(...)pi and NH(...)pi within the famotidine anion, which stabilize the complex structure. The pi(...)pi stacking interactions between neighboring complex cations are also observed. Antibacterial and antifungal activity of famotidine and its newly synthesized complex against representative bacteria: Escherichia coli, Staphilococcus aureus and Micrococcus lysodeikticus and fungi: Aspergillus niger and Candida albicans were examined. The results indicate a higher selectivity of the famotidine-Co(III) complex, as well as better growth inhibitory activity (lower MIC values (MIC, minimal inhibitory concentration)) in comparison with the drug alone.