New Bioactive Peptides from the Mediterranean Seagrass Posidonia oceanica (L.) Delile and Their Impact on Antimicrobial Activity and Apoptosis of Human Cancer Cells

The demand for new molecules to counter bacterial resistance to antibiotics and tumor cell resistance is increasingly pressing. The Mediterranean seagrass Posidonia oceanica is considered a promising source of new bioactive molecules. Polypeptide-enriched fractions of rhizomes and green leaves of the seagrass were tested against Gram-positive (e.g., Staphylococcus aureus, Enterococcus faecalis) and Gram-negative bacteria (e.g., Pseudomonas aeruginosa, Escherichia coli), as well as towards the yeast Candida albicans. The aforementioned extracts showed indicative MIC values, ranging from 1.61 μg/mL to 7.5 μg/mL, against the selected pathogens. Peptide fractions were further analyzed through a high-resolution mass spectrometry and database search, which identified nine novel peptides. Some discovered peptides and their derivatives were chemically synthesized and tested in vitro. The assays identified two synthetic peptides, derived from green leaves and rhizomes of P. oceanica, which revealed interesting antibiofilm activity towards S. aureus, E. coli, and P. aeruginosa (BIC50 equal to 17.7 μg/mL and 70.7 μg/mL). In addition, the natural and derivative peptides were also tested for potential cytotoxic and apoptosis-promoting effects on HepG2 cells, derived from human hepatocellular carcinomas. One natural and two synthetic peptides were proven to be effective against the “ in vitro” liver cancer cell model. These novel peptides could be considered a good chemical platform for developing potential therapeutics

A Novel Peptide with Antifungal Activity from Red Swamp Crayfish Procambarus clarkii

The defense system of freshwater crayfish Procambarus clarkii as a diversified source of bioactive molecules with antimicrobial properties was studied. Antimicrobial activity of two polypeptideenriched extracts obtained from hemocytes and hemolymph of P. clarkii were assessed against Gram positive (Staphylococcus aureus, Enterococcus faecalis) and Gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria and toward the yeast Candida albicans. The two peptide fractions showed interesting MIC values (ranging from 11 to 700 g/mL) against all tested pathogens. Polypeptideenriched extracts were further investigated using a high-resolution mass spectrometry and database search and 14 novel peptides were identified. Some peptides and their derivatives were chemically synthesized and tested in vitro against the bacterial and yeast pathogens. The analysis identified a synthetic derivative peptide, which showed an interesting antifungal (MIC and MFC equal to 31.2 g/mL and 62.5 g/mL, respectively) and antibiofilm (BIC50 equal to 23.2 g/mL) activities against Candida albicans and a low toxicity in human cells

Antitumoral compounds from vertebrate sister group: A review of Mediterranean ascidians

Among the diseases that afflict the human population, cancer is one for which many drug treatments are not yet known or effective. Moreover, the pharmacological treatments used often create serious side effects in sick patients and for this reason, it is essential to find effective and less harmful treatments. To date, marine biodiversity is a real source of metabolites with antitumoral activity and among invertebrates’ ascidians have been the main source to obtain them. Mediterranean area is the richest in biodiversity and contains several ascidian species used in drugs development during the years. However, many more Mediterranean ascidian species have not been studied and could be a source of useful bioactive compounds. This review aims to summarize the scientific studies that analyzed the antitumor compounds obtained from different Mediterranean ascidians species, encouraging them to search further compounds in other new species to improve pharmacological treatments and human population life

ANTIMICROBIAL ACTIVITY FROM POLYPEPTIDE-RICH EXTRACTS OF THE SEAGRASS POSIDONIA OCEANICA

The present study was carried out to assess the antibacterial, antifungal and antibiofilm properties of polypeptide-rich extracts isolated from green leaves and rhizomes of Mediterranean seagrass Posidonia oceanica (L. Delile) (Posidoniaceae). The seagrass was collected, washed with freshwater, grinded with liquid nitrogen in order to obtain fine powders that were exposed to extraction by acetic acid and antiproteases. The crude extracts isolated from leaves and rhizomes of P. oceanica were subjected to microbiological assays to evaluate the antibacterial, antifungal and antibiofilm activity of polypeptide fraction against two reference bacterial strains Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 15442, and the fungus Candida albicans ATCC 10231. The antimicrobial and antifungal activity of the extracts were evaluated starting from 50% v/v concentration of each sample and the results are expressed in terms of Minimum inhibitory concentration (MIC), with the values detailed in percentage v/v and in concentration g/ml of protein content. The most interesting result has been deduced from rhizomes that showed a MIC of 12.5% v/v, corresponding to 3.37 g/ml of protein content, against three selected pathogens compared to the sample from the leaves that revealed a MIC of 25% v/v, corresponding to a protein concentration of 4.25 g/ml. The crude extracts isolated from P. oceanica were also active to combat the biofilm formation at sub-MIC concentration. The inhibition was evident with crude extracts from rhizomes in S. aureus ATCC 25923 at IC50 of 0.54 g/ml, compared to a value of IC50 of 0.74g/ml with the extracts from leaves. Moreover, the polypeptide fraction of leaves of P. oceanica was also able to inhibit the biofilm formation in C. albicans ATCC 10231 at IC50 = 0.58 g/ml. Peptide fractions displaying antimicrobial activity were further investigated by by High-Pressure Liquid Chromatography/nano-Electrospray Ionization tandem Mass Spectrometry (RP-HPLC/nESI-MS/MS) and database search. Database search allowed the characterization of fourteen peptides, one of them is related to a Viridiplantae-derived protein, whereas the others are attributable to bacterial proteins present in the investigated database. Moreover, most of identified peptides showed similarities with already described antimicrobial peptides (AMPs) from bacteria, animals and plants

Environmental Aspect Concerning Phthalates Contamination: Analytical Approaches and Assessment of Biomonitoring in the Aquatic Environment

This review is a survey of recent progress in studies concerning the impact of phthalic acid esters in aquatic organisms. After introducing the classification, properties, sources, fate, and toxic effects related to phthalates, an overview of the techniques of extraction and analysis of these substances is provided. As a result, the general concepts of environmental bioindicators, biomonitoring systems, and other concepts related to phthalate contamination in the aquatic environment are presented. Recent bioaccumulation data of different phthalates are summarised in a table and organised according to the type of organism, tissue, and geographical area of sampling. Bioindicator organisms that are more representative of the different phthalates are highlighted and discussed as along with other variables that may be relevant in the assessment of the environmental pollution of these substances. The final part looks at the environmental perspectives and suggests new directions and research objectives to be achieved in the future