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

Abstract

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.

In Vitro Cytotoxic Effect of Aqueous Extracts from Leaves and Rhizomes of the Seagrass Posidonia oceanica (L.) Delile on HepG2 Liver Cancer Cells: Focus on Autophagy and Apoptosis

“…At present, we have no data confirming whether these proteins present in the aqueous samples can be effectively internalized by the cells and can exert their putative functions, apart from peptidyl-prolyl cis-trans isomerase that has been successfully administered as an antioxidant to HepG2 cells and superoxide dismutase that, along with its conjugates and mimetics, possesses an acknowledged significant therapeutic action/potential against several diseases in humans and animals [ 88 , 91 , 93 ]. On the other hand, it is worth-mentioning that we [ 94 ] have recently demonstrated that an isolated peptide obtained from RE shows an apoptotic-promoting ability on HepG2 cells, thus providing a first direct indication of the contribution of the protein component of the extract to the cytotoxic effect.…”

Natural Anticancer Peptides from Marine Animal Species: Evidence from In Vitro Cell Model Systems

“…These natural metabolites, whose chemical communication ability encompasses different taxonomic lineages and even kingdoms, have found broad use in various applications, such as healthcare management, biomaterial manufacturing and environmental remediation, and, due to their peculiar chemical structures and properties, also in the development of new classes of molecules through the design of analogs with greater bioavailability and efficacy and less toxicity. To cite a few examples, this is the case for extracts, or isolated primary and secondary metabolites, obtained from marine vertebrates and invertebrates and seaweeds, which have shown anticancer, anti-angiogenic, anti-inflammatory and wound healing/skin regeneration abilities [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Moreover, the processing of by-products from marine animals and plants has also granted a number of beneficial properties due to their abundance in polyunsaturated fatty acids, amino acids, chitosan, carotenoids and polyphenols, among others [ 20 , 21 ].…”

Exploring the Potential of Crassostrea nippona Hydrolysates as Dietary Supplements for Mitigating Dexamethasone-Induced Muscle Atrophy in C2C12 Cells

“…These compounds have antioxidant, anti-microbial, anti-diabetic, anti-hypertension, anti-obesity, anti-cancer, and anti-aging properties [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Further, due to their high potential, they contribute to drug discovery, cancer therapies, anti-microbial functions, and many other applications in the current world effectively [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Shellfish play a crucial role in supporting muscle hypertrophy due to their rich nutritional profile.…”