Bioactive antimicrobial peptides from Didemnum Albidum: An MALDI-TOF MS analysis

Abstract

Ascidians, also known as sea squirts, belong to the Phylum Chordata and the Class Ascidiacea. They are the largest and most diverse class within the Sub-Phylum Tunicata, which is also called Urochordata. Antimicrobial peptides (AMPs) are crucial components of the innate immune system. They are highly effective in defending against pathogens and have a wide-ranging impact against bacteria, fungi, and enveloped viruses. Ascidians are a rich source of bioactive peptides, including AMPs. This study focuses on isolating and identifying antimicrobial peptides from the ascidian species Didemnum albidum. Additionally, it seeks to assess the antioxidant and anticancer properties of these peptides. The findings indicated that the antimicrobial peptides (AMPs) had a low molecular weight of approximately 4 kDa, as determined by MALDI-TOF MS/MS analysis. These peptides exhibited their strongest antimicrobial activity against P. mirabilis, with a zone of inhibition measuring 23.10 +/- 0 .25mm. Additionally, they demonstrated significant antioxidant potential, with a total antioxidant activity of 60.08 % and 80.1 % DPPH radical scavenging activity. In vitro experiments using the HepG-2 hepatic cancer cell line revealed that the antimicrobial peptide from the ascidian Didemnum albidum inhibited cell growth by 52 % at a concentration of 1000 mu g/ml after 72 h of incubation. Based on these results, it can be inferred that the antimicrobial peptides derived from Didemnum albidum possess notable antimicrobial, antioxidant, and anticancer properties.