LFB: A Novel Antimicrobial Brevinin-Like Peptide from the Skin Secretion of the Fujian Large Headed Frog, Limnonectes fujianensi

Abstract

Amphibians are a natural source of abundant antimicrobial peptides and thus have been widely investigated for isolation of such biomolecules. Many new antimicrobial peptide families have been discovered from amphibians. In this study, a novel antimicrobial peptide named Limnonectes fujianensis Brevinvin (LFB) has been identified in the skin secretion from the Fujian large headed frog, Limnonectes fujianensis. The cDNA sequence was cloned from a skin secretion library and the predicted mature peptide was identified through MS/MS fragmentation sequencing of reverse phase HPLC fractions on the same sample. LFB was predicted to be an amphipathic, hydrophobic, alpha helical, and beta turn peptide that inserts into a lipid bilayer in order to kill the cells. In antimicrobial assays, a synthetic replicate of this novel antimicrobial peptide demonstrated significant activity against the Gram-positive bacterium Staphylococcus aureus, the Gram-negative bacterium Escherichia coli and the yeast, Candida albicans. This novel peptide was highly potent (MIC 4.88 uM) against Gram-negative bacterium, and also has the ability to inhibit the growth of human cancer cell lines with IC50 values ranging from 18.9 μM down to 2.0 μM. These findings help to enrich our understanding of Brevinin-like peptides. Moreover, the data presented here validate frog secretion as a source of potential novel antimicrobial peptides, that also exhibit anti-tumor properties, that could be useful for the treatment of cancer.

Antimicrobial peptides: mechanism of action, activity and clinical potential

“…This is because that: (1) as a component of the innate immune system, production of AMPs by the host cells requires less time and energy than antibody synthesis by the acquired immunity; (2) these small molecule peptides can reach the target faster than immunoglobulins; and (3) some eukaryotes lack of lymphocyte-based immune system, such as insects mainly rely on the synthesis of a series of antibacterial compounds to remove invading microorganisms [ 16 ]. Since the first AMP was discovered in the American silkworm chrysalis, a large number of AMPs have been widely found in various organisms, including microorganisms [ 17 ], plants [ 18 ], invertebrates [ 19 ], fish [ 20 ], amphibians [ 21 ], reptiles [ 22 ], birds [ 23 ] and mammals [ 24 ].…”

Antimicrobial Peptides as Anticancer Agents: Functional Properties and Biological Activities

“…In fact, LFB reduced the proliferation rate of HCT116 cells in a dose-dependent manner and at high concentrations caused cell death through membrane disruption, without inducing apoptosis. Lastly, LFB exhibited significant hemolytic activity [ 103 ].…”

Endophytic fungus, Chaetomium globosum, associated with marine green alga, a new source of Chrysin

“…The purified fungal chrysin (FChr) and SChr were subjected to MTT assay as described earlier, to check for their in vitro cytotoxic activity on MCF-7 and HEK 293 T cells for 72 h at different concentrations (20 to 250 µM) while 0.1% DMSO treated cells were used as negative control 18 , 55 .…”