Biological Activity of Cyclic Peptide Extracted from Sphaeranthus amaranthoides Using De Novo Sequencing Strategy by Mass Spectrometry for Cancer

SIMPLE SUMMARY: Cancer therapy today has benefited from multifaceted approaches in early detection and diagnosis, but weak prognosis still hinders progress, as it is a barricade for guaranteed successful treatment. The present study checks the anticancer properties of AMPs, or antimicrobial peptides, isolated from Sphaeranthus amaranthoides, a traditional medicinal plant in a fibroblast cell line. A technique named ‘de novo’ sequencing was used for identifying the biological potential of the isolated molecule. That molecule was administered in zebrafish embryos. The zebrafish was used as a model organism, as it has close proximity with humans. One specific peptide biomolecule out of 86 peptides showed promising anticancer properties. Therefore, from the results, that specific biomolecule, upon detailed analyses of other parameters, can be taken for upscaling purposes in the pharmaceutical sector for early cancer therapy. ABSTRACT: Though there are several advancements and developments in cancer therapy, the treatment remains challenging. In recent years, the antimicrobial peptides (AMPs) from traditional herbs are focused for identifying and developing potential anticancer molecules. In this study, AMPs are identified from Sphaeranthus amaranthoides, a natural medicinal herb widely used as a crucial immune stimulant in Indian medicine. A total of 86 peptide traces were identified using liquid-chromatography–electrospray-ionisation mass spectrometry (LC-ESI-MS). Among them, three peptides were sequenced using the manual de novo sequencing technique. The in-silico prediction revealed that SA923 is a cyclic peptide with C-N terminal interaction of the carbon atom of ASP7 with the nitrogen atom of GLU1 (1ELVFYRD7). Thus, SA923 is presented under the orbitides class of peptides, which lack the disulfide bonds for cyclization. In addition, SA923, steered with the physicochemical properties and support vector machine (SVM) algorithm mentioned for the segment, has the highest in silico anticancer potential. Further, the in vitro cytotoxicity assay revealed the peptide has anti-proliferative activity, and toxicity studies were demonstrated in Danio rerio (zebrafish) embryos.