Identification and Biochemical Characterization of a New Antibacterial and Antifungal Peptide Derived from the Insect Sphodromantis viridis

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Hadi Zare-Zardini^1,2,3, Asghar Taheri-Kafrani³, Mahtab Ordooei^4*, Leila Ebrahimi⁵, Behnaz Tolueinia⁶, and Mojgan Soleimanizadeh⁷

¹Young Researchers and Elite Club, Yazd Branch, Islamic Azad University, Yazd, Iran

²Hematology and Oncology Research Center, Shahid Sadoughi University of Medical Sciences and Health Services, Yazd, Iran

³Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, Iran

⁴Pediatric Endocrinologist, Yazd Diabetes Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran; fax: +98-351-8229104; E-mail: dr.rdooei@yahoo.com; mahtab.ordooei@gmail.com

⁵Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran

⁶Department of Biology, Faculty of Sciences, Iranshahr Branch, Payam Noor University of Sistan and Baluchestan, Iranshahr, Iran

⁷Biotechnology Department, Agriculture Faculty, Ferdowsi University of Mashhad, Mashhad, Iran

^* To whom correspondence should be addressed.

Received September 19, 2014; Revision received November 26, 2014

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Antimicrobial peptides are members of the immune system that protect the host from infection. In this study, a potent and structurally novel antimicrobial peptide was isolated and characterized from praying mantis Sphodromantis viridis. This 14-amino acid peptide was purified by RP-HPLC. Tandem mass spectrometry was used for sequencing this peptide, and the results showed that the peptide belongs to the Mastoparan family. The peptide was named Mastoparan-S. Mastoparan-S demonstrated that it has antimicrobial activities against a broad spectrum of microorganisms (Gram-positive and Gram-negative bacteria and fungi), and it was found to be more potent than common antibiotics such as kanamycin. Mastoparan-S showed higher antimicrobial activity against Gram-negative bacteria compared to Gram-positive ones and fungi. The minimum inhibitory concentration (MIC) values of Mastoparan-S are 15.1-28.3 µg/ml for bacterial and 19.3-24.6 µg/ml for fungal pathogens. In addition, this newly described peptide showed low hemolytic activity against human red blood cells. The in vitro cytotoxicity of Mastoparan-S was also evaluated on monolayer of normal human cells (HeLa) by MTT assay, and the results illustrated that Mastoparan-S had significant cytotoxicity at concentrations higher than 40 µg/ml and had no any cytotoxicity at the MIC (≤30 µg/ml). The findings of the present study reveal that this newly described peptide can be introduced as an appropriate candidate for treatment of topical infection.

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KEY WORDS: antimicrobial peptides, cytotoxicity, Sphodromantis viridis, immune system, hemolytic activity

DOI: 10.1134/S0006297915040069

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