Designofnovelpeptideanalogswithpotentfungicidalactivity,basedon PMAP-23 antimicrobial peptide isolated from porcine myeloid Dong Gun Lee, a Pyung Il Kim, a Yoonkyung Park, a Eun-Rhan Woo, a Ji Suk Choi, a Cheol-Hee Choi, a,b and Kyung-Soo Hahm a, * a Research Center for Proteineous Materials (RCPM), Chosun University, 375 Seosuk-Dong, Dong-Ku, Kwangju 501-759, Republic of Korea b Department of Pharmacology, Chosun University Medical School, 375 Seosuk-Dong, Dong-Ku, Kwangju 501-759, Republic of Korea Received 19 March 20027 Abstract PMAP-23 is a 23-mer peptide derived from porcine myeloid. To develop novel antifungal peptides useful as therapeutic drugs, it would require a strong fungicidal activity against pathogenic fungal cells. To this goal, several analogs, with amino acid substi- tutions, were designed to increase the net hydrophobicity by Trp (W)-substitution at positions 10, 13, or 14 at the hydrophilic face of PMAP-23 without changing the hydrophobic helical face. The Trp (W)-substitution (P6) showed an enhanced fungicidal and an- titumor activities, with the fungicidal activity inhibited by salts and the respiratory inhibitor, NaN 3 . The results suggested that the increase of hydrophobicity of the peptides correlated with fungicidal activity. The fungicidal effects of analog peptides were further investigated using 1,6-diphenyl-1,3,5-hexatriene (DPH) as a membrane probe. In Candida albicans, the analog peptide (P6) exerted its fungicidal effect on the blastoconidia in 20% fetal bovine serum by disrupting the mycelial forms. Furthermore, P6 caused significant morphological changes, and these facts suggested that the fungicidal function of the novel analog peptide (P6) was by damaging the fungal cell membranes. Thus, this peptide may provide a useful template for designing novel antifungal peptides useful for the treatment of infectious diseases. Ó 2002 Elsevier Science (USA). All rights reserved. Keywords: PMAP-23; Antifungal peptides; Analog peptides; Hydrophobicity Antimicrobial peptides have been recognized as playing important roles in the innate host defense mechanisms of most living organisms including plants, insects, amphibians, and mammals [1–6]. They are also known to possess potent antibiotic activity against bacteria, fungi, and even certain viruses [7–11]. Recently, the rapid emergence of microorganism pathogens, which are resistant to currently available antibiotics, has triggered considerable interest in the isolation and investigation of the mode of action of antimicrobial peptides. Antibiotics act in two different ways, first by targeting the physiology of the pathogen, and second, by dis- rupting the cellular structure of the host cells. In the latter case, antibiotics are relatively safe from encoun- ters with resistant host strains, since mutations in the overall plasma membrane structure are less likely than variations in the enzyme physiology within a host cell. Therefore, the disruption of plasma membranes, by pore or ion channel formation, has been widely used in an- tibiotic agents. In mammals, the cytoplasmic granules of neutro- philes are an abundant source of a number of antimi- crobial peptides. cDNAs of several neutrophil-derived antimicrobial peptides have been cloned. Among these, PMAP-23 peptide was identified by cDNA cloning, and has been shown to possess potent antibacterial activity with chemically synthesized peptides [12,13]. Also, PMAP-23 has already shown fungicidal effects and modes of action [14]. With this study, to obtain peptides having improved fungicidal activity, novel analog peptides with amino acid substitutions were designed and synthesized based on the sequence and a-helical wheel diagram of PMAP- 23. In the present study, the fungicidal effect and anti- cancer activity of synthetic peptides, against pathogenic Biochemical and Biophysical Research Communications 293 (2002) 231–238 www.academicpress.com * Corresponding author. Fax: +82-62-227-8345. E-mail address: kshahm@mail.chosun.ac.kr (K.-S. Hahm). 0006-291X/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. PII:S0006-291X(02)00222-X