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Antimicrobial activity and mechanism of action of a novel cationic α‐helical octadecapeptide derived from α‐amylase of rice
Author(s) -
Taniguchi Masayuki,
Ochiai Akihito,
Takahashi Kiyoshi,
Nakamichi Shunichi,
Nomoto Takafumi,
Saitoh Eiichi,
Kato Tetsuo,
Tanaka Takaaki
Publication year - 2015
Publication title -
peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.22605
Subject(s) - antimicrobial , chemistry , streptococcus mutans , propidium iodide , candida albicans , microbiology and biotechnology , cytotoxicity , porphyromonas gingivalis , biochemistry , bacteria , biology , in vitro , apoptosis , programmed cell death , genetics , organic chemistry
ABSTRACT AmyI‐1–18, an octadecapeptide derived from α‐amylase (AmyI‐1) of rice (Oryza sativa L. japonica), is a novel cationic α‐helical antimicrobial peptide (AMP) that contains two lysine and two arginine residues. The antimicrobial activity of AmyI‐1–18 against human pathogens was quantitatively evaluated using a chemiluminescence method that measures ATP derived from viable cells. Of the ten kinds of human pathogens, AmyI‐1–18 exhibited antimicrobial activity against nine. Its 50% growth‐inhibitory concentrations (ICs 50 ) against Porphyromonas gingivalis , Propionibacterium acnes , Pseudomonas aeruginosa , Candida albicans , and Streptococcus mutans were 13, 19, 50, 64, and 77 μ M , respectively. AmyI‐1–18 had little or no hemolytic activity even at 500 μ M , and showed negligible cytotoxicity up to 1200 μ M . The degree of 3,3′‐dipropylthiadicarbocyanine iodide release from P. gingivalis cells induced by the addition of AmyI‐1–18 was significantly lower than that induced by the addition of melittin. Flow cytometric analysis showed that the percentages of P. aeruginosa , S. mutans , and C. albicans cells stained with propidium iodide (PI), a DNA‐intercalating dye, were 89%, 43%, and 3%, respectively, when AmyI‐1–18 was added at a concentration equal to its 4×IC 50 . Therefore, the antimicrobial activity of AmyI‐1–18 against P. aeruginosa and S. mutans appears to be mainly attributable to its membrane‐disrupting activity. In contrast, its antimicrobial activity against P. gingivalis and C. albicans most likely depends upon interactions with intracellular targets other than their cell membranes. Collectively, these results indicate that AmyI‐1–18 is useful as a safe and potent AMP against the pathogens described above in many fields of healthcare. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 104: 73–83, 2015.