title: Anti-ice nucleating activity of polyphenol compounds against silver iodide.
abstract: Freeze-avoiding organisms survive sub-zero temperatures without freezing in several ways, such as removal of ice nucleating agents (INAs), production of polyols, and dehydration. Another way is production of anti-ice nucleating agents (anti-INAs), such as has been reported for several antifreeze proteins (AFPs) and polyphenols, that inhibit ice nucleation by inactivating INAs. In this study, the anti-ice nucleating activity of five polyphenol compounds, including flavonoid and tannin compounds of both biological and synthetic origin, against silver iodide (AgI) was examined by measuring the ice nucleation temperature in emulsified polyphenol solutions containing AgI particles. The emulsified solutions eliminated the influence of contamination by unidentified INAs, thus enabling examination of the anti-ice nucleating activity of the polyphenols against AgI alone. Results showed that all five polyphenol compounds used here have anti-ice nucleating activities that are unique compared with other known anti-INAs, such as fish AFPs (type I and III) and synthetic polymers (poly(vinyl alcohol), poly(vinylpyrrolidone) and poly(ethylene glycol)). All five polyphenols completely inactivated the ice nucleating activity of AgI even at relatively low temperatures, and the first ice nucleation event was observed at temperatures between -14.1 and -19.4°C, compared with between -8.6 and -11.8°C for the fish AFPs and three synthetic polymers. These anti-ice nucleating activities of the polyphenols at such low temperatures are promising properties for practical applications where freezing should be prevented.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Namiki 1-2-1, Tsukuba, Ibaraki 305-8564, Japan.
authors.forename: Toshie
authors.initials: T
authors.lastname: Koyama
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Namiki 1-2-1, Tsukuba, Ibaraki 305-8564, Japan. Electronic address: t-inada@aist.go.jp.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Inada
authors.affiliation: Research Faculty and Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Kuwabara
authors.affiliation: Research Faculty and Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Arakawa
authors.affiliation: Research Faculty and Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Seizo
authors.initials: S
authors.lastname: Fujikawa
mesh_terms: D000818:Animals; D021301:Antifreeze Proteins / Q000737:chemistry; D003451:Cryoprotective Agents / Q000737:chemistry*; D003460:Crystallization; D005399:Fishes; D005615:Freezing; D007053:Ice / Q000032:analysis*; D007454:Iodides / Q000737:chemistry*; D059808:Polyphenols / Q000737:chemistry*; D018030:Silver Compounds / Q000737:chemistry*; D012996:Solutions
chemical_list: D021301:Antifreeze Proteins; D003451:Cryoprotective Agents; D007053:Ice; D007454:Iodides; D059808:Polyphenols; D018030:Silver Compounds; D012996:Solutions; C030584:silver iodide
keywords: Antifreeze protein; Emulsion; Ice nucleation; Polyphenol; Silver iodide; Supercooling