title: The green tea polyphenol (-)-epigallocatechin gallate precipitates salivary proteins including alpha-amylase: biochemical implications for oral health.
abstract: Green tea is a popular drink throughout the world, and it contains various components, including the green tea polyphenol (-)-epigallocatechin gallate (EGCG). Tea interacts with saliva upon entering the mouth, so the interaction between saliva and EGCG interested us, especially with respect to EGCG-protein binding. SDS-PAGE revealed that several salivary proteins were precipitated after adding EGCG to saliva. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) peptide mass fingerprinting indicated that the major proteins precipitated by EGCG were alpha-amylase, S100, and cystatins. Surface plasmon resonance revealed that EGCG bound to alpha-amylase at dissociation constant (K(d)) = 2.74 × 10(-6) M, suggesting that EGCG interacts with salivary proteins with a relatively strong affinity. In addition, EGCG inhibited the activity of alpha-amylase by non-competitive inhibition, indicating that EGCG is effective at inhibiting the formation of fermentable carbohydrates involved in caries formation. Interestingly, alpha-amylase reduced the antimicrobial activity of EGCG against the periodontal bacterium Aggregatibacter actinomycetemcomitans. Therefore, we considered that EGCG-salivary protein interactions might have both protective and detrimental effects with respect to oral health.
authors.affiliation: Department of Oral Health Sciences, Graduate School of Biomedical Sciences, Hiroshima University, Minamiku, Hiroshima, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Hara
authors.forename: Masaru
authors.initials: M
authors.lastname: Ohara
authors.forename: Ikue
authors.initials: I
authors.lastname: Hayashi
authors.forename: Takamune
authors.initials: T
authors.lastname: Hino
authors.forename: Rumi
authors.initials: R
authors.lastname: Nishimura
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Ogawa
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Ohyama
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Hideaki
authors.initials: H
authors.lastname: Amano
mesh_terms: D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects; D000900:Anti-Bacterial Agents / Q000037:antagonists & inhibitors; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D015891:Cystatins / Q000037:antagonists & inhibitors; D003731:Dental Caries / Q000517:prevention & control*; D004040:Dietary Carbohydrates / Q000037:antagonists & inhibitors; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D020543:Proteome / Q000032:analysis; D012463:Saliva / Q000201:enzymology; D012471:Salivary Proteins and Peptides / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013662:Tea / Q000737:chemistry; D055815:Young Adult; D000516:alpha-Amylases / Q000032:analysis* / Q000037:antagonists & inhibitors
chemical_list: D000900:Anti-Bacterial Agents; D015891:Cystatins; D004040:Dietary Carbohydrates; D020543:Proteome; D012471:Salivary Proteins and Peptides; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate; D000516:alpha-Amylases