title: Blood pressure-lowering peptides from neo-fermented buckwheat sprouts: a new approach to estimating ACE-inhibitory activity.
abstract: Neo-fermented buckwheat sprouts (neo-FBS) contain angiotensin-converting enzyme (ACE) inhibitors and vasodilators with blood pressure-lowering (BPL) properties in spontaneously hypertensive rats (SHRs). In this study, we investigated antihypertensive mechanisms of six BPL peptides isolated from neo-FBS (FBPs) by a vasorelaxation assay and conventional in vitro, in vivo, and a new ex vivo ACE inhibitory assays. Some FBPs demonstrated moderate endothelium-dependent vasorelaxation in SHR thoracic aorta and all FBPs mildly inhibited ACE in vitro. Orally administered FBPs strongly inhibited ACE in SHR tissues. To investigate detailed ACE-inhibitory mechanism of FBPs in living body tissues, we performed the ex vivo assay by using endothelium-denuded thoracic aorta rings isolated from SHRs, which demonstrated that FBPs at low concentration effectively inhibited ACE in thoracic aorta tissue and suppressed angiotensin II-mediated vasoconstriction directly associated with BPL. These results indicate that the main BPL mechanism of FBP was ACE inhibition in living body tissues, suggesting that high FBP's bioavailability including absorption, tissue affinity, and tissue accumulation was responsible for the superior ACE inhibition in vivo. We propose that our ex vivo assay is an efficient and reliable method for evaluating ACE-inhibitory mechanism responsible for BPL activity in vivo.
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, Minamiminowa Village, Nagano, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Koyama
authors.affiliation: Department of Bioscience and Biotechnology, Graduate School of Agriculture, Shinshu University, Minamiminowa Village, Nagano, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Hattori
authors.affiliation: Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Nagano City, Nagano, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Amano
authors.affiliation: Department of Food, Life and Environmental Science, Faculty of Agriculture, Yamagata University, Tsuruoka City, Yamagata, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, Minamiminowa Village, Nagano, Japan; Department of Bioscience and Biotechnology, Graduate School of Agriculture, Shinshu University, Minamiminowa Village, Nagano, Japan; Academic Assembly, Institute of Agriculture, Shinshu University, Minamiminowa Village, Nagano, Japan.
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
mesh_terms: D000803:Angiotensin I / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D019612:Fagopyrum / Q000737:chemistry*; D005285:Fermentation; D066298:In Vitro Techniques; D008297:Male; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D011918:Rats, Inbred SHR
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D010936:Plant Extracts; D000804:Angiotensin II; D000803:Angiotensin I