Kajiya K, Inokuchi H, Sakakibara Y, Takamatsu H, Yamanouchi H . Preventive and inhibitory effects of Salacia on sustained contraction of vascular smooth muscle cells and characterization of th2026 · 記述言語： 英語 出版者・発行元： Biochemistry and Biophysics Reports Sustained contraction of vascular smooth muscles can abruptly restrict blood flow, leading to ischemia. While mild, prolonged contractions may cause dizziness and migraines, severe vasoconstriction (vasospasm) can result in cerebral or myocardial infarction and may be fatal. Sphingosylphosphorylcholine (SPC) is a known inducer of pathological sustained contraction that occurs independently of Ca<sup>2+</sup>-dependent mechanisms. Although lipid-soluble dietary compounds have been reported to inhibit SPC-induced contractions, their clinical utility is limited by poor suitability for aqueous formulations and a tendency to accumulate in membranes and adipose tissue. In this study, we sought to identify water-soluble compounds that selectively inhibit pathological sustained contraction without impairing Ca<sup>2+</sup>-dependent vascular contraction. We focused on Salacia , a medicinal plant extensively studied for its metabolic effects, but whose vascular actions remain poorly characterized. Extracts from both aboveground (stems and trunks) and belowground (roots) parts of Salacia , applied either before or during SPC exposure, significantly inhibited SPC-induced sustained contraction. The active compounds were identified as 3,4-dihydroxybenzoic acid (3,4-DHBA), trans -3-, trans -4-, and trans -5-caffeoylquinic acids (CQAs), ortho -hydroxybenzoic acid ( o -HBA), and para -HBA ( p -HBA). Inhibitory potency followed the order 3,4-DHBA ≈ CQA > HBA. Notably, 3,4-DHBA and CQAs readily permeated vascular endothelial cells to reach smooth muscle, and their inhibitory effects were synergistically enhanced when 3,4-DHBA was present in excess. These findings suggest that water-soluble compounds from Salacia may prevent or attenuate SPC-induced vasospasm and its associated severe vascular diseases. DOI： 10.1016/j.bbrep.2026.102530 Scopus PubMed
Yamanouchi H., Minami Y., Kajiya K. . Evaluation and validation of angiotensin-converting enzyme inhibitory activity of moringa oleifera, quercetin, and isoquercetin: A comparative stud2025 · 担当区分： 最終著者, 責任著者 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Food Research International Moringa oleifera, known for its nutritional benefits and biological functions, such as antihypertensive effects, has cultivated in Japan. However, there is limited information available on moringa cultivated in Japan. Cardiovascular diseases, including ischemic heart disease and stroke, cause many deaths worldwide each year, with hypertension being the most significant risk factor. This study investigated the inhibitory activity of angiotensin-converting enzyme (ACE), which is one of the blood pressure elevation mechanisms, aiming to identify the active compounds in moringa leaves cultivated in Kagoshima prefecture, Japan (Kagoshima-moringa). Additionally, we evaluated the potential overestimation of the ACE inhibitory activity when measured using the fluorescence method. The ACE inhibitor compounds in the methanol-rich extract of Kagoshima-moringa were purified, and mass, aglycone, and glycoside analyses suggested isoquercetin as one of the active compounds. ACE inhibitory activity was evaluated using a fluorescent derivatization method with o-phthalaldehyde (OPA). However, the inhibitory effect of isoquercetin may have been overestimated, as the OPA fluorescence measurement indicated that isoquercetin could inhibit fluorescence readings. Therefore, the absorbance method was performed, revealing that captopril demonstrated similar inhibitory activity, whereas Kagoshima-moringa extracts showed low activity. These results indicate that the ACE inhibitory activity of flavonoids, or samples rich in flavonoids, may be overestimated when assessed by the fluorescence method using OPA. Hence, evaluating ACE inhibitor activity requires the careful selection of measurement methods; multiple activity measurement methods should be used if possible. The study underscores the importance of appropriate measurement methods for evaluating ACE inhibitory activity, guiding future research practices. DOI： 10.1016/j.foodres.2025.115768 DOI： 10.1016/j.foodres.2025.115768 Scopus
