Browsing by Author "Koketsu, Mamoru"

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    Iodine-Catalyzed Etherification of Morroniside
    (2009-09) Sunghwa, Fortunatus; Sakurai, Hiroaki; Saiki, Ikuo; Koketsu, Mamoru
    In this study, we describe a highly selective etherification procedure of unprotected morroniside catalyzed by molecular iodine in acetone. The etherification reaction furnished 7-O-alkyl ether derivatives in reasonable yields within few hours under neutral conditions. Studies of the obtained products on cytotoxicity activity in colon 26-L5 cell line were examined. Among the tested compounds, 7-O-dodecylmorroniside showed moderate cytotoxic activity, having IC50 values equal to 20.9 μM.
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    Morroniside cinnamic acid conjugate as an anti-inflammatory agent
    (2010-08) Takeda, Yoshinori; Tanigawa, Naomi; Sunghwa, Fortunatus; Ninomiya, Masayuki; Hagiwara, Makoto; Matsushita, Kenji; Koketsu, Mamoru
    A morroniside cinnamic acid conjugate was prepared and evaluated on E-selectin mediated cell-cell adhesion as an important role in inflammatory processes. 7-O-Cinnamoylmorroniside exhibited excellent anti-inflammatory activity (IC(50)=49.3 microM) by inhibiting the expression of E-selectin; further, it was more active than another cinnamic-acid-conjugated iridoid glycoside (harpagoside; IC(50)=88.2 microM), 7-O-methylmorroniside, and morroniside itself. As a result, 7-O-cinnamoylmorroniside was observed to be a potent inhibitor of TNF-alpha-induced E-selectin expression.
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    Phenolic and bis-iridoid glycosides from Strychnos cocculoides
    (2009-10) Sunghwa, Fortunatus; Koketsu, Mamoru
    A new bis-iridoid glucoside, cocculoside (1), has been isolated, together with five known compounds from Strychnos cocculoides (Loganiaceae), collected in Tanzania. The structure of cocculoside (1) has been determined as an ester dimer of loganin and secologanin dimethyl acetal between C-7 and C-11