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Recognition of phosphate monoester dianion by an alkoxide-bridged dinuclear zinc(II) complex (Zn2L3+) has been studied (L = alkoxide species of 1,3-bis[bis(pyridin-2-ylmethyl)amino]propan-2-ol). Potentiometric pH titration study disclosed a 1 : 1 phenyl phosphate complexation with Zn2L3+ in aqueous solution. The dissociation constant (=(More)
Two cyclic diarylheptanoids, acerogenins A (1) and B (2) have been isolated from the bark of Acer nikoense as inhibitors of Na(+)-glucose cotransporter (SGLT). Acerogenins A (1) and B (2) inhibited both isoforms, SGLT1 and SGLT2. Structure-activity relationship of acerogenin derivatives on inhibitory activity of SGLT as well as conformational analysis of 1(More)
Four new chromone alkaloids, chrotacumines A-D (1-4), consisting of a 5,7-dihydroxy-2-methylchromone, an N-Me piperidine ring, and an ester side chain were isolated from Dysoxylum acutangulum, and their structures including absolute configurations were elucidated on the basis of spectroscopic data interpretation including 2D NMR, CD spectra, and X-ray(More)
Four new 4-hydroxy-2-pyridone alkaloids, didymellamides A-D (1-4), were isolated from the marine-derived fungus Stagonosporopsis cucurbitacearum. The structures of 1-4 were elucidated from spectroscopic data (NMR, MS, and IR), and the absolute configuration of 1 was determined by X-ray diffraction analysis. Didymellamide A (1) exhibited antifungal activity(More)
Three new diterpenes, myrocin D (1), libertellenone E (2), and libertellenone F (3), and a new isocoumarin, decarboxyhydroxycitrinone (4), were isolated from the marine fungus Arthrinium sacchari, together with three known compounds (5-7). The structures of 1-4 were elucidated from spectroscopic data (NMR, MS, IR), and the absolute configurations of 1-3(More)
13 α,21-Dihydroeurycomanone (1), a known quassinoid of Eurycoma longifolia Jack was recrystallized from chloroform into a novel crystal structure in space group P2 (1). Its X-ray data were compared with those of eurycomanone ( 2). Following intraperioneal injections at similar doses of 2.44 µmol/kg/day for 3 consecutive days, 2 displayed comparable potency(More)
Lobaric acid (1) has been isolated from lichen, Stereocaulon sasakii together with a new benzofuran, sakisacaulon A (2). Lobaric acid (1) inhibited the polymerization of tubulin. Structure-activity relationship of lobaric acid and its derivatives on inhibitory activity of tubulin polymerization was discussed.