Publications by authors named "Niichiro Kitagawa"

Acylated oleanane-type triterpene saponins, namely chakasaponins I () and II (), floratheasaponin A (), and their analogs, together with catechins-including (-)-epigallocatechin 3--gallate (), flavonoids, and caffeine-have been isolated as characteristic functional constituents from the extracts of "tea flower", the flower buds of (Theaceae), which have common components with that of the leaf part. These isolates exhibited antiproliferative activities against human digestive tract carcinoma HSC-2, HSC-4, MKN-45, and Caco-2 cells. The antiproliferative activities of the saponins (-, IC = 4.

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A quantitative analytical method for five aporphine alkaloids, nuciferine (1), nornuciferine (2), N-methylasimilobine (3), asimilobine (4), and pronuciferine (5), and five benzylisoquinoline alkaloids, armepavine (6), norarmepavine (7), N-methylcoclaurine (8), coclaurine (9), and norjuziphine (10), identified as the constituents responsible for the melanogenesis inhibitory activity of the extracts of lotus flowers (the flower buds of Nelumbo nucifera), has been developed using liquid chromatography-mass spectrometry. The optimum conditions for separation and detection of these 10 alkaloids were achieved on a πNAP column, a reversed-phase column with naphthylethyl group-bonded silica packing material, with CH₃CN-0.2% aqueous acetic acid as the mobile phase and using mass spectrometry equipped with a positive-mode electrospray ionization source.

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A quantitative analytical method has been-developed for four alkaloids (1-4), identified as constituents responsible for the melanogenesis inhibitory activity of the.extracts of wintersweet, the flower buds of Chimonanthus praecox (L.) Link (Calycanthaceae).

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Seven oleanane-type triterpene saponin bisdesmosides, perennisaponins N-T (1-7), were newly isolated from a methanol extract of daisy, the flowers of Bellis perennis L. (Asteraceae). The structures were determined based on chemical and physicochemical data and confirmed using previously isolated related compounds as references.

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Using the recently developed two analytical protocols, distributions were analyzed of five catechins (1-5), ten flavonoids (6-15), caffeine (16), and nine saponins (17-25) in 12 samples of flower buds of Camellia sinensis (L.) O. Kuntze, collected at different points in Taiwan.

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A new dammarane-type triterpene ketone, panaxadione, was isolated from the seeds of Panax ginseng C. A. MEYER (Araliaceae) together with two dammarane-type and lupane-type triterpenes, an aromatic oligoglycoside, three sterol glycosides, and three dammarane-type triterpene oligoglycosides (ginsenosides Rd, Re, and Rg(2)).

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