Toshiya Masuda

Anti-oxidative and anti-inflammatory curcumin-related phenolics from rhizomes of Curcuma domestica

Abstract Two new natural phenolics were isolated from the rhizomes of Curcuma domestica along with four known curcuminoids. The structures of the former wer

Antioxidative curcuminoids from rhizomes of Curcuma xanthorrhiza

A new curcumin analogue has been isolated from the rhizomes of Curcuma xanthorrhiza along with four known curcuminoids, and its structure has been determined as 1-(4-hydroxy-3,5-dimethoxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)-(1E,6E)-1,6-heptadiene-3,4-dione by spectral data. The new compound showed potent antioxidant activity against autoxidation of linoleic acid in a water-alcohol system.

Antimicrobial phenylpropanoids from Piper sarmentosum

Abstract One new and three known phenylpropanoids have been isolated from the leaves of Piper sarmentosum . They are 1-allyl-2,6-dimethoxy-3,4-methylenedioxybenzene, 1-allyl-2,4,5-trimethoxybenzene, 1-(1- E -propenyl)-2,4,5-trimethoxybenzene and 1-allyl-2-methoxy-4,5-methylenedioxybenzene. The new compound showed antimicrobial activity against Escherichia coli and Bacillus subtilis .

Orthosiphol A and B, novel diterpenoid inhibitors of TPA (12-O-tetradecanoylphorbol-13-acetate)-induced inflammation, from Orthosiphon stamineus

Abstract Two novel highly oxygenated pimarane diterpenes, orthosiphol A (1) and B (2), have been isolated from the dry leaves of Orthosiphon stamineus Benth (Labiatae). Their structures were elucidated by spectroscopic and chemical methods. Orthosiphol A and B showed potent inhibitory activity against the inflammation induced by a tumor promoter, TPA (12-O-tetradecanoylphorbol-13-acetate), on mouse ears

Acetylated flavonol glycosides from Zingiber zerumbet

Abstract Three new acetylated and one known kaempferol glycosides have been isolated from the rhizomes of Zingiber zerumbet and their structures determined to be the 3- O -(2- O -acetyl-α- l -rhamnopyranoside), 3- O -(3- O -acetyl-α- l -rhamnopyranoside), 3- O -(4- O -acetyl-α- l -rhamnopyranoside) and 3- O -α- l -rhamnopyranoside on the basis of spectroscopic methods.

Phenylbutenoid monomers from the rhizomes of Zingiber cassumunar

Two new phenylbutenoid dimers, (±)-trans-3-(2,4,5-trimethoxyphenyl)-4-[(E)-3,4-dimethoxystyryl]-cyclohexene and cis-1,2-bis[(E)-3,4-dimethoxystyryl]cyclobutane, have been isolated from the fresh rhizomes of Zingiber cassumunar along with the two known phenylbutenoid dimers. Their structures were elucidated by spectroscopic and chemical methods. The stereochemistry of these cyclohexene compounds was clarified on the basis of 1H NMR data of their derivatives. The substituted positions for the 3,4-dimethoxystyryl groups of the cyclobutane compound were confirmed from a Cope rearrangement product in the pyrolysis of the cyclobutane, and the stereochemistry of the cyclobutane was confirmed by 1H NMR evidence.

Isolation and Structure Determination of Cassumunarins A, B, and C: New Anti-Inflammatory Antioxidants from a Tropical Ginger, Zingiber cassumunar

New antioxidants, cassumunarins A, B, and C, were isolated from the rhizomes ofZingiber cassumunar, and the structures were determined by spectroscopic methods to be complex curcuminoids. The antixidant efficiency of cassumunarins was determined by inhibitory activity of autoxidation of linoleic acid in a buffer-ethanol system. The anti-inflammatory effect was measured by inhibition of edema formation on mouse ear induced by 12-O-tetradecanoylphorbol-13-acetate. Both types of activities were stronger for the cassumunarins than for the curcumin.

7-Hydroxycoumarin derivatives from the juice oil of Citrus hassaku

Abstract Three new 7-hydroxycoumarin derivatives have been isolated from the juice oil of whole fruits of Citrus hassaku , and their structures determined to be 7-(6 R -hydroxy-3,7-dimethyl-2 E ,7-octadienyloxy)coumarin, (±)-7-hydroxy- 6-linalylcoumarin and ( R )-6- O -(4-geranyloxy-2-hydroxy)cinnamoylmarmin by spectral data and chemical evidence.

Orthosiphol A, a highly oxygenated diterpene from the leaves of orthosiphon stamineus

Abstract The structure of orthosiphol A( 1 ), a highly oxygenated pimarane diterpene, has been established on the basis of spectroscopic and chemical methods.

Conversion to purpurogallin, a key step in the mechanism of the potent xanthine oxidase inhibitory activity of pyrogallol

Abstract In this study, the mechanism of the xanthine oxidase (XO) inhibitory activity of pyrogallol, the main inhibitor found in roasted coffee, was investigated. Pyrogallol was unstable and readily converted to purpurogallin in a pH 7.4 solution, a physiological model of human body fluids. The XO inhibitory activity of the produced purpurogallin was higher than that of pyrogallol, as evidenced by comparing their IC50 values (0.2 &mgr;mol L−1 for purpurogallin, 1.6 &mgr;mol L−1 for pyrogallol). The XO activity of pyrogallol was enhanced by pre‐incubation in pH 7.4 solution. Although the initial XO inhibitory activity of 4‐methylpyrogallol was weak (IC50 33.3 &mgr;mol L−1), its XO inhibitory activity was also enhanced by pre‐incubation in the pH 7.4 solution. In contrast, 5‐methylpyrogallol, which could not be transformed into corresponding purpurogallin derivatives, did not show XO inhibitory activity before or after incubation in pH 7.4 solution. Molecular docking simulations clarified that purpurogallins have stronger affinities for XO than corresponding pyrogallols. These results revealed that the potent XO inhibitory activity seemingly observed in pyrogallol is actually derived from its chemical conversion, under alkaline conditions, into purpurogallin. Graphical abstract Figure. No Caption available. HighlightsPyrogallol is unstable under alkaline conditions.Pyrogallol and 4‐methylpyrogallol afford purpurogallin derivatives.Purpurogallin derivatives have potent xanthine oxidase inhibitory activity.Affinity of purpurogallin to xanthine oxidase is higher than that of pyrogallol.Purpurogallin is important to enhance XO inhibitory activity of pyrogallol.