Isolation and antioxidant activity of galloyl flavonol glycosides from the seashore plant, Pemphis acidula.

Four kinds of galloyl flavonol glycosides were found in the leaf extract of Pemphis acidula, a plant growing on the subtropical seashore. Their chemical structures were elucidated to be quercetin or kaempferol 6"-O-galloyl-beta-D-glycosides by using spectroscopic and chemical analyses. One of the flavonols, kaempferol-3-O-(6-O-galloyl-beta-D-galactopyranoside), was newly isolated from natural sources and its structure was completely determined in this investigation. The antioxidant-related activities of the galloyl flavonoids were examined by the DPPH antiradical activity, inhibition of methyl linoleate oxidation, and inhibition of oxidative cell death. These results were compared with those of the corresponding non-galloylated flavonol glycosides and their aglycones. The galloyl flavonoids showed more efficient activity than that of the corresponding flavonol glycosides, but not more than that of the corresponding aglycones in the three assays applied.

New constituents of the leaves of Alpinia flabellata.

Two new compounds were isolated from the leaves of Alpinia flabellata. The structures of these compounds were determined by a combination of NMR techniques and HREIMS as 4-hydroxy-2-(2,4,5-trimethoxyphenyl)-2E-butenal (1) and rel-labd-12-en-15(16)-olid-7-one-8R-spiro-1'-[2S-(2,4,5-trimethoxyphenyl)-3-cyclohexene] (2).

Phenylbutanoid dimers from the leaves of Alpinia flabellata.

Three phenylbutanoid dimers, cis- and trans-1-(2,4,5-trimethoxy-E-styryl)-2-(2,4,5-trimethoxy-Z-styryl)cyclobutane and 1,2-bis(2,4,5-trimethoxy-Z-styryl)- cyclobutane, were isolated from the leaves of Alpinia flabellata Ridley, together with three known compounds (2,4,5-trimethoxybenzaldehyde, 2,4,5-trimethoxycinnamaldehyde and 3,5-dihydroxy-7,4'-dimethoxyflavone). The structures of these compounds were determined by spectroscopic analysis.

Isolation and structure determination of new antioxidative ferulic acid glucoside esters from the rhizome of Alpinia speciosa, a Zingiberaceae plant used in Okinawan food culture.

An assay-guided isolation gave three antioxidants including two newly identified compounds from the rhizomes of Alpinia speciosa, which is used as an important plant in the food culture of the Okinawa area of Japan. Spectroscopic analysis of the two new compounds revealed them to be new glucoside esters of ferulic acid. The antioxidant activity of the esters was measured using two different methods. Both compounds showed greater activity than that of Trolox in the TLC method; however, one of the compounds showed weaker inhibitory activity than that of Trolox and epicatechin against AMVN-induced methyl linoleate oxidation.

Evaluation of the antioxidant activity of environmental plants: activity of the leaf extracts from seashore plants.

The antioxidant activity of the methanolic extracts of the leaves of 39 plant species was examined. These leaves were collected from the plants growing on subtropical seashores. The activity was evaluated by three kinds of assay methods, which included the DPPH radical scavenging assay, linoleic acid oxidation assay, and oxidative cell death assay. Two extracts from Excoecaria agallocha and Terminalia catappa showed remarkably potent activity in all assay systems. The HPLC analysis of the extracts indicated the presence of the same antioxidant and isolation work for the compound identified ellagic acid. The isolated ellagic acid showed strong antioxidant activity in the assay systems used.

Phenolic constituents in Erythrina x bidwilli and their activity against oral microbial organisms.

Five flavonoid compounds, including two new isoflavanones, were isolated from the root bark of Erythrina x bidwilli. Their structures were determined to be 2,10-di(gamma,gamma-dimethylallyl)-3,9-dihydroxypterocarpan (erythrabyssin II), 6,8-di(gamma,gamma-dimethylallyl)-7,2',4'-trihydroxyisoflavanone (bidwillon A), 8-gamma,gamma-dimethylallyl-2',4'-dihydroxy-[6",6"-di-methylpyrano - (2",3":7,6)]isoflavanone (bidwillon B), 8-gamma,gamma-dimethylallyl-7,4'-dihydroxyisoflavone (8-gamma,gamma-dimethyl-allyldaidzein), and 8-gamma,gamma-dimethylallyl-5,2',4'-trihydroxy-[6",6"-dimethylpyrano+ ++- (2",3":7,6)]isoflavone (auriculatin), by means of spectroscopic analysis. Some potent activities against oral microbial organisms (Fusobacterium nucleatum and Prevotella intermedia) were shown in these flavonoid compounds.