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A new tetrahydrofuranoketone lignan (1) and two new tetrahydrofuranoketone lignan glycosides (2, 3) were isolated from the ethanol extract of the aerial part of Mananthes patentiflora. The structure elucidations of these compounds were mainly established on the basis of 1D, 2D NMR and HR-mass spectroscopic analysis. All three compounds revealed potent antioxidant activities within the concentration range tested (0.08-50.0 microM).

Three new (1-3) and four known (4-7) compounds were isolated from the stems of Baccaurea ramiflora. By analysis of 1D, 2D NMR, and MS data, the new compounds were identified as 4'-O-(6- O-vanilloyl)-beta-D-glucopyranosyl tachioside D (1), 6'-O-vanilloylpicraquassioside D (2), and 6'-O-vanilloylicariside B(5) (3). Compound 1 exhibited significant DPPH radical-scavenging activity, with an IC(50) value of 36.9 microM, while compound 4 revealed weak antioxidant activity against H (2)O(2)-induced impairment in PC12 cells.

Eight new lignan glucosides, tarennanosides A-H (1-8, resp.), were isolated from the whole plant of Tarenna attenuata, together with three known compounds, fernandoside, (-)-lyoniresinol, and (-)-isolariciresinol. The planar structures of new compounds were elucidated mainly by analysis of physical and spectroscopic data, and the absolute configurations were determined by acid hydrolysis as well as CD spectroscopy. Compounds 1 and 2 exhibited potent antioxidant activities against H2O2-induced impairment in PC12 cells. Preliminary mechanism study by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method showed that these two compounds could act as radical scavengers.

Two new phenols, 6'- O-vanilloylisotachioside ( 1) and 6'- O-vanilloyltachioside ( 2), together with nine known compounds, were isolated from the leaves of Baccaurea ramiflora (Euphorbiaceae). The structures of the new compounds were elucidated mainly by analysis of physical and spectroscopic data. Compounds 1 - 10 were tested for antioxidant activities by using MTT and DPPH assays. Seven compounds, 1, 2, and 4 - 8, revealed potent antioxidant activities against H (2)O (2)-induced impairment in PC12 cells, and exhibited significant DPPH radical-scavenging activities with IC (50) values of 86.9, 142.9, 15.2, 37.6, 35.9, 30.2, and 79.8 microM, respectively.

Two novel chalcone constituents, tarennane (1) and tarennone (2), together with nine known compounds, were isolated from the whole plant of Tarenna attenuata. By analysis of physical and spectroscopic data, the structures of new compounds were elucidated as (E)-4-[3-(4-hydroxy-3-methoxyphenyl)-acryl]3,4,5-trimethoxycyclohexa-2,5-dienone (1) and 1,2-bis(3,5-dimethoxy-4-hydroxyphenyl)-3-hydroxypropan-1 -one (2). These two compounds were tested for antioxidant activities in the MTT and DPPH assays. Compound I revealed potent antioxidant activities against H2O2-induced impairment in PC12 cells, but neither of them showed DPPH radical-scavenging activity with lC(50) values of 181.1 and 210.3 mu M, respectively.

Six new mixed lignan-neolignans and 20 known compounds were isolated from the whole plant of Tarenna attenuata. By analysis of physical and spectroscopic data, the structures of the new compounds were elucidated as (1R,5R,6R)-6-{4-O-[2-(1-(4-hydroxy-3-methoxyphenyl))glycerol]-3,5-dimethoxyphenyl}-3,7-dioxabicyclo[3.3.0]octan-2-one (1), 5' '-methoxyhedyotisol A (2), 4' '-O-(8-guaiacylglycerol)buddlenol A (3), 5' '-methoxy-4' '-O-(8-guaiacylglycerol)buddlenol A (4), 4,6-dimethoxy-5-hydroxy-3-hydroxymethyl-2-(3,4,5-trimethoxyphenyl)-2,3-dihydrobenzofuran (5), and 7-O-ethylguaiacylglycerol (6). Compounds 1, 5, 6, and 8 showed potent antioxidant activities against H2O2-induced impairment in PC12 cells, and compounds 1, 2, 5, and 7 scavenged DPPH radical strongly with IC50 values of 72, 87, 45, and 55 microM, respectively.

NaCl significantly enhanced the longer oligoarginine formation in the oligomerization of L-arginine activated by N,N'-carbonyldiimidazole (CDI) in homogeneous aqueous solution. The optimal concentration of NaCl for the highest yield of longer oligoarginine formation is around 1M. It is suggested that the weak interactions of Cl(-) with the positive-charged guanidinium group of the oligoarginines formed in the oligomerization of L-arginine are responsible for the enhancement by NaCl.