Five lignan glycosides, lyoniside, nudiposide, 5-methoxy-9-b-xylopyranosyl-(À)-isolariciresinol, icariside E 3 , and schizandriside, and three flavonoids, (À)-epicatechin, epiafzelechin-(4b?8)-epicatechin and procyanidin B 2 , together with b-sitosterol glucoside, were isolated from a methyl alcohol (MeOH) extract of Saraca asoca dried bark. Their structures were determined by 1D and 2D nuclear magnetic resonance (NMR) and mass spectroscopic analysis. Antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay.Keywords Saraca asoca Á Caesalpiniaceae Á Lignan glycoside Á Flavonoid Á Antioxidant activity Saraca asoca (Roxb.) De Wilde or S. indica Linn. (Family: Caesalpiniaceae; local names: Ashok, Anganapriya, etc.) is a medicinal plant of Bangladesh whose bark is astringent and used in menorrhagia, bleeding haemorrhoids and haemorrhagic dysentery [1]. The isolation of tannins [2], flavonoids [3], proanthocyanidins [4] and leucoanthocyanidins [5] were previously reported from the bark. In our assay method, a methyl alcohol (MeOH) extract of the dried bark showed potent antioxidant activity determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay [6]. Following this activity, we isolated eight compounds (1-8) from this plant (Fig. 1). This paper describes isolation and identification of isolated compounds together with their antioxidative potential. The bark of S. asoca was collected from Satkhira, Bangladesh, in August 2005. A voucher specimen has been deposited in The dried bark of S. asoca was ground into a coarse powder (195 g), which was extracted with 1.3 L MeOH to get the extract (14.7 g). Based on the medicinal uses, the extract was tested for antioxidant activity using DPPH radical-scavenging assay that showed a potent effect with an IC 50 value of 25 lg/ml. The extract was then suspended in 440 ml 10% aqueous MeOH and partitioned successively with n-hexane, ethyl acetate (EtOAc) and n-butanol (n-BuOH) that afforded four extracts (n-hexane extract: 217 mg; EtOAc extract: 3.11 g; n-BuOH extract: 8.74 g; water extract: 2.87 g). Among them, EtOAc and n-BuOH extracts showed clear DPPH positive spots on thin-layer chromatography (TLC). These two extracts were then subjected to further separations by repeated-column chromatography. From the n-BuOH extract (4.0 g), compounds 1 (20 mg), 2 (16 mg), 3 (4 mg) and 4 (8 mg) were isolated. Compounds 1 (5 mg), 3 (2 mg), 5 (5 mg), 6 (20 mg), 7 (36 mg) and 8 (17 mg), together with b-sitosterol glucoside (12 mg) [7], were isolated from the EtOAc extract (3.0 g). Compounds 1-5 were lignan glycosides, which were identified as lyoniside ½a 21 D þ 22 (c 1.0, MeOH) [8],

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A new lignan, polystachyol (1), two lignan glycosides, lyoniside (2) and nudiposide (3), and a sterol, ergosta-4,6,8(14),22-tetraen-3-one (4), with stigmasterol, and oleic and linoleic acids, have been isolated from an MeOH extract of the dried bark of Aphanamixis polystachya. The structures of the isolated compounds were elucidated by analysis of 1D and 2D NMR and mass spectroscopic data. The compounds did not have growth inhibitory activity against HeLa cells.

Chloroform and ethyl acetate extracts of Aspergillus fischeri TISTR 3272 showed good growth inhibitory activity on Mimosa pigra and Echinochloa crus-galli. Bioassay-directed fractionation of the active extracts led to the isolation of five known compounds, (+)-terrein (1), (-)-6-hydroxymellein (2), two diketopiperazines (cyclo-(S-Pro-S-Leu) (3) and cyclo-(S-Pro-S-Val) (4)) and butyrolactone I (5). Compounds 2-5 were reported for the first time in this fungus. Their structural determinations were based on analyses of spectroscopic data and their weed growth inhibitory effects were assessed.

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