Swarnalin and cis-swarnalin, two new tetrahydrofuran derivatives with free radical scavenging activity, from the aerial parts of Cuscuta reflexa.

The reversed-phase HPLC analysis of a methanol extract of the aerial parts of Cuscuta reflexa afforded a non-separable mixture (55 : 45) of two novel tetrahydrofuran derivatives, named swarnalin (1) and cis-swarnalin (2), and a known coumarin, 5,6,7-trimethoxycoumarin (3). The structures of the compounds were elucidated unequivocally by UV, HRFABMS and a series of 1D and 2D NMR analyses. The mixture of 1 and 2 showed significant free radical scavenging activity in the DPPH assay and the RC50 value was found to be 3.80 x 10(-4) mg mL(-1) for the mixture, compared to 2.88 x 10(-5) mg mL(-1) for the positive control, quercetin.

Gedunin, a limonoid from Xylocarpus granatum, inhibits the growth of CaCo-2 colon cancer cell line in vitro.

Xylocarpus granatum J. König (Meliaceae), commonly known as 'dhundul', is a Bangladeshi mangrove tree, and well distributed in a number of other countries of south-east Asia, Australia and east Africa. Traditionally, X. granatum has been used as an astringent and febrifuge, and also for the treatment of fever, malaria, thrush, cholera, dysentery and diarrhoea in many countries including Bangladesh. Two limonoids, gedunin and 1alpha-hydroxy-1,2-dihydrogedunin, the latter being new, have been isolated from the bark of Xylocarpus granatum by reversed-phase preparative HPLC, and the structures were confirmed by spectroscopic means. The cytotoxic potential of gedunin has been evaluated by the Promega's CellTiter 96 non-radioactive cell proliferation assay using the CaCo-2 colon cancer cell line (IC(50) = 16.83 microM). A summary of the biological activities of gedunin reported to date is also presented.

Screening seeds of some Scottish plants for free radical scavenging activity.

From a consideration of ethnobotanical and taxonomic information, seeds of 45 Scottish plant species encompassing 23 different families were obtained from authentic seed suppliers. The n-hexane, dichloromethane (DCM) and methanol (MeOH) extracts were assessed, both qualitatively and quantitatively, for free radical scavenging activity in the DPPH assay. The MeOH extracts of 37 species exhibited low to high levels of free radical scavenging activity (RC50 values ranging from 2.00 to 4.7 x 10(-4) mg/mL), and Alliaria petiolata, Prunus padus and Prunus spinosa were the most potent antioxidant extracts. The DCM extracts of 17 species showed similar levels of activity, and among those, Prunus padus and Prunus spinosa extracts were the most active with RC50 values of 2.5 x 10(-4) and 5.0 x 10(-4) mg/mL, respectively. The n-hexane extracts were much less active than the MeOH and DCM extracts, and 17 species, with the exception of Glechoma hederacea (RC50 = 1.94 x 10(-4)) displayed low to moderate levels of free radical scavenging property (RC50 values ranging from 2.00 to 8.7 x 10(-3) mg/mL).

The assessment of biological activities associated with the major constituents of the methanol extract of 'wild carrot' (Daucus carota L) seeds.

Daucus carota L. (Family: Apiaceae alt. Umbelliferae), commonly known as 'wild carrot' or 'Queen Anne's-lace,' is an ecologically invasive erect biennial naturalized to Scotland. The ethnobotanical uses of this species include applications in the treatment of cough, diarrhea, dysentery, cancer, malaria and tumors, and as an antiseptic, abortifacient, aphrodisiac, carminative, stimulant, stomachic and tonic. The major constituents isolated from the methanol extract of D. carota seeds by reversed-phase preparative high performance chromatography were luteolin, luteolin 3'-O-beta-D-glucopyranoside and luteolin 4'-O-beta-D-glucopyranoside, three flavones. The constituents were assessed for their antibacterial and free radical scavenging activities, as well as toxicity towards brine shrimp. Among these three flavones, luteolin showed the highest degree of free radical scavenging activity (RC50 = 4.3 x 10(-4) mg/mL) in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Both luteolin and its 4'-O-glucoside demonstrated bactericidal activity against Staphylococcus aureus and Escherichia coli (Minimum Inhibitory Concentration [MIC] = 5.0 x 10(-2) - 1.0 x 10(-1) mg/mL). Luteolin also demonstrated antibactericidal activity against Bacillus cereus and Citrobacter freundii (MIC = 5.0 x 10(-2) mg/mL). Luteolin 3'-O-glucoside showed bactericidal activity against Bacillus cereus and Lactobacillus plantarum (MIC = 2.5 x 10(-1) mg/mL and 5 x 10(-1) mg/ mL, respectively). In the brine shrimp lethality assay, the LD50 value of luteolin was 5.3 x 10(-2) mg/mL, and that of its 3'-O-glucoside and 4'-O-glucoside were > 1.0 mg/mL.

Iridoid glycosides from Eremostachys glabra.

Reversed-phase preparative HPLC of a methanol extract of the rhizomes of Eremostachys glabra yielded three new iridoid glycosides, namely, 6,9-epi-8-O-acetylshanziside methyl ester, 5,9-epi-penstemoside, and 5,9-epi-7,8-didehydropenstemoside. Their structures were elucidated on the basis of spectroscopic data interpretation. The free-radical scavenging activity of these compounds was assessed using the DPPH assay.

The supramolecular structure of 6-hydroxy-1,3-benzoxathiol-2-one (tioxolone).

The planar molecules of 6-hydroxy-1,3-benzoxathiol-2-one, C(7)H(4)O(3)S, are linked by extensive O-H.O and C-H.O hydrogen bonding and are further stablilized by face-to-face pi-pi interactions.

New salicylic acid and isoflavone derivatives from Flemingia paniculata.

A new salicylic acid derivative, 2-carboxy-3-(2-hydroxypropanyl)phenol (1), and four new isoflavones, 5,7,4'-trihydroxy-8-(1,1-dimethylprop-2-enyl)isoflavone (2), 5,7,2',4'-tetrahydroxy-8-(1,1-dimethylprop-2-enyl)isoflavone (3), 5,2',4'-trihydroxy-4' ',4' ',5' '(xi)-trimethyl-4' ',5' '-dihydrofurano-(7,6,2' ',3' ')isoflavone (4), and 5,2',4'-trihydroxy-7-(3-methylbut-2-enyloxy)isoflavone (5), were isolated from the stem bark of Flemingia paniculata. The structures of these compounds were established unambiguously by spectroscopic data interpretation. The biogenetic pathways to 1 and 2-4 have been postulated.