The effects of sodium nitroprusside (SNP; nitric oxide donor) treatment on drought stress induced by PEG for different periods of time in wheat seedlings were investigated. Our results suggested that treatment for 2, 4 and 6 d with 15 % PEG could be termed as mild, moderate and severe stress, respectively. Drought stress induced accumulation of hydrogen peroxide and resulted in lipid peroxidation. On the other hand, activities of SOD, CAT and PAL increased under mild stress to counteract the oxidative injury and then decreased when the stress became severe (6 d). As the effect of SNP treatment, 0.2 mM enhanced wheat seedlings growth and kept high relative water content and alleviated the oxidative damage. However, 2 mM SNP aggravated the stress as a result of uncontrolled generation of reactive oxygen species and ineffectiveness of antioxidant systems.Additional key words: ascorbate peroxidase, catalase, guaiacol peroxidase, L-phenylalanine ammonia lyase, reactive oxygen species, superoxide dismutase, Triticum aeslivum. ⎯⎯⎯⎯Drought stress is one of the main causes for crop yield reduction in the majority of agricultural regions of the world (Bajaj et al. 1999). A common effect of drought stress is the disturbance between the generation and quenching of reactive oxygen species (ROS) (Smirnoff 1998). ROS are highly reactive and in the absence of effective protective mechanism, can seriously damage plants by lipid peroxidation, protein degradation, breakage of DNA and cell death (Beligni and Lamattina 1999). Plant cells can tolerate ROS by endogenous protective mechanisms involving nonenzymic as well as enzymatic systems (Asada 1994).Many previous studies have reported presence of NO in the plant kingdom and its involvement in growth, development and defense responses (Beligni and Lamattina 1999). Tu et al. (2003) found that 0.1 mM SNP delayed the senescence of wheat leaves by inhibition of the degradation of chlorophyll and soluble proteins, especially Rubisco, while 0.5 mM would accelerate the process. However, there is very little information about the effect of exogenously applied NO and drought stress in wheat seedlings. In this study, we used SNP as NO donor to determine the effect of NO on drought stress induced by PEG treatment in wheat seedlings.Selected wheat (Triticum aestivum L. cv. W7) seeds, provided by Dr. T. Wang, Chengdu Institute of Biology, CAS, were surface sterilized with 0.1 % HgCl 2 (m/v) for 3 min, washed thoroughly under tap water and finally with distilled water. Then they were sown in silicon sands and after germination the seedlings were cultivated in phytotron, with day/night temperature of 22/18 °C and a 14-h photoperiod with irradiance of 120 µmol m -2 s -1(determined by CI-301PS, CID Inc., Vancouver, Washington, USA) provided by fluorescence lamps at 400 -700 nm and a relative humidity of 60 %. The seedlings were irrigated with half strength Hoagland's solution containing 0, 0.2, 2 mM SNP respectively. After complete extension of the second leaf, the seedlings were treated wi...

The aims of this study were to complement the current knowledge on the antioxidative composition of alcohol extracts from the fruits of Lycium barbarum and to evaluate their antioxidant activities. Three new dimers of phenolic amides, named lyciumamides A (3), B (4), and C (5), together with two monomers, N-E-coumaroyl tyramine (1) and N-E-feruloyl tyramine (2), were isolated from the fruits for the first time with the help of activity-guided chromatography. Compounds 1-5 were evaluated for their antioxidant activities in scavenging 2,2-diphenyl-1-picrylhydrazyl free radical and inhibiting lipid peroxidation in rat liver microsomes induced by ascorbate/Fe, cumine hydroperoxide, or CCl/reduced form of nicotinamide-adenine dinucleotide phosphate, and the results showed that all of them exhibited strong activities, whereas compounds 1 and 2 were more potent than the reference tert-butyl-4-hydroxyanisole.

Ten new polyhydroxysteroidal glycosides, anthenosides B-K (2-11), were isolated from the ethanol extract of the starfish Anthenea chinensis. Their structures were elucidated by extensive spectroscopic studies and chemical evidence. The unprecedented carbohydrate chain 6-O-methyl-beta-d-galactofuranosyl-(1-->3)-(6-O-methyl-beta-d-galactofuranose) was present in all the compounds except compounds 10 and 11. Compounds 5, 7, a mixture of 8 and 9, and a mixture of 10 and 11 showed inhibitory activity against human tumor K-562 and BEL-7402 cells. Furthermore, the mixture of 10 and 11 also exhibited cytotoxicity against human tumor U87MG cells and promoted tubulin polymerization.

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Saponins are natural glycosides consisting of a triterpene or steroid aglycone with a range of pharmacological properties such as significant anti-tumor activity. In this article, we review our recent progress in the studies of the saponins possessing anticancer effects, especially anti-glioblastoma effects from twelve species of marine organisms and terrestrial plants. The anti-glioblastoma active saponins discovered by other researchers in recent decades are also reviewed and compared. Systematic extraction, isolation and structural elucidation on the saponin constituents from three species of starfishes, five species of sea cucumbers and four species of medicinal plants led to the identification of more than 129 saponins, among which 76 saponins are new compounds. Most of the new compounds were found to possess relatively rare structural features showing in vitro cytotoxicity against tumor cells, especially glioblastoma cells. Several saponins exhibited significant anti-glioblastoma effects in vivo by in situ administration (interstitial chemotherapy) and their haemolytic side effects were avoided in the tests. Multiple mechanisms of action, such as interfering with cell cycle progression, inducing apoptosis, promoting stabilization of microtubule, as well as several signal transduction pathways, were involved in their anticancer effects. The review provided valuable leads for pursuing new anti-glioblastoma drugs, and established a new viewpoint for further development of these marine and terrestrial organisms. The successful approach to administrate saponins in situ conquered the bottleneck in the development of saponins as new drugs- haemolytic effects. It means that saponins may be developed as potential chemotherapeutic agents in pursuing new antiglioblastoma drugs.

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The objective of this study is to utilize an expanded granular sludge bed reactor for removing heavy metals and sulfate from synthetic acid-mine drainage (AMD) using sewage sludge fermentation centrate as the substrate. The reactor was bioaugmented with an enriched consortium of sulfate-reducing bacteria (SRB). The bioreactor performance was studied with different chemical oxygen demand [Formula: see text] ratios, liquid upflow velocity (V), hydraulic retention time (HRT) and influent pH. The highest COD, sulfate and heavy metal removal efficiencies were achieved at a [Formula: see text] ratio of 1.5, V of 4.0 m/h, HRT of 15 h and influent pH of 6.0 (68.2%, 92.1% and 100%, respectively). The activity of SRB greatly increases the effluent pH. Even at an influent pH of 3.0, 60.8% of sulfate, 41.3% of COD and 91.2% of heavy metals could be removed, and the effluent quality can meet the national discharge standard of China. The activity tests demonstrate that the sludge fermentation centrate is an excellent carbon source for SRB. This study shows the potential of synchronous treatment of residual sewage sludge and treatment of AMD.

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