Role of Antioxidant Phytochemicals in Prevention, Formation and Treatment of Cancer

Reactive oxygen species (ROS) played an important role in cancer. Although low levels of ROS can be beneficial in normal physiological functions, chronic exposure to ROS is associated with increased risk of cancers. Increased ROS levels can also induce apoptosis and cell death in various types of cancer. Taken together, the role of ROS in cancer prevention, formation and therapy is extremely complex and very challenging to study. Although the antioxidant activity of phytochemicals is well recognized and generally used to prevent cancer, they can have pro-oxidant and ROS generating activities under certain conditions, especially at high doses or in the presence of metal ions. The basal redox levels of cancer cells are also different from those of normal cells. Therefore, higher levels of free form of metal ions and higher levels of endogenous ROS production in cancer cells sensitizes them to phytochemicals mediated pro-oxidant cytotoxicity. In conclusion, people tend to intake of antioxidant phytochemicals for the detrimental effects of ROS. However, excessive intake of phytochemicals could have cancer development or therapeutic potential by generating ROS. In this section, the role of phytochemicals in the prevention, development and removal of cancer has been discussed

Regulation of growth and some key physiological processes in salt-stressed maize (Zea mays L.) plants by exogenous application of asparagine and glycerol

Maize seedlings were subjected to concentrations of 0 and 100mM of NaCl in Hoagland’s nutrient solution medium in plastic pots containing perlite. Two levels of asparagine (5 and 10 mM) and glycerol (20 and 40 mM) were sprayed onto the leaves of maize seedlings 10 days after germination. Saline stress caused considerable decline in total dry mass, chlorophyll content and relativewater content in the maize plants. It increased the activities of superoxide dismutase, catalase and polyphenol oxidase as well as electrolyte leakage, but did not alter the activity of non-specific peroxidise. Foliar application of asparagine or glycerol was found to be effective in checking shoot growth inhibition under NaCl stress. Exogenously applied asparagine or glycerol reduced superoxide dismutase, non-specific peroxidase and polyphenol oxidase activities in salt-stressed maize plants compared to those not treated with these organic compounds. Salinity increased Na+ contents but reduced those of K+, Ca2+ and P in the roots of the used genotype of maize. Foliar application of asparagine or glycerol increased the contents of K+, Ca2+ and P, but it reduced that of Na+ in salt-stressed maize plants as compared to those of the salt-stressed plants not supplied with glycerol or asparagine. Glycerol was more effective than asparagine in improving salinity tolerance of maize plants in terms of growth and physiological attributes measured in the present study

Effectiveness of water pillow irrigation method on yield and water use efficiency on hot pepper (Capsicum annuum L.)

A study was conducted to elucidate the effect of water pillow (WP) irrigation method, a new alternative method to furrow irrigation, on the yield and water use efficiency (WUE) of hot pepper in a semi-arid climatic condition. In this research, treatments used were: (i) WP method and its 7-day irrigation interval (WP(7)) (ii) WP method and its 9-day irrigation interval (WP(9)), (iii) WP method and its 11-day irrigation interval (WP(11)) and (iv) furrow irrigation (FI) method and its 5-day irrigation interval (control) were employed. Although the plants were grown under different irrigation methods and interval conditions, there were no statistical differences in yield and biomass of hot pepper plants between FI and WP treatments (P < 0.05). Water use efficiency (WUE) and irrigation water use efficiency (IWUE) values significantly increased with the application of WP irrigation method (P < 0.05). The highest WUE and IWUE values obtained from WP(11) treatment in both years. As a result, we conclude that WP method is a way to save water and increase the yield in semi-arid areas where climatic conditions require repeated irrigation in the hot pepper production area. (C) 2008 Elsevier B.V. All rights reserved

POTENTIAL OF PSEUDOMONAS AND BACILLUS ISOLATES AS BIOCONTROL AGENTS AGAINST FUSARIUM WILT OF EGGPLANT

Plant growth-promoting rhizobacteria (PGPR) are beneficial bacteria found on plant roots that induce growth by a wide variety of mechanisms. Ten isolates of Pseudomonas and Bacillus were isolated from eggplant rhizosphere soil and evaluated for their volatile compound efficacy against mycelial growth of Fusarium oxysporum f. sp. melongenae (Fomg) and tested for their ability to colonize eggplant (Solanum melongena L) roots in vitro. PGPR strains inhibited mycelial growth of the target pathogen and the percentage of inhibition varied from 38 % to 72 % by means of inhibitory activities. Pseudomanas aeruginosa (P07-1) and putida (P11-4) were determined to be successful colonizers in eggplant seedlings. Also, a pot experiment was conducted to assess the induced resistance to Fusarium wilt of eggplant by PGPR strains. Among the PGPR isolates, P aeruginosa (P07-1), P putida (P11-4), P aeruginosa (85A-2), Bacillus amyloliquefaciens (76A-1) and B. cereus (B10a) significantly reduced Fusarium wilt disease incidence by up to 85 %. However, their combination was not more effective in suppressing the disease than the application of those isolates alone. The induction of peroxidase (PDX EC 1.11.1.7) and polyphenol oxidase (PPO, EC 1.14.18.1) enzymes was found to be significantly higher in comparison with the control group. Similarly, the proline levels in eggplants showed an increasing trend with the above isolates. However, catalase (CAT, 1.11.1.6) activity was not found to significantly contribute to the induced resistance mechanism. This study revealed that the promising PGPR isolates could be potentially very useful for the biocontrol of Fomg via enhancing disease resistance in eggplant plants

Screening of rhizobacteria against Fusarium oxysporum f. sp melongenae, the causal agent of wilt disease of eggplant

Rhizosphere isolates of Bacillus and Pseudomonas species isolated from the roots of eggplants (Solanum melongena L.) were collected in eggplant cultivated areas in various geographical districts of Turkey. Isolates were evaluated for siderophore, protease and cyanide production along with the cell wall degrading enzyme production as well as phosphate solubilizing and nitrogen fixing capacities. The isolates showing good performance were tested against Fusarium oxysporum f. sp. melongenae, a highly destructive fungal agent for eggplants, for the antagonistic activities. The isolates designated as 11-4, 13-1, 56K-3, 65A-3, 67A-2, 76A-1, 85A-2, 10a, 318b, 346a, 379c, 007-1, 007-4, and 048-2 were found promising in inhibition of F. oxysporum f. sp. melongenae in vitro conditions. The isolates differing in their antagonistic responses to F. oxysporum f. sp. melongenae would be identified in species level. Also, the best performing isolates for the reduction of disease severity and increased plant growth would be further evaluated via more biochemical parameters such as indole acetic acid production (IAA) and total antioxidant status (TAS)

Water pillow irrigation compared to furrow irrigation for soybean production in a semi-arid area

Field studies were done in 2003 and 2006 to evaluate the performance of water pillow (WP) irrigation as an alternative to furrow irrigation (FI) for soybean growth in semi-arid climatic conditions. There were four irrigation treatments: two of which (FI and WP(1.0)) were full irrigation, in that the water deficit in the soil profile (0.9 m) was brought to field capacity in 10-day intervals. The other two treatments (WP(0.75) and WP(0.50)) were deficit irrigation treatments, and received 75% and 50% of WP(1.0) irrigation amount. The highest seed yield was achieved with the WP(1.0) treatment. Irrigation water use efficiency (IWUE) and water use efficiency (WUE) were influenced significantly by the irrigation methods and levels (P <= 0.05). The highest values of WUE and IWUE were obtained by the WP(0.75) and WP(0.50) treatment, respectively, in both study years. However, the smallest irrigation amount resulted in lower total yield for the WP(0.50) treatment, and is not recommended. in conclusion, the WP(0.75) treatment is recommended for soybean production in order to attain higher values of IWUE and WUE, and to conserve water and maximize yield with the same volume of water. (C) 2008 Elsevier B.V. All rights reserved