A common problem with vegetable production in saline areas is poor crop stand, but for black cumin (
Nigella sativa
L.) germination data are limited and inconsistent. The effects of chemical priming ...with Urmia lake salt and urea solutions for 16 h at 30 °C on seed germination and seedling growth of black cumin (
Nigella sativa
L.) were studied under various osmotic stress levels. For a more detailed assessment of chemical priming, the effects of hydropriming for 16 h at 30 °C were also studied. A seed lot that was not exposed to any treatment, except disinfection, was used as control. Osmotic stress levels were − 2, − 4, − 6, and − 8 bar, which were achieved with polyethylene glycol 6000 (PEG 6000). Seed germination of black cumin was reduced by 16.2%, 33.8%, 50.9%, and 74.9% under osmotic potential − 2, − 4, − 6, and − 8 bar, respectively, compared with non-stressed control. Improved germination index values, reduced mean germination time, and increased coefficients of velocity of germination were observed under osmotic stress in primed seeds compared with non-primed control. Averaged over priming treatments, priming improved the final germination percentage by 10.5%, 24.3%, 45.5%, and 74.6% under osmotic potential − 2, − 4, − 6, and − 8 bar, respectively. Post-germination growth was also inhibited under low osmotic potential compared with the non-stressed control. Nevertheless, priming improved length and weight of black cumin seedlings and enhanced peroxidase and catalase activity at all osmotic potential levels compared with non-primed seeds. Higher seedling vigor indices were recorded in seedlings from primed seeds with decreasing osmotic potential levels than non-primed seeds. Urmia lake salt priming had the greatest impact on improving seed germination and vigor indices, especially under osmotic stress conditions. Although seed priming did not completely eliminate the symptoms of osmotic stress in black cumin germination, it is an efficient method to mitigate the impact of osmotic stress on germination of this species.
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•PEG 6000/CO2 system was used as a model to investigate thermodynamic and transport data.•Density, viscosity and interfacial tension of CO2 saturated PEG 6000 solution were ...measured.•Interfacial tension and viscosity were correlated with particle size and particle morphology.
In our study, a PEG 6000/CO2 system was used as a model in order to investigate basic thermodynamic and transport data such as density, viscosity and interfacial tension of a CO2 saturated PEG 6000 solution. Additionally, particle size and particle morphology were correlated for the first time with the interfacial tension and viscosity of a PEG 6000 CO2 saturated solution. Binary systems were measured at four temperatures: 333 K, 343 K, 353 K and 363 K from ambient pressure up to pressure of 35 MPa. Density increases linearly with increasing pressure and is significantly reduced with increasing temperature at isobaric conditions. Interfacial tension is reduced when the pressure increases; on the other hand, temperature effect is minimal. Temperature variation has a significant effect on viscosity reduction. The addition of CO2 and consequently increasing pressure result in even lower viscosity.
Abstract
Objective: To compare various solubilizing agents for their solubilizing propensity as well as effect of pH, concentration and time on solubility of a highly hydrophobic drug.
Materials and ...methods: Dendrimers were synthesized by divergent method. Solubilization studies were carried out at different pH, concentration and time using Paclitaxel (PTX) as model drug. Hemolytic toxicity study was also performed.
Results: The solubility of PTX was increased with increasing concentration of solubilizing agents and the order of solubility enhancement effect of different solubilizing agents was found to be in the following order: fifth generation (5.0 G) poly(propylene imine) (PPI) dendrimers > β-CD > Tween 80 > polyethylene glycol 6000. The solubility of PTX was found to be highest at pH 5.0 followed by pH 7.4 than pH 9.2. The result of hemolytic toxicity studies displayed that when these solubilizing agents are given in combination with PTX, the toxicity was found to be reduced as compare to plain drug.
Conclusions: The solubility of PTX was found to be significantly higher in the presence of 5.0 G PPI dendrimers as compared to the other solubilizing agents. It is also concluded that 5.0 G PPI dendrimers not only enhanced the solubility of PTX many folds but also reduced the toxicity of PTX.
The present work aimed to evaluate the osmotic conditioning and shading on the germination and on the initial growth of aroeira seedlings. The seeds were pre-imbibed in solutions with different ...concentrations of PEG (polyethylene glycol) and KNO3 and incubated at 10°C and 20°C temperatures, during 0 (control), 12 and 24 hours. After these periods, the seeds were dried until they reached the initial levels of humidity. After that, they were put for germinating in BOD (Biochemical Oxygen Demand) chambers, at alternated 20-30°C. The control treatment and the pre-conditionings that presented the best results in BOD germination were selected, PEG (-1.0 MPa) + KNO3 (-1.0 MPa) and KNO3 (-1.0 MPa), with pre-imbibition for 12 h and incubated in BOD at 20°C. The seeds were sowed on trays and then they were transplanted, keeping under a net covered with 50% and 70% of shading and at sunlight. The osmotic conditioning did not change the seeds germination in BOD, but the highest aerial part size was observed in PEG -1.0 MPa + KNO3-1.0 MPa treatment. The shading levels at 50% and 70% and the osmotic conditioning with PEG -1.0 MPa + KNO3-1.0 MPa offered a higher emergence in a greenhouse condition; however, at sunlight the seeds presented a better index of quality on the 145th day.
Water stress caused by drought affects the productivity of the sugarcane crop. A breeding alternative is the selection of drought-tolerant sugarcane cultivars. The objective of this study was the in ...vitro screening of cultivars tolerant to water stress using polyethylene glycol (PEG) as a stressing agent. Cultivars (cv) Mex 69-290, CP 72-2086, Mex 79-431 and MOTZMex 92-207 were subjected to different concentrations of PEG 6000 (0, 3, 6 and 9% w/v) using Murashige and Skoog semi-solid culture medium. At 30 days of culture, different developmental variables and dry matter (DM), total protein (TP), proline (Pr) and glycine-betaine (GB) contents were evaluated. The results showed reduced development in cv CP 72-2086, Mex 79-431 and MOTZMex 92-207 with increasing PEG concentration. The cv Mex 69-290 showed tolerance to osmotic stress of −0.45 MPa using 3% PEG. Overall, TP content decreased with increasing PEG concentration, while DM, Pr and GB contents rose with increasing PEG concentration in all evaluated cultivars. Our results suggest that cv Mex 69-290 has a slight tolerance to water stress and could be used for rainfed cultivation with low rainfall or reduced irrigation for better water use efficiency. In conclusion, the in vitro screening technique of cultivars tolerant to PEG-induced water stress is an alternative for early determination of drought stress in sugarcane.
In the present study, solid dispersions of ibuprofen were prepared to improve aqueous solubility of ibuprofen. A series of formulations were prepared where PEG 6000 with polymers named PVP K30, cross ...PVP, poloxamer 237, HPMC ASLF, pregelatinized starch, Na-CMC, Eudragit L100, and kollidon IR were used in different ratios. Among 41 formulations, solid dispersions of ibuprofen in PEG 6000 with each of PVP K30, poloxamer 237, and Na-CMC at ratio of 2:9:7 revealed improved solubility of 952.73 ± 1.31, 878.18 ± 0.97, and 1263.64 ± 1.58 μg/ml, respectively. The physicochemical properties of these preparations were ascertained by FTIR, SEM, DSC, and particle size analyses. FTIR spectrum showed absence of chemical interactions and physical compatibilities between ibuprofen and polymers were confirmed by DSC. Disappearance of individual surface properties in solid dispersions were revealed by SEM studies, which indicated the formation of effective preparations. On the other hand, particle size analysis showed reduction in particle size of ibuprofen from solid dispersions that demonstrated solubility enhancement of ibuprofen. The above studies suggested that solid dispersions of ibuprofen in PEG 6000 at ratios of 2:9:7 with each of PVP K30, poloxamer 237, and Na-CMC were found to be effective to improve aqueous solubility.
Dhaka Univ. J. Pharm. Sci. 17(2): 183-190, 2018 (December)
Water deficient or drought stress is a major factor causing deterioration or instability of malt barley quality. In the studies on the influence of drought stress during grain filling on malt quality ...formation or metabolic changes, it is quite difficult to obtain the uniform plant individuals and water condition in pot or field experiments. In this study, we combined barley spike in vitro culture and PEG-6000 simulated drought to determine the genotypic difference in the changes of grain metabolites and the expression level of the genes encoding β-amylase and β-glucan using two Tibetan wild barley accessions and two cultivated genotypes differing in malt quality stability under drought stress. Under simulated drought, grain weight and β-glucan content were dramatically reduced and β-amylase activity was increased, and a lot of metabolites were markedly changed for all genotypes. On the whole, the changes were relatively smaller in the wild barley. Meanwhile, the expressions of
Bmy1
related to β-amylase synthesis and
GSL1, GSL4
and
GSL7
related to β-glucan synthesis were up-regulated and down-regulated under drought stress, respectively, being consistent with the changes of β-amylase activity and β-glucan content in the four barley genotypes. The current results showed that PEG-6000 simulated drought and spike in intro culture may provide the basically similar information on grain development or metabolites as do in the field experiments, and it is suitable for use in studies on the influence of drought stress on quality traits during grain filling stage of barley or other cereal crops.
► In this study ALA-pretreated cucumber seedlings were exposed to PEG-induced drought stress. ► ALA pretreatment increased antioxidant activities in drought-stressed leaves. ► ALA also improved ...growth inhibition and decreased ROS levels under drought stress. ► ALA mitigated drought stress through regulating antioxidant activities. ► ALA had an application potential in alleviating drought stress.
To promote the application of 5-aminolevulinic acid (ALA) in agricultural production, a cucumber variety (
Cucumis sativus L. cv. Yuexiu no. 3) was pretreated with 3
μM ALA for 2
d and then was exposed to drought stress induced by 10% polyethylene glycol (PEG) 6000. We investigated whether exogenous ALA could protect cucumbers from drought stress and whether the protective effect was associated with the regulation of antioxidant enzymes. After 2
d of ALA pretreatment, no changes were observed in plant growth indexes including plant heights and the fresh and dry weights of shoots and roots and the second leaves. Meanwhile, we obtained the increased activities of superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (GPX, EC 1.11.1.7), glutathione peroxidase (GSH-Px, EC 1.11.1.9), ascorbate peroxidase (APX, EC 1.11.1.11), glutathione reductase (GR, EC 1.6.4.2), and monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) in ALA-pretreated leaves and as well got the elevated content of reduced glutathione (GSH). When the ALA-pretreated plants were subjected to drought, the antioxidants changed further. Drought stress increased the activities of SOD, catalase (CAT, EC 1.11.1.6), GPX, GSH-Px, APX, GR, dehydroascorbate reductase (DHAR, EC 1.8.5.1) and MDHAR in leaves and also enhanced the contents of GSH and ascorbate. However, the combination of ALA pretreatment and drought enhanced the antioxidant activities even more. Moreover, drought decreased plant growth indexes, resulted in 83.3% withered leaves and increased the levels of superoxide radical (O
2
−) and hydrogen peroxide (H
2O
2) in leaves. When ALA pretreatment was combined with drought, we observed the improved growth inhibition and 48.2% withered leaves, and found the decreased levels of O
2
− and H
2O
2 in comparison to non-pretreated stressed plants. We propose that exogenous ALA can regulate antioxidant activities, which are altered further after ALA pretreatment is combined with PEG-induced drought stress; thus ALA pretreatment protects cucumbers from drought stress.
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