HPLC-DAD Analysis and Versatile Bioactivities of Turkish Sunflower Honeys Using Chemometric Approaches

Sunflower honey (SH) is bright yellow, fragrant, pollen-flavoured, slightly herbaceous and has a unique taste. The present research aims to examine the enzyme inhibitory, antioxidant, anti-inflammatory, antimicrobial and anti-quorum sensing activities and phenolic compositions of 30 sunflower honeys (SHs) produced from several regions of Turkey with chemometric study. SAH from Samsun exhibited the best antioxidant activity in β-carotene linoleic acid (IC₅₀: 7.33±0.17 mg/mL) and CUPRAC (A_0.50: 4.94±0.13 mg/mL) assays, anti-urease activity (60.63±0.87 %) and anti-inflammatory activity against COX-1 (73.94±1.08 %) and COX-2 (44.96±0.85 %). SHs exhibited mild antimicrobial activity against the test microorganisms while they showed high quorum sensing inhibition zones measured in the range of 42–52 mm against the CV026 strain. The phenolic composition was determined by high performance liquid chromatography with diode array detection (HPLC-DAD) system and levulinic, gallic, p-hydroxybenzoic, vanillic and p-coumaric acids were identified in all studied SHs. The classification of SHs was performed the using PCA and HCA. This study revealed that phenolic compounds and biological properties are effective in classification of SHs according to their geographical origin. The results suggest that studied SHs could be valued as potential agents with versatile bioactivities in oxidative stress-related disease, microbial infections, inflammation, melanoma, and peptic ulcer.     

Adequate magnesium nutrition mitigates adverse effects of heat stress on maize and wheat

Aims

Heat stress is a growing concern in crop production because of global warming. In many cropping systems heat stress often occurs simultaneously with other environmental stress factors such as mineral nutrient deficiencies. This study aimed to investigate the role of adequate magnesium (Mg) nutrition in mitigating the detrimental effects of heat stress on wheat (Triticum aestivum) and maize (Zea mays).

Methods

Wheat and maize plants were grown in solution culture with low or adequate Mg supply at 25/22 °C (light/dark). Half of the plants were, then, exposed to heat stress at 35/28 °C (light/dark). Development of leaf chlorosis and changes in root and shoot growth, chlorophyll and Mg concentrations as well as the activities of major antioxidative enzymes were quantified in the experimental plants. Additionally, maize plants were analyzed for the specific weights (e.g., dry or fresh weight per a given leaf surface area) and soluble carbohydrate concentrations of sink and source leaves.

Results

Visual leaf symptoms of Mg deficiency were aggravated in wheat and maize when exposed to heat stress. In both species, root growth was more sensitive to Mg deficiency than shoot growth, and the shoot-to-root ratios peaked when heat stress was combined with Mg deficiency. Magnesium deficiency markedly reduced soluble carbohydrate concentrations in young leaf; but resulted in substantial increase in source leaves. Magnesium deficiency also increased activities of antioxidative enzymes, especially when combined with heat stress. The highest activities of superoxide dismutase (up to 80 % above the control), glutathione reductase (up to 250 % above the control) and ascorbate peroxidase (up to 300 % above the control) were measured when Mg-deficient plants were subjected to heat, indicating stimulated formation of reactive oxygen species (ROS) in Mg deficient leaves under heat stress.

Conclusions

Magnesium deficiency increases susceptibility of wheat and maize plants to heat stress, probably by increasing oxidative cellular damage caused by ROS. Ensuring a sufficiently high Mg supply for crop plants through Mg fertilization is a critical factor for minimizing heat-related losses in crop production.     

L-Cysteine influx and efflux: a possible role for red blood cells in regulation of redox status of the plasma

The objective of this study was to investigate if erythrocytes play a role in the maintenance of redox homeostasis of the plasma. Thus, we studied L-cysteine efflux and influx in vitro in human erythrocytes. In the present study, we exposed the erythrocytes to different concentrations of L-cysteine and then measured the intracellular free -SH concentrations. Erythrocytes treated in the same manner were later utilized for the cysteine efflux studies. The effect of temperature on the influx and the efflux processes were also evaluated. Change in the free -SH content of the buffer was evaluated as a measure for the presence of an efflux process. The effects of free -SH depletion on L-cysteine transport is also investigated. We also determined the rate of L-cysteine efflux in the presence and absence of buthionine sulfoximine (BSO) in erythrocytes that are pretreated with 1-chloro-2,4-dinitro benzene, a glutathione (GSH) depletory. Our L-cysteine influx studies demonstrated that erythrocytes can respond to increases in L-cysteine concentration in the extracellular media and influx L-cysteine in a concentration-dependent manner. Free -SH concentrations in erythrocytes treated with 1 mM L-cysteine reached to 1.64 +/- 0.06 mM in 1 h whereas this concentration reached to 4.30 +/- 0.01 mM in 10 mM L-cysteine treated erythrocytes. The L-cysteine efflux is also determined to be time-and concentration-dependent. Erythrocytes that are pretreated with higher L-cysteine concentrations displayed a higher efflux process. Outside concentration of free -SH in 1 mM L-cysteine pretreated erythrocytes reached to 0.200 +/- 0.005 mM in 1 h whereas this concentration reached to 1.014 +/- 0.002 with 10 mM L-cysteine pretreated erythrocytes. Our results also indicate that the rate of inward and outward transport of L-cysteine is affected by the oxidative status of the erythrocytes. When GSH is depleted and GSH synthesis is blocked, the L-cysteine uptake and the efflux processes are significantly decreased. Depending on our results, it could be concluded that erythrocytes play a role in the regulation of the plasma redox status and intracellular level of GSH determines the rate of the L-cysteine efflux.     

Proteomic insight into phenolic adaptation of a moderately halophilic Halomonas sp. strain AAD12

A gram-negative, moderately halophilic bacterium was isolated from ?amalt? Saltern area, located in the Aegean Region of Turkey. Analysis of its 16S rRNA gene sequence and physiological characteristics showed that this strain belonged to the genus Halomonas ; hence, it was designated as Halomonas sp. strain AAD12. The isolate tolerated up to 800 mg?L(-1) phenol; however, at elevated concentrations, phenol severely retarded cell growth. The increase in lag phase with increasing phenol concentrations indicated that the microorganism was undergoing serious adaptative changes. To understand the physiological responses of Halomonas sp. strain AAD12 to phenol, a 2-dimensional electrophoresis approach combined with mass spectrometric analysis was used. This approach showed that the expression of 14 protein spots were altered as phenol concentration increased from 200 to 800 mg?L(-1). Among the identified proteins were those involved in protein biosynthesis, energy, transport, and stress metabolism. So far, this is the first study on phenolic adaptation of a gram-negative, moderately halophilic bacteria using proteomic tools. The results provided new insights for understanding the general mechanism used by moderately halophilic bacteria to tolerate phenol and suggested the potential for using these microorganisms in bioremediation.     

Secretory Expression of Human Vascular Endothelial Growth Factor (VEGF165) in Kluyveromyces lactis and Characterization of Its Biological Activity

International Journal of Peptide Research and Therapeutics - Vascular endothelial growth factor 165 (VEGF165) is the best characterized member and most potent endothelial cell mitogenic factor...     

Evaluation of Essential and Toxic Trace Elements in Pseudoexfoliation Syndrome and Pseudoexfoliation Glaucoma

Pseudoexfoliation syndrome (PEX), an age-related disorder of the eye, is associated with significant ophthalmic morbidity and can lead to pseudoexfoliation glaucoma (PEG). The etiology of this disorder has not been clearly understood. Trace elements have been suggested to have roles in the pathogenesis of several disorders. This study aimed to determine whether trace element levels have a role in the development of PEX and/or PEG. Levels of zinc (Zn), copper (Cu), selenium (Se), manganese (Mn), chromium (Cr), cobalt (Co), molybdenum (Mo), nickel (Ni), vanadium (V), arsenic (As), aluminum (Al), mercury (Hg), cadmium (Cd), and strontium (Sr) were determined in serum samples of 32 cases of PEX, 30 cases of PEG, and 32 control subjects using inductively coupled plasma–mass spectrometry. Mn, Mo, and Hg concentrations were found to be significantly increased in patients with PEX. Logistic regression revealed Mn and Hg as the strongest determinants of PEX and Mo as the strongest determinant of PEG in the studied Turkish subjects. Levels of Mn, Cr, Co, Mo, Al, Hg, Sr, Ni, V, and As were determined for the first time in these ophthalmological disorders. Increased levels of serum Mn, Mo, and Hg suggest a possible role of these elements in the pathobiology of PEX.     

In vitro and in vivo effects of iron on the expression and activity of glucose 6‐phosphate dehydrogenase, 6‐phosphogluconate dehydrogenase,and glutathione reductase in rat spleen

Iron is an indispensable element for vital activities in almost all living organisms. It is also a cofactor for many proteins, enzymes, and other essential complex biochemical processes. Therefore, iron trafficking is firmly regulated by Hepcidin (Hamp), which is regarded as the marker for iron accumulation. The disruption of iron homeostasis leads to oxidative stress that causes various human diseases, but this mechanism is still unclear. The aim of this study is to provide a better in vivo and in vitro understanding of how long‐term iron overload affects the gene expression and activities of some antioxidant enzymes, such as glucose 6‐phosphate dehydrogenase (G6PD), 6‐phosphogluconate dehydrogenase (6PGD), and glutathione reductase (GR) in the spleen. The findings of this study show that iron overload reduces the gene expression of G6pd, 6pgd, and Gr, but its actual effect was on the protein level.