Constitutive Glycolytic Metabolism Supports CD8+ T Cell Effector Memory Differentiation during Viral Infection.

Extensive metabolic changes accompany T cell activation, including a switch to glycolytic energy production and increased biosynthesis. Recent studies suggest that subsequent return to reliance on oxidative phosphorylation and increasing spare respiratory capacity are essential for the differentiation of memory CD8+ T cells. In contrast, we found that constitutive glycolytic metabolism and suppression of oxidative phosphorylation in CD8+ T cells, achieved by conditional deletion of hypoxia-inducible factor regulator Vhl, accelerated CD8+ memory cell differentiation during viral infection. Despite sustained glycolysis, CD8+ memory cells emerged that upregulated key memory-associated cytokine receptors and transcription factors and showed a heightened response to secondary challenge. In addition, increased glycolysis not only permitted memory formation, but it also favored the formation of long-lived effector-memory CD8+ T cells. These data redefine the role of cellular metabolism in memory cell differentiation, showing that reliance on glycolytic metabolism does not hinder formation of a protective memory population.

Determining the Nutrient Content of Hydroponically-Cultivated Microgreens with Immersible Silicon Photonic Sensors: A Preliminary Feasibility Study.

Microgreens have gained attention for their exceptional culinary characteristics and high nutritional value. The present study focused on a novel approach for investigating the easy extraction of plant samples and the utilization of immersible silicon photonic sensors to determine, on the spot, the nutrient content of microgreens and their optimum time of harvest. For the first time, it was examined how these novel sensors can capture time-shifting spectra caused by the molecules' dynamic adhesion onto the sensor surface. The experiment involved four types of microgreens (three types of basil and broccoli) grown in a do-it-yourself hydroponic installation. The sensors successfully distinguished between different plant types, showcasing their discriminative capabilities. To determine the optimum harvest time, this study compared the sensor data with results obtained through standard analytical methods. Specifically, the total phenolic content and antioxidant activity of two basil varieties were juxtaposed with the sensor data, and this study concluded that the ideal harvest time for basil microgreens was 14 days after planting. This finding highlights the potential of the immersible silicon photonic sensors for potentially replacing time-consuming analytical techniques. By concentrating on obtaining plant extracts, capturing time-shifting spectra, and assessing sensor reusability, this research paves the way for future advancements in urban farming.

S-2-hydroxyglutarate regulates CD8+ T-lymphocyte fate.

R-2-hydroxyglutarate accumulates to millimolar levels in cancer cells with gain-of-function isocitrate dehydrogenase 1/2 mutations. These levels of R-2-hydroxyglutarate affect 2-oxoglutarate-dependent dioxygenases. Both metabolite enantiomers, R- and S-2-hydroxyglutarate, are detectible in healthy individuals, yet their physiological function remains elusive. Here we show that 2-hydroxyglutarate accumulates in mouse CD8+ T cells in response to T-cell receptor triggering, and accumulates to millimolar levels in physiological oxygen conditions through a hypoxia-inducible factor 1-alpha (HIF-1α)-dependent mechanism. S-2-hydroxyglutarate predominates over R-2-hydroxyglutarate in activated T cells, and we demonstrate alterations in markers of CD8+ T-cell differentiation in response to this metabolite. Modulation of histone and DNA demethylation, as well as HIF-1α stability, mediate these effects. S-2-hydroxyglutarate treatment greatly enhances the in vivo proliferation, persistence and anti-tumour capacity of adoptively transferred CD8+ T cells. Thus, S-2-hydroxyglutarate acts as an immunometabolite that links environmental context, through a metabolic-epigenetic axis, to immune fate and function.

Chemical Characterization, Antioxidant and Antimicrobial Properties of Different Types of Tissue of Cedrus brevifolia Henry Extracts.

This study aimed to determine the chemical composition of different types of tissue of Cedrus brevifolia Henry (Pinaceae) methanolic extracts, namely needles, twigs, branches, and bark. Cedrus brevifolia is a narrow endemic coniferous tree species of Cyprus, growing in a sole population in the mountainous area of Paphos Forest. Chemical analysis of the extracts was performed using liquid chromatography combined with time-of-flight high-resolution mass spectrometry (LC/Q-TOF/HRMS). The majority of the 36 compounds tentatively identified belonged to the flavonoids family. The extract of needles was the richest extract in terms of secondary metabolites. The extracts were studied for their antioxidant activity using the DPPH free radical scavenging assay. Additionally, the antibacterial activity was evaluated by determining both the minimum inhibitory concentration and the minimum bactericidal concentration against Staphylococcus aureus and Escherichia coli. All extracts demonstrated antioxidant property, while bark gave the highest antioxidant capacity (IC50 value of 0.011 mg/mL) compared to the other tissues. Antibacterial activity was observed against both types of bacteria, with the extract of branches presenting the strongest activity against S. aureus (MIC, 0.097 mg/mL and MBC, 0.195 mg/mL). This is the first time that extracts of needles, twigs, branches, and bark of C. brevifolia are compared regarding their chemical composition as well as their antimicrobial and antioxidant properties.

Cytotoxic Effect of Rosmarinus officinalis Extract on Glioblastoma and Rhabdomyosarcoma Cell Lines.

Rosmarinus officinalis is a well-studied plant, known for its therapeutic properties. However, its biological activity against several diseases is not known in detail. The aim of this study is to present new data regarding the cytotoxic activity of a hydroethanolic extract of Rosmarinus officinalis on glioblastoma (A172) and rhabdomyosarcoma (TE671) cancer cell lines. The chemical composition of the extract is evaluated using liquid chromatography combined with time-of-flight mass spectrometry, alongside its total phenolic content and antioxidant activity. The extract showed a promising time- and dose-dependent cytotoxic activity against both cell lines. The lowest IC50 values for both cell lines were calculated at 72 h after treatment and correspond to 0.249 ± 1.09 mg/mL for TE671 cell line and 0.577 ± 0.98 mg/mL for A172 cell line. The extract presented high phenolic content, equal to 35.65 ± 0.03 mg GAE/g of dry material as well as a strong antioxidant activity. The IC50 values for the antioxidant assays were estimated at 12.8 ± 2.7 µg/mL (DPPH assay) and 6.98 ± 1.9 µg/mL (ABTS assay). The compound detected in abundance was carnosol, a phenolic diterpene, followed by the polyphenol rosmarinic acid, while the presence of phenolic compounds such as rhamnetin glucoside, hesperidin, cirsimaritin was notable. These preliminary results suggest that R. officinalis is a potential, alternative source of bioactive compounds to further examine for abilities against glioblastoma and rhabdomyosarcoma.

Crocins, the Bioactive Components of Crocus sativus L., Counteract the Disrupting Effects of Anesthetic Ketamine on Memory in Rats.

Consistent experimental evidence suggests that anesthetic doses of the non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist ketamine cause severe memory impairments in rodents. Crocins are among the various bioactive ingredients of the plant Crocus sativus L., and their implication in memory is well-documented. It has not yet been elucidated if crocins are able to attenuate the memory deficits produced by anesthetic ketamine. The present study was undertaken aiming to clarify this issue in the rat. For this aim, the object recognition, the object location and the habituation tests, reflecting non-spatial recognition memory, spatial recognition memory and associative memory, respectively, were utilized. A post-training challenge with crocins (15-30 mg/kg, intraperitoneally (i.p.), acutely) counteracted anesthetic ketamine (100 mg/kg, i.p.)-induced performance impairments in all the above-mentioned behavioral memory paradigms. The current findings suggest that crocins modulate anesthetic ketamine's amnestic effects.

Response Surface Methodology to Optimize the Isolation of Dominant Volatile Compounds from Monofloral Greek Thyme Honey Using SPME-GC-MS.

This study aimed at an experimental design of response surface methodology (RSM) in the optimization of the dominant volatile fraction of Greek thyme honey using solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). For this purpose, a multiple response optimization was employed using desirability functions, which demand a search for optimal conditions for a set of responses simultaneously. A test set of eighty thyme honey samples were analyzed under the optimum conditions for validation of the proposed model. The optimized combination of isolation conditions was the temperature (60 °C), equilibration time (15 min), extraction time (30 min), magnetic stirrer speed (700 rpm), sample volume (6 mL), water: honey ratio (1:3 v/w) with total desirability over 0.50. It was found that the magnetic stirrer speed, which has not been evaluated before, had a positive effect, especially in combination with other factors. The above-developed methodology proved to be effective in the optimization of isolation of specific volatile compounds from a difficult matrix, like honey. This study could be a good basis for the development of novel RSM for other monofloral honey samples.

Chemometric Study of Fatty Acid Composition of Virgin Olive Oil from Four Widespread Greek Cultivars.

Virgin olive oil (VOO) is one of the key components of the Mediterranean diet owing to the presence of monounsaturated fatty acids and various bioactive compounds. These beneficial traits, which are usually associated with the cultivar genotype, are highlighting the demand of identifying characteristics of olive oil that will ensure its authenticity. In this work, the fatty acid (FA) composition of 199 VOO samples from Koroneiki, Megaritiki, Amfissis, and Manaki cultivars was determined and studied by chemometrics. Olive cultivar greatly influenced the FA composition, namely, oleic acid (from 75.36% for Amfissis to 65.81% for Megaritiki) and linoleic acid (from 13.35% for Manaki to 6.70% for Koroneiki). Spearman's rho correlation coefficients revealed differences and similarities among the olive oil cultivars. The use of the forward stepwise algorithm identified the FAs arachidonic acid, gadoleic acid, linoleic acid, α-linolenic acid, palmitoleic acid, and palmitic acid as the most significant for the differentiation of samples. The application of linear and quadratic cross-validation discriminant analysis resulted in the correct classification of 100.00% and 99.37% of samples, respectively. The findings demonstrated the special characteristics of the VOO samples derived from the four cultivars and their successful botanical differentiation based on FA composition.

Botanical origin discrimination of Greek honeys: physicochemical parameters versus Raman spectroscopy.

BACKGROUND: The authenticity of honey is of high importance since it affects its commercial value. The discrimination of the origin of honey is of prime importance to reinforce consumer trust. In this study, four chemometric models were developed based on the physicochemical parameters according to European and Greek legislation and one using Raman spectroscopy to discriminate Greek honey samples from three commercial monofloral botanical sources. RESULTS: The results of physicochemical (glucose, fructose, electrical activity) parameters chemometric models showed that the percentage of correct recognition fluctuated from 92.2% to 93.8% with cross-validation 90.6-92.2%, and the placement of test set was 79.0-84.3% successful. The addition of maltose content in the previous discrimination models did not significantly improve the discrimination. The corresponding percentages of the Raman chemometric model were 95.3%, 90.6%, and 84.3%. CONCLUSION: The five chemometric models developed presented similar and very satisfactory results. Given that the recording of Raman spectra is simple, fast, a minimal amount of sample is needed for the analysis, no solvent (environmentally friendly) is used, and no specialized personnel are required, we conclude that the chemometric model based on Raman spectroscopy is an efficient tool to discriminate the botanical origin of fir, pine, and thyme honey varieties. © 2020 Society of Chemical Industry.

Quantitative determination of aloin, antioxidant activity, and toxicity of Aloe vera leaf gel products from Greece.

BACKGROUND: Aloe vera is a popular medicinal plant used widely by the cosmetic, pharmaceutical, and food industries. The A. vera leaf gel, which is used mostly for its positive effects on human health, contains over 75 different bioactive compounds, including aloin. Aloin is a toxic compound, and its content in A. vera leaf gel products depends on the different cultivation conditions and especially on leaf processing. RESULTS: In this study, A. vera leaf gel products, varied in terms of leaf processing, were analyzed using liquid chromatography for their aloin content, their antioxidant activity by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS·+ ) and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH· ) antioxidant activity assays and their toxicity against Aliivibrio fisheri and SH-SY5Y cells. In the samples processed with industrial methods and in those filtered in the lab, the content of aloin was found below the limit (0.1 mg L-1 ) of the EU legislation however, the unprocessed and unfiltered samples were found to contain more than 10 mg L-1 . Antioxidant activity was estimated to vary from 1.64 to 9.21 µmol Trolox mL-1 for DPPH· and from 0.73 to 5.14 µmol Trolox mL-1 for ABTS·+ . Toxicity values on A. fisheri, expressed as the concentration at 50% loss of initial luminescence, ranged from 0.03 to 0.09 mg mL-1 . The cytotoxic study indicated that aloin A at low concentrations (1 and 10 µg mL-1 ) protects SH-SY5Y cells from toxicity induced by hydrogen peroxide. CONCLUSIONS: Consequently, the filtration process of A. vera leaf gels, either laboratory or industrial, resulted in aloin A content below the EU legislation detection limits. © 2020 Society of Chemical Industry.

Discrimination of botanical origin of olive oil from selected Greek cultivars by SPME-GC-MS and ATR-FTIR spectroscopy combined with chemometrics.

BACKGROUND: Consumers today wish to know the botanical origin of the olive oil they purchase. The objective of the present study was the development of robust chemometric models based on gas chromatography-mass spectrometry (GC-MS) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) for the purpose of botanical differentiation of three commercial Greek olive oil cultivars. RESULTS: Using the solid-phase microextraction technique (SPME), volatile compounds (VC) were obtained and analyzed by GC-MS. Five hydrocarbons and one ester were selected by the forward stepwise algorithm, which best discriminated the olive oil samples. From ATR-FTIR analysis, the spectral regions chosen from the forward stepwise algorithm were associated with CO stretching vibration of the esters of triglycerides and the CH bending vibrations of the CH2 aliphatic group and double bonds. Application of the supervised methods of linear and quadratic discriminant cross-validation analysis, based on VC data, provided a correct classification score of 97.4% and 100.0%, respectively. Corresponding statistical analyses were used in the mid-infrared spectra, by which 96.1% of samples were discriminated correctly. CONCLUSION: ATR-FTIR and SPME-GC-MS techniques in conjunction with the appropriate feature selection algorithm and classification methods proved to be powerful tools for the authentication of Greek olive oil. The proposed methodology could be used in an industrial setting for determination of the botanical origin of Greek olive oil. © 2020 Society of Chemical Industry.

Rapid screening on aflatoxins' presence in Pistachia vera nuts using diffuse reflectance infrared Fourier transform spectroscopy and chemometrics.

Aflatoxin contamination in pistachios has been analyzed in this work, using Diffuse Reflectance Infrared Spectroscopy (DRIFTS) with chemometrics. Forty-nine Greek pistachio samples of different aflatoxin concentrations were classified into aflatoxin and non-aflatoxin groups using the 3035-2821, 1770-1721, 1570-1481 and 1260-1061 cm-1 spectral regions in Kubelka-Munk conversion and first derivative form. A chemometric model was developed using twenty-eight samples as calibration, 11 as validation and 10 as test set. The discrimination analysis separated correctly the 100% of the calibration and the validation set and the 80% of the test set. The proposed chemometric model is simple, rapid, economical and environmentally friendly since it does not require chemical pre-treatment of the samples. It is expected that the present method may be proved useful in food industry and the inspection authorities as a rapid decision-making tool to detect batches that must be rejected and enhance consumers' protection from aflatoxin contaminated pistachios.

The GABAA-Benzodiazepine Receptor Antagonist Flumazenil Abolishes the Anxiolytic Effects of the Active Constituents of Crocus sativus L. Crocins in Rats.

Anxiety is a chronic severe psychiatric disorder. Crocins are among the various bioactive components of the plant Crocus sativus L. (Iridaceae) and their implication in anxiety is well-documented. However, which is the mechanism of action underlying the anti-anxiety effects of crocins remains unknown. In this context, it has been suggested that these beneficial effects might be ascribed to the agonistic properties of these bioactive ingredients of saffron on the GABA type A receptor. The current experimentation was undertaken to clarify this issue in the rat. For this research project, the light/dark and the open field tests were used. A single injection of crocins (50 mg/kg, i.p., 60 min before testing) induces an anti-anxiety-like effect revealed either in the light-dark or open field tests. Acute administration of the GABAA-benzodiazepine receptor antagonist flumazenil (10 mg/kg, i.p., 30 min before testing) abolished the above mentioned anxiolytic effects of crocins. The current findings suggest a functional interaction between crocins and the GABAA receptor allosteric modulator flumazenil on anxiety.

Crocins from Crocus sativus L. in the Management of Hyperglycemia. In Vivo Evidence from Zebrafish.

Diabetes mellitus is a disease characterized by persistent high blood glucose levels and accompanied by impaired metabolic pathways. In this study, we used zebrafish to investigate the effect of crocins isolated from Crocus sativus L., on the control of glucose levels and pancreatic ß-cells. Embryos were exposed to an aqueous solution of crocins and whole embryo glucose levels were measured at 48 h post-treatment. We showed that the application of crocins reduces zebrafish embryo glucose levels and enhances insulin expression. We also examined whether crocins are implicated in the metabolic pathway of gluconeogenesis. We showed that following a single application of crocins and glucose level reduction, the expression of phosphoenolpyruvate carboxykinase1 (pck1), a key gene involved in glucose metabolism, is increased. We propose a putative role for the crocins in glucose metabolism and insulin management.

Characterization of the chemical composition of Drimia numidica plant parts using high-resolution mass spectrometry: study of their total phenolic content and antioxidant activity.

Drimia species have been used since ancient times for their medicinal properties. Their bulbs are considered as the main source of secondary metabolites with biological activity but the chemical composition of the other plant parts has not yet been considered. The aim of this study is to contribute to the existing knowledge with new data on the total phenolic content, the antioxidant activity and the chemical profile of different parts of Drimia numidica. The total phenolic content was estimated by the Folin-Ciocalteu assay and the antioxidant activity with DPPH· and ABTS·+ reagents. The separation and the identification of the compounds were performed with liquid chromatography combined with time-of-flight high-resolution mass spectrometry (LC/Q-TOF/HRMS). The extract of leaves presented the highest phenolic content while the highest antioxidant activity was presented by the extract of flowers. Results of the chemical analysis verify the presence of bufadienolides and phenolic compounds. Graphical abstract.

Effects of the active constituents of Crocus sativus L. crocins and their combination with memantine on recognition memory in rats.

Crocus sativus L., is a plant cultivated in many countries of the world. Crocins are among the active constituents of C. sativus and their implication in cognition has been proposed. The present study was designed to investigate in the rat the effects of crocins on distinct recognition memory components (encoding, storage and retrieval). Subsequently, the potential use of crocins as adjunctive agents for the treatment of memory disorders was examined. Thus, the effects exerted by a combination of subthreshold doses of crocins and memantine on recognition memory were evaluated. To assess the effects of compounds on memory, the novel object-recognition task (NORT) was used. In a preliminary study, the influence of the retention time (the delay between the two trials) on the performance of rats was assessed. Rats' recognition memory abilities remained intact up to 6 h, but were extinguished when a delay of 24 h was utilized. Crocins, at any dose tested (5, 15, and 30 mg/kg), did not affect rats' performance, whereas administration of higher doses (15 and 30 mg/kg) reversed delay-dependent deficits in the NORT. The combination of subthreshold doses of crocins (5 mg/kg) and memantine (3 mg/kg) did not influence the performance, but counteracted delay-dependent deficits in the NORT. These findings suggest that crocins counteract natural forgetting and may modulate different aspects of recognition memory, and that the combined use of crocins and memantine might represent a novel strategy to treat memory disorders.

Conductive polymer-based bioelectrochemical assembly for in vitro cytotoxicity evaluation: Renoprotective assessment of Salvia officinalis against carbon tetrachloride induced nephrotoxicity.

BACKGROUND: The rise of organic electronics represents one of the most prominent technological developments of the last two decades, with its interface with biological systems highlighting new directions of research. The "soft" nature of conducting polymers renders them unique platforms for cell-based microdevices, allowing their implementation in drug discovery, pharmaceutical effect analysis, environmental pollutant testing etc. METHODS: Cellular adhesion, proliferation and viability experiments were carried out to verify the biocompatibility of a PEDOT conductive polymer surface. Cyclic voltammetry was employed for estimating the electrocatalytic activity of the renal cell/electrode interface. The nephrotoxicity agent CCl4 and the medicinal plant Salvia officinalis were used on the proposed assembly. Renal cell viability was also assayed through the MTT assay. RESULTS: Renal cells were able to adhere and proliferate on the conducting polymer surface. Electrochemical responses of the polymer exhibited good correlation with cell number and CCl4 concentration. Amelioration of the CCl4-induced renotoxicity by co-incubation with Salvia officinalis extract was demonstrated by both the MTT assay and the electrode's capacitance. CONCLUSIONS: A conducting polymer-based bioelectrochemical assembly was established for in vitro mammalian cytotoxicity/cytoprotection assessment, employing renal cell monolayers as the primary transducers for signal generation and biological sensing. GENERAL SIGNIFICANCE: The knowledge on PEDOT mammalian cell biocompatibility and possible applications was expanded. The proposed interdisciplinary approach connects soft electronics with biology and could provide a useful tool for preliminary crude drug screening and bioactivity studies of natural products or plant extracts in vitro.

Special Issue "Saffron (Crocus sativus, L.): Omics and Other Techniques in Authenticity, Quality, and Bioactivity Studies".

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Oxidovanadium(IV/V) complexes as new redox mediators in dye-sensitized solar cells: a combined experimental and theoretical study.

Corrosiveness is one of the main drawbacks of using the iodide/triiodide redox couple in dye-sensitized solar cells (DSSCs). Alternative redox couples including transition metal complexes have been investigated where surprisingly high efficiencies for the conversion of solar to electrical energy have been achieved. In this paper, we examined the development of a DSSC using an electrolyte based on square pyramidal oxidovanadium(IV/V) complexes. The oxidovanadium(IV) complex (Ph4P)2[V(IV)O(hybeb)] was combined with its oxidized analogue (Ph4P)[V(V)O(hybeb)] {where hybeb(4-) is the tetradentate diamidodiphenolate ligand [1-(2-hydroxybenzamido)-2-(2-pyridinecarboxamido)benzenato}and applied as a redox couple in the electrolyte of DSSCs. The complexes exhibit large electron exchange and transfer rates, which are evident from electron paramagnetic resonance spectroscopy and electrochemistry, rendering the oxidovanadium(IV/V) compounds suitable for redox mediators in DSSCs. The very large self-exchange rate constant offered an insight into the mechanism of the exchange reaction most likely mediated through an outer-sphere exchange mechanism. The [V(IV)O(hybeb)](2-)/[V(V)O(hybeb)](-) redox potential and the energy of highest occupied molecular orbital (HOMO) of the sensitizing dye N719 and the HOMO of [V(IV)O(hybeb)](2-) were calculated by means of density functional theory electronic structure calculation methods. The complexes were applied as a new redox mediator in DSSCs, while the cell performance was studied in terms of the concentration of the reduced and oxidized form of the complexes. These studies were performed with the commercial Ru-based sensitizer N719 absorbed on a TiO2 semiconducting film in the DSSC. Maximum energy conversion efficiencies of 2% at simulated solar light (AM 1.5; 1000 W m(-2)) with an open circuit voltage of 660 mV, a short-circuit current of 5.2 mA cm(-2), and a fill factor of 0.58 were recorded without the presence of any additives in the electrolyte.

Interaction of chromium(III) with a N,N'-disubstituted hydroxylamine-(diamido) ligand: a combined experimental and theoretical study.

Reaction of hydroxylamine hydrochloride with prop-2-enamide in dichloromethane in the presence of triethylamine resulted in the isolation of the N,N'-disubstituted hydroxylamine-(diamido) ligand, 3,3'-(hydroxyazanediyl)dipropanamide (Hhydia). The ligand Hhydia was characterized by multinuclear NMR, high-resolution electrospray ionization mass spectrometry (ESI-MS), and X-ray structure analysis. Interaction of Hhydia with trans-[Cr(III)Cl2(H2O)4]Cl·2H2O in ethanol yields the ionization isomers [Cr(III)(Hhydia)2]Cl3·2H2O(1·2H2O) and cis/trans-[Cr(III)Cl2(Hhydia)2]Cl·2H2O (2·2H2O). The X-ray structure analysis of 1 revealed that the chromium atom in [Cr(III)(Hhydia)2](3+) is bonded to two neutral tridentate O,N,O-Hhydia ligands. The twist angle, θ, in [Cr(III)(Hhydia)2](3+) is 54.5(6)(0), that is, very close to an ideal octahedron. The intramolecular hydrogen bonds developed between the N-OH group of the first ligand and the amidic oxygen atom of the second ligand and vice versa contribute to the overall stability of the cation [Cr(III)(Hhydia)2](3+). The reaction rate constant of the formation of Cr(III) complexes 1·2H2O and 2·2H2O was found to be 8.7(±0.8) × 10(-5) M(-1) s(-1) at 25 °C in methyl alcohol and follows a first-order law kinetics based on the biologically relevant ligand Hhydia. The reaction rate constant is considerably faster in comparison with the corresponding water exchange rate constant for the hydrated chromium(III). The modification of the kinetics is of fundamental importance for the chromium(III) chemistry in biological systems. Ultraviolet-visible and electron paramagnetic resonance studies, both in solution and in the solid state, ESI-MS, and conductivity measurements support the fact that, irrespective of the solvent used in the interaction of Hhydia with trans-[Cr(III)Cl2(H2O)4]Cl·2H2O, the ionization isomers[Cr(III)(Hhydia)2]Cl3·2H2O (1·2H2O) and cis/trans-[Cr(III)Cl2(Hhydia)2]Cl·2H2O (2·2H2O) are produced.The reaction medium affects only the relevant percentage of the isomers in the solid state. The thermodynamic stability of the ionization isomers 1·2H2O and cis/trans-2·2H2O, their molecular structures as well as the vibrational spectra and the energetics of the Cr(III)- Hhydia/hydia(-) were studied by means of density functional theory calculations and found to be in excellent agreement with our experimental observations.