Search Results (33)

Microalgae represent promising biotechnological platforms for bioactive compound production with pharmaceutical applications. This study investigated the phytochemical composition and biological activities of lipid extracts from three Chlorella species to evaluate their potential as antioxidant and antidiabetic sources. Lipid extraction using chloroform–methanol (2:1) followed by GC–MS analysis revealed distinct compound distributions: 29 compounds in C. ellipsoidea, 33 in C. sorokiniana, and 19 in C. vulgaris. Major bioactive compounds included 2-hexanol, 1,3,6-heptatriene, 4-(2,3-dimethyl-2-cyclopenten-1-yl)-4-methylpentanal, n-hexadecanoic acid, and octadecanoic acid. Biological activity screening encompassed antioxidant assessment through DPPH• and •NO radical scavenging assays and FRAP analysis, while antidiabetic potential was evaluated using α-glucosidase and α-amylase inhibition assays. C. sorokiniana exhibited superior bioactivity with the highest antioxidant capacity (DPPH• IC₅₀ = 329.03 ± 4.30 µg/mL; •NO IC₅₀ = 435.53 ± 10.20 µg/mL; FRAP = 94.74 ± 5.72 mg TE/g) and strongest enzyme inhibition (α-glucosidase IC₅₀ = 752.75 ± 57.95 µg/mL; α-amylase IC₅₀ = 3458.50 ± 104.01 µg/mL). This is the first report on C. sorokiniana strain KU.B2′s biological properties and phytochemical profile. These findings establish C. sorokiniana as a valuable biotechnological platform for pharmaceutical bioactive compound development. Full article

This study aims to evaluate the effect of extraction solvent type on the physicochemical properties and bioactive compounds of Actinostemma lobatum Maxim. kernel oil for two successive harvest years. Oils were extracted using the bio-based solvent 2-methyltetrahydrofuran (2-MeTHF) and conventional petroleum-derived solvents (n-hexane and 2-methylpentane). Results indicated that 2-MeTHF achieved significantly higher oil yields (27.60% in 2021 and 29.77% in 2022) compared to n-hexane and 2-methylpentane. Unfortunately, 2-MeTHF-extracted oils exhibited greater susceptibility to oxidation, displaying elevated levels of primary and secondary oxidation products relative to other solvents. Meanwhile, 2-methylpentane-extracted oil showed a relatively high oxidative stability index. In addition, differential scanning calorimetry results also aligned with the oxidative status. Further variance analysis revealed that the harvest year exerted a more pronounced impact on fatty acid and triacylglycerol profiles than the solvent type. Additionally, tocopherols and tocotrienols were abundant, with β- and δ-tocopherols predominating. 2-MeTHF-extracted oils harvested in 2022 contained the highest total tocols (1118.83 mg/kg) among all samples. Also, phytosterols were detected, with β-sitosterol constituting the predominant compound. Furthermore, the 2-MeTHF-extracted oils contained higher β-carotene contents compared to other samples. These above findings concluded that 2-MeTHF is a good alternative to conventional solvents for extracting of A. lobatum kernel oil. Full article

This study evaluates the influence of terroir on the physico-chemical characteristics and aromatic profiles of Fetească albă wines from five major Romanian wine regions. By analysing key factors such as soil types, climatic conditions, and winemaking techniques, the study aims to understand their impact on wine composition and quality. The study includes the analysis of superior alcohols, fatty acids, esters, carbonyl compounds, terpenes, and 4-mercapto-4-methylpentan-2-one, which are essential in defining the aromatic complexity of the wines. The results show how fermentation conditions, temperature control, microbial activity, and oxidative exposure contribute to the evolution of these compounds, influencing the sensory profiles. Significant differences in compound concentrations were observed across the regions, with wines from Dealu Mare and Murfatlar exhibiting high ester content and aromatic complexity, while those from Dealul Bujorului and Panciu showed elevated volatile acids and aromatic alcohols, suggesting distinct fermentation dynamics. Climatic factors, such as temperature and precipitation, played a crucial role in shaping the volatile composition, with elevated temperatures in 2021 enhancing ester formation and higher alcohol production. This study demonstrates the critical role of terroir and winemaking practices in shaping the aromatic and sensory characteristics of Romanian Fetească albă wines. Full article

The effect of electron-donating and electron-withdrawing groups grafted onto polyethylene on electron mobility was studied using density functional theory. In order to ensure the accuracy of the calculation results, 17 basis sets from six methods were screened. 3-methylpentane was selected as the cross-linked polyethylene model. Compared with the experimental values, the theoretical calculation results show that wB97XD/6-311G(d,p) is more suitable for studying the electron mobility system. The roles of electron-donating and electron-withdrawing functional groups were studied. The results show that the electron mobility of grafting nitrobenzene (Ebnb) to polyethylene is the smallest among the studied molecules. As the ability of electron-donating groups increases, the electron mobility gradually increases, while the addition of the electron-withdrawing group reduces the electron mobility and the electron mobility gradually increases with increasing temperature. This investigation is expected to provide reliable information for the development of insulation materials for cables. Full article

The present study comprises the second part of our previous work that dealt mainly with the phytochemical and physicochemical characterization of commercial unroasted green coffee beans, clove, cinnamon–clove and nutmeg ethanolic extracts of grape origin. In the present study, we focused on producing a discriminating model concerning commercial unroasted green coffee beans, clove, cinnamon, cinnamon and clove mixture (1:1, w/w), and nutmeg fine powders based on multivariate analysis of variance and supervised learning from tentative data of volatile compounds analysis, carried out with solid phase dynamic extraction in combination with gas chromatography–mass spectrometry. Results showed that 7 volatile compounds, i.e., ethylene, methanol, 3-methylpentane, ethyl acetate, 9-hexadecen-1-ol, toluene, and methyl acetate, could differentiate the investigated samples resulting in a 100% classification rate using the cross-validation method of linear discriminant analysis. Results were further confirmed using partial least squares regression analysis. The study contributes to the typification of commercial unroasted green coffee beans, cinnamon, clove, cinnamon and clove mixture, and nutmeg, based on selected volatile compounds. In addition, the study provides further support to the literature by means of a possible substitution of these products in rapid analysis tests, given the statistical models developed. Full article

In the current work, the non-invasive approach of breath analysis is implemented for the first time in an eccentric exercise protocol that investigated the effect of spirulina supplementation on exercise-induced oxidative stress. We assessed whether volatile alkanes in exhaled breath can serve as alternative biomarkers of oxidative stress. A randomized, double-blinded, placebo-controlled, crossover supplementation study was carried out enrolling 14 participants. The volunteers consumed 42 mg·kg⁻¹ body weight of either Spirulina Nigrita^® or maltodextrin, as a placebo, daily for 15 days. Afterward, they followed a damaging eccentric exercise protocol of the upper limbs. Expired breath samples were collected from them just before supplementation (baseline measurement), prior to exercise, and 1 h, 24 h, 48 h, and 72 h after exercise. The samples were analyzed by Gas Chromatography/Mass Spectrometry (GC-MS) coupled with a thermal desorption unit (TDU) to determine the alveolar gradient (AG) of several alkanes, C5–C14, that are known to be related to oxidative stress. Apart from breath analysis, TBARSs were also determined as a crude marker of lipid peroxidation. Two-way repeated measures ANOVA tests were applied to the alkanes’ AGs between the spirulina (SPI) and placebo (PL) groups across time. In the PL group, a trend of increasing almost all alkanes immediately after exercise, with a gradual return to pre-exercise levels up to 72 h later was revealed. A statistically significant time effect was observed for 2-methylhexane, 3-methylhexane, heptane, octane, and undecane. The administration of spirulina appeared to reduce the increases in alkanes after exercise, and a statistically significant attenuation was observed for 2-methylpentane and 2-methylhexane. An examination of TBARSs confirmed that the reduced increases observed in the SPI group were due to changes in lipid peroxidation, while a positive correlation between the iAUC of TBARSs and that of 2-methylhexane and 3-methylhexane was revealed. In conclusion, the analysis of volatile alkanes in exhaled breath may serve as an attractive alternative for assessing redox changes after eccentric exercise compared to traditional blood biomarkers. Full article

Hydrotalcite-derived materials are eco-friendly, cheap, and efficient catalysts of different reactions. However, their application in liquid-phase hydrogenation could be more extensive. Hence, this work concerns the application of three hydrotalcite-derived materials with different CuZnAl molar ratios in the liquid-phase continuous-flow hydrogenation of 2-methyl-2-pentenal (MPEA) at a wide range of temperature (298–378 K) and pressure (1 × 10⁶–6 × 10⁶ Pa). The catalytic investigations were supported by catalysts characterization by ICP-OES, TPR, in situ XRD, XPS, NH₃-TPD, CO₂-TPD, and TEM measurements on different stages of their biography. It was shown that the catalytic activity of these samples is related to the Cu⁰/Cu⁺ ratio. Depending on the reaction conditions, selectivity control is possible. All catalysts were 100% selective to 2-methylpentanal (MPAA)—sedative drug precursor, with low conversion, at temperatures ≤ 338 K at every pressure. However, the selectivity of the second desired product, fragrance intermediate, 2-methyl-2-penten-1-ol (MPEO), increased significantly at higher temperatures and pressures. It reached the unique value of 54% with 60% substrate conversion at 378 K and 6 × 10⁶ Pa for the catalyst with the highest Cu loading. It was revealed that the production of significant amounts of MPEO is related to the reaction conditions, the Cu⁺ predominance on the surface, the hydrogen spillover effect, and the acid–base properties of these systems. Full article

A new chloroquine-derived photoaffinity probe has been prepared by a convergent synthesis from derivative of 4,7-dichloroquinoline and N1,N1-diethyl-N4-methylpentane. The features of this probe are a unique 3-azido photolabel, the pyridine ring of the quinoline, and the presence of a secondary amine at the 4-position of the quinoline. These features, particularly the 4-amino methylation, prevent triazole formation through combination of the 3-azide and the 4-amine. This undergoes facile cleavage with exposure to a medium-pressure mercury lamp with a 254 nm excitation wavelength. Trapping of the nitrene byproduct is accomplished with its reaction with N-phenylmaleimide as its cycloazidation product. The structure of a ring-opened DBU amine has been structurally characterized. Full article

In the search for new alternative biocontrol strategies, phytopathogenic fungi could represent a new frontier for weed management. In this respect, as part of our ongoing work aiming at using fungal pathogens as an alternative to common herbicides, the foliar pathogen Nigrospora sphaerica has been evaluated to control buffelgrass (Cenchrus ciliaris). In particular, in this work, the isolation and structural elucidation of two new biosynthetically related metabolites, named nigrosphaeritriol (3-(hydroxymethyl)-2-methylpentane-1,4-diol) and nigrosphaerilactol (3-(1-hydroxyethyl)-4-methyltetrahydrofuran-2-ol), from the phytotoxic culture filtrate extract were described, along with the identification of several known metabolites. Moreover, the absolute stereochemistry of (3R,4S,5S)-nigrosphaerilactone, previously reported as (3S,4R,5R)-4-hydroxymethyl-3,5-dimethyldihydro-2-furanone, was determined for the first time by X-ray diffraction analysis. Considering their structural relationship, the determination of the absolute stereochemistry of nigrosphaerilactone allowed us to hypothesize the absolute stereochemistry of nigrosphaeritriol and nigrosphaerilactol. Full article

Two strains of Saccharomyces cerevisiae (Sc01 and Sc02) and one strain of Wickerhamomyces anomalus (Wa) were isolated from organic Verdejo spontaneous fermentations and used for the development of experimental winemaking. Sc01 and Sc02 represented 52.7% of the population of the Saccharomyces strains isolated throughout the fermentation process. W. anomalus appeared as the predominant species among the non-Saccharomyces yeasts. Wa turned out to be the strain of this species with the shortest lag phase and positive enzymatic activities, and it was selected for white wine production. Fermentations with unique inoculation of S. cerevisiae strains were compared with sequential inoculation with W. anomalus. The results showed that the sequential inoculations did not affect the fermentation kinetics or physicochemical characteristics of the wines compared with the unique inoculations. However, this study identified a significant impact on the aromatic profiles of the produced wines due to the sequential inoculations. This modification resulted in a similar new aromatic profile in both sequential inoculations, demonstrating common characteristics related to the contribution of W. anomalus. In general, the sequential fermentations were mainly characterized by lower levels of acetate esters and an increase in ethyl acetate levels, whereas lower levels of ethyl octanoate and ethyl dec-9-enoate were detected. Propan-1-ol and butan-1-ol showed an increase in the sequential fermentations, while 4-methylpentan-1-ol and 2-phenylethanol were found in lower concentrations. These results highlight the great influence that the presence of specific strains of native non-Saccharomyces yeasts exerts on the characteristics of elaborate wines. Full article

Breath volatile organic compound (VOC) analysis is a non-invasive tool for assessing health status; the compositional profile of these compounds in the breath of patients with chronic kidney disease is believed to change with decreasing renal function. We aimed to identify breath VOCs for recognizing patients with chronic kidney disease. Using thermal desorption–gas chromatography/mass spectrometry, untargeted analysis of breath markers was performed using breath samples of healthy controls (n = 18) versus non-dialysis (n = 21) and hemodialysis (n = 12) patients with chronic kidney disease in this cross-sectional study. A total of 303 VOCs alongside 12 clinical variables were used to determine the breath VOC profile. Metabolomic analysis revealed that age, systolic blood pressure, and fifty-eight breath VOCs differed significantly between the chronic kidney disease group (non-dialysis + hemodialysis) and healthy controls. Thirty-six VOCs and two clinical variables that showed significant associations with chronic kidney disease in the univariate analysis were further analyzed. Different spectra of breath volatile organic compounds between the control and chronic kidney disease groups were obtained. A multivariate model incorporating age, 2-methyl-pentane, and cyclohexanone showed high performance (accuracy, 86%) in identifying patients with chronic kidney disease with odds ratios of 0.18 (95% CI, 0.07–2.49, p = 0.013); 2.10 (0.94–2.24, p = 0.025); and 2.31 (0.88–2.64, p = 0.008), respectively. Hence, this study showed that renal dysfunction induces a characteristic profile of breath VOCs that can be used as non-invasive potential biomarkers in screening tests for CKD. Full article

While the use of l-proline-derived peptides has been proven similarly successful with respect to enantioselectivity, the physico-chemical and conformational properties of these organocatalysts are not fully compatible with transition state and intermediate structures previously suggested for l-proline catalysis. l-Proline or l-4-hydroxyproline catalysis is assumed to involve proton transfers mediated by the carboxylic acid group, whereas a similar mechanism is unlikely for peptides, which lack a proton donor. Herein, we prepared an array of hydroxyproline-based dipeptides through amide coupling of Boc-protected cis- or trans-4-l-hydroxyproline (cis- or trans-4-Hyp) to benzylated glycine (Gly-OBn) and l-valine (l-Val-OBn) and used these dipeptides as catalysts for a model aldol reaction. Despite the lack of a proton donor in the catalytic site, we observed good stereoselectivities for the R-configured aldol product both with dipeptides formed from cis- or trans-4-Hyp at moderate conversions after 24 h. To explain this conundrum, we modeled reaction cycles for aldol additions in the presence of cis-4-Hyp, trans-4-Hyp, and cis- and trans-configured 4-Hyp-peptides as catalysts by calculation of free energies of conformers of intermediates and transition states at the density functional theory level (B3LYP/6-31G(d), DMSO PCM as solvent model). While a catalytic cycle as previously suggested with l-proline is also plausible for cis- or trans-4-Hyp, with the peptides, the energy barrier of the first reaction step would be too high to allow conversions at room temperature. Calculations on modeled transition states suggest an alternative pathway that would explain the experimental results: here, the catalytic cycle is entered by the acetone self-adduct 4-hydroxy-4-methylpentan-2-one, which forms spontaneously to a small extent in the presence of a base, leading to considerably reduced calculated free energy levels of transition states of reaction steps that are considered rate-determining. Full article

Vapor–liquid equilibrium (VLE) and density data for binary systems of branched alkanes + ethyl acetate are scarce in the literature. In this study, the binary mixtures 3-methylpentane + ethyl acetate and 2,3-dimethylbutane + ethyl acetate were investigated. Density measurements at atmospheric pressure were performed using a vibrating tube density meter at 293.15, 298.15 and 303.15 K. Large and positive excess molar volumes were calculated and correlated using a Redlich–Kister-type equation. Isobaric VLE data at 101.3 kPa were obtained using a Gillespie-type recirculation ebulliometer. Equilibrium compositions were determined indirectly from density measurements. The experimental data were checked for consistency by means of the Fredenslund test and the Wisniak (L-W) test and were then successfully correlated using the NRTL model. The newly studied binary systems display high deviations from ideality and minimum boiling azeotropes, the coordinates of which are reported in this work. Full article

The aim of this study was to determine volatile compounds in red wines of Zweigelt and Rondo varieties using HS-SPME/GC-MS and to find a marker and/or a classification model for the assessment of varietal authenticity. The wines were produced by using five commercial yeast strains and two types of malolactic fermentation. Sixty-seven volatile compounds were tentatively identified in the test wines; they represented several classes: 9 acids, 24 alcohols, 2 aldehydes, 19 esters, 2 furan compounds, 2 ketones, 1 sulfur compound and 8 terpenes. 3,7-dimethyl-1,5,7-octatrien-3-ol (hotrienol) was found to be a variety marker for Zweigelt wines, since it was detected in all the Zweigelt wines, but was not present in the Rondo wines at all. The relative concentrations of volatiles were used as an input data set, divided into two subsets (training and testing), to the support vector machine (SVM) and k-nearest neighbor (kNN) algorithms. Both machine learning methods yielded models with the highest possible classification accuracy (100%) when the relative concentrations of all the test compounds or alcohols alone were used as input data. An evaluation of the importance value of subsets consisting of six volatile compounds with the highest potential to distinguish between the Zweigelt and Rondo varieties revealed that SVM and kNN yielded the best classification models (F-score of 1, accuracy of 100%) when 3-ethyl-4-methylpentan-1-ol or 3,7-dimethyl-1,5,7-octatrien-3-ol (hotrienol) or subsets containing one or both of them were used. Moreover, the best SVM model (F-score of 1) was built with a subset containing 2-phenylethyl acetate and 3-(methylsulfanyl)propan-1-ol. Full article

Parishin compounds are rare polyphenolic glucosides mainly found in the rhizome of the traditional Chinese medicinal plant, Gastrodia elata. These constituents are reported to have several biological and pharmacological activities. In the present study, two novel parishin derivatives not previously reported as plant-based phytochemicals were identified from a twig of Maclura tricuspidata (MT) and two new compounds were elucidated as 1-(4-(β-d-glucopyranosyloxy)benzyl)-3-hydroxy-3-methylpentane-1,5-dioate (named macluraparishin E) and 1,3-bis(4-(β-d-glucopyranosyloxy)benzyl)-3-hydroxy-3-methylpentane- 1,5-dioate (macluraparishin C), based on the experimental data obtained by UV–Visible (UV–Vis) spectroscopy, high performance liquid chromatography–quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) and nuclear magnetic resonance (NMR) spectroscopy. Additionally, gastrodin, parishin A and parishin B were positively identified by spectroscopic evidence and the comparison of HPLC retention time with the corresponding authentic standards. Gastrodin, parishin A and parishin B, macluraparishin E and macluraparishin C were found to be the most abundant constituents in the MT twig. The compositions and contents of these constituents were found to vary depending on the different parts of the MT plant. In particular, the contents of parishin A, parishin B, macluraparishin C and macluraparishin E were higher in the twig, bark and root than in the leaves, xylem and fruit. Full article