Search Results (401)

Salicylic acid (SA) is involved in plant defense responses to environmental stressors by modulating gene expression and specialized metabolites production, enhancing plant adaptive resilience through systemic signaling pathways. This study investigates the impact of exogenous application of SA on the metabolism of iridoids and phenolic compounds—characteristic specialized metabolites of the Nepeta species, associated with diverse biological activities. Nepetalactone (NL) is a characteristic monoterpene iridoid, while rosmarinic acid (RA) represents the most abundant phenolic compound within the genus. We explored the effects of varying SA concentrations (2 µM, 5 µM, 10 µM, and 20 µM) on iridoid and phenolic metabolism in in vitro-grown Nepeta nuda, following 7 days and 28 days of elicitation. A significant increase in trans,trans-NL content was observed after 7-day exposure to 2 µM SA, while prolonged exposure led to a decrease in its levels, particularly at higher SA concentrations. Gene expression analysis revealed that 7 days of exposure to lower concentrations of SA upregulated genes coding for NAD-dependent nepetalactol-related short-chain dehydrogenase/reductases (NEPSs), key regulatory enzymes catalyzing the final steps of NL biosynthesis. In contrast, prolonged exposure to 20 µM SA downregulated genes coding for geraniol 8-hydroxylase (NnG8H) and 8-hydroxygeraniol oxidoreductase (Nn8HGO), which resulted in reduced iridoid content. Conversely, SA treatment notably increased RA content after prolonged exposure to 20 µM SA, which is a result of the enhanced expression of all analyzed RA biosynthesis-related genes. These findings demonstrate that both concentration and duration of SA treatment are critical determinants of elicitation outcomes in N. nuda. Strategic manipulation of these parameters can redirect metabolic flux toward either iridoid or phenolic compounds production, and enhance biotechnological production of specialized metabolites in N. nuda. Full article

Volatile amphiphiles and surfactant mixtures have gained wide applications in diverse areas of industry, cosmetics, and medicine. The surface tension isotherms, measured at different solute ratios, and data processing, using appropriate theoretical models, provide quantitative information on their bulk and interfacial properties. Here, this approach is applied for mixtures of volatile amphiphile (benzyl acetate, linalool, geraniol, menthol, citronellol) and sodium dodecyl sulfate (SDS). All surface tension isotherms are described by the van der Waals model for a two-component adsorption layer, taking into account the counterion binding in the Stern layer, by varying only one adjustable parameter (interfacial pair interaction energy between adsorbed molecules). Knowing the parameters of the model, we computed various properties of the adsorption layers (adsorptions of different components, occupancy of the Stern layer, and interfacial electrostatic potential). The experimental aqueous solubilities of mixtures are fitted using the regular solution theory to obtain the pair bulk interaction parameter. The mixing of SDS and: (i) benzyl acetate and citronellol is antagonistic; (ii) linalool and geraniol is synergistic; and (iii) menthol is ideal. The reported properties of the volatile amphiphiles and SDS mixtures could be of interest for increasing the range of their applicability in practice. Full article

The evolution of resistance in mosquitoes to conventional insecticides such as pyrethroids presents a challenge to vector control. Thus, alternative active ingredients for insecticides to manage pyrethroid-resistant populations of mosquitoes are needed. The goal of this study was to evaluate the toxic and repellent efficacy of geraniol, a plant secondary metabolite, as a potential alternative for controlling pyrethroid-resistant Aedes aegypti. We found that addition of geraniol to rearing water of 1st instar larvae caused concentration-dependent mortality within 24 h in both strains. The resistance ratio of geraniol (2.8) was modest compared to that of cypermethrin (435.3). Topical application of geraniol to adult female mosquitoes caused dose-dependent mortality in both strains within 24 h. The resistance ratio of geraniol (1.1) was minimal compared to that for cypermethrin (457). In spatial repellency assays, geraniol repelled adult females from both strains in a dose-dependent manner. The repellency resistance ratio of geraniol (2.6) was modest compared to that for pyrethrum extract (>132). Our findings suggest that geraniol has potential use as a toxicant and repellent for controlling pyrethroid-resistant populations of Ae. aegypti. Full article

This study characterizes the volatile organic compound (VOC) profiles of young monovarietal red wines from five cultivars widely grown in Alentejo, Portugal—Aragonez, Castelão, Merlot, Syrah, and Trincadeira, across two consecutive vintages (2021 and 2022), in a total of 20 samples. Understanding how grape variety and harvest year shape VOC composition is essential for defining varietal typicity, supporting authenticity assessments, and guiding quality-driven enological practices. VOCs were extracted using headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography coupled to time-of-flight mass spectrometry (GC–TOFMS), providing a semi-quantification of 142 volatile compounds across nine chemical families. Statistical analyses, including ANOVA and Principal Component Analysis (PCA), unveiled significant effects of variety, vintage, and their interactions on VOC composition, enabling clear discrimination of the wines. Notably, terpenes and C₁₃-norisoprenoids exhibited strong varietal differentiation patterns: Castelão and Trincadeira showed higher relative proportions of monoterpenes like linalool, β-citronellol, and geraniol, whereas Aragonez presented increased sesquiterpene levels including β-bisabolene and α-muurolene, and Syrah and Merlot displayed more diverse terpenoid patterns. Despite their lower abundance, C₁₃-norisoprenoids, particularly trans-β-ionone, consistently differentiated wines across vintages. A 100% ribbon chart of the main terpenoids and C₁₃-norisoprenoids highlighted genotype-driven and vintage-independent patterns, underscoring their potential as robust markers of Portuguese red wines. This study presents a high-resolution HS-SPME–GC–TOFMS chemometric workflow for the profiling and classification of young Alentejo red wines, highlighting consistent varietal patterns in terpene and C₁₃-norisoprenoid distributions under the studied conditions. Full article

Molecularly imprinted polymers (MIPs) are widely employed for selective adsorption of target molecules in sensing and separation applications. The architecture of MIP films can influence adsorption behavior, interfacial stability, and reusability, yet systematic investigations of these effects are limited. This study aimed to evaluate how different polypyrrole (PPy) MIP film architectures affect the adsorption, stability, and regeneration characteristics of geraniol-imprinted layers on gold electrodes. Geraniol-imprinted and non-imprinted PPy films were electropolymerized onto quartz crystal microbalance (QCM) substrates. Two film architectures were compared: (i) a single-layer geraniol-imprinted PPy film, and (ii) a double-layer film consisting of a non-imprinted PPy underlayer followed by a geraniol-imprinted layer. Film characterization was performed using cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM) measurements. Adsorption–desorption cycles were conducted to assess mass uptake, signal stability, and regeneration performance. EQCM analysis revealed that the double-layer architecture exhibited enhanced frequency signal stability during repeated adsorption–desorption cycles compared to single-layer films, suggesting a stabilizing effect of the underlying non-imprinted PPy layer at the electrode interface. Geraniol-imprinted films demonstrated significantly higher mass uptake than non-imprinted controls, confirming the sensitivity provided by molecular imprinting. Single-layer films showed more variability in signal response and less consistent regeneration performance. The architecture of MIP films significantly affects adsorption behavior, stability, and regeneration on electrode surfaces. Incorporating a non-imprinted PPy underlayer can improve signal reproducibility and enhance the robustness of MIP-based sensing interfaces. These findings provide guidance for the rational design of MIP coatings for electrochemical sensors and QCM-active platforms. Full article

Seasonal environmental conditions can modulate the chemical composition and biological activity of essential oils from medicinal plants. This study investigated the phytochemical profile, antioxidant potential, cytotoxic activity, and cytoprotective effects of Lippia alba essential oils collected during dry and rainy seasons. Gas chromatography analysis revealed that all samples preserved a citral chemotype. Principal Component Analysis (PCA) confirmed citral as the primary discriminant metabolite, while quantitative seasonal variations were mainly associated with minor oxygenated monoterpenes, particularly geraniol, carvone, and nerolidol. The essential oil obtained during the rainy season (A5T–RS) exhibited significantly higher antioxidant activity, as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power, total antioxidant capacity, and hydrogen peroxide scavenging assays. Intracellular reactive oxygen species (ROS) evaluation using the 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) method demonstrated that both oils reduced oxidative stress in murine fibroblasts—L929, with enhanced cytoprotective effects observed for A5T–RS. Cytotoxicity assays against non-tumor (murine fibroblast-NIH/3T3, L929, Chinese hamster ovary—CHO-K1) and tumor (human cervical carcinoma—HeLa, and human hepatocellular carcinoma—HepG2) cell lines revealed selective antiproliferative activity, with tumor cells displaying greater sensitivity, particularly to the rainy-season oil. These results demonstrate that seasonal metabolomic modulation enhances the biological performance of L. alba essential oil without altering its chemotypic identity, highlighting the importance of environmental factors in the development of bioactive plant-derived products. Full article

Nowadays, there is a global trend of consuming lower-alcohol beverages, while there is a market trend for consuming ready-to-drink products. The present study describes the development of new alcoholic beverages by the simple addition of rose water to the traditional marc spirit tsipouro. New beverages have lower alcohol content (30% v/v) than the mother tsipouro (40% v/v), exhibiting noteworthy antioxidant activity. Tsipouro–rose water beverages exhibited several aroma volatiles which originated from rose water, as determined by SPME GC-MS. Among them were the phenylethyl alcohol, eucalyptol, linalool, citronellol, geraniol, alpha-terpineol, which are known as rose water aroma compounds. The antioxidant activity of tsipouro–rose water beverages as estimated by the Folin, FRAP and DPPH assays appeared to be higher than the diluted tsipouro of the same alcohol content in a dose-dependent manner after mixing and after storage for 30 and 60 days. Preliminary organoleptic evaluation indicated that tsipouro–rose water products exhibit a rose-like aroma and were of acceptable organoleptic quality, especially that with a lower concentration of rose water. Full article

Rhodiola species are traditionally used to mitigate hypoxia-related symptoms, but comparative evidence on their chemical bases and active constituents is limited. We implemented an integrated “qualitative analysis–pharmacological exploration–correlation analysis–molecular validation” workflow to compare Rhodiola crenulata, R. kirilowii, and R. rosea. Ultra-high-performance liquid chromatography–Q Exactive mass spectrometry (UPLC-QE-MS) profiling identified 175 metabolites across the three species, of which 161 were shared; multivariate analyses (principal component analysis, PCA; partial least squares–discriminant analysis, PLS-DA) revealed 30 differential compounds. In a normobaric hypoxia mouse model using herbal powder solutions, all three species significantly increased survival time versus control (p < 0.05), with mean survival times of 48.16 min (RR), 47.07 min (RC), and 44.82 min (RK) compared with 44.34 min for the positive control. Chemometric correlation (partial least squares regression, PLSR) combined with grey relational analysis (GRA) prioritized 14 compounds consistently associated with anti-hypoxia efficacy; six representative metabolites—epicatechin, 3-O-galloylquinic acid, salidroside, p-coumaric acid-4-O-glucoside, citric acid, and geraniol—were selected for in silico assessment. Molecular docking against hypoxia-inducible factor-1α (HIF-1α) yielded favorable binding poses (docking scores < −4.0), providing preliminary molecular-level plausibility without claiming mechanistic proof. This multi-level approach clarifies chemical–pharmacological relationships among Rhodiola species and provides prioritized candidate compounds for targeted isolation and mechanistic validation. Full article

Background: Geraniaceae species are widely used in traditional medicine. Pelargonium radula and Geranium macrorrhizum are aromatic medicinal plants traditionally used in Bulgaria for their antimicrobial, anti-inflammatory, and wound-healing properties. Comparative phytochemical data on Pelargonium radula and Geranium macrorrhizum cultivated in Bulgaria, however, remain limited. The present work aimed to characterize and compare the chemical composition of essential oils and main phenols, in support of future pharmacological evaluation. Methods: Essential oils from aerial parts of both species were obtained by hydrodistillation and analyzed by GC-MS. Through HPLC-UV, ethanol extracts were evaluated to quantify the major phenolic acids and flavonoids. Results: The yield of essential oils was 0.10% for P. radula and 0.03% for G. macrorrhizum, dominated by oxidized monoterpenes, mainly citronellol and geraniol-type compounds. HPLC analysis revealed marked differences in their phenolic profiles. P. radula showed a composition with six phenolic acids—primary protocatechuic and ferulic acids, and very low levels of flavonoids, with rutin being the only quantifiable glycoside. In contrast, G. macrorrhizum contained nine phenolic acids and four flavonoids, with remarkably high levels of salicylic, rosmarinic, and p-coumaric acids, as well as catechins, absent in P. radula. Conclusions: The two species showed different phytochemical characteristics in both their volatile and non-volatile fractions. P. radula is characterized by a citronellol/geraniol-rich essential oil and a moderate phenolic profile, while G. macrorrhizum exhibits significantly higher phenolic diversity and abundance. These findings expand the current phytochemical knowledge of both taxa and provide a solid basis for future chemotaxonomic and pharmacological studies. The obtained results suggest that Geranium macrorrhizum may be more promising for antioxidant and anti-inflammatory applications, while Pelargonium radula may be preferentially explored for ant-microbial purposes. Full article

Essential oils (EO) have been used for skin treatments for centuries due to their wide range of beneficial pharmacological properties. Their adsorption in solids with confined spaces can be an excellent support for their slow delivery. Geraniol and linalool are octadienol isomers, often found in many natural EO. Both possess interesting therapeutic properties that can be optimized for protecting them from degradation using adsorption systems and controlled delivery. Cyclodextrins (CDs) and natural clay minerals are excellent materials to serve as hosts for drugs. In this work we investigate the adsorption and desorption of these essential oil components with both hosts, β-CD and montmorillonite (MNT). Molecular modeling studies were conducted using the INTERFACE force field (FF), yielding promising results, by reproducing the experimental crystal lattice cell parameters of the β-CD-geraniol and β-CD-linalool crystallized complexes within 5%, thereby validating this FF. The adsorption of these drugs onto β-CD rings is energetically more favorable than into MNT at low EO concentrations. However, the delivery of these drugs is more favorable from the clay mineral than from β-CD. At high EO concentrations, intercalation into MNT is energetically favorable. The behavior of both isomers is similar. Surprisingly the intercalation of β-CD-geraniol and β-CD-linalool into MNT is energetically favorable, predicting a complex and hybrid composite for intercalation. These natural composites can be suitable as additives in therapeutic skin treatments. Full article

This study involved developing a novel lemon flower-scented white tea (LT) through multiple aroma-imparting cycles, and taking an integrated approach to investigating its flavour formation mechanism. Sensory evaluation and electronic tongue analysis revealed that the LT exhibited more balanced taste characteristics, with significantly reduced bitterness and astringency, attributed to the decreased caffeine content and conversion of esterified catechins. Electronic nose and HS-SPME/GC-MS results confirmed that the LT had acquired a distinctive aroma characterised by floral and citrus notes, primarily originating from lemon flower volatiles such as methyl anthranilate and limonene. Multivariate statistical analysis identified 32 key differential compounds (variable importance in projection value > 1), with methyl anthranilate, β-ionone, and geraniol (relative odour activity value > 80) jointly forming the shared flavour base among teas. These findings demonstrate that lemon flower infusion can effectively enhance the sensory quality of white tea and provide theoretical support for the development of diverse floral teas. Full article

Objectives: The aroma profile is a key determinant of fruit quality. Methods: In this study, mature ‘Summer Black’ grape berries were collected from 36 major producing areas in southern China to evaluate regional differences in fruit quality, volatile compounds were analyzed by via GC-MS, and a representative volatile profile was established. Furthermore, transcriptome sequencing was employed to identify key genes involved in the phenylpropanoid biosynthesis pathway related to aroma formation. Results: The results showed the following: (1) Samples from CD-2 exhibited the highest soluble solid content and the largest TSS/TA ratio. (2) A total of 20 volatile compounds were selected as indicators for the aroma fingerprint. MS-1 samples contained the most diverse aroma compounds (19 types), while CS-2 had the fewest (12 types). (3) Eight aroma compounds were consistently detected across all regions: hexanal, trans-2-hexenal, n-hexanol, β-citronellol, geraniol, nerol, benzyl alcohol, and phenethyl alcohol. Among these, hexanal and trans-2-hexenal were the most abundant; phenylethyl alcohol exhibited the most significant variation in percentage content across all samples, and was determined to be the representative and dominant volatile compound in ‘Summer Black’ grapes. (4) A transcriptome analysis of six representative regions identified 15 differentially expressed genes associated with phenylpropanoid biosynthesis and metabolism. Among them, PAO (Vitvi04g01467) was significantly correlated with phenethyl alcohol content. Conclusions: These findings provide a basis for evaluating the aroma quality of ‘Summer Black’ grapes and offer insights for regional cultivation selection. Full article

Grade and cultivar are the important factors influencing white tea quality, but their relative metabolic contributions are not fully understood. Twelve white tea samples representing four major Fujian cultivars across three grades were analyzed using UHPLC–MS-based non-volatile metabolomics, HS-SPME–GC–MS volatile profiling, and sensory correlation analysis. In total, 47 non-volatile and 21 volatile markers were associated with grade differences, while 44 non-volatile and 26 volatile markers were linked to cultivar differences. Catechins and amino acids declined as grade decreased, whereas flavonol glycosides and gallic acid increased, accompanied by stronger astringency and reduced umami and sweetness. Aroma profiles showed a similar trend, with higher-grade teas dominated by floral notes and lower-grade teas exhibiting more herbal characteristics. Dimeric catechins, oxylipins, and aroma glycosides varied among cultivars. Volatile profiles separated the cultivars into two aroma groups: Fuding Dabai and Fuding Dahao showed more floral–fruity aromas, whereas Fuan Dabai and Zhenghe Dabai exhibited stronger herbal and aged aromas. Odor activity value analysis showed that linalool, geraniol, and (E,Z)-3,6-nonadien-1-ol were among the most abundant aroma-active compounds across white tea samples. These results provide chemical evidence for distinguishing white tea by grade and cultivar, with potential relevance to quality evaluation. Full article

Research for sustainable viticulture practices has fostered interest in ultraviolet-C (UV-C) radiation as non-chemical tool for vineyard pathogen control; however, little information is available on their potential elicitation of berry metabolites. This two-year study investigated the impact of supplementary in-field UV-C applications, in addition to the vineyard sanitary protocols, on berry composition in Cabernet Sauvignon grapevines. In both experimental years, vegetative, yield, and berry technological parameters were determined at harvest, but they were not altered by UV-C treatments. Significantly higher concentrations of berry secondary metabolites were measured at harvest trough GC-MS and HPLC. UV-C treated vines had higher berry anthocyanins, particularly tri-hydroxylated forms (malvidin, delphinidin, petunidin), and flavonol concentrations (quercetin, myricetin derivatives), improving the potential for wine color stability and copigmentation. Glycosylated berry aroma compounds were also increased in UV-C vines, particularly some monoterpenes (geraniol, nerol, citronellol), C₁₃-norisoprenoids (β-damascenone, β-ionone, 3-oxo-α-ionol), and volatile phenols (eugenol, 4-vinyl-guaiacol). These results highlighted the potential of UV-C in-field applications, in addition to pest management control, to increase grape quality traits by modulating berry phenolic and aroma profile without affecting productivity. Full article

In the medical industry, strong disinfectants are used to limit bacterial proliferation on the surface of polymer-based materials; however, they may leave hazardous residues. To prevent potential harm to human health, safer disinfection substitutes are continuously searched. This study evaluates the effect of a natural biocidal modifier, geraniol (GR), on the properties of flax-reinforced biocomposites. Biocomposites containing 80 wt% polylactide (PLA) and 20 wt% flax fibres were prepared, and fibres were modified with 1%, 5%, 10%, or 20% GR. The materials were examined using tensile tests, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetry (TG), contact angle measurements, scanning electron microscopy (SEM), and antibacterial activity tests. The incorporation of flax fibres increased the storage modulus from 2730 MPa (PLA) to 3447 MPa, while GR-modified fibres further enhanced stiffness up to 3769 MPa for the 20% GR sample. Strong antibacterial activity against Escherichia coli and Staphylococcus aureus was achieved in biocomposites containing ≥10% GR, with R = 5 and R ≥ 6, respectively. Surface hydrophobicity also improved progressively, and a water contact angle of 92° was obtained at 20% GR. These results demonstrate that geraniol-modified flax fibres effectively impart antibacterial activity and hydrophobicity to PLA biocomposites, indicating their potential for use in sustainable packaging applications and materials for the medical sector. Full article