Linalool Oxide Research Articles

Free monoterpenoid accumulation in ‘Riesling’ (Vitis vinifera L.) is light-sensitive and uncoupled from grape hexose accumulation

Monoterpenoid biosynthesis mirrors hexoses accumulation in grape berries during ripening and is affected by environmental factors such as solar radiation. However, no research has confirmed the dependency of monoterpenoid accumulation on grape maturity. Using potted ‘Riesling’ (Vitis vinifera L.) vines, we girdled (GD) shoots at veraison to halt leaf photoassimilate translocation to berries and also utilized light-impenetrable bags to exclude light exposure (LE) to grape clusters to <2 μmol m-2s-1 during ripening. GD and LE were compared to an untreated control (CT), and a combined (GDxLE) treatment. GD caused leaf photosynthetic assimilation to decline from one-week post-treatment until harvest maturity due to feedback inhibition of photosynthesis. This was coupled to a decrease in hexoses and ABA accumulation in GD berries. Meanwhile, LE did not affect photosynthetic assimilation, or hexoses and ABA accumulation. We hypothesized that the accumulation of free and bound monoterpenoids in ‘Riesling’ berries would also be reduced by GD, if monoterpenoid accumulation was dependent on grape maturity. LE significantly decreased free monoterpenoids compared to CT. However, GD did not alter total free and bound monoterpenoid concentrations. GD decreased free Linalool Oxide I and II and bound Linalool Oxide I compared to CT, and increased Citral I and II and α-Terpineol. Although exogenous jasmonate applications stimulate monoterpenoid biosynthesis in grapes, we showed that endogenous jasmonate concentrations were not altered by GD or LE; therefore, any monoterpenoid modulation by GD and LE treatments was not mediated by endogenous jasmonate levels. This study indicates that free monoterpenoid biosynthesis during ripening is “uncoupled” from hexose accumulation and is strongly regulated by solar radiation.

Comprehensive analysis reveals the contribution of “rolling-anaerobic” processing to the improved aroma, taste and color of GABA black tea

GABA black tea (GABT), produced by the combination of anaerobic treatment and Chinese traditional black tea processing technology, has a unique flavor and health benefits. However, how to manufacture high-quality GABT efficiently is the major challenge for this area. In this study, a processing improvement of multiple rolling-anaerobic treatment cycle was applied to prepare tailored GABTs, and their comprehensive quality including aroma, taste and color were analyzed. The sensory evaluation results showed that the improvement significantly optimized the overall GABT quality. The accumulation of linalool oxide Ⅰ, citronellol, etc. was the main reason for the superior aroma of tailored GABT, while the dynamic changes of sweet/umami amino acids, catechins and tea pigments played critical roles in the GABT taste and color quality formation during processing. Furthermore, correlation analysis was applied to determine the contribution of various processing steps. These findings provide a novel manufacturing method for high-quality GABT products.

Dynamic Changes in Aroma Compounds during Processing of Flat Black Tea: Combined GC-MS with Proteomic Analysis.

Flat black tea (FBT) has been innovatively developed to alleviate homogenisation competition, but the dynamic changes in aroma components during the process remain unclear. This study employed HS-SPME-GC-MS to analyse the aroma components of tea samples from various processing stages of FBT, and to make a comparative assessment with conventional strip-like Congou black tea (SBT). Additionally, a proteomic analysis was conducted on fresh leaves, withered leaves, and frozen-thawed leaves. Significant changes were observed in the aroma components and proteins during the processing. The results of the multivariate and odour activity value analysis demonstrated that the principal aroma components present during the processing of FBT were linalool, (E)-2-hexen-1-al, methyl salicylate, geraniol, hexanal, benzeneacetaldehyde, (Z)-3-hexenyl butyrate, dimethyl sulphide, 2-methylbutanal, 2-ethylfuran, nonanal, nonanol, 3-methylbutanal, (Z)-3-hexen-1-ol, 2-pentylfuran, linalool oxide I, and β-myrcene. Freezing-thawing and final roasting are the key processing steps for forming the aroma quality of FBT. The final roasting yielded a considerable quantity of pyrazines and pyrroles, resulting in a high-fried aroma, but caused a significant reduction in linalool, geraniol, β-myrcene, and esters, which led to a loss of floral and fruity aromas. The freezing-thawing treatment resulted in an accelerated loss of aroma substances, accompanied by a decrease in the expression level of lipoxygenase and 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase. The formation of aroma substances in the linoleic acid metabolic pathway and terpenoid metabolic process was hindered, which had a negative impact on tea aroma. This study elucidates the causes of unsatisfactory aroma quality in tea products made from frozen tea leaves, providing theoretical support for the utilisation of frostbitten tea leaves, and helps us to understand the mechanism of aroma formation in black tea.

Shorten spreading duration enhance the quality of summer Meitan Cuiya tea

Meitan Cuiya (MTCY), a representative green tea from Guizhou, China, may exhibit lower quality in summer due to increased bitterness and astringency. Spreading is a common method to enhance tea quality, but its impact on summer MTCY remains unclear. This study combined transcriptomics and volatile metabolomics to investigate the effects of spreading duration on quality of summer fresh tea leaves and MTCY. Results showed that spreading time shortened to 4 h improved the taste of MTCY, due to lower catechins and higher theanine levels. This duration also yielded woody floral scent in MTCY, marked by high levels of trans-Cubebol, linalool, (Z)-linalool oxide. Transcriptomic analysis linked the 4-h spreading to proteasome activities. Aroma formation was related to diterpenoid and flavonoid biosynthesis. Additionally, gibberellins and auxin were associated with quality formation in fresh tea leaves. This research lays a foundation for improving quality of fresh tea leaves and MTCY in summer.

A special “Golden Flower” fungus with yellow cleistothecium: Its impact on the flavor of golden flower loose tea produced from summer-autumn tea

Summer-autumn tea leaves are abundant, yet their utilization remains low. Our study enhances the quality and flavor of Golden Flower loose tea (GFLT) from fresh summer-autumn tea leaves by using a special “Golden Flower” fungus (strain ACF-2). The strain ACF-2, identified as Aspergillus cristatus with yellow cleistothecium and isolated from Fu Brick Tea, was characterized by colony morphology, microstructural analyses, and phylogenetic examination using a 3-gene dataset (BenA, CaM, RPB2). Inoculation of raw dark tea products with A. cristatus led to a significant increase in tea water extract and a reduction in tea polyphenols, soluble sugars, flavonoids, and total amino acids, thereby enhancing the quality and flavor of GFLT. HS-SPME-GC-MS analysis of GFLT aroma revealed that A. cristatus substantially improved the tea’s aroma profile. 9 volatile compounds—(Z)-jasmone I, β-cyclocitral, linalool oxide I, linalool, hexanal, 1-octen-3-ol, (Z)-citral, citral, and methyl salicylate, were found to be significantly elevated in GFLT compared to the controls. Our findings provide both theoretical and practical insights into optimizing the utilization of summer-autumn tea leaves, identifying the “Golden Flower” fungus, and understanding its impact on GFLT quality. In summary, fermenting A. cristatus to produce GFLT may be a new channel to utilize summer-autumn tea.

Characterization of the influence of extraction factors on instant Pu-erh tea: Focusing on changes in sensory quality and aroma profile

The objective of this study is to explore the influence of extraction factors, including extraction temperatures, extraction time, and tea-water ratios, on the sensory quality and aroma characteristics of instant Pu-erh tea (IPET). Sensory evaluation, quantitative descriptive analysis (QDA) and HS-SPME-GC × GC-TOF/MS were utilized for analysis. The result showed that the optimal process condition of IPET was a tea-to-water ratio 1:8, an extraction temperature 75 °C, and an extraction time 60 min. A total of 235 volatile compounds were identified and 65 key odor-active compounds with ROAV>1 in all samples. Based VIP > 1, 19 key differential odor-active compounds were identified, including linalool oxide I, 1-dodecanol, linalool oxide II, etc. Further Pearson correlation analysis of key differential odor-active compounds and aroma characteristics showed that positive correlations between woody and ethyl nonanoate and 1-dodecanol, and between herbal and 1-methylnaphthalene. This research provides theoretical support for the production of high-quality IPET.

Metabolomics reveals a differential attitude in phytochemical profile of black tea (Camellia Sinensis Var. assamica) during processing

Black tea's quality and flavor are largely influenced by its processing stages, which affect its volatile and non-volatile phytochemicals. This study aimed to optimized black tea manufacturing by investigating withering time, fermentation time, and temperature's impact on sensory quality. Using a U*15 (157) uniform design, optimal conditions were determined: 14 h of withering, 5.6 h of fermentation, and a 34 °C temperature. A verification experiment analyzed the volatile and non-volatile profiles. HPLC, GC–MS, and LC-MS revealed dynamic changes in phytochemicals. Among 157 VOCs and 2642 metabolites, 19 VOCs (VIP > 1.5) were crucial for aroma, while 50 (VIP > 1.5, p < 0.01) characteristic metabolites were identified. During processing, fragrant volatile compounds like linalool oxides, geraniol, benzeneacetaldehyde, benzaldehyde, methyl salicylate, and linalyl acetate increased, contributing to rose and honey like aromas. These changes were crucial in developing the characteristic flavor and color of black tea. Twenty-four new compounds formed, while 80 grassy odor volatiles decreased. Non-volatile metabolites changed notably, with decreased catechins and increased gallic acid. Theaflavin compounds rose initially but declined later. This study outlines metabolite changes in Yunkang 10 black tea, crucial for flavor enhancement and quality control.

Chemical Composition, Antioxidant and Anti-Enzymatic Activities, and In Vitro Insecticidal Potential of Origanum compactum (Benth.) Essential Oils.

This study aimed to investigate the variation in the chemical composition of Origanum compactum essential oils (EOs) from four geographically distinct locations. Additionally, we evaluated their antioxidant properties and potential inhibitory effects on acetylcholinesterase (AChE), tyrosinase, and α-glucosidase enzymes and their insecticidal proprieties. Notably, this research also marks the first examination of the mineral composition of O. compactum. The chemical composition was determined using gas chromatography-mass spectrometry (GC-MS), which identified thymol (28.72-80.39%), carvacrol (6.54-61.84%), p-cymene (0.27-8.64%), linalool (1.44-1.96%), and caryophyllene oxide (1.34-1.56%) as the major constituents. Concurrently, inductively coupled plasma atomic emission spectroscopy (ICP-AES) revealed significant levels of macro and microelements, including calcium (295.50-512.20 mg/kg), potassium (195.99-398.45 mg/kg), magnesium (59.70-98.45 mg/kg), and iron (43.55-112.60 mg/kg). The EOs demonstrated notable antiradical activities through DPPH (1,1-diphenyl-2-picrylhydrazyl), FRAP (ferric reducing antioxidant power), and β-carotene bleaching assays. Regarding the insecticidal effect, all studied essential oils showed a significant toxicity against C. capitata adults, and the toxicity was dose and time dependent. The highest insecticidal effect was observed for O. compactum essential oils collected from Gouman (LC50 = 2.515 µL/mL, LC90 = 5.502 µL/mL) after 48 h of treatment. Furthermore, at a concentration of 1 mg/mL, the EOs exhibited strong inhibitory effects against AChE (84.75-94.01%), tyrosinase (84.75-94.01%), and α-glucosidase (79.90-87.80%), highlighting their potential as natural inhibitors of these enzymes. The essential oils of O. compactum contain components that could be used as a basis for synthetizing derivatives or analogs with potential medicinal applications and pest control properties.

Revealing the differences in aroma of black tea under different drying methods based on GC–MS, GC-O

Drying greatly affects the aroma of black tea. In this study, the differences in aroma of black tea under hot-air drying (HD), sun drying (SD), and pan-fired drying (PD) were investigated through quantitative descriptive analysis. Headspace solid-phase microextraction and solvent assisted flavor evaporation combined with gas chromatography–mass spectrometry and gas chromatography-olfactory were used to analyze the overall aroma profile of black tea. Aroma extract dilution analysis and odor activity values revealed that 15 aroma-active compounds led to differences in aroma, namely linalool, geraniol, phenylethyl alcohol, phenylacetaldehyde, (Z) -linalool oxide (furanoid), β-damascenone, dimethyl sulfide, methional, 2-methylbutanal, 3-methylbutanal, methyl salicylate, β-myrcene, hexanal, 1-octen-3-ol, and heptanal. Among them, geraniol, linalool, and methional significantly enhanced the floral and roasty aroma of HD, while hexanal enhanced the green aroma of SD. Finally, our results were validated through aroma recombination and addition experiments. This study provides a theoretical basis for improving the aroma of black tea.

Characterization of the key differential aroma compounds in five dark teas from different geographical regions integrating GC–MS, ROAV and chemometrics approaches

Dark tea (DT) holds a rich cultural history in China and has gained sizeable consumers due to its unique flavor and potential health benefits. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS), relative odor activity value (ROAV), and chemometrics approaches were used to detect and analyze aroma compounds differences among five dark teas from different geographical regions. The results revealed that the five DTs from different geographical regions differed in types, quantities, and relative concentrations of volatile compounds. A total of 1372 volatile compounds of were identified in the 56 DT samples by HS-SPME-GC–MS. Using ROAV and chemometrics approaches, based on ROAV>1 and VIP>1. Eighteen key aroma compounds can be used as potential indicators for DT classification, including dihydroactinidiolide, linalool, 1,2,3-trimethoxybenzene, geranyl acetone, 1,2,4-trimethoxybenzene, cedrol, 3,7-dimethyl-1,5,7-octatrien-3-ol, β-ionone, 4-ethyl-1,2-dimethoxybenzene, methyl salicylate, α-ionone, geraniol, linalool oxide I, linalool oxide II, 6-methyl-5-hepten-2-one, α-terpineol, 1,2,3-trimethoxy-5-methylbenzene, and 1,2-dimethoxybenzene. These compounds provide a certain theoretical basis for distinguishing the differences in five DTs from different geographical regions. This study provides a potential method for identifying the volatile substances in DTs and elucidating the differences in key aroma compounds.Abbreviations: DT, dark tea; FZT, Fuzhuan tea; LPT, Guangxi Liupao tea; QZT, Hubei Qingzhuan tea; TBT, Sichuan Tibetan tea; PET, Yunnan Pu-erh tea; ROAV, Relative odor activity value; OT, Odor threshold; HS-SPME, Headspace solid-phase microextraction; GC–MS, Gas chromatography-mass spectrometry; PCA, Principal components analysis; PLS-DA, Partial least squares-discriminant analysis; HCA, Hierarchical clustering analysis.

Characteristic of phenotype, amino acids and volatile compounds for fresh tea leaves of Korean tea cultivars (Camellia sinensis (L.) O. Kuntze)

Tea (Camellia sinensis (L.) O. Kuntze) is a popular beverage consumed worldwide. To establish fundamental scientific data, we analyzed the amino acids and volatile compounds in seven tea cultivars grown in Korea investigated phenotype also. Phenotypically, the leaf area and greenness index of young shoots and leaf blades were particularly different among the four Korean cultivars. Nine amino acids were detected from each cultivar, with the total amino acid and theanine contents being 9.08–41.42 and 2.81–24.60 mg/g, respectively. Moreover, 107 volatile compounds were identified as common components among tea cultivars using headspace solid-phase microextraction / gas chromatography–mass spectrometry (HS-SPME/GC-MS), and 38 key compounds were identified using partial least squares-discriminant analysis (PLS-DA) and hierarchical cluster analysis (HCA). The (Z)-linalool oxide (furanoid) concentrations were significantly high in Korean tea plant cultivars, and linalool concentrations were also high or low, but had high relative contents. Linalool and its various oxides are the major compounds responsible for the tea aroma. In conclusion, Korean tea cultivars have distinct characteristics, and the results of this study will form the basis for identifying Korean tea plant cultivars that can produce high-value tea products.

Mechanisms of single and mixed microbial fermentation to improve summer-autumn green tea

To investigate the effect of individual and collaborative fermentation on summer-autumn green tea (SAGT) quality. Liquid fermentation with individual inoculation of Aspergillus cristatus (ACFT), Aspergillus niger (ANFT) and mixed inoculation of A. cristatus/A. niger (MFT), respectively, with SAGT extracts (CT) as raw materials. The volatile organic compounds (VOCs), characteristic non-volatile compounds and sensory evaluation of tea samples were determined. The results showed a significant decrease in the content of tea polyphenols, carbohydrates and nongalloylated catechins (C, EC) and a significant increase in the amount of VOCs in MFT compared to ANFT and ACFT. The results of metabolic pathway analysis and sensory evaluation showed that ACFT went through the terpene and phenylpropanoic acid metabolic pathway, which produced large amounts of α-terpineol, phenethyl alcohol, and methyl salicylate, which in turn conferred ACFT with distinctly sweet, floral, and herbal aroma. ANFT produces large amounts of linalool oxides I and II, mainly through the linalool oxide metabolic pathway, making ANFT a distinctive aged and woody aroma. MFT may be due to the strong woody aroma of linalool oxides masking other weaker and better aromas, thus giving MFT a significant woody, herbal and stale aroma. This study provides new insights and a theoretical basis for mixed fungal fermentation to improve the quality of SAGT.

Physicochemical, sugar, and volatile profile characterization of blong song, bidens, coffee, and mint honeys originating from Vietnam

In this study, the pollen analysis, physicochemical and volatile profiles of blong song, bidens, coffee, and mint honeys from Vietnam were analyzed. The primary pollen content was 87.0%, 37.5%, 5.7%, and 2.7% in the blong song, coffee, bidens, and mint honey, respectively. The average values of the physicochemical properties ranged from 9.4 to 33.5 mS m−1 for electrical conductivity, from 9.5 to 19.7 meq kg−1 for free acidity, from <2 to 10.7 DN for diastase activity, from 0 to 44.7 mm Pfund for color, and from 2.9 to 39.2 mg kg−1 for 5-hydroxymethyl-2-furfural (5-HMF) showed statistically significant differences (p < 0.05) among the four types of honey. Principal component analysis (PCA) of sugars revealed that trehalose was typical for blong song honey; melibiose, sucrose, and maltose for bidens honey; and turanose for mint honey. Using headspace solid phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS) several specific volatile compounds for each honey type were identified: linalool oxide isomers for blong song honey, acetic acid phenylethyl ester for bidens honey, citral, nonanoic acid, α-terpineol, 1-nonanol, and benzeneacetaldehyde for coffee honey and menthol isomers, and isomethyl acetate for mint honey. The results provide comprehensive data on chemometrics, melissopalynological profiles, and volatile compounds analysis for the classification of honey with different floral origins from Vietnam.

Nano-emulsification of Osmanthus essential oil: Characterizations, stability and molecular interactions explaining antibacterial activity

The practical usage of Osmanthus essential oil (OEO) in foods is limited due to its poor solubility in water, higher volatility, and instability. This research aimed to prepare OEO nano-emulsion (OEO-NE) by high-pressure homogenization technique and characterize its nano-form (particle size, zeta potential, structure, FTIR, and thermodynamic stability). The antibacterial activity of OEO was researched using network pharmacology and molecular docking. Furthermore, the antibacterial and antioxidant activities of OEO-NE and OEO were researched. The OEO-NE exhibited long-term storage stability compared to the OEO, with particle size changing to 40.90 nm ∼ 68.09 nm and zeta potential changing to −38.37 mV ∼ −35 mV over 31 storage days at 4 °C and 25 °C. Dihydro-β-ionone and linalool oxide showed better binding affinity for S. aureus TyrRS than E. coli 24 kDa. In addition, nano-emulsification effectively stabilizes the antibacterial and antioxidant activity of OEO. Therefore, OEO-NE is an effective strategy to enhance stability and bioavailability.

Aromatic Characterisation of Moscato Giallo by GC-MS/MS and Validation of Stable Isotopic Ratio Analysis of the Major Volatile Compounds.

Among the Moscato grapes, Moscato Giallo is a winegrape variety characterised by a high content of free and glycosylated monoterpenoids, which gives wines very intense notes of ripe fruit and flowers. The aromatic bouquet of Moscato Giallo is strongly influenced by the high concentration of linalool, geraniol, linalool oxides, limonene, α-terpineol, citronellol, hotrienol, diendiols, trans/cis-8-hydroxy linalool, geranic acid and myrcene, that give citrus, rose, and peach notes. Except for quali-quantitative analysis, no investigations regarding the isotopic values of the target volatile compounds in grapes and wines are documented in the literature. Nevertheless, the analysis of the stable isotope ratio represents a modern and powerful tool used by the laboratories responsible for official consumer protection, for food quality and genuineness assessment. To this aim, the aromatic compounds extracted from grapes and wine were analysed both by GC-MS/MS, to define the aroma profiles, and by GC-C/Py-IRMS, for a preliminary isotope compound-specific investigation. Seventeen samples of Moscato Giallo grapes were collected during the harvest season in 2021 from two Italian regions renowned for the cultivation of this aromatic variety, Trentino Alto Adige and Veneto, and the corresponding wines were produced at micro-winery scale. The GC-MS/MS analysis confirmed the presence of the typical terpenoids both in glycosylated and free forms, responsible for the characteristic aroma of the Moscato Giallo variety, while the compound-specific isotope ratio analysis allowed us to determine the carbon (δ13C) and hydrogen (δ2H) isotopic signatures of the major volatile compounds for the first time.

Solidago virgaurea L.: Chemical composition, antibacterial, and antileishmanial activity of essential oil from aerial part

Solidago virgaurea L. popularly called Goldenrod is a member of the Asteraceae family. S. virgaurea sample were obtained from Binsar, Almora (Indian state of Uttarakhand). The essential oil from the aerial part was distilled out using steam distillation, and GC and GC-MS were employed for analysis. A total of 27 constituents from aerial part were identified constituting 92.92% of total oil composition. The aerial parts of S. virgaurea were found to contain limonene (25.57%), α-humulene (12.19%), linalool oxide (8.65%), benzyl salicylate (6.40%), 1,4-cineole (6.22%) and humulene epoxide (II) (5.93%). The antibacterial activity of this essential oil was studied using disk diffusion and broth microdilution methods on five human pathogen bacteria and six plant pathogenic bacteria. There was moderate to good antibacterial activity in the oil sample extracted from the entire aerial portion of the plant. We did the antileishmanial activity of essential oils with Leishmania donovani (Dd8) promastigotes and intracellular amastigotes. EO was safer on the J774.A1 macrophages and lethal to promastigotes and intracellular amastigotes at different concentrations (10, 50, and 100 μg/ mL). These findings support the traditional uses of S. virgaurea and suggest its potential as a natural remedy for bacterial infections and leishmaniasis.

The enhancement of flowery-like aroma in green tea under optimized processing conditions by sensory-directed flavor analysis

Flowery-like aroma are positive contributors to green tea. Here, the optimal processing conditions for green tea with flowery-like aroma were designed using spreading time, fixation time and drying temperature as three factors designed by response surface methodology (RSM), and the response value of aroma sensory evaluation score. The volatiles in batches of tea samples were analyzed by GC–MS. The optimal quality was obtained with a flowery-like aroma by RSM under a spreading time of 8.97 h, fixation time of 162.3 s, and drying temperature of 103.32 °C. GC-O and odor activity values further revealed floral-like volatiles, including decanal, linalool oxide, β-lonone, geraniol, (Z)-jasmone, linalool, nonanal, and benzeneacetaldehyde. The recombination of these floral volatiles confirmed the consistency with the floral green tea. Furthermore, the extending spreading duration (8–10 h), reducing fixation duration (160–190 s), and increasing drying temperature (100–115 °C) promote their accumulation in green tea. This study provides new perspectives for the precise enhancement of floral odorants for green tea.

Molybdenum Complexes Derived from 2-Hydroxy-5-nitrobenzaldehyde and Benzhydrazide as Potential Oxidation Catalysts and Semiconductors.

This study aimed to synthesize molybdenum complexes coordinated with an aroyl hydrazone-type ligand (H2L), which was generated through the condensation of 2-hydroxy-5-nitrobenzaldehyde with benzhydrazide. The synthesis yielded two types of mononuclear complexes, specifically [MoO2(L)(MeOH)] and [MoO2(L)(H2O)], as well as a bipyridine-bridged dinuclear complex, [(MoO2(L))2(4,4'-bpy)]. Those entities were thoroughly characterized using a suite of analytical techniques, including attenuated total reflectance infrared spectroscopy (IR-ATR), elemental analysis (EA), thermogravimetric analysis (TGA), and single-crystal X-ray diffraction (SCXRD). Additionally, solid-state impedance spectroscopy (SS-IS) was employed to investigate the electrical properties of these complexes. The mononuclear complexes were tested as catalysts in the epoxidation of cyclooctene and the oxidation of linalool. Among these, the water-coordinated mononuclear complex, [MoO2(L)(H2O)], demonstrated superior electrical and catalytic properties. A novel contribution of this research lies in establishing a correlation between the electrical properties, structural features, and the catalytic efficiency of the complexes, marking this work as one of the pioneering studies in this area for molybdenum coordination complexes, to the best of our knowledge.

Biomarker Aroma Compounds of Monofloral Honey From Kazakhstan by Gas Chromatography–Mass Spectrometry (GC–MS) and Chemometric Analysis*

The aroma compounds of honey provide useful information to determine the geographical origin. This work focuses on the study of aroma compounds of 16 honey samples using headspace (HS)-solid-phase microextraction (SPME) gas chromatography–mass spectrometry (GC-MS) to reaffirm the geographical features of 4 monofloral honey. 7 sunflower, 3 buckwheat, 2 agrimonia, and 4 tamarix monofloral honey samples were obtained from four regions of Kazakhstan. Moreover, the GC-MS data were applied to chemometric analysis for the common aroma compounds to discriminate the monofloral honeys. In total, 76 aroma compounds were detected and 72 were identified. α-Pinene, benzaldehyde, octanal, hotrienol, limonene, cosmene, nonanol, linalool oxide, dehydro-p-cymene, β-linalool, 2-nonen-1-ol, carvacrol, lilac aldehyde A, β-citral, 2-decen-1-al, and β-damascenone were identified as common aroma compounds for all honey types. According to principal component analysis (PCA), the aroma compounds of sunflower, buckwheat, agrimonia, and tamarix honey were distinguished. Dehydro-p-cymene, β-linalool, 2-nonen-1-ol, and linalool oxide were determined as dominant compounds for agrimonia honey, while nonanol, benzaldehyde, octanol, dehydro-p-cymene and β-linalool for buckwheat, β-citral, lilac aldehyde A, 2-decen-1-al, D-limonene, β-damascenone, linalool oxide for tamarix honey, and hotrienol, cosmene, α-pinene, and carvacrol for the sunflower product. PCA revealed that the dominant compounds for each honey could be used as biomarker compounds to detect the origin of the honey and possible adulteration, such as blending and inverted sugar addition.

Polymer Beads Increase Field Responses to Host Attractants in the Dengue Vector Aedes aegypti.

This study investigates the efficacy of three different olfactory cues - cyclohexanone, linalool oxide (LO), and 6-methyl-5-heptan-2-one (sulcatone) - in attracting Aedes aegypti, the primary vector of dengue, using BG sentinel traps in a dengue-endemic area (urban Ukunda) in coastal Kenya. Two experiments were conducted. Experiment 1 compared solid formulations of the compounds in polymer beads against liquid formulations with hexane as the solvent. CO2-baited traps served as controls. In Experiment 2, traps were baited with each compound in the polymer beads, commercial BG-Lure, and CO2. Our results indicate that CO2-baited traps recorded the greatest Ae. aegypti captures in both Experiment 1 and 2, whereas trap captures with polymer beads and solvent-based treatments were comparable. In experiment 2, polymer bead-based treatments yielded significantly greater female captures, each recording ~ 2-fold more captures than traps baited with the BG-Lure. There was no significant difference, however, between the treatments. Female Ae. aegypti captured in CO2-baited traps were mainly unfed (91%), with fewer gravid mosquitoes (6.4%) compared to traps with test compounds (range; 12.7-21.1%). Male captures were lower in LO and BG-Lure baited traps compared to other treatments. Gravimetric analysis showed LO had a slower release rate compared to other compounds. The findings suggest that host-associated compounds loaded on polymer beads are more effective in trapping Ae. aegypti than commercial BG-Lure and reveal sex-specific differences in mosquito responses. These results have implications for mosquito surveillance and control programs, highlighting the potential for selective trapping strategies.