Gas Chromatography Research Articles

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.

The effect of fat model variation on muscle fat fraction quantification in a cross-sectional cohort.

Spectroscopic imaging, rooted in Dixon's two-echo spin sequence to distinguish water and fat, has evolved significantly in acquisition and processing. Yet precise fat quantification remains a persistent challenge in ongoing research. With adequate phase characterization and correction, the fat composition models will impact measurements of fatty tissue. However, the effect of the used fat model in low-fat regions such as healthy muscle is unknown. In this study, we investigate the effect of assumed fat composition, in terms of chain length and double bond count, on fat fraction quantification in healthy muscle, while addressing phase and relaxometry confounders. For this purpose, we acquired bilateral thigh datasets from 38 healthy volunteers. Fat fractions were estimated using the IDEAL algorithm employing three different fat models fitted with and without the initial phase constrained. After data processing and model fitting, we used a convolutional neural net to automatically segment all thigh muscles and subcutaneous fat to evaluate the fitted parameters. The fat composition was compared with those reported in the literature. Overall, all the observed estimated fat composition values fall within the range of previously reported fatty acid composition based on gas chromatography measurements. All methods and models revealed different estimates of the muscle fat fractions in various evaluated muscle groups. Lateral differences changed from 0.5% to 5.3% in the hamstring muscle groups depending on the chosen method. The lowest observed left-right differences in each muscle group were all for the fat model estimating the number of double bonds with the initial phase unconstrained. With this model, the left-right differences were 0.64% ± 0.31%, 0.50% ± 0.27%, and 0.50% ± 0.40% for the quadriceps, hamstrings, and adductors muscle groups, respectively. Our findings suggest that a fat model estimating double bond numbers while allowing separate phases for each chemical species, given some assumptions, yields the best fat fraction estimate for our dataset.

Quantification of cresols in liquid smoke samples employing liquid–liquid extraction with low-temperature purification and analysis by gas chromatography–mass spectrometry

Liquid smoke is a food additive and cresols are among its chemical constituents, potentially toxic to human health. Thus, the objective of this study was to develop a method to quantify cresols in liquid smoke. First, the liquid-liquid extraction with low temperature purification (LLE-LTP) was validated for cresols in water, as there are no cresol-free liquid smoke samples. Analyzes were performed by gas chromatography coupled to mass spectrometry in full scan mode. LLE-LTP was subsequently applied in five commercial samples of liquid smoke. Validation results showed that the proposed extraction method was selective for cresols, linear in the range of 0.5 to 35 mg L−1, limit of quantification of 0.5 mg L−1, recovery rate between 90% and 104% and relative standard deviation lower than 10%. The quantification of cresols in liquid smoke samples ranged from 3.0 to 38.3 mg L−1 and the concentration of these chemical contaminants in liquid smoke remained constant for at least 21 days at 25 °C.

Oriented oxidation of all alkanes by iron inactivation of hydrophilic functional groups in soil organic matter

While extensive studies concentrated on catalyst modification in Fenton technology, few focused on functional groups of soil organic matter inactivation by iron in soil remediation. This study aimed to investigate the mechanism of oriented oxidation of total petroleum hydrocarbons (TPH) by regulating the hydrophilic functional groups of soil organic matter (SOM). The oriented oxidation experiment was conducted using petroleum hydrocarbon contaminated soil by stepwise addition of Fe ions and H2O2, with the initial TPH of 21068 mg/kg and SOM of 54000 mg/kg. The results revealed that the oxidation of TPH in the inactive Fe-SOM group was 1.9 times higher than that in the active Fe-SOM group (4059 mg/kg versus 2187 mg/kg). Conversely, the oxidation of SOM decreased by a factor of 2.4-fold in the active Fe-SOM group (7532 mg/kg versus 3153 mg/kg). Moreover, the oriented oxidation of all alkanes such as short, medium, and long-alkanes (C13-C17: 409.07 mg/kg, C18-C24: 402.17 mg/kg, C25-C30: 400.09 mg/kg) was considerable compared to active Fe-SOM group. Furthermore, based on the characterization of FT-IR, XPS and 3DEEM, the inactivation of SOM was attributed to the formation of FeOOH, Fe-C-O, Fe-N by the combination of Fe and hydrophilic functional groups. Additionally, the possible oxidation pathway was proposed by gas chromatography. The relative reaction coefficient of hydroxyl radicals (•OH) contributes to improving the oriented oxidation of all alkanes by optimizing TPH allocation after SOM inactivation. This study enriches our understanding of oriented oxidation of all alkanes in petroleum-contaminated soil.

Microbial Biosynthesis of Medium-Chain-Length Polyhydroxyalkanoate (mcl-PHA) from Waste Cooking Oil

Waste cooking oil is a common byproduct in the culinary industry, often posing disposal challenges. This study explores its conversion into the valuable bioplastic material, medium-chain-length polyhydroxyalkanoate (mcl-PHA), through microbial biosynthesis in controlled bioreactor conditions. Twenty-four bacterial isolates were obtained from oil-contaminated soil and waste materials in Mahd Ad-Dahab, Saudi Arabia. The best PHA-producing isolates were identified via 16S rDNA analysis as Neobacillus niacini and Metabacillus niabensis, with the sequences deposited in GenBank (accession numbers: PP346270 and PP346271). This study evaluated the effects of various carbon and nitrogen sources, as well as environmental factors, such as pH, temperature, and shaking speed, on the PHA production titer. Neobacillus niacini favored waste cooking oil and yeast extract, achieving a PHA production titer of 1.13 g/L, while Metabacillus niabensis preferred waste olive oil and urea, with a PHA production titer of 0.85 g/L. Both strains exhibited optimal growth at a neutral pH of 7, under optimal shaking -flask conditions. The bioreactor performance showed improved PHA production under controlled pH conditions, with a final titer of 9.75 g/L for Neobacillus niacini and 4.78 g/L for Metabacillus niabensis. Fourier transform infrared (FT-IR) spectroscopy and gas chromatography–mass spectrometry (GC-MS) confirmed the biosynthesized polymer as mcl-PHA. This research not only offers a sustainable method for transforming waste into valuable materials, but also provides insights into the optimal conditions for microbial PHA production, advancing environmental science and materials engineering.

Identification of Biomarkers Associated with Phyllosticta citricarpa Tolerance

Citrus black spot (CBS) is a fungal disease caused by Phyllosticta citricarpa Kiely, (McAlpine Van der Aa), with most cultivars being susceptible to infection. Currently, disease control is based on the application of protective fungicides, which is restricted due to resistance, health and environmental concerns. Although using natural products for disease management is gaining momentum, more advances are required. This study obtained the metabolic profiles of the essential oil and cuticular waxes of two citrus cultivars with a varying susceptibility to CBS infection using gas chromatography–mass spectrometry. A multivariate data analysis identified possible biomarker compounds that contributed to the difference in susceptibility between the two cultivars. Several identified biomarkers were tested in vitro for their antifungal properties against P. citricarpa. Two biomarkers, propanoic acid and linalool, were able to completely inhibit pathogen growth at 750 mg/L and 2000 mg/L, respectively.

Association of Omega-3 Polyunsaturated Fatty Acids with Sarcopenia in Liver Cirrhosis Patients with Hepatocellular Carcinoma.

Sarcopenia is associated with the prognosis of patients with liver cirrhosis and hepatocellular carcinoma (HCC). Given their diverse physiological activities, we hypothesized that plasma fatty acids might influence the progression of sarcopenia. This study aimed to clarify the association between fatty acids and sarcopenia in cirrhotic patients with HCC. In this single-center retrospective study, we registered 516 cases and analyzed 414 cases of liver cirrhosis and HCC. The skeletal muscle mass index was measured using a transverse computed tomography scan image at the third lumbar vertebra. The cutoff value for sarcopenia followed the criteria set by the Japan Society of Hepatology. Fatty acid concentrations were measured by gas chromatography. Fatty acid levels, particularly omega-3 (n-3) polyunsaturated fatty acid (PUFA), were lower in patients with poor liver function (Child-Pugh grade B/C) and were negatively correlated with the albumin-bilirubin score (p<0.0001). The prognosis of HCC patients with low PUFA levels was significantly worse. Among the different fatty acid fractions, only n-3 PUFAs significantly correlated with skeletal muscle mass index (p=0.0026). In the multivariate analysis, the n-3 PUFA level was an independent variable associated with sarcopenia (p=0.0006). A low level of n-3 PUFAs was associated with sarcopenia in patients with liver cirrhosis and HCC.

Antimicrobial Potential of Brassica oleracea Extracts (White and Broccoli) and Their Resistance Compared to Doxycycline Against Gram‐Positive and Gram‐Negative Bacteria

AbstractBrassica oleracea L is low in carbohydrates and fiber, making it ideal for low‐carb diets. But they are rich in vitamins, minerals, and other essential nutrients. The present article investigated the antimicrobial effect of B. oleracea extract (white and broccoli) (BOE‐WB) on Gram‐positive and Gram‐negative strains and its resistance to doxycycline. BOE‐WB was used as the soaking method. It was analyzed by gas chromatography–mass spectroscopy (GC–MS), high‐performance liquid chromatography (HPLC), and 2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH) methods. The samples were prepared with three concentrations. It used Mueller Hinton Agar culture medium of fresh bacteria. It was incubated for 24 h in a 37°C incubator. It identified 33 compounds. For BOE‐W, 77% of the compounds are oxygenated, while for BOE‐B, this percentage is 79%. For BOE‐B, 79% had oxygenated compounds. BOE‐WB has significant antibacterial effects on Pseudomonas aerogenosa and Bacillus cereus. The lethal impact of BOE‐WB on strains is very close to that of doxycycline, and it can be introduced as a new antimicrobial drug to the medical world. The research shows that the percentage of oxygenated compounds in foods containing BOE‐B is much higher than that of BOE‐W. It has a significant impact on the antioxidant effect. Foods containing BOE‐W have a high percentage of azo compounds and sulfur. One of the benefits of sulfur in the body is disinfecting the blood. In addition, sulfur increases the body's resistance to bacteria.

Essential oil and waste hydrosol of Ocimum tenuiflorum L.: A low-cost raw material source of eugenol, botanical pesticides, and therapeutic potentiality.

In this study, essential oils and waste hydrosols of leaves of Ocimum tenuiflorum in four different geographical locations were extracted by hydrodistillation method and using gas chromatography / mass spectrometry (GC/MS) for chemical composition analysis. All four essential oil samples contained the main components (E)-β-caryophyllene (27.8-49.0%), trans-β-elemene (20.3-37.1%) and eugenol (9.0-44.0%). Three of the four hydrosol samples had eugenol in absolute content (94.5-98.6%), while the remaining hydrosol sample had two main components, elemicin (77.8%) and eugenol (14.2%). Essential oils and hydrosols demonstrated larvicidal activities against four important disease-transmitting mosquito species including Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Culex fuscocephala with 24-h LC50 values in the range 15.42-56.01 µg/mL and 53.88-97.80 µg/mL for the essential oils and the hydrosols, respectively. Essential oils and hydrosols strongly inhibited the acetylcholinesterase (AChE) enzyme of electric eels with IC50 values in the range of 25.35-107.19 µg/mL. Microemulsion (ME) can be considered as a sustainable pesticide formulation over 300 days and has improved larvicidal activity compared to free essential oil. The O. tenuiflorum in Vietnam can be considered a low-cost source of eugenol, botanical pesticides that control disease-transmitting mosquitoes, as well as having therapeutic potential to be further investigated.

Bone lesions and intestinal barrier disruption caused by the isolated novel goose parvovirus infection in ducks

Short beak and dwarfism syndrome (SBDS) is attributed to Novel Goose Parvovirus (NGPV), which has inflicted significant economic losses on farming in China. Despite its significant impact, limited research has been conducted on the pathogenesis of this disease. The SD strain, a parvovirus variant isolated from ducks in Shandong province, was identified and characterized in our study. Phylogenetic analysis and sequence comparisons confirmed the classification of the SD strain as a member of NGPV. Based on this information, we established an animal model of SBDS by inoculating Cherry Valley ducks with the SD strain. Our findings indicate that infection with the SD strain leads to a reduction in body weight, beak length, width, and tibia length. Notably, significant histopathological alterations were observed in the thymus, spleen, and intestine of the infected ducks. Furthermore, the SD strain induces bone disorders and inflammatory responses. To evaluate the impact of NGPV on intestinal homeostasis, we performed 16S rDNA sequencing and gas chromatography to analyze the composition of intestinal flora and levels of short-chain fatty acids (SCFAs) in the cecal contents. Our findings revealed that SD strain infection induces dysbiosis in cecal microbial and a decrease in SCFAs production. Subsequent analysis revealed a significant correlation between bacterial genera and the clinical symptoms in NGPV SD infected ducks. Our research providing novel insights into clinical pathology of NGPV in ducks and providing a foundation for the research of NGPV treatment targeting gut microbiota.

Fatty acids and squalene and quality parameters of extra virgin olive oil (Olea europaea L.) produced in Mexico

The extra virgin olive oil (EVOO) has a high lipid composition, which is unique and desirable for product diversification, therefore, this oil is frequently adulterated. The objectives of this study are to evaluate fatty acids (FAs) and squalene (SQ) in EVOO produced in El Olivo, Mexico (OMx) and its quality, compared to commercial Olive Oils (COO). The FAs and SQ quantifications in the EVOO-OMx were done with gas chromatography and column chromatography, respectively. The quality of the EVOO-OMx was measured with acidity index (AI) and iodine index (II), and compared with the following COO: (1) OO-Spain, (2) EVOO-Spain, (3) EVOO-Mx, (4) a mixture of vegetable oil (MVO-Mx) and (5) EVOO-OMx. The concentration of unsaturated FAs predominated (89.60 %), where oleic was the majority (76.76 %), and its SQ content was high (10 mg g−1 of oil). The AI in EVOOs was ≤ 0.8 % oleic acid, as reported by international organizations and standards. EVOO-OMx was the one with an II value within that specified for EVOO (78.44 cg I2 g−1). The EVOO-OMx has a higher quality in FAs, SQ and stability than the COO.

The use of essential oils as an alternative for the control of Tetranychus urticae (Acari: Tetranychidae)

Considering that the use of essential oils is a promising technique and a valuable alternative in the control of unwanted organisms, this study aimed to chemically characterize the essential oil of Acanthospermum australe (Loefl.) O. Kunze (Asteraceae) through gas chromatography, as well as to evaluate the repellent and acaricidal effect of the essential oils from A. australe and Baccharis psiadioides (Less.) Joch.Müll (Asteraceae) against Tetranychus urticae Koch (Tetranychidae). For the repellency test, concentrations of 0.25, 0.5 and 1% were used for both oils, and concentrations of 10 μL/L(air) and 20 μL/L(air) to evaluate acaricidal effects. Eight compounds were identified in the essential oil of A. australe, with thymyl isobutyrate (63.4%) being the major compound, followed by thymol (13.4%) and thymyl 2-methylbutyrate (4.96%). The results demonstrated higher repellency to the essential oil of A. australe at a concentration of 0.5%, followed by B. psiadioides at a concentration of 1%. The mortality rate of TSSM exceeds 90% when exposed to both tested concentrations of the essential oil of A. australe proving effective in both cases.

Comparative Analysis of Hydrosol Volatile Components of Citrus × Aurantium ‘Daidai’ and Citrus × Aurantium L. Dried Buds with Different Extraction Processes Using Headspace-Solid-Phase Microextraction with Gas Chromatography–Mass Spectrometry

Comparative Analysis of Hydrosol Volatile Components of Citrus × Aurantium ‘Daidai’ and Citrus × Aurantium L. Dried Buds with Different Extraction Processes Using Headspace-Solid-Phase Microextraction with Gas Chromatography–Mass Spectrometry

Qualitative Analysis and Anti-oxidant Potential of Ethanolic Extract ofManilkara zapota (L.) P. Royen Leaves

Background: The normal metabolic functioning of aerobic cells is related to free radical formation. The oxygen utilized in the cell growth gives rise to a number of oxygen free radicals. Further, these oxygen free radicals interact with lipidic molecules to produce hydroxyperoxides and various other peroxides also, radicals like superoxide, hydroxyls, and lipoid peroxides, which lead to cytotoxicity due to their interaction with biological systems. The uncontrolled generation of free radicals may lead to various diseases and disorders like prostate cancer, coronary heart disease and also ageing. The therapeutic potential of the plant M. zapota has been demonstrated in various diseases, such as cancers (e.g., breast, prostate, cervical, and hepatocellular cancer), diabetes mellitus, arthritis, bacterial infections, and gastrointestinal disorders (e.g., diarrhea and ulcers) and many medical conditions. The main phytocomponents of this plant are polyphenols, alkaloids, glycosides, flavonoids, saponins, triterpenoids, carbohydrates, tannins, and sterols. Objective: The objective of this study is to investigate qualitative analysis and anti-oxidant potential of ethanolic extract of Manilkara zapota (L.) P. Royen Leaves. In demand to minimize the damage caused by free radicals. It is very essential to develop such antioxidants which protect the body from the effect of free radicals and also do not cause much harm to the human body. The main phytocomponents of the plant are polyphenols, alkaloids, glycosides, flavonoids, saponins, triterpenoids, carbohydrates, tannins and sterols which are responsible for antioxidant activity. Materials and Methods: Phytochemical screening methods, Gas chromatography–mass spectrometry (GC-MS), Fourier transform infrared (FTIR), and Hydrogen Peroxide scavenging assay for analysis of an ethanolic extract of plant leaves. Results and Discussion: Antioxidant activity was determined by a hydrogen peroxide assay. Plant extract was examined using phytochemical screening, GC-MS analysis, and FTIR spectra. The plant extract showed hydrogen peroxide scavenging activity (IC50 = 16.45 μg/ml) compared to the IC50 values of standard ascorbic acid (IC50 = 9.079 μg/ml). Conclusion: The present study concluded the antioxidant and phytochemical assessment of the ethanolic extract of the leaves of Manilkara zapota. The results of the present research study demonstrated that the antioxidant activity of the plant extract was strong as compared to ascorbic acid.

Sweat-based stress screening with gas chromatography–ion mobility spectrometry and electronic nose

BackgroundDiagnosis of stress generally involves uses of questionnaires which can provide biased results. The more reliable approach relies on observation of individual symptoms by psychiatrists which is time consuming and could not be applicable for massive scale screening tests. This research established alternative approaches with gas chromatography–ion mobility spectrometry (GC–IMS) and electronic nose (e-nose) to perform fast stress screening based on fingerprinting of highly volatile compounds in headspaces of sweat. The investigated samples were obtained from 154 female nurse volunteers who also provided the data of questionnaire-based mental health scores with the high stress cases confirmed by psychiatrists. ResultsThe interviews by psychiatrists revealed 14 volunteers with high stress. Their axillary sweat samples and that from 32 nurses with low/moderate stress (controls) were collected onto cotton rods and analysed with GC–IMS. The possible marker peaks were selected based on the accuracy data. They were tentatively identified as ammonia, diethyl ether, methanol, octane, pentane, acetone and dimethylamine which could involve different endogenous mechanisms or the relationships with the local microbiomes. The data were further analysed using partial least squares discriminant analysis with the receiver operating characteristic curves showing the optimum accuracy, sensitivity and selectivity of 87%, 86% and 88%, respectively. Providing that the samples were obtained from the nurses without deodorant uses, the high stress cases could be screened using e-nose sensors with the accuracy of 89%. The sensor responses could be correlated with the marker peak area data in GC–IMS with the coefficients ranging from −0.70 to 0.80. SignificanceThis represents the first investigation of highly volatile compound markers in sweat for high stress screening. The established methods were simple, reliable, rapid and non-invasive, which could be further adapted into the portable platform of e-nose sensors with the practical application to perform the screening tests for nurses in Phra Nakorn Si Ayutthaya hospital, Thailand.

Influence of annealing temperature on the structure, morphology, optical property and antibacterial response of phytochemicals-assisted synthesized zinc oxide nanoparticles

Abstract Antibiotic overuse has caused a variety of bacterial pathogens to develop new resistance mechanisms. As a result, discovering an appropriate replacement for the standard antibiotics has become an immediate concern. The present work demonstrates a facile, eco-friendly and economical method for the synthesis of hexagonal wurtzite zinc oxide nanoparticles (ω-ZONPs) using the ethanolic extract of triphala. Gas chromatography–mass spectrometry analysis of the triphala extract proved the presence of certain secondary metabolites, which aids in the formation of ω-ZONPs. The influence of annealing temperature on the antibacterial action of as-synthesized ω-ZONPs was studied for three different annealing temperatures. X-ray diffraction, dynamic light scattering, field emission electron microscopy and energy dispersive X-ray spectroscopy analyses were used to examine the impact of annealing temperature on the structure, particle size and morphology of ω-ZONPs. Fourier transform infrared spectra revealed the change in intensity of the characteristic peaks in ω-ZONPs with different annealing temperatures. From UV–Visible diffuse reflectance spectroscopy, variation in the band gap of ω-ZONPs with increasing annealing temperature was detected. Kirby Bauer disc diffusion was adopted to examine the antibacterial potential of ω-ZONPs against bacterial strains such as Staphylococcus aureus, Enterococcus faecium, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The ω-ZONPs annealed at 200 °C inhibited the growth of three bacterial pathogens, E. coli, B. subtilis and P. aeruginosa and exhibited effective antibacterial activity in comparison with ω-ZONPs annealed at relatively high temperatures. Thus, the antibacterial potential of ω-ZONPs could be further explored as disease controlling agents and such prototypes could be made available for commercial mass production.

A Comprehensive Strategy for Metabolites Profiling of Flowers and Leaves from Camellia tienii, an Endemic Golden Tea of Vietnam.

Golden camellia is defined as a species of the Camellia genus with yellow flowers, which have long been used as a medicine, food, and cosmetic in many Asian countries. To date, more than 50 golden camellia species are considered endemic in Vietnam; however, more information is needed about its chemical constituents and biological activity. This work aims to unveil the potential of Camellia tienii Ninh, a golden camellia species, as an herbal beverage by examining the presence and abundance of chemical components in flowers and leaves. A comprehensive strategy has been developed using both liquid and gas chromatography coupled with mass spectrometry. Specifically, LC-MS-based widely targeted analyses were opted to characterize 158 polar metabolites belonging mainly to flavonoids, catechins, and amino acids classes, and an untargeted approach using GC-MS annotated 42 major volatile compounds such as terpenes and fatty acids. The extensive profile revealed by these techniques could help understand the significant discrimination between two organs. C. tienii flowers accumulated more flavonoids, amino acids, and fatty acids, while leaves contain more terpenes, suggesting different pharmacological properties of these materials. Overall, this pipeline can be applied for other Camellia species and valorization of these valuable resources for health benefits purposes.

Attractiveness of Tetragonula laeviceps (Hymenoptera: Apidae) to Citrus Volatile Compounds and Flower Colors in Indoor Microclimate Conditions

Tetragonula laeviceps plays a vital role as a primary pollinator of citrus flowers for successful pollination. However, there is still a lack of understanding about how T. laeviceps can find citrus flowers. This study aimed to elucidate the factors influencing the attraction of T. laeviceps to citrus flowers, focusing on microclimate conditions, and visual and olfactory factors. For this, we conducted six-choice assays in a stingless bee house using artificial flowers as visual cues and citrus essential oils as olfactory stimuli. Three pairs of red or white artificial flowers were displayed to adult workers, with each pair placed in glass vials filled with diluted orange (Citrus reticulata) essential oil, lemon (Citrus limon) essential oil, or solvent. Simultaneously, microclimate conditions were measured, including temperature, relative humidity, and light intensity. We observed that the highest number of T. laeviceps visited the artificial flowers at 11:00, irrespective of visual and olfactory factors. We also found a positive correlation between the number of visits and both temperature and light intensity, whereas there was a negative correlation with humidity. The number of visits did not exhibit a significant difference between flower colors. In contrast, we observed the highest visitation to the orange essential oil, followed by the lemon essential oil and solvent. Gas Chromatograph – Mass Spectrometry (GC-MS) analysis revealed common terpenes in orange and lemon essential oils, while linalool and α-citral were predominantly detected in the orange essential oil. These characteristic terpenes could potentially be the attractants for T. laeviceps.

Chemical composition, antioxidant and antimicrobial activities of Rumex obtusifolius L. essential oil from the highlands of Ecuador

The chemical composition, antioxidant and antimicrobial activities of the essential oil from the aerial parts of Rumex obtusifolius L. were studied. To the best of the authors’ knowledge, this essential oil has never been fully characterized. The component analysis of the essential oil was done by gas chromatography with flame ionization detector (GC-FID) and mass selective detector (GC-MS). A total of 104 compounds, representing 97.8% of the essential oil, were identified. Aliphatic compounds, mainly methyl ketones (74.2%) and monoterpene hydrocarbons (13.7%) were found to be the most abundant compounds. The major compounds were undecan-2-one (47.6%) and nonan-2-one (13.4%). The antioxidant activity of the essential oil, evaluated by DPPH (IC50 9.11 mg/mL) and ABTS (IC50 36.72 mg/mL) assays, exhibited a weak ability in scavenging radicals. The essential oil also showed a low ferric reducing activity. The essential oil exhibited very good activity against E. coli and S. aureus, but low activities against S. enterica serovar, P. aeruginosa and C. albicans. MIC values of the essential oil varied from 0.38-27.04 μL/mL, with the lowest for E. coli.

LC-MS/MS-based phospholipid profiling of plant-pathogenic bacteria with tailored separation of methyl-branched species.

Plant-pathogenic bacteria are one of the major constraints on agricultural yield. In order to selectively treat these bacteria, it is essential to understand the molecular structure of their cell membrane. Previous studies have focused on analyzing hydrolyzed fatty acids (FA) due to the complexity of bacterial membrane lipids. These studies have highlighted the occurrence of branched-chain fatty acids (BCFA) alongside normal-chain fatty acids (NCFA) in many bacteria. As several FA are bound in the intact phospholipids of the bacterial membrane, the presence of isomeric FA complicates lipid analysis. Furthermore, commercially available reference standards do not fully cover potential lipid isomers. To address this issue, we have developed a reversed-phase high-performance liquid chromatography (RP-HPLC) method with tandem mass spectrometry (MS/MS) to analyze the phospholipids of various plant-pathogenic bacteria with a focus on BCFA containing phospholipids. The study revealed the separation of three isomeric phosphatidylethanolamines (PE) depending on the number of bound BCFA to NCFA. The validation of the retention order was based on available reference standards in combination with the analysis of hydrolyzed fatty acids through gas chromatography with mass spectrometry (GC/MS) after fractionation. Additionally, the transferability of the retention order to other major lipid classes, such as phosphatidylglycerols (PG) and cardiolipins (CL), was thoroughly examined. Using the information regarding the retention behavior, the phospholipid profile of six plant-pathogenic bacteria was structurally elucidated. Furthermore, the developed LC-MS/MS method was used to classify the plant-pathogenic bacteria based on the number of bound BCFA in the phospholipidome.