GC-flame Ionization Detection Research Articles

Chemical components and antioxidant potential of essential oil of Rhanterium epapposum growing in sandy habitat in Saudi Arabia: In silico study on cytochrome P450 1A1 and xanthine oxidase

Rhanterium epapposum Oliv. (Family: Asteraceae) is a common plant in Saudi Arabia, possessing a variety of traditional uses. The current targets were studying the comparative chemical profile and antioxidant of the essential oil (EO) of R. epapposum collected from a sandy habitat at Qareenah, Riyadh, Saudi Arabia. The EO profiling was constructed via gas chromatography-mass spectrometry (GC-MS) and GC-flame ionization detection (GC-FID). Forty-eight compounds were found, including monoterpenes (hydrocarbons 3.25% and oxygenated 48.64%), sesquiterpenes (hydrocarbons 12.64 % and oxygenated 32.38%), which are the backbone of the oil along with a minor of other non-terpenoid compounds (1.31%). Linalool (18.02%), α-eudesmol (11.98%), trans-sesquisabinene hydrate (11.63%), aromadendrene oxide-(1) (7.68%), nerol (6.88%), and α-terpineol (5.01%) were identified as the dominant components. The EO was evaluated for its antioxidant activity using in vitro DPPH, ABTS, and FRAP methods. The results demonstrated that R. epapposum EO possesses a dosage-dependent ability for antioxidant scavenging activity as per all three techniques. This EO exhibited IC50 values of 517.59, 350.24, and 713.72 μg/mL for the DPPH, ABTS, and FRAP, respectively, through the comparison with the ascorbic acid with respective values of 36.10, 26.12, and 44.58 μg/mL. The main compounds were subjected to docking analysis on cytochrome P450 1A1 and xanthine oxidase. All evaluated compounds exhibited good binding affinities especially α-eudesmol and linalool for both enzymes, respectively. The current research confirmed the potent free radical scavenging properties of R. epapposum EO. More research on the antioxidant content of this oil and/or its primary constituents in pure form on the two enzymes, cytochrome P450 1A1 and xanthine oxidase, is proposed to develop a better understanding of the oxidative action routes in vivo and in vitro.

Phenotypic and molecular characterization of clinically isolated antibiotics-resistant S. aureus (MRSA), E. coli (ESBL) and Acinetobacter 1379 bacterial strains.

Antibiotic-resistant bacteria causing nosocomial infections pose a significant global health concern. This study focused on examining the lipid profiles of both non-resistant and clinically resistant strains of Staphylococcus aureus (MRSA 1418), E. coli (ESBL 1384), and Acinetobacter 1379. The main aim was to investigate the relationship between lipid profiles, hydrophobicity, and antibiotic resistance so as to identify the pathogenic potential and resistance factors of strains isolated from patients with sepsis and urinary tract infections (UTIs). The research included various tests, such as antimicrobial susceptibility assays following CLSI guidelines, biochemical tests, biofilm assays, and hydrophobicity assays. Additionally, gas chromatography mass spectrometry (GC-MS) and GC-Flame Ionization Detector (GC-FID) analysis were used for lipid profiling and composition. The clinically isolated resistant strains (MRSA-1418, ESBL-1384, and Acinetobacter 1379) demonstrated resistance phenotypes of 81.80%, 27.6%, and 63.6%, respectively, with a multiple antibiotic resistance index of 0.81, 0.27, and 0.63. Notably, the MRSA-1418 strain, which exhibited resistance, showed significantly higher levels of hemolysin, cell surface hydrophobicity, biofilm index, and a self-aggregative phenotype compared to the non-resistant strains. Gene expression analysis using quantitative real-time PCR (qPCR). Indicated elevated expression levels of intercellular adhesion biofilm-related genes (icaA, icaC, and icaD) in MRSA-1418 (pgaA, pgaC, and pgaB) and Acinetobacter 1379 after 24h compared to non-resistant strains. Scanning electron microscopy (SEM) was employed for structural investigation. These findings provide valuable insights into the role of biofilms in antibiotic resistance and suggest potential target pathways for combating antibiotic-resistant bacteria.

Simultaneous quantification of six flavouring agents in herbal freshness gel toothpaste by gas chromatography

AbstractThere are many methods reported to identify and quantify volatile compounds. Many of them are based on chromatographic techniques, such as high‐performance liquid chromatography (HPLC), gas chromatography with flame ionization detector (GC‐FID), and GC coupled with mass spectrometry (GC–MS). But among all GC‐FID and GC–MS are majorly used for the detection and quantification of volatile compounds. A new gas chromatographic method has been developed for simultaneous determination of six flavouring agents [menthol, benzyl alcohol, methyl salicylate, anethole, menthol carboxamide (WS‐3) and eugenol] in herbal freshness gel toothpaste. All six flavours were separated using a DB‐WAX (Agilent) capillary GC column (30 m × 0.25 mm × 0.25 μm) and flame ionization detector (FID). This method was validated for various parameters such as precision, linearity, accuracy, stability, robustness, limit of detection, and limit of quantification as per ICH guidelines, AOAC internationals Appendix K. All the validation parameters were found to be within acceptable limits. The method was successfully applied for the quantification of all flavouring agents in toothpaste formulations.

Application of the relative molar sensitivity method using GC-FID to quantify safranal in saffron (Crocus sativus L.).

Safranal is one flavor component of saffron, which is used as a spice, food additive, and crude drug. In ISO3632, safranal is defined as the compound that contributes to the quality of saffron, and many quantitative determination methods for safranal have been reported. However, safranal is volatile and degrades easily during storage, and an analytical standard with an exact known purity is not commercially available, making it difficult to quantify accurately the content of safranal in saffron. Here, we developed a method for quantifying safranal using relative molar sensitivity (RMS), called the RMS method, using a GC-flame ionization detector (GC-FID). We determined the RMS of safranal to 1,4-bis(trimethylsilyl)benzene-d4, a certified reference material commercially available, by a combination of quantitative NMR and chromatography. Using two GC-FID instruments made by different manufacturers to evaluate inter-instrument effect, the resultant RMS was 0.770, and the inter-instrument difference was 0.6%. The test solution, with a known safranal concentration, was measured by the RMS method, with an accuracy of 99.4-101%, repeatability of 0.81%, and reproducibility of 0.81-1.3%. Given the ease of degradation, high volatility, and uncertain purity of safranal reagents, the RMS method is a more accurate quantification approach compared to the calibration curve method and methods based on absorption spectrophotometry. Moreover, our findings revealed that the GC-FID makeup gas affected the RMS and quantitative values.

Pharmaceutical Residual Solvent Analysis: A Comparison of GC-FID and SIFT-MS Performance

Residual solvents in pharmaceutical excipients, active pharmaceutical ingredients (APIs), and finished products are usually analyzed using gas chromatography (GC)-based techniques according to a pharmacopeial monograph, such as the United States Pharmacopeia’s (USP) chapter <467>. GC analyses are often slow, which limits sample throughput. Selected ion flow tube mass spectrometry (SIFT-MS) removes the rate-limiting chromatographic separation step, potentially offering faster sample analyses. This approach was demonstrated recently with the publication of an alternative SIFT-MS procedure which was successfully validated against the performance criteria in USP chapter <1467>. The present study expands upon the previous work by conducting a head-to-head comparison of GC-flame ionization detection (GC-FID) and SIFT-MS procedures. The results obtained in this cross-platform study demonstrated similar performance for the GC-FID and SIFT-MS procedures for linearity (R2 > 0.94 and 0.97, respectively) and repeatability (<17%RSD and <10%RSD). For accuracy and recovery, acceptance criteria (within 20%) were achieved for most compounds across the two drug products (SIFT-MS suffered fewer failures, possibly due to shorter wait times prior to analysis). Additionally, SIFT-MS analyzed samples over 11-fold faster than GC-FID, increasing daily sample throughput and reducing the time taken to determine the result. This study therefore suggests that residual solvent analysis using SIFT-MS may support workflow improvements for pharmaceutical manufacturers.

Water-soluble essential oil components of flowers of Paeonia × suffruticosa cultivars and in silico analysis with antidepressant targets

The present study focused on water-soluble essential oil recovered from the hydrolate of ten Paeonia × suffruticosa cultivars. Thirty-seven components, mostly oxygenated compounds (94.6–99.6%), were detected by gas chromatography–mass spectrometry (GC-MS) and GC–flame ionisation detector (GC-FID). The geranic acid chemotype was discovered (in cultivar ‘Lan BaoShi’). Eight key oxygenated components were analysed in silico with antidepressant targets sodium-dependent serotonin transporter (SERT), 5-hydroxytryptamine receptor 1 A (5-HT1A), and monoamine oxidase type A (MAO-A). Geraniol, nerol, citronellol, and geranic acid presented superior docking properties. Phenylethyl alcohol and 1,3,5-trimethoxybenzene were also well docked. These molecules were bound to the active sites successfully (with partial occupancy in SERT). They might increase serotonin level or mimic its effect in central nervous system. (Z)-3-Hexen-1-ol and 1-hexanol showed weak binding. The in silico analysis revealed for the first time that the key water-soluble essential oil components of P. × suffruticosa potentially targeted antidepressant targets.

Profiling of Redox-Active Lipophilic Constituents in Leaf Mustard (Brassica juncea (L.) Czern.) Cultivars Using LC-MS and GC-MS.

Leaf mustard is an important commercial and culinary vegetable. However, only limited information is available on the content and composition of the nutritionally important lipophilic constituents in these leaves. This research presents information on the contents and composition of carotenoids, tocols, phytosterols, and fatty acids in four cultivars of leaf mustard. The carotenoids and tocols were analyzed utilizing liquid chromatography (LC)-mass spectrometry (MS) with single ion monitoring (SIM), while phytosterols and fatty acids were analyzed using gas chromatography (GC)-MS and GC-flame ionization detection (FID), respectively. The LC-MS results revealed the dominance of (all-E)-lutein, within the range of 37.12 (cv. Asia Curled)-43.54% (cv. Jeok) of the total carotenoids. The highest amount of all of the individual carotenoids and total carotenoids (143.85 µg/g fresh weight; FW) were recorded in cv. Cheong. Among the studied leaf samples, 67.16 (cv. Asia Curled)-83.42 µg/g FW (cv. Cheong) of α-tocopherol was recorded. Among the phytosterols, β-sitosterol was the most dominant one among the studied mustard leaves, accounting for 80.42 (cv. Jeok)-83.14% (cv. Red frill) of the total phytosterols. The fatty acid analysis revealed the presence of a significant amount of rare hexadecatrienoic acid (C16:3n3) in the studied mustard leaves, which accounted for 27.17 (cv. Asia Curled)-32.59% (cv. Red frill) of the total fatty acids. Overall, the cv. Cheong represented the highest contents of carotenoids, tocols, and phytosterols. Moreover, cv. Red frill contains the highest amount of n-3 PUFAs and antioxidant compounds. Thus, these cultivars can be promoted in cuisines which can be eaten to obtain the highest health benefits.

A direct GC‐FID method for analysis of palm‐based fatty alcohol carbon chain distribution

AbstractPalm oil‐based fatty alcohol is a basic oleochemical with many different applications depending on its carbon chain length. The carbon chain distribution using a GC‐flame ionization detector (GC‐FID) is a quality control tool for monitoring the composition of either single or blended fatty alcohol. There is a published GC‐FID method but it requires a derivatization step. The objective of this work is to develop a derivatization‐free method with simple preparation steps. It can be used for routine analysis of the carbon chain distribution to determine the composition of palm‐based fatty alcohol. The GC‐FID method developed used a ZB‐FFAP (60 m × 0.25 mm i.d., 0.25 μm film thickness) consisting of polyethylene glycol bonded nitroterephthalic acid phase for separation of eight types of fatty alcohol with a run time of 40 min. The method showed good validation parameters performance in terms of accuracy (as compared with FAL standards), linearity (R2 > 0.9999) and intraday and intermediate precision (CV < 0.05% for retention time and CV < 1.5% for peak area). Monitoring of commercial FAL from local manufacturers showed that the composition was consistent with the required specifications.

An evaluation of aromatic hydrocarbons in recycled PET fibers by a reliable and effective static headspace GC-FID method

The volatile organic compounds (VOCs) released from recycled polyethylene terephthalate products has raised much concern in consideration of ecological safety. This work has established a reliable and effective headspace GC-flame ionization detection (HS-GC-FID) method for the determination of aromatic hydrocarbons (including benzene, toluene, ethylbenzene, xylene, styrene and cumene) in R-PET fibers. The optimum equilibration time and temperature, and sample weight were identified as 40 min, 110C and 1.0 g, respectively. By contrasting with 15 mL headspace bottle, the testing results of samples incubated in 120 mL headspace bottle provided a higher data repeatability. The linear equations to calculate VOCs content were obtained by linear regression analysis, and the linear regression coefficients were validated to be over 0.997. Limits of detection for benzene, toluene, ethylbenzene, p-xylene + m-xylene, o-xylene + styrene and cumene were calculated as 3.95 ng, 3.68 ng, 4.16 ng, 3.30 ng, 2.59 ng, 8.64 ng, respectively. Reproducibility tests of the method generated relative standard deviations of 6.0% or less, with recoveries in the range of 82%–109%. The availability of proposed method in application of VOCs detection in R-PET fibers was confirmed by detecting VOCs contents of virgin PET fibers, and R-PET fibers produced by physical, chemical and physical-co-chemical processes.。

Reductive Catalytic Depolymerization of Semi-industrial Wood-Based Lignin.

The current work studies the reductive catalytic depolymerization (RCD) of lignin from a novel semi-industrial process. The aim was to obtain aromatic mono-, di-, tri-, and tetramers for further valorization. The substrate and products were characterized by multiple analytical methods, including high pressure size-exclusion chromatography (HPSEC), gas chromatography–mass spectrometry, GC-flame ionization detector (FID), GC-FID/thermal conductivity detector (TCD), and NMR. The RCD was studied by exploring the influence of different parameters, such as lignin solubility, reaction time, hydrogen pressure, reaction temperature, pH, type and loading of the catalyst, as well as type and composition of the organic/aqueous solvent. The results show that an elevated temperature, a redox catalyst, and a hydrogen atmosphere are essential for the depolymerization and stability of the products, while the reaction medium also plays an important role. The highest obtained mono- to tetramers yield was 98% and mono- to dimers yield over 85% in the liquid phase products. The reaction mechanisms influenced the structure of the aliphatic chain in the monomers, but left the phenolic structure along with the methoxy groups largely unaltered. The current work contributes to the development and debottlenecking of the novel and sustainable overall process, which utilizes efficiently all the fractions of wood, in line with the principles of green engineering and chemistry.

Spent yeast polysaccharides in mixed alcoholic fermentation between Pichia kluyveri, Pichia fermentans and Saccharomyces cerevisiae retarded wine fruity ester hydrolysis

Synthetic grape juice was fermented with Pichia fermentans Z9Y-3 and Pichia kluyveri PK-19, along with S. cerevisiae of different antagonistic abilities, to investigate their impact on aroma stability. During 12-month storage, wine was stored for 2 months with lees and for 10 months without lees. Levels of fruity esters and polysaccharides were monitored using gas chromatography (GC)-mass spectrometry and GC-flame ionization detector, respectively, and wine aroma attributes were quantified by trained panelists. Results showed that co-fermentation elevated fruity ester content during fermentation and retarded fruity ester hydrolysis during storage, which increased the intensity of fruity traits, especially in the highly antagonistic group. Spent yeast from co-fermentation released more polysaccharides, which was predominantly composed of 50 % glucose, 30 % galacturonic acid, and 20 % mannose. During storage, the polysaccharide content decreased until it reached equilibrium at 6 months. Pearson analysis revealed that polysaccharide content correlated positively with fruity ester content and profile.

Radical scavenging activity and metabolomic profiling study of ylang-ylang essential oils based on high-performance thin-layer chromatography and multivariate statistical analysis

Ylang-ylang (YY) essential oil (EO) is distilled from the fresh-mature flowers of the Annonaceae family tropical tree Cananga odorata [Lam.] Hook. f. & Thomson, and is widely used in perfume and cosmetic industries for its fragrant character. Herein, two different metabolomic profiles obtained using high-performance thin-layer chromatography (HPTLC), applying different stains, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH·) and p-anisaldehyde, were used for discrimination of 52 YY samples across geographical origins and distillation grades. The first profile is developed using the DPPH· stain based on the radical scavenging activity (RSA) of YY EOs. Results of the HPTLC-DPPH· assay confirmed that RSA of YY EOs is in proportion to the length of distillation times. Major components contributing to the RSA of YY EOs were tentatively identified as germacrene D and α-farnesene, eugenol and linalool, by gas chromatography-mass spectrometry (GC–MS) and GC-flame ionisation detector (GC-FID). The second profile was developed using the general-purpose p-anisaldehyde stain based on the general chemical composition of YY EOs. Untargeted metabolomic discrimination of YY EOs from different geographical origins was performed based on the HPTLC-p-anisaldehyde profiles, followed by principal component analysis (PCA). A discrimination and prediction model for identification of YY distillation grade was developed using PCA and partial least squares regression (PLS) based on binned HPTLC-ultraviolet (254 nm) profiles, which was successfully applied to distillation grade determination of blended YY Complete EOs.

Altitudinal differentiation in the leaf wax-mediated flowering bud protection against frost in a perennial Arabidopsis.

An altitudinal gradient of leaf water repellency is often observed between and within species. In a previous study of Arabidopsis halleri, cauline leaves (stem leaves that wrap flowering buds) showed higher water repellency in exposed semi-alpine plants than in understory low-elevation plants. Here, we examined altitudinal variations in the cuticular wax content of the leaf surface and experimentally evaluated the role of high water repellency of cauline leaves. Leaf cuticular wax was analysed using comprehensive two-dimensional gas chromatography (GC)-mass spectrometry and a GC-flame ionisation detector. Young flowering buds wrapped by cauline leaves were exposed to freezing temperatures with or without water, and frost damage to the flowering buds was compared between plants from semi-alpine and low-elevation habitats. Higher amounts of C29, C31, and C33 alkanes were observed in the cauline leaves of semi-alpine plants than in those of low-elevation plants. In the freezing experiment, water application increased damage to the flowering buds of low-elevation plants, and the extent of damage to the flowering buds was lower in semi-alpine plants than in low-elevation plants when water was applied to the plant surface. Genetic variations in the amounts of alkanes on the leaf surface depending on the altitude occurred specifically in cauline leaves. Our results indicate that the water repellency of cauline leaves presumably minimises frost damage to flowering buds at high altitudes.

Trials for Gathering Information on an Unknown Peak in the GC-MS Spectra of Horse and Pony Hair Extracts

The volatile compounds from horse and pony hairs and skin were analyzed to determine bioactive molecules that are kairomones used for host location by blood-feeding diptera. In this study, horse and pony hair samples were extracted with organic solvents (pentane or hexane) and analyzed by gas chromatography-mass spectrometry analysis (GC-MS) with closed electron ionization (CEI). Using the GC-MS analysis, we observed a compound peak, which could not be identified by comparison to mass spectra in the mass spectral library. This unknown compound was often the largest peak in the chromatogram and had a retention index and mass spectral fragmentation similar to nonanal. However, there were several differences in the fragmentation pattern. When compared to a nonanal reference standard, it was evident that this was a different compound. Hydrodistillation of pony hair was another extraction method to obtain the unknown component in higher concentrations. Analysis of this extract with GC-flame ionization detector (FID) with GC-MS confirmed the same unknown peak. Further experiments and analysis with the various mass spectroscopy tools gave the possible molecular ion with mass-to-charge ratio (m/z) 142, corresponding to the unknown component.

Brain PUFA Concentrations Are Differentially Affected by Interactions of Diet, Sex, Brain Regions, and Phospholipid Pools in Mice

PUFAs play vital roles in the development, maintenance, and functioning of circuitries that regulate reward and social behaviors. Therefore, modulations in PUFA concentrations of these brain regions may disrupt reward and social circuitries contributing to mood disorders, developmental disabilities, and addictions. Though much is known about regional and phospholipid-pool-specific PUFA concentrations, less is known about the effects of dietary interventions that concurrently lowers n-6 PUFA and supplements n-3 PUFA, on brain PUFA concentrations. There is even less knowledge on the effects of sex on brain PUFA concentrations. This study aimed to comprehensively examine the interaction effects of diet (D), sex (S), brain regions (BR), and phospholipid pools (PL) on brain PUFA concentrations. Male and female C57BL/6J mice were fed 1 of 4 custom-designed diets varying in linoleic acid (LNA) (8en% or 1 en%) and eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) (0.4 en% or 0 en%) concentrations from in utero to 15 weeks old. At 15 weeks old, the prefrontal cortex, dorsal striatum, and cerebellum were collected. Fatty acids of 5 major PL were quantified by GC-flame ionization detection. Repeated measures ANOVA was used to test for differences among the groups for D, S, BR, and PL. No significant 4-way interactions on PUFA concentrations. DHA, predominant n-3 PUFA, concentrations were dependent on significant D × BR × PL interactions. DHA concentration was not affected by sex. Arachidonic acid (ARA; predominant n-6 PUFA) concentrations were not dependent on 3-way interactions. However, significant 2-way D × PL, BR × PL, and D × Sinteractions affected ARA concentrations. Brain fatty acid concentrations were differentially affected by various combinations of D, S, BR, and PL interactions. Though DHA concentrations are not affected by sex, ARA concentrations are affected by interactions of the 4 variables examined. This study provides comprehensive references in the investigation of complex interactions between factors that affect brain PUFA concentrations in mice.

Characterization of Phenolic Compounds, Vitamin E and Fatty Acids from Monovarietal Virgin Olive Oils of "Picholine marocaine" Cultivar.

Olive oil is an important product in the Mediterranean diet, due to its health benefits and sensorial characteristics. Picholine marocaine is the most cultivated variety in Morocco. The present research aims to evaluate the phenolic compounds, vitamin E and fatty acids of commercial Picholine marocaine virgin olive oils (VOOs) from five different North Moroccan provinces (Chefchaouen, Taounate, Errachidia, Beni Mellal and Taza), using HPLC-photodiode array (PDA)/electrospray ionization (ESI)-MS, normal phase (NP)-HPLC/ fluorescence detector (FLD) and GC-flame ionization detector (FID)/MS, respectively. The obtained results showed an average content of 130.0 mg kg−1 of secoiridoids (oleuropein aglycone, 10-hydroxy-oleuropein aglycone and ligstroside aglycone, oleocanthal and oleacein), 108.1 mg kg−1 of phenolic alcohols (tyrosol and hydroxytyrosol), 34.7 mg kg−1 of phenolic acids (caffeic acid, ferulic acid and elenolic acid), and 8.24 mg kg−1 of flavonoids (luteolin, luteolin glucoside, apigenin). With regard to vitamin E, α-tocopherol was the most abundant vitamin E (57.9 mg kg−1), followed by α-tocotrienol (2.5 mg kg−1), γ-tocopherol (4.5 mg kg−1) and β-tocopherol (1.9 mg kg−1), while δ-tocopherol was not detected. Moreover, 14 fatty acids were found and, among them, oleic acid (76.1%), linoleic acid (8.1%) palmitic acid (8.7%) and stearic acid (2.5%) were the major fatty acids detected. Finally, heat map and principal component analysis allowed us to classify the studied provinces in terms of VOO chemical composition: Chefchaouen (tyrosol and hydroxytyrosol), Taounate (oleuropein aglycone), Errachidia (ferulic acid, w-3 and w-6), Beni Mellal (oleocanthal) and Taza (luteolin and oleic acid).

Characterization of By-Products from Commercial Cannabidiol Production.

The chemical compositions of by-products from commercial cannabidiol (CBD) extraction were characterized and quantitated by employing gas chromatography mass spectrometry (GC-MS) and GC flame-ionization detection (GC-FID). The four major by-products included an ethanol-wax suspension (WAX), terpenoid distillate (DIST-A), tar-like residue (TAR), and red resin (RES). The composition of WAX consisted of ∼28 wt % n-alkanes and ∼33-38 wt % cannabidiolic acid and CBD combined. The DIST-A consisted of ∼40 wt % sesquiterpenoids and ∼58 wt % cannabinoids. The DIST-A terpenoid profile was compared to dried unprocessed inflorescences (HEMP) to observe changes in monoterpene content after the distillation process. The TAR was composed of ∼5-9 wt % higher n-alkanes and up to 91 wt % cannabinoids, while RES consisted of up to 99 wt % cannabinoids. Several impurities including cannabidibutol and dehydroabietic acid were identified in commercial CBD samples. Compositional information of these by-products may provide manufacturers with the opportunity to optimize processing conditions.

Letrozole – The Antiestrogen Drug Increases FADS2 Function

Abstract Objectives Our main aim is to test the effect of estrogen and antiestrogen (letrozole) on the modulation of fatty acid desaturation and ScA levels in vitro using human cancer cells. Methods We used two sets of cells, MCF7 cells stably expressing FADS1 and FADS2 genes and a series of wild type (MCF7, HepG2, SK-N-SH, Caco2 and Y79) cancer cells. Cells were treated with estrogen (0 to 200 ppm) or letrozole (0 to 100 ppm) at the time of seeding and at confluence 50 μM albumin bound 20:2n-6 was added to FBS-free media. FAME was quantified by GC-flame ionization detector (GC-FID) and structures were identified by gas chromatography (GC) – covalent adduct chemical ionization mass spectrometry (CACI-MS/MS). Results Estrogen caused a dose dependent decrease in ScA via apparent inhibition of FADS1 activity in all wild type and had no effect on FADS2 (Δ8 desaturation) mediated synthesis of DGLA. In MCF7 cells, letrozole caused a dose dependent increase in FADS2 catalyzed DGLA and a decrease in ScA. Conclusions We provide the first biochemical evidence demonstrating MCF7 cells treated with letrozole increase DGLA, the immediate precursor to the anti-inflammatory eicosanoid PGE1. Letrozole is the first hormone-active agent to have opposing effects on FADS1 and FADS2. Funding Sources NIH grant R01 AT007003.

Fatty Acid Desaturase 2 (FADS2) Actions on Branched Chain and Normal Odd Chain Saturated Fatty Acids

Abstract Objectives Branched chain fatty acids (BCFA), linear chain/normal odd chain fatty acids (n-OCFA) and sapienic acid (16:1n-10), are the most abundant lipids on human skin, especially sebaceous gland (SG) wax esters. Sapienic acid synthesis is mediated by fatty acid desaturase 2 (FADS2) in the sebaceous glands. FADS2 is an abundant mRNA in human skin, producing a classical transcript that introduces a double bond at the Δ6, Δ4 and Δ8 positions acting on at least eleven substrates, including one saturate (n-16:0). Our main objective was to test the hypothesis that FADS2 catalyze desaturation reaction(s) operating on specific BCFA and n-OCFA. Methods We created MCF-7 cells stably expressing FADS1 and FADS2 by using pcDNA3.1 expression vector system along with empty vector cells as control. Cells were cultured in standard MEM-α media and incubated at concentration of 50 μM of bovine serum albumin (BSA)-bound fatty acid substrates individually (anteiso-15:0, iso-16:0, iso-17:0, anteiso-17:0, iso-18:0 or n-17:0). FAME were structurally identified by gas chromatography (GC) - covalent adduct chemical ionization mass spectrometry (CACI-MS/MS) and quantified by GC-flame ionization detector (GC-FID). Results FADS2 desaturated BCFA as follows: iso-16:0 → iso-6Z-16:1, iso-17:0 → iso-6Z-17:1, anteiso-17:0 → anteiso-6Z-17:1 and iso-18:0 → iso-6Z-18:1. FADS2 had no action on anteiso-15:0. FADS2 converted n-17:0 → n-6Z-17:1. FADS1 had no activity towards any of these substrates. Conclusions We provide the first molecular evidence demonstrating novel FADS2-coded enzymatic activity towards BCFA and n-OCFA producing predominant human sebaceous monounsaturated fatty acids (MUFA). Our results extends FADS2 activity to BCFA and n-OCFA and expands FADS2 actions on saturated fatty acid substrates from one to six. Changes in the levels or the activity of FADS2 can influence the fatty acid composition of the sebum, which may play a role in certain skin abnormalities. Funding Sources NIH R01 AT007003.

Chemical Composition of Actinodaphne pilosa Essential Oil From Vietnam, Mosquito Larvicidal Activity, and Antimicrobial Activity

Leaves of Actinodaphne pilosa were collected at 2 different seasons from the Pù Hoạt Nature Reserve, Vietnam. The leaf samples were hydrodistilled to give essential oils, which were analyzed by gas chromatography (GC)–mass spectrometry and GC-flame ionization detection. The major components in the essential oils were α-pinene, ( Z)-β-ocimene, ( E)-β-ocimene, β-caryophyllene, germacrene D, bicyclogermacrene, and spathulenol. The essential oils were screened for antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans, as well as mosquito larvicidal activity against Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus. Actinodaphne pilosa leaf essential oils showed broad antimicrobial activity (minimum inhibitory concentration = 32, 64, 64, 16, and 16 μg/mL against E. faecalis, S. aureus, B. cereus, P. aeruginosa, and C. albicans, respectively) and excellent larvicidal activity (24-hour 50% lethal concentration = 19.0, 24.7, and 48.1 μg/mL against A. aegypti, A. albopictus, and C. quinquefasciatus, respectively).