Fractionation of Carlina acaulis L. Root Methanolic Extract as a Promising Path towards New Formulations against Bacillus cereus and Methicillin-Resistant Staphylococcus aureus.

The root of Carlina acaulis L. has been widely used in traditional medicine for its antimicrobial properties. In this study, the fractionation of methanol extract from the root was conducted. Four fractions (A, B, C, and D) were obtained and tested against a range of bacteria and fungi. The results showed promising antibacterial activity, especially against Bacillus cereus, where the minimal inhibitory concentration (MIC) was determined to be equal to 0.08 mg/mL and 0.16 mg/mL for heptane (fraction B) and ethyl acetate (fraction C), respectively. In the case of the methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 strain, the same fractions yielded higher MIC values (2.5 and 5.0 mg/mL, respectively). This was accompanied by a lack of apparent cytotoxicity to normal human BJ foreskin fibroblasts, enterocytes derived from CaCo2 cells, and zebrafish embryos. Further analyses revealed the presence of bioactive chlorogenic acids in the fractionated extract, especially in the ethyl acetate fraction (C). These findings support the traditional use of the root from C. acaulis and pave the way for the development of new formulations for treating bacterial infections. This was further evaluated in a proof-of-concept experiment where fraction C was used in the ointment formulation, which maintained high antimicrobial activity against MRSA and displayed low toxicity towards cultured fibroblasts.

One-carbon unit supplementation fuels purine synthesis in tumor-infiltrating T cells and augments checkpoint blockade.

Nucleotides perform important metabolic functions, carrying energy and feeding nucleic acid synthesis. Here, we use isotope tracing-mass spectrometry to quantitate contributions to purine nucleotides from salvage versus de novo synthesis. We further explore the impact of augmenting a key precursor for purine synthesis, one-carbon (1C) units. We show that tumors and tumor-infiltrating T cells (relative to splenic or lymph node T cells) synthesize purines de novo. Shortage of 1C units for T cell purine synthesis is accordingly a potential bottleneck for anti-tumor immunity. Supplementing 1C units by infusing formate drives formate assimilation into purines in tumor-infiltrating T cells. Orally administered methanol functions as a formate pro-drug, with deuteration enabling kinetic control of formate production. Safe doses of methanol raise formate levels and augment anti-PD-1 checkpoint blockade in MC38 tumors, tripling durable regressions. Thus, 1C deficiency can gate antitumor immunity and this metabolic checkpoint can be overcome with pharmacological 1C supplementation.

A rationally designed miniature of soluble methane monooxygenase enables rapid and high-yield methanol production in Escherichia coli.

Soluble methane monooxygenase (sMMO) oxidizes a wide range of carbon feedstocks (C1 to C8) directly using intracellular NADH and is a useful means in developing green routes for industrial manufacturing of chemicals. However, the high-throughput biosynthesis of active recombinant sMMO and the ensuing catalytic oxidation have so far been unsuccessful due to the structural and functional complexity of sMMO, comprised of three functionally complementary components, which remains a major challenge for its industrial applications. Here we develop a catalytically active miniature of sMMO (mini-sMMO), with a turnover frequency of 0.32 s-1, through an optimal reassembly of minimal and modified components of sMMO on catalytically inert and stable apoferritin scaffold. We characterise the molecular characteristics in detail through in silico and experimental analyses and verifications. Notably, in-situ methanol production in a high-cell-density culture of mini-sMMO-expressing recombinant Escherichia coli resulted in higher yield and productivity (~ 3.0 g/L and 0.11 g/L/h, respectively) compared to traditional methanotrophic production.

Comparative Study of Microwave, Pulsed Electric Fields, and High Pressure Processing on the Extraction of Antioxidants from Olive Pomace.

Olive oil production is characterized by large amounts of waste, and yet is considerably highly valued. Olive pomace can serve as a cheap source of bioactive compounds (BACs) with important antioxidant activity. Novel technologies like Pulsed Electric Fields (PEF) and High Pressure (HP) and microwave (MW) processing are considered green alternatives for the recovery of BACs. Different microwave (150-600 W), PEF (1-5 kV/cm field strength, 100-1500 pulses/15 µs width), and HP (250-650 MPa) conditions, in various product/solvent ratios, methanol concentrations, extraction temperatures, and processing times were investigated. Results indicated that the optimal MW extraction conditions were 300 W at 50 °C for 5 min using 60% v/v methanol with a product/solvent ratio of 1:10 g/mL. Similarly, the mix of 40% v/v methanol with olive pomace, treated at 650 MPa for the time needed for pressure build-up (1 min) were considered as optimal extraction conditions in the case of HP, while for PEF the optimal conditions were 60% v/v methanol with a product/solvent ratio of 1:10 g/mL, treated at 5000 pulses, followed by 1 h extraction under stirring conditions. Therefore, these alternative extraction technologies could assist the conventional practice in minimizing waste production and simultaneously align with the requirements of the circular bioeconomy concept.

Evaluation of Gastroprotective Activity of the Methanolic Extract of Justicia pectoralis Jacq. (Acanthaceae).

INTRODUCTION: Justicia pectoralis Jacq. is traditionally applied in folk medicine in Brazil and in several Latin American countries. The leaves are used in tea form, especially in the treatment of respiratory disorders, acting as an expectorant. It also has activity in gastrointestinal disorders, and it is anti-inflammatory, antioxidant, sedative, and estrogenic, among others. AIMS: To investigate the gastroprotective activity of the methanol extract of the leaves of Justicia pectoralis Jacq. (MEJP) in different experimental models of gastric ulcers. MATERIALS AND METHODS: The adult leaves of Justicia pectoralis Jacq. were collected and cultivated in beds, with an approximate spacing of 40 × 40 cm, organic fertilization, irrigation with potable water and without shelter from light. The MEJP was prepared from the dried and pulverized leaves and concentrated under reduced pressure in a rotary evaporator. For the experimental model of gastric ulcer, Swiss male albino mice were used. The inputs used in the experiment were MEJP at three different concentrations (250, 500 and 1000 mg/kg p.o.), cimetidine (50 mg/kg p.o.), indomethacin (50 mg/kg s.c.) and vehicle (10 mL/kg p.o.). RESULTS: MEJP (250, 500 and 1000 mg/kg p.o.) demonstrated gastroprotective activity, with levels of protection of 45.65%, 44.80% and 40.22%, respectively, compared to the control (vehicle). Compared with cimetidine (48.29%), MEJP showed similar gastroprotective activity. CONCLUSIONS: This study demonstrated the gastroprotective activity of MEJP and contributes to validate the traditional use the species for gastric disorders and provides a pharmacological basis for its clinical potential.

Metabolic Composition of Methanolic Extract of the Balkan Endemic Species Micromeria frivaldszkyana (Degen) Velen and Its Anti-Inflammatory Effect on Male Wistar Rats.

Extracts from medicinal plants are widely used in the treatment and prevention of different diseases. Micromeria frivaldszkyana is a Balkan endemic species with reported antioxidant and antimicrobial characteristics; however, its phytochemical composition is not well defined. Here, we examined the metabolome of M. frivaldszkyana by chromatography-mass spectrometry (GC-MS), ultra-performance liquid chromatography-mass spectrometry (UPLC-MS-MS), and inductively coupled plasma mass spectrometry (ICP-MS). Amino acids, organic acids, sugars, and sugar alcohols were the primary metabolites with the highest levels in the plant extract. Detailed analysis of the sugar content identified high levels of sucrose, glucose, mannose, and fructose. Lipids are primary plant metabolites, and the analysis revealed triacylglycerols as the most abundant lipid group. Potassium (K), magnesium (Mg), zinc (Zn), and calcium (Ca) were the elements with the highest content. The results showed linarin, 3-caffeoil-quinic acid, and rosmarinic acid, as well as a number of polyphenols, as the most abundant secondary metabolites. Among the flavonoids and polyphenols with a high presence were eupatorin, kaempferol, and apigenin-compounds widely known for their bioactive properties. Further, the acute toxicity and potential anti-inflammatory activity of the methanolic extract were evaluated in Wistar rats. No toxic effects were registered after a single oral application of the extract in doses of between 200 and 5000 mg/kg bw. A fourteen-day pre-treatment with methanolic extract of M. frivaldszkyana in doses of 250, 400, and 500 mg/kg bw induced anti-inflammatory activity in the 1st, 2nd, and 3rd hours after carrageenan injection in a model of rat paw edema. This effect was also present in the 4th hour only in the group treated with a dose of 500 mg/kg. In conclusion, M. frivaldszkyana extract is particularly rich in linarin, rosmarinic acid, and flavonoids (eupatorin, kaempferol, and apigenin). Its methanolic extract induced no toxicity in male Wistar rats after oral application in doses of up to 5000 mg/kg bw. Additionally, treatment with the methanolic extract for 14 days revealed anti-inflammatory potential in a model of rat paw edema on the 1st, 2nd, and 3rd hours after the carrageenan injection. These results show the anti-inflammatory potential of the plant, which might be considered for further exploration and eventual application as a phytotherapeutic agent.

Effect of methanol extract of Plectranthus esculentus N.E.Br tuber and its fractions on indices of benign prostatic hyperplasia in Wistar rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Many ethnopharmacological properties (anti-tumor, etc.) have been credited to Plectranthus esculentus tuber but the scientific basis has not been established. AIM OF THE STUDY: To evaluate the effect of methanol extract of P. esculentus tuber (MEPET) (phase 1) and its fractions (phase 2) on benign prostatic hyperplasia (BPH) in rats. MATERIALS AND METHODS: The study was conducted in two phases. Phase 1, thirty-five male albino rats (6 weeks old) were divided into seven groups of five rats each: normal control (NC) received olive oil (subcutaneously) and water (orally); disease control (DC) received testosterone propionate (TP) (3 mg/kg) and water; test groups (1,2,3 and 4) received TP + MEPET at 100, 200, 400, 600 mg/kg respectively; positive control, received TP + finasteride (5 mg/70 kg). After 28 days, their relative prostate weights (RPW) and prostate specific antigen (PSA) were determined. Phase 2, thirty rats were divided into 6 groups of 5 rats each: NC received olive oil (subcutaneously daily) and dimethyl sulfoxide (DMSO) (orally); DC received TP (3 mg/kg), and DMSO; test group 1 received TP and aqueous fraction of MEPET (400 mg/kg); test group 2 received TP and methanol fraction of MEPET (400 mg/kg); test group 3 received TP, and ethyl acetate fraction of MEPET (400 mg/kg); positive control received TP and finasteride (5 mg/70 kg). After 28 days, their erythrocyte sedimentation rates, RPW, prostate levels of PSA, DHT, inflammatory, apoptotic markers and prostate histology were determined. RESULTS: Ethyl acetate fraction of MEPET modulated most of the parameters of BPH in the rats in a manner akin to finasteride as corroborated by prostate histology. CONCLUSIONS: EFPET could be useful in the treatment of BPH.

Antidiabetic and antiulcer activity of methanolic extract of Tradescantia spathacea in rats.

The present study was designed to assess Tradescantia spathacea's antidiabetic ability, as well as the antiulcer activity of the entire plant extract. The diabetic condition was evaluated using Streptozotocin's oral glucose tolerance test, diabetes-alloxan and diabetes-models. Antiulcer activities were observed in rats where gastric ulcers were either caused by oral administration of ethanol, or pyloric ligation. Standards include ranitidine, glibenclamide and sucralfate. In all models, the blood glucose levels of animals treated with the test extract were found to be significantly lower compared to diabetic care. Similarly, in all models, the ulcer index in the animals treated with the test extract was found to be significantly lower relative to the animals under vehicle supervision. Our findings say T. Spathacea extract has essential anti-diabetic properties, as well as antiulcer properties.

Organic-solvent ditch overlap in reversed-phase liquid chromatography: A molecular dynamics simulation study in cylindrical 6-12 nm-diameter pores.

Mass transport through the mesopore space of a reversed-phase liquid chromatography (RPLC) column depends on the properties of the chromatographic interface, particularly on the extent of the organic-solvent ditch that favors the analyte surface diffusivity. Through molecular dynamics simulations in cylindrical RPLC mesopore models with pore diameters between 6 and 12 nm we systematically trace the evolution of organic-solvent ditch overlap due to spatial confinement in the mesopore space of RPLC columns for small-molecule separations. Each pore model of a silica-based, endcapped, C18-stationary phase is equilibrated with two mobile phases of comparable elution strength, namely 70/30 (v/v) water/acetonitrile and 60/40 (v/v) water/methanol, to consider the influence of the mobile-phase composition on the onset of organic-solvent ditch overlap. The simulations show that, as the pore diameter decreases from 9 to 6 nm, the bonded-phase density extends and compacts towards the pore center, which leads to increased accumulation of organic-solvent excess and thus enhanced organic-solvent diffusivity in the ditch. Because the acetonitrile ditch is more pronounced than the methanol ditch, acetonitrile ditch overlap sets in at less severe spatial confinement than methanol ditch overlap. The pore-averaged methanol and acetonitrile diffusivities are considerably raised by ditch overlap in the 6 nm-diameter pore, but also benefit from the ditch (without overlap) in the 7 to 12 nm-diameter pores, whereby local and pore-averaged effects are generally larger for acetonitrile than methanol.

Time-resolved keto-enol tautomerization of the medicinal pigment curcumin.

Curcumin is a medicinal agent that exhibits anti-cancer and anti-Alzheimer's disease properties. It has a keto-enol moiety that gives rise to many of its chemical properties including metal complexation and acid-base equilibria. A previous study has shown that keto-enol tautomerization at this moiety is implicated in the anti-Alzheimer's disease effect of curcumin, highlighting the importance of this process. In this study, tautomerization of curcumin in methanol, acetone and acetonitrile was investigated using time-resolved 1H nuclear magnetic resonance spectroscopy. Curcumin undergoes hydrogen-deuterium exchange with the solvents and the proton resonance peak corresponding to the hydrogen at the α-carbon position (Cα) decays as a function of time, signifying deuteration at this position. Because tautomerization is the rate limiting step in the deuteration of curcumin at the Cα position, the rate of tautomerization is inferred from the rate of deuteration. The rate constant of tautomerization of curcumin shows a temperature dependence and analysis using the Arrhenius equation revealed activation energies (Ea) of tautomerization of (80.1 ± 5.9), (64.1 ± 1.0) and (68.3 ± 5.5) kJ mol-1 in methanol, D2O/acetone and D2O/acetonitrile, respectively. Insight into the role of water in tautomerization of curcumin was further offered by density functional theory studies. The transition state of tautomerization was optimized in the presence of water molecules. The results show a hydrogen-bonded solvent bridge between the diketo moiety and Cα of curcumin. The Ea of tautomerization of curcumin shows a strong dependence on the number of water molecules in the solvent bridge, indicating the critical role played by the solvent bridge in catalyzing tautomerization of curcumin.

Impact of four different extraction methods and three different reconstitution solvents on the untargeted metabolomics analysis of human and rat urine samples.

Unsuitable sample preparation may result in loss of important analytes and consequently affect the outcome of untargeted metabolomics. Due to species differences, different sample preparations may be required within the same biological matrix. The study aimed to compare the in-house sample preparation method for urine with methods from literature and to investigate the transferability of sample preparation from human urine to rat urine. A total of 12 different conditions for protein precipitation were tested, combining four different extraction solvents and three different reconstitution solvents using an untargeted liquid-chromatography high resolution mass spectrometry (LC-HRMS) metabolomics analysis. Evaluation was done based on the impact on feature count, their detectability, as well as the reproducibility of selected compounds. Results showed that a combination of methanol as extraction and acetonitrile/water (75/25) as reconstitution solvent provided improved results at least regarding the total feature count. Additionally, it was found that a higher amount of methanol was most suitable for extraction of rat urine among the tested conditions. In comparison, human urine requires significantly less volume of extraction solvent. Overall, it is recommended to systematically optimize both, the extraction method, and the reconstitution solvent for the used biofluid and the individual analytical settings.

Microwave-assisted and methanol/acetic acid-free method for rapid staining of proteins in SDS-PAGE gels.

We describe a microwave-assisted, methanol and acetic acid-free, inexpensive method for rapid staining of SDS-PAGE proteins. Only citric acid, benzoic acid, and Coomassie brilliant blue G-250 (CBG) were used. Microwave irradiation reduced the detection duration, and proteins in a clear background were visualized within 30 min of destaining, after 2 min of fixing and 12 min of staining. By using this protocol, comparable band intensities were obtained to the conventional methanol/acetic acid method.

Conductometric investigation of nano MnSO4 association parameters and complex formation with glycylglycine in aqueous and methanol-water mixtures: Thermodynamic parameters and potential applications.

This study aimed to investigate the ion pair association values and association parameters of nano MnSO4 in water and methanol-water mixtures (20 % and 40 % methanol by mass percentage) at varying temperatures (298.15, 303.15, 308.15, and 313.15 K) using the conductometric technique. Additionally, the parameters for complex formation between nano MnSO4 and glycylglycine as a ligand were determined. The focus was on elucidating the thermodynamic formation parameters for the nano Mn2+-glycylglycine interaction, with particular emphasis on comparing the 1: 1 and 1: 2 (M: L) complexes to understand the complexation behavior more comprehensively. The results indicated that the complexation process was spontaneous, as evidenced by negative ΔGf (formation free energy change) values, which increased with temperature, highlighting the enhanced spontaneity of the process. The findings provide valuable insights into designing new materials and procedures by enhancing our understanding of the complexation behavior of nano MnSO4 with ligands like glycylglycine, thus contributing to advancements in various applications such as chemical synthesis, medicines, and environmental remediation. By elucidating the thermodynamic aspects of these interactions, the study aimed to provide valuable information that could be utilized in practical applications and further research endeavors.

In Vitro Inhibition of Colorectal Cancer Gene Targets by Withania somnifera L. Methanolic Extracts: A Focus on Specific Genome Regulation.

An approach that shows promise for quickening the evolution of innovative anticancer drugs is the assessment of natural biomass sources. Our study sought to assess the effect of W. somnifera L. (WS) methanolic root and stem extracts on the expression of five targeted genes (cyclooxygenase-2, caspase-9, 5-Lipoxygenase, B-cell lymphoma-extra-large, and B-cell lymphoma 2) in colon cancer cell lines (Caco-2 cell lines). Plant extracts were prepared for bioassay by dissolving them in dimethyl sulfoxide. Caco-2 cell lines were exposed to various concentrations of plant extracts, followed by RNA extraction for analysis. By explicitly relating phytoconstituents of WS to the dose-dependent overexpression of caspase-9 genes and the inhibition of cyclooxygenase-2, 5-Lipoxygenase, B-cell lymphoma-extra-large, and B-cell lymphoma 2 genes, our novel findings characterize WS as a promising natural inhibitor of colorectal cancer (CRC) growth. Nonetheless, we recommend additional in vitro research to verify the current findings. With significant clinical benefits hypothesized, we offer WS methanolic root and stem extracts as potential organic antagonists for colorectal carcinogenesis and suggest further in vivo and clinical investigations, following successful in vitro trials. We recommend more investigation into the specific phytoconstituents in WS that contribute to the regulatory mechanisms that inhibit the growth of colon cancer cells.

"GC-MS profiling, sub-acute toxicity study and total phenolic and flavonoid content analysis of methanolic leaf extract of Schima wallichii (D.C.) Korth-a traditional antidiabetic medicinal plant".

ETHNOPHARMACOLOGICAL RELEVANCE: Schima wallichii (D.C.) Korth is traditionally used in Manipur, India for treatment of diabetes and hypertension. However, there is no data reported regarding safety profile of this medicinal plant upon repeated per oral administration over a period of time. AIM OF THE STUDY: In the current study phytochemical profile, toxicological profile and total phenolic and flavonoid compound content of Schima wallichii leaves extract were evaluated. MATERIALS AND METHODS: Gas chromatography coupled to mass spectrometry was performed for chemical profiling by using Gas Chromatography-Mass Spectrometry/Mass Spectrometry (GC-MS/MS), Shimadzu, TQ8040 system. A 28 days sub-acute toxicity study was carried out using albino Wistar rats by administering 3 different doses (200, 400 and 800 mg/kg body weight per oral) of methanol leaves extract. Changes in body weights were recorded weekly. Serum biochemical parameters were estimated as well as blood-cell count was done to check the effect of extract on haematopoietic system. Histopathology of vital organs viz. kidney, heart, brain, liver was performed to find any pathological indications. Since, liver is main the site for xenobiotic metabolism, estimation of the level of glutathione, catalase and lipid peroxidation were done. Further, total phenolic and flavonoid compound content estimation was performed for the leaves extract. RESULTS: GC-MS revealed 14 major compounds with area percentage >1% of which quinic acid, n-Hexadecanoic acid, 9,12,15-Octadecatrienoic acid, (Z,Z,Z)-, Octatriacontyl trifluoroacetate, are three major compounds. No mortality was observed after the treatment with extract. Blood-cell count and biochemical parameters didn't show significant deviation as compared to control group. Histopathology study of vital organs viz. (liver, kidney, heart and brain) showed normal cellular construction comparing to control group. There was no sign of membrane lipid peroxidation, depletion of catalase level and glutathione level in liver. The result demonstrates that NOAEL (no-observed-adverse-effect levels) in the sub-acute toxicity was above 800 mg/kg. The leaves extract showed significant total phenol and flavonoid content. CONCLUSION: The present study revealed that Schima wallichii possessed important bioactive compounds with therapeutic values. The plant was safe for consumption after repeated high doses administration in rats and possesses significant amount of total phenol and flavonoid content.

Protective effect of Petroselinum crispum methanolic extract against acrylamide-induced reproductive toxicity in male rats through NF-ĸB, kinesin, steroidogenesis pathways.

This study examined the protective effects of a Petroselinum crispum (P. crispum) methanolic extract on reproductive dysfunction induced by acrylamide in male rats. A total of 40 rats were divided into four groups (n=10). The control group received distilled water, the acrylamide group received 10 mg/kg of acrylamide, the P. crispum group received 100 mg/kg of P. crispum extract, and the combined group was pretreated with P. crispum for two weeks before co-administration of P. crispum and acrylamide. All administrations were administered orally using a gastric tube for eight weeks. Acrylamide decreased testosterone levels but did not affect levels of FSH or LH. It also increased testicular levels of (MDA) malondialdehyde and reduced activity of (SOD) superoxide dismutase and impairment of sperm parameters. Furthermore, the administration of acrylamide resulted in an elevation of tumor necrosis factor-alpha (TNF-α) levels and a reduction in the levels of steroidogenic acute regulatory protein (STAR) and cytochrome P450scc (P450scc). Acrylamide negatively affected the histopathological outcomes, Johnsen's score, the diameter of seminiferous tubules, and the thickness of the germinal epithelium. It also upregulated the expression of NF-ĸB P65 and downregulated the expression of kinesin motor protein. In contrast, treatment with P. crispum extract restored the levels of antioxidant enzymes, improved sperm parameters, and normalized the gene expression of TNF-α, IL-10, IL-6, iNOS, NF-ĸB, STAR, CYP17A1, 17ß-HSD and P450scc. It also recovered testicular histological parameters and immunoexpression of NF-ĸB P65 and kinesin altered by acrylamide. P. crispum showed protective effects against acrylamide-induced reproductive toxicity by suppressing oxidative damage and inflammatory pathways.

Real-Time Monitoring of the Evaporation and Fission of Electrospray-Ionized Polystyrene Beads and Bacterial Pellets at Elevated Temperatures.

This study uses real-time monitoring, at microsecond time scales, with a charge-sensing particle detector to investigate the evaporation and fission processes of methanol/micrometer-sized polystyrene beads (PS beads) droplets and bacterial particles droplets generated via electrospray ionization (ESI) under elevated temperatures. By incrementally raising capillary temperatures, the solvent, such as methanol on 0.75 µm PS beads, experiences partial evaporation. Further temperature increase induces fission, and methanol molecules continue to evaporate until PS ions are detected after this range. Similar partial evaporation is observed on 3 µm PS beads. However, the shorter period of the fission temperature range is necessary compared to 0.75 µm PS beads. For the spherical-shaped bacterium, Staphylococcus aureus, the desolvation process shows a similar fission period as compared to 0.75 µm PS beads. Comparably, the rod-shaped bacteria, Escherichia coli EC11303, and E. coli strain W have shorter fission periods than S. aureus. This research provides insights into the evaporation and fission mechanisms of ESI droplets containing different sizes and shapes of micrometer-sized particles, contributing to a better understanding of gaseous macroion formation.

Improved lipid analysis using a 2D-LC-MS system with a novel injection procedure.

The aim of this study was to improve analysis of nonpolar lipidomics sample extracts using reversed phase (RP) chromatography. A 4/3/3 (v/v/v) mixture of methanol/methyl tert-butyl ether/chloroform (MeOH/MTBE/CHCl3, MMC) was chosen for sample extraction solvent based on its proven extraction capability for several lipid classes. To avoid carry over, loss of analytes and peak distortion the loops and all capillaries of the presented LC system were flushed and filled up with methanol until the analytical column. The choice of methanol was due to its weak elution strength and being infinitely miscible with MMC and several other nonpolar solvents. This allowed injection of a 100 µl sample that was 20 µl nonpolar extraction solvent diluted fivefold with methanol. All lipids of 25 lipid classes were transferred quantitatively to the column head where the online dilution of methanol was carried out with aqueous eluent for focusing the lipid analytes. The weak elution strength of methanol prevented peak distortions. The consecutive reversed phase elution resulted in remarkably narrow peaks (full width at half maximum was 0.07-0.08 min typically) and enhanced sensitivity (limit of detection usually in sub nM region) because of increased sample injection volume and narrow peaks. Calibration and quality control samples made by diluting commercial lipid standards 200-50000 times confirmed the applicability of this approach both for targeted lipid quantification and for untargeted quantitative comparison of lipids from different sources.

Preparation of high-efficiency HILIC capillary columns utilizing slurry packing at 2100 bar.

Complex mixture analysis requires high-efficiency chromatography columns. Although reversed phase liquid chromatography (RPLC) is the dominant approach for such mixtures, hydrophilic interaction liquid chromatography (HILIC) is an important complement to RPLC by enabling the separation of polar compounds. Chromatography theory predicts that small particles and long columns will yield high efficiency; however, little work has been done to prepare HILIC columns longer than 25 cm packed with sub-2 µm particles. In this work, we tested the slurry packing of 75 cm long HILIC columns with 1.7 µm bridged-ethyl-hybrid amide HILIC particles at 2,100 bar (30,000 PSI). Acetonitrile, methanol, acetone, and water were tested as slurry solvents, with acetonitrile providing the best columns. Slurry concentrations of 50-200 mg/mL were assessed, and while 50-150 mg/mL provided comparable results, the 150 mg/mL columns provided the shortest packing times (9 min). Columns prepared using 150 mg/mL slurries in acetonitrile yielded a reduced minimum plate height (hmin) of 3.3 and an efficiency of 120,000 theoretical plates for acenaphthene, an unretained solute. Para-toluenesulfonic acid produced the lowest hmin of 1.9 and the highest efficiency of 210,000 theoretical plates. These results identify conditions for producing high-efficiency HILIC columns with potential applications to complex mixture analysis.