Liquid Chromatography-photodiode Array Research Articles

A Vancomycin HPLC Assay for Use in Gut Microbiome Research.

ABSTRACTThe human microbiome project has revolutionized our understanding of the interaction between commensal microbes and human health. By far, the biggest perturbation of the microbiome involves use of broad-spectrum antibiotics excreted in the gut. Thus, pharmacodynamics of microbiome changes in relation to drug exposure pharmacokinetics is an emerging field. However, reproducibility studies are necessary to develop the field. A simple and fast high-performance liquid chromatography-photodiode array detector (HPLC) method was validated for quantitative fecal vancomycin analysis. Reproducibility of results were tested based on sample storage time, homogeneity of antibiotic within stool, and concentration consistency after lyophilization. The HPLC method enabled the complete elution of vancomycin within ~4.2 min on the reversed-phase C18 column under the isocratic elution mode, with excellent recovery (85% to 110%) over a 4-log, quantitative range (0.4–100 μg/mL). Relative standard derivations (RSD) of intra-day and inter-day results ranged from 0.4% to 5.4%. Using sample stool aliquots of various weights consistently demonstrated similar vancomycin concentrations (mean RSD: 6%; range: 2–16%). After correcting for water concentrations, vancomycin concentrations obtained after lyophilization were similar to the concentrations obtained from the original samples (RSD less than 10%). These methodologies establish sample condition standards for a quantitative HPLC to enable vancomycin pharmacokinetic studies with the human microbiome.IMPORTANCE Research on antibiotic effect on the gut microbiome is an emerging field with standardization of research methods needed. In this study, a simple and fast high-performance liquid chromatography method was validated for quantitative fecal vancomycin analysis. Reproducibility of results were tested to standardize storage time, homogeneity of antibiotic within stool, and concentration consistency after lyophilization. These methodologies establish sample condition standards for a quantitative HPLC to enable vancomycin pharmacokinetic studies with the human microbiome.

Binder-Free Decorated Cu Cluster-Based Metal-Organic Framework on Copper Film for Thin-Film Microextraction of Polycyclic Aromatic Hydrocarbons Followed by High-Performance Liquid Chromatography-Photo Diode Array Detection

The present study explains the in situ growth of Cu cluster-based metal-organic framework on copper substrate for thin film microextraction approach. Cu cluster-based metal-organic framework has been growth via a hydrothermal method on electrochemically anodized copper substrate. After thin film microextraction, some polycyclic aromatic hydrocarbons were quantified via high performance liquid chromatography- photo diode array detection. The influence of effective parameters such as extraction time, extraction temperature, agitator speed and ionic strength of the sample was investigated and the optimum conditions were chosen. Calibration curves were obtained in 0.0001–10 µgL−1 range with acceptable linearity as R2 > 0.986. The range of 1 and 3 pgL−1 was calculated as limits of detection, with the relative standard division below 5.1% in the optimal condition. For evaluating the model, samples from river water and wastewater were used and investigated. It was found that relative recoveries were between 96-104%. The proposed method provided a simple, efficient and environmental approach for the rapid and convenient determination of polycyclic aromatic hydrocarbons in real samples.

Quality control of cannabis inflorescence and oil products: Response factors for the cost-efficient determination of ten cannabinoids by HPLC

The quality control of medicinal cannabis should include quantification of as many cannabinoids as practicable in a routine analytical lab, to accurately reflect the quality of the product. However, the cost and availability of some cannabinoid standards is an impediment to their routine use. This work seeks to overcome this obstacle by analysing samples using relative retention times (RRT) and relative response factors (RRF), relative to CBD and CBDA reference standards which are readily available. A high-performance liquid chromatography-photodiode array method was developed to quantify ten cannabinoids (Δ9-THC, Δ8-THC, THCA-A, CBN, CBD, CDBA, CBC, CBDV, CBG, and CBGA) in dried cannabis inflorescence and cannabis oil. This method was validated according to ICH guidelines. The proposed method has detection limits ranging from 20 to 78 µg/g, which provided sufficient sensitivity for the panel of cannabinoids. Non-cannabinoid surrogate matrices were used for spike recovery studies to determine method accuracy – analyte recoveries for the inflorescence and oil ranged from 90.1 to 109.3% (inflorescence mean, 100.9%; oil mean, 99.6%). The RRT and RRF values determined independently by three analysts were comparable, indicating the method is robust. The validity of analysis using RRT and RRF was further confirmed by testing six inflorescence samples, as it was found that concentrations above the order of magnitude of the LoQ agreed satisfactorily (range, 95.0 to 111.9%; mean, 100.0%) with the concentrations obtained through the conventional approach of multipoint calibration using pure standards. The proposed method is therefore suitable for the rapid and simple determination of a panel of ten cannabinoids without having to repeatedly purchase every expensive pure standard. Accordingly, analysts in the medicinal cannabis field may explore the use of RRF and RRT for their methods and instruments.

Correlation of Glucosinolates and Volatile Constituents of Six Brassicaceae Seeds with Their Antioxidant Activities Based on Partial Least Squares Regression.

Brassicaceae comprises various species representing an economically important source of industrial or pharmaceutical crops. The present study aimed to identify glucosinolates (GSLs) and volatile compounds in six Brassicaceae seeds cultivated in Egypt. An (High Performance Liquid Chromatography-Photodiode Array) HPLC–PDA analysis of GSLs in the alcoholic extracts of Raphanus raphanistrum L. (Rr), Raphanus sativus L. (Rs), Brassica oleracea var. capitata L. (Boc), Brassica oleracea var. botrytis L. (Bob), Brassica rapa L. (Br), and Eruca sativa L. (Es) was carried out using a mixture of 23 standard GSLs. Nineteen GSLs were detected in the studied seeds. Rs had the highest GSL content (135.66 μmol/g Dry weight, DW), while Boc had the lowest GSL content (93.66 μmol/g DW). Glucobrassicin was the major identified compound in Rr, Rs, and Bob. Its highest content was in Rs (28.96 μmol/g DW). Sinigrin was the major identified GSL in Boc (18.02 μmol/g DW), although present with higher content in Bob (22.02 μmol/g DW). Neoglucobrassicin was the major GSL in Br (30.98 μmol/g DW), while glucoerucin was the major GSL in Es (17.84 μmol/g DW). The yields of the steam-distilled oils of the studied seeds ranged between 3.25 ± 0.36 and 9.68 ± 0.25% v/w. A GC–MS analysis of the oils could detect 3, 23, 18, 16, 7, and 9 compounds in Rr, Rs, Boc, Bob, Br, and Es oils, respectively. Sulfur and nitrogenous compounds predominated in all studied oils except Rs, which contained a higher percentage of alkanes. The major identified compound in Rr oil was 4-isothiocyanato-1-(methylthio)-1-butene (94.77 ± 1.25%), while in Br it was 3-butenyl isothiocyanate (69.55 ± 1.02%), thiolane in Rs (15.15 ± 0.22%), and erucin in Es (97.02 ± 1.514%). Both Boc and Bob had the same major compound 4-(methylthio) butanenitrile, which represented 40.35 ± 1.15 and 50.52 ± 1.02% in both oils, respectively. Radical scavenging activity for both GSL extracts and essential oils on DPPH radical ranged between 18.01 ± 0.72 and 114.28 ± 1.15 µg/mL (IC50). The highest antioxidant capacity was for Es oil, while the lowest one was for Rr oil. Generally, it was observed that the GSLs had better antioxidant activity than their corresponding essential oils except for Es oil, which had higher activity. A principal component analysis (PCA) was successfully applied to discriminate among six Brassicaceae seeds based on both HPLC and GC–MS, where complete segregation was achieved among all samples with high correlation between Boc and Bob. Partial Least Squares-Regression (PLS-R) models showed that there is a better correlation between the antioxidant activity and glucosinolate profile when being compared to that of a volatile one. This profiling and variation of GSLs and volatile metabolites of the studied Brassicaceae seeds may be employed in further studies regarding their health-promoting properties.

Fabrication of Magnetic Al-Based Fe3O4@MIL-53 Metal Organic Framework for Capture of Multi-Pollutants Residue in Milk Followed by HPLC-UV.

The efficient capture of multi-pollutant residues in food is vital for food safety monitoring. In this study, in-situ-fabricated magnetic MIL-53(Al) metal organic frameworks (MOFs), with good magnetic responsiveness, were synthesized and applied for the magnetic solid-phase extraction (MSPE) of chloramphenicol, bisphenol A, estradiol, and diethylstilbestrol. Terephthalic acid (H2BDC) organic ligands were pre-coupled on the surface of amino-Fe3O4 composites (H2BDC@Fe3O4). Fe3O4@MIL-53(Al) MOF was fabricated by in-situ hydrothermal polymerization of H2BDC, Al (NO3)3, and H2BDC@Fe3O4. This approach highly increased the stability of the material. The magnetic Fe3O4@MIL-53(Al) MOF-based MSPE was combined with high-performance liquid chromatography-photo diode array detection, to establish a novel sensitive method for analyzing multi-pollutant residues in milk. This method showed good linear correlations, in the range of 0.05–5.00 μg/mL, with good reproducibility. The limit of detection was 0.004–0.108 μg/mL. The presented method was verified using a milk sample, spiked with four pollutants, which enabled high-throughput detection and the accuracies of 88.17–107.58% confirmed its applicability, in real sample analysis.

Quantitative analysis of methoxyflavones discriminates between the two types of Kaempferia parviflora.

Kaempferia parviflora or black ginger is abundantly cultivated because its rhizomes contain methoxyflavones that have many pharmacological properties. K. parviflora can be divided into two types, based on morphological characteristics, but differences in their chemical compositions have never been explored. This research aims to find chemical markers that can be used to differentiate between the two types of K. parviflora, the red-leaf and green-leaf types, by quantifying the amounts of methoxyflavones. K. parviflora samples were collected from 39 locations in Thailand. Their genetic diversity was assessed by a genotyping-by-sequencing (GBS) technique to construct the population structure. Their chemical compositions were analyzed by high performance liquid chromatography-photodiode array detection to determine the methoxyflavone contents. The population structure based on >3,000 single nucleotide polymorphism (SNP) markers showed that the samples can be divided into two groups, which were consistent with the classification by leaf margin color (red-leaf and green-leaf types). HPLC analysis revealed 3,5,7,3',4'-pentamethoxyflavone (PMF), 5,7-dimethoxyflavone (DMF), 5,7,4'-trimethoxyflavone (TMF), 3,5,7-trimethoxyflavone and 3,5,7,4'-tetramethoxyflavone as major methoxyflavones that can be used as chemical markers. The red-leaf type showed higher amounts of PMF, TMF and 3,5,7,4'-tetramethoxyflavone than the green-leaf type, while the green-leaf type showed higher amounts of DMF and 3,5,7-trimethoxyflavone than the red-leaf type. These results provide another approach to discriminate the two types of K. parviflora using chemical profiles alongside genetic and morphological analyses. Therefore, a specific type of K. parviflora can be selected over the other based on preferences for a certain methoxyflavone.

Extraction and analysis of an organophosphate salt nucleating agent from irradiated polypropylene resin

Although it is well-established that irradiation of produce can reduce food-borne pathogens and spoilage organisms, data on the effect of irradiation on polymer additives in food packaging materials are limited, particularly for those additives used in packaging leafy greens or in current food packaging materials. We investigated the effects of irradiating a nucleating agent, aluminium, hydroxybis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo [d,g][1,3,2]dioxaphosphocin 6-oxidato]- (CAS Reg. No. 151841-65-5), at doses of 1–20 kGy in polypropylene. That nucleating agent was then extracted using accelerated solvent extraction and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), liquid chromatography-photodiode array detection (LC-PDA), and solid-state nuclear magnetic resonance (SSNMR) spectroscopy. We found this nucleating agent was not significantly affected by radiation treatment up to 20 kGy. Therefore, this nucleating agent could potentially be useful in food packaging materials that will be irradiated at doses of 20 kGy or less. Establishing which additives are stable under anticipated irradiation doses will help support safety evaluation of food packaging materials.

Chemical Fingerprinting, Antioxidant, and Anti-Inflammatory Potential of Hydroethanolic Extract of Trigonella foenum-graecum.

In the current study, the antioxidant and anti-inflammatory potential of hydroethanolic extract of T. foenum-graecum seeds was evaluated. Phenolic profiling of T. foenum-graecum was conducted through high-performance liquid chromatography-photodiode array (HPLC-PDA) as well as through the mass spectrometry technique to characterize compounds responsible for bioactivity, which confirmed almost 18 compounds, 13 of which were quantified through a chromatographic assay. In vitro antioxidant analysis of the extract exhibited substantial antioxidant activities with the lowest IC50 value of both DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) inhibition assays. The extract was found to be non-toxic against human RBCs and murine macrophage RAW 264.7 cells. Moreover, the extract significantly (p < 0.001) reduced the lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α), intrlukin-6 (IL-6), prostaglandin E2 (PGE2), and nitric oxide (NO) in RAW 264.7 cells in a concentration-dependent manner. The hydroethanolic extract of T. foenum-graecum exhibited considerable anti-inflammatory potential by decreasing the cellular infiltration to the inflammatory site in both carrageenan-induced peritonitis and an air pouch model of inflammation. Pretreatment with T. foenum-graecum extract caused significant improvement in antioxidants such as superoxide dismutase (SOD), CAT (catalase), malondialdehyde (MDA), and myeloperoxidase (MPO) against oxidative stress induced by carrageenan. Based on our results of in vivo and in vitro experimentation, we concluded that hydroethanolic extract of T. foenum-graecum is a potential source of phenolic compounds with antioxidant and anti-inflammatory potential.

Development and Validation of Ultra Performance Liquid Chromatography (UPLC) Method for the Quantitative Estimation of Caffeine in Non-Alcoholic Soft and Energy Drinks.

The popularity of beverages such as cold coffee, iced tea, and energy drinks has risen tremendously among athletes and youths. Energy drinks are used to enhance performance due to the presence of a high amount of caffeine (CFN) and sugars, as well as other constituents such as vitamins, amino acids, taurine, extracts of Ginkgo biloba, ginseng, guarana, and other herbal products. Commercial drinks are promoted as being beneficial to health; thus it is an important concern regarding adverse effects linked with these drinks or products. The aim of the study is to develop and validate the ultra performance liquid chromatography-photodiode array detector (UPLC-PDA) method for the estimation of CFN in eight marketed non-alcoholic drinks including two soft drinks and six energy drinks. The chromatographic separation of CFN was achieved on Acquity UPLC® CSHTM C18 1.7 µm, 2.1 × 100 mm column, using isocratic mode, mobile phase comprising acetonitrile and water (30:70, v/v) at a flow rate 0.3 mL/min using injection volume 1 µL. The elution of CFN occurred at 1.06 min, and the calibration curve of the CFN was computed from the peak area ratio detected at 273 nm. All the validation parameters were found within the assay variability limits as per ICH guidelines. The obtained results revealed that the soft drinks SD1 and SD2 have 87.21 ± 1.28 and 101.81 ± 1.52% (w/w), whereas CFN concentration in energy drink brands ED1, ED2, ED3, ED4, ED5, and ED6 was 95.90 ± 1.62, 64.0 ± 1.07, 76.68 ± 1.95, 74.97 ± 2.33, 82.09 ± 2.43, and 88.04 ± 2.94% (w/w) of labeled claims, respectively. The developed UPLC method was found suitable for the quality control of commercial soft and energy drinks containing CFN. The developed chromatographic method is very simple, cost effective and could be utilized for the routine analysis of caffeine in the soft and energy drinks.

A reversed-phase ultra-fast liquid chromatography-photodiode array detector (RP-UFLC-PDA) method for simultaneous estimation of ayapanin and umbelliferone in Ayapana triplinervis Vahl.

A rapid validated ultra-fast liquid chromatography-photodiode array detector (UFLC-PDA) method was developed to identify and quantify ayapanin (AY) and umbelliferone (UM) simultaneously in Ayapana triplinervis Vahl methanolic extract. The method was validated for linearity, limit of detection (LOD; 3:1σ/S), limit of quantification (LOQ; 10:1σ/S), precision, accuracy, specificity and robustness. The response was linear with a good correlation between concentration and mean peak area through a correlation coefficient of 0.9996, y = 7025.7x - 2269.8 and 0.9997, y = y = 16,262x - 946 with LOD of 6.256 ± 0.52 and 3.325 ± 0.36, and LOQ of 18.838 ± 0.18 and 8.870 ± 0.85 for AY (0.67% w/w) and UM (0.18% w/w), respectively. The relative standard deviation (%) of precision and recovery of AY and UM was <2.0%. The proposed method was simple, accurate, specific, precise and reproducible.

Identification of Phenolic Compounds in Australian-Grown Bell Peppers by Liquid Chromatography Coupled with Electrospray Ionization-Quadrupole-Time-of-Flight-Mass Spectrometry and Estimation of Their Antioxidant Potential

Bell peppers are widely considered as healthy foods that can provide people with various phytochemicals, especially phenolic compounds, which contribute to the antioxidant property of bell peppers. Nevertheless, the acknowledgment of phenolic compounds in bell peppers is still limited. Therefore, this study aimed to determine the phenolic content and the antioxidant potential in pulps and seeds of different bell peppers (green, yellow, and red) by several in vitro assays followed by the characterization and quantification of individual phenolics using liquid chromatography coupled with electrospray ionization-quadrupole-time-of-flight-mass spectrometry (LC-ESI-QTOF-MS/MS) and high-performance liquid chromatography photodiode array (HPLC-PDA) quantification, respectively. The captured results showed that the pulp of red bell peppers exhibited the highest phenolic content in the total polyphenol content (1.03 ± 0.07 mg GAE/gf.w.), total flavonoid content (137.43 ± 6.35 μg QE/gf.w.), and total tannin content (0.22 ± 0.01 mg CE/gf.w.) as well as the most antioxidant potential in all antioxidant capacity estimation assays including total antioxidant capacity (3.56 ± 0.01 mg AAE/gf.w.), 2,2′-diphenyl-1-picrylhydrazyl (0.89 ± 0.01 mg AAE/gf.w.), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (1.36 ± 0.12 mg AAE/gf.w.), and ferric reducing antioxidant power (0.15 ± 0.01 mg AAE/gf.w.). LC-ESI-QTOF-MS/MS isolated and identified a total of 59 phenolic compounds, including flavonoids (21), phenolic acids (20), other phenolic compounds (12), lignans (5), and stilbenes (1) in all samples. According to HPLC-PDA quantification, the seed portions showed a significantly higher amount of phenolic compounds. These findings indicated that the waste of bell peppers can be a potential source of phenolic compounds, which can be utilized as antioxidant ingredients in foods and nutritional products.

Determination of triazines residues in fruits and vegetables: Methods comparison of ultrasonic solvent extraction with and without solid phase clean-up

ABSTRACT An ultrasonic solvent extraction (USE) method followed by liquid chromatography-photodiode array detector has been optimized and applied with and without solid-phase clean-up for analysis of triazines in fruits and vegetables. The correlation coefficient (r 2) > 0.999 was obtained for all the analytes at a linear range of 100–1000 µg/L. The recoveries obtained were 75–81% and 86–121% for USE with and without SPE clean-up, respectively, with relative standard deviation <20% implying good accuracy and precision. The detection limits ranged from 1.1–1.8 µg/kg to 0.6–1.0 µg/kg for USE with and without SPE clean-up, respectively. The quantification limits ranged from 3.4–5.2 µg/kg to 1.7–2.9 µg/kg for USE with and without SPE clean-up, respectively. The concentrations of triazines detected in fruits and vegetables ranged from 9 to 222 µg/kg. All the triazines were quantified at levels below the MRLs revealing no threat to human health. It can be concluded that the proposed inexpensive, environmentally friendly method can be effectively employed for regular monitoring of the concentration of the selected triazines fruits and vegetables. Moreover, it can be recommended that ultrasonic solvent extraction can be accurately applied without additional SPE clean-up.

Identification and quantification of oligomeric proanthocyanidins, alkaloids, and flavonoids in lotus seeds: A potentially rich source of bioactive compounds

Untargeted metabolomics was performed to study the profiles of 101 chemicals in lotus seeds using ultrahigh-performance liquid chromatography–photodiode array detection–high-resolution tandem mass spectrometry. Among them, 16 dimeric, 18 trimeric, and 4 tetrameric proanthocyanidins were theoretically identified based on the degree of polymerization, and the number of linkages and the presence of two dihydroflavonols and three glycosylated alkaloids were determined for the first time. The proanthocyanidin, flavonoid, amino acid, and total compound contents were quantified, revealing decreases in their levels during maturation as well as a polymerization process formation of polymers from monomers during seed maturation. Interestingly, glycosylated alkaloids were only detected in seed cotyledons being highest at green–brown stage, whereas proanthocyanidins were present at a concentration of 8,226.19 ± 249.96 μg/g (dry weight) in green–brown stage of seed coats. Our findings may provide insights into the utilization of lotus seeds as a functional food.

Analysis of phenolic profile, total phenolic content and antioxidant activity in Anacardium occidentale leaves

Anacardium occidentale young leaves are consumed traditionally as part of a Southeast Asian diet. The regular consumption is believed to have beneficial effects on health in general and potentially against type 2 Diabetes mellitus due to its high content of polyphenols. This study was aimed to investigate the polyphenol content of the plant using two methanol extracts; Free Phenolic Extract (FPE) and Bound Phenolic Extract (BPE) as well as highlight the presence of six phenolic acids and flavonoids namely; gallic acid, sinapinic acid, caffeic acid, ferulic acid, quercetin and kaempferol using High performance liquid chromatography-photodiode array (HPLC-UV-Vis). The results for polyphenols and flavonoids content showed high amounts of total polyphenols in BPE with 8.5±0.57 mg GAE/g as well as high amounts of total flavonoids in both extracts FPE and BPE with 0.58±0.06 and 0.86±0.05 mg QE/g respectively (p&lt;0.05). The presence of these polyphenols was further confirmed by measuring the antioxidant activity through the scavenging of the free radical DPPH which showed an IC50 value for FPE (5.17±0.64 µg/ mL, BPE (4.96±0.12 µg/mL) compared to the positive control ascorbic acid (4.91±0.43 µg/mL). The high-performance liquid chromatography-photodiode array confirmed the presence of all four targeted phenolic acids with the highest amount showing in gallic acid and sinapinic acid in BPE with 148.12±6.44 µg gallic acid/g dry weight and 47.02±1.94 µg sinapinic acid/g dry weight respectively. As for flavonoids, quercetin was present in both extracts with 20.38±1.22 µg/g dry weight in BPE and 5.21±0.1 µg/g dry weight in FPE while Kaempferol was not detectable in either extract. These findings confirmed the importance of A. occidentale as a rich source of polyphenols which can be further investigated to determine its effects in-vitro and in-vivo on non-communicable diseases such as type 2 diabetes.

Protective effects on ovalbumin-induced mouse asthma models and qualitative and quantitative analysis of multiple compounds in Gerberae Piloselloidis Herba.

Gerberae Piloselloidis Herba is widely used to treat cough and asthma in China. However, its effects on allergic asthma as related to its chemical compositions have not been fully elucidated, and there is a scarcity of methods to determine multi-component contents for quality control. In this study, protective effects of Gerberae Piloselloidis Herba on ovalbumin-induced asthma models were investigated, while qualitative and quantitative analyses of multiple constituents in Gerberae Piloselloidis Herba were conducted by using an ultrahigh-performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry and an ultrahigh-performance liquid chromatography-photodiode array detection. The results showed that Gerberae Piloselloidis Herba could significantly mitigate asthma symptoms, reduce eosinophils counts in the bronchoalveolar lavage fluid, as well as decrease IgE, IL-5, and IL-13 concentration, and inflammatory cellular infiltration in lung tissues. A total of 51 compounds were tentatively identified, in which the content of 10 representative compounds was determined in 24 batches of Gerberae Piloselloidis Herba by using an ultrahigh-performance liquid chromatography method with good linearity, precision, repeatability, accuracy, and stability. This research presents a comprehensive strategy combining biological activity evaluation with chemical profiling, providing a useful and comprehensive reference for further application and quality control of Gerberae Piloselloidis Herba.

Development and validation of an ultra-high performance liquid chromatography photodiode array method for the quantification of donepezil in human plasma and its application

Development and validation of an ultra-high performance liquid chromatography photodiode array method for the quantification of donepezil in human plasma and its application

In-tip solid-phase microextraction: a method for determination of sulphonamide residues in environmental water samples

ABSTRACT This study involved the development of an in-pipette tip solid-phase microextraction (SPME) method using activated charcoal as an adsorbent. Simultaneous determination of three sulphonamide antibiotic residues in environmental water was performed using this method, coupled with high-performance liquid chromatography-photodiode array (HPLC-PDA) detection. Seven extraction parameters were optimised by one-variable-at-a-time (OVAT) and response surface (RSM) methods. Optimum extraction efficiency was achieved when 10 mL of sample solution at a natural pH (pH 5–6) was loaded through a 1 mL pipette tip packed with 10 mg of adsorbent, washed with 1 mL of hexane and eluted with 500 µL of 1% ammonium in methanol solution. Under the optimised experimental condition, this method manifested good linearity (5–500 µg L−1) at the coefficient of determination, R2 of 0.9992 to 0.9993, high sensitivity (limit of detection, LOD: 0.38–1.14 µg L−1; limit of quantification, LOQ: 1.14–3.35 µg L−1), and satisfactory recoveries (82.8–108.7%) with acceptable reproducibility (RSD < 4.6%). Real sample analysis of five environmental water samples sourced from Universiti Malaya, Kuala Lumpur and Malacca showed that the samples contained either none or traces of the target sulphonamides (SAs) with their concentration lower than the LOQs. In contrast to other methods, the comparison outcomes depicted that this in-tip SPME method was beneficial in terms of its simple, reusable, cost-saving setup together with a significant reduction in chemical consumption.

Phenolic Composition, In Vitro Alpha-Amylase and Pancreatic Lipase Inhibitory Effects, Anti-Inflammatory and Antioxidant Activities of Ephedra altissima

This study aimed to investigate the phytochemical composition, alpha-amylase and pancreatic lipase inhibitory activities and anti-inflammatory and antioxidant properties of the crude extracts (petroleum ether, ethyl acetate and n-butanol) obtained from the aerial parts of Ephedra altissima. The characterization of the phenolic compounds in crude extracts was performed by high performance liquid chromatographyphotodiode array detection-electrospray ionization-mass spectrometry and the in vitro alpha-amylase and pancreatic lipase inhibitory activities were evaluated using starch and p-nitrophenyl butyrate as substrates, respectively. Furthermore, the anti-inflammatory activity was carried out by bovine serum albumin denaturation method and the antioxidant capacity was assessed using five different assays. Flavonol and ï¬avone glycoside derivatives and phenolic acids, especially isovitexin-2-O-rhamnoside and vicenin II were the major compounds in the n-butanol extract. Otherwise, the ethyl acetate extract presented kaempferol-3-O-rhamnoside, quercetin-3-O-rhamnoside and protocatechuic acid as its main compounds. The n-butanol extract revealed the highest content of total phenolic compounds. The results for antioxidant activity showed that ethyl acetate extract possesses the strongest activity in all the tested methods. Moreover, the ethyl acetate extract displayed the best anti-inflammatory, alpha-amylase and pancreatic lipase inhibitory activities with half-maximal inhibitory concentration values of 126.43, 9.02 and 289.11 μg/ml, respectively. These results give obvious support to the use of Ephedra altissima in traditional medicine for the treatment of diabetic diseases. Also, the moderate alpha-amylase inhibitory activity of Ephedra altissima extracts make advantage of its therapeutic applications compared to the synthetic drugs, since their strong alphaamylase inhibitory effects are associated to many digestive adverse effects including the abnormal bacterial fermentation in the colon.

Lactobacillus acidophilus BIOTECH 1900 decreases the transepithelial mucosal-to-serosal transport of colchicine in an ex vivo non-everted gut sac model.

Colchicine (COL) is a permeability-glycoprotein (P-gp) substrate drug used for familial Mediterranean fever, acute pericarditis, and the management of acute gout. It has a narrow therapeutic index which implies that a small change in the drug's absorption profile may lead to either toxicity or therapeutic failure. Absorption can be altered by modulating the function of P-gp via the concomitant use of drugs, herbal medicines, or food supplements such as probiotics. Here, we investigated the effect of probiotic Lactobacillus acidophilus BIOTECH 1900 on COL's transepithelial mucosal-to-serosal transport in the jejunum of ICR mice. A high-performance liquid chromatography-photodiode array (HPLC-PDA) method for the assay of COL was developed and validated. The HPLC-PDA method was applied in an ex vivo non-everted gut sac model to measure COL's cumulative mucosal-to-serosal transport and apparent permeability (Papp). Treatment of L. acidophilus BIOTECH 1900 resulted to a significantly lower COL transport and Papp value compared to the control group. Additionally, the activity of L. acidophilus BIOTECH 1900 was found to be similar to dexamethasone, a known P-gp inducer. We report that L. acidophilus BIOTECH 1900 decreases the transepithelial mucosal-to-serosal transport of COL, suggesting possible P-gp induction. Further studies are recommended to substantiate this transporter-based drug-probiotic interaction.

Evaluation of 30-days stability of morphine hydrochloride and clonidine at high and low concentrations in polypropylene syringes

ObjectivesClonidine is an alpha-2 adrenoreceptor agonist and is frequently combined with opioids (ie, morphine hydrochloride (HCl)) for the management of chronic pain. In palliative care, the administration of clonidine and...