Displaying publications 781 - 800 of 1723 in total

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  1. Aris NIF, Rahman NA, Wahid MH, Yahaya N, Abdul Keyon AS, Kamaruzaman S
    R Soc Open Sci, 2020 Mar;7(3):192050.
    PMID: 32269813 DOI: 10.1098/rsos.192050
    Superhydrophilic graphene oxide/electrospun cellulose nanofibre (GO/CNF) was synthesized, characterized and successfully used in a solid-phase membrane tip adsorption (SPMTA) as an adsorbent towards a simultaneous analysis of polar organophosphorus pesticides (OPPs) in several food and water samples. Separation, determination and quantification were achieved prior to ultra-performance liquid chromatography coupled with ultraviolet detector. The influence of several parameters such as sample pH, adsorption time, adsorbent dosage and initial concentration were investigated. SPMTA was linear in the range of 0.05 and 10 mg l-1 under the optimum adsorption conditions (sample pH 12; 5 mg of adsorbent dosage; 15 min of adsorption time) for methyl parathion, ethoprophos, sulfotepp and chlorpyrifos with excellent correlation coefficients of 0.994-0.999. Acceptable precision (RSDs) as achieved for intraday (0.06-5.44%, n = 3) and interday (0.17-7.76%, n = 3) analyses. Low limits of detection (0.01-0.05 mg l-1) and satisfactory consistency in adsorption (71.14-99.95%) were obtained for the spiked OPPs from Sungai Pahang, Tasik Cheras, cabbages and rice samples. The adsorption data were well followed the second-order kinetic model and fits the Freundlich adsorption model. The newly synthesized GO/CNF showed a great adsorbent potential for OPPs analysis.
    Matched MeSH terms: Chromatography, Liquid
  2. Ahmad W, Husain I, Ahmad N, Amir M, Sarafroz M, Ansari MA, et al.
    3 Biotech, 2020 Apr;10(4):165.
    PMID: 32206499 DOI: 10.1007/s13205-020-2154-1
    Boerhavia diffusa (BD) Linn. (Nyctaginaceae) is one of the most commonly used herbs in the Indian traditional system of medicine for the urinary disorders. The aim of the current investigation was to carry out initiation, development, and maintenance of BD callus cultures and quantitative estimation of punarnavine in plant and callus extracts. Leaves and stem of BD were used as explant for the tissue culture studies using Murashige and Skoog (MS) basal medium. MS Media comprising 2,4-Dichlorophenoxy acetic acid (2,4-D) (1 ppm) and 2,4-D (1 ppm) + Indole-3-acetic acid (IAA) (1.0 ppm) were found to yield friable callus from leaf explant; similarly, 2,4-D (0.3 ppm) + IAA (0.75 ppm) + Kinetin (0.3 ppm) and 2,4-D (0.5 ppm) + Naphthalene acetic acid (NAA) (1.5 ppm) + Kinetin (0.3 ppm) were found to yield friable callus from the stem explant. High-performance thin-layer chromatography method was been developed for the quantitative estimation of punarnavine (Rf = 0.73) using mobile phase containing toluene: ethyl acetate: formic acid in the ratio (7.0:2.5:0.7, v/v/v) at 262 nm. The validated method was found linear (r2 = 0.9971) in a wide range (100-1000 ng spot-1), precise, accurate, and robust. The values of limit of detection, LOD = 30.3 ng spot-1, and limit of quantification, LOQ = 100.0 ng spot-1. The robustness of the method was proved by applying the Box-Behnken design (BBD). The developed method found appropriate for the quality control of medicinal plants containing punarnavine as a constituent.
    Matched MeSH terms: Chromatography, Thin Layer
  3. Tan WC, Lim SJ, Wan Aida Wan Mustapha
    Sains Malaysiana, 2017;46:439-448.
    Dalam kajian ini, bakteria asid laktik (LAB) serta sebatian aroma ikan pekasam daripada spesies yang berbeza
    ditentukan. Persampelan ikan pekasam iaitu tilapia, loma, lampam, sepat dan gelama diperoleh daripada pembekal
    Perusahaan Ikan Pekasam Kiah di Kuala Kangsar, Perak. Penentuan spesies LAB dijalankan melalui kaedah pencairan
    bersiri, pengkulturan LAB, ujian katalase, ujian pewarnaan spora serta ujian pengesanan Gram bakteria dan morfologi.
    Pengesahan spesies LAB dijalankan melalui pengekstrakan asid deoksiribonukleik (DNA), amplifikasi dengan tindak
    balas rantaian polimerasi (PCR), analisis elektroforesis gel dan penjujukan DNA. Hasil jujukan DNA yang diperoleh
    dibandingkan dengan jujukan dalam pangkalan data GenBank di NCBI menggunakan BLAST. Didapati Lactobacillus
    brevis KB290 DNA dan Lactobacillus casei W56 wujud dalam pekasam tilapia, Lactobacillus plantarum 16 dalam
    pekasam lampam, Lactobacillus casei BD-II kromosom dan Lactobacillus plantarum WCFS1 dalam pekasam sepat,
    Corynebacterium vitaeruminis DSM 20294 dan Streptococcus anginosus C1051 dalam pekasam gelama. Manakala
    Staphylococcus carnosus subsp. carnosus TM300 kromosom adalah LAB dominan dalam pekasam loma. Sementara
    itu, sebatian aroma ditentukan melalui kaedah pengekstrakan cecair menggunakan pelarut metanol dan heksana.
    Pemprofilan sebatian aroma dijalankan dengan kromatografi gas-spektometer jisim (GC-MS). Sebatian aroma dalam
    ekstrak metanol dan heksana daripada lima jenis ikan pekasam dibandingkan. Bilangan sebatian aroma yang diekstrak
    menggunakan metanol adalah lebih banyak berbanding dengan yang menggunakan heksana. Sebatian aroma yang
    paling banyak dikesan adalah daripada pekasam loma. Asid karboksilik merupakan sebatian yang paling dominan
    dalam ikan pekasam dan memberi bau hamis serta tengik.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  4. Fouad Fadhil Al-Qaim, Md Pauzi Abdullah, Jalifah Latip, Wan Mohd Afiq Wan Mohd Khalik, Nurfaizah Abu Tahrim, Nurul Auni Zainal Abidin, et al.
    Sains Malaysiana, 2016;45:803-810.
    The big challenge for the detection of pharmaceutical residues in water samples is the type of ionization mode in
    terms of positive or negative ionization which plays an important role to identify and quantify the analytes using liquid
    chromatography/mass spectrometry. An analytical method was applied to analysis of gliclazide (diabetic drug) in surface
    water and wastewater from sewage treatment plants and hospitals. The proposed analytical method allows simultaneous
    isolation and concentration procedure using solid phase extraction (Oasis HLB) prior to separation using high-performance
    liquid chromatography. The detection and confirmation was achieved by applying time-of-flight analyzer. The limits of
    quantification were as low as 1.4 ng/L (deionized water), 4 ng/L (surface water), 27 ng/L (hospital influent), 10 ng/L
    (hospital effluent), 6 ng/L (sewage treatment plant effluent) and 21 ng/L (sewage treatment plant influent), respectively. On
    average, good recoveries of higher than 87% were obtained for gliclazide in the studied samples. The proposed method
    successfully determined and quantified gliclazide in surface water and wastewater. The results showed that gliclazide
    is a persistent compound in sewage treatment effluents as well as in the recipient rivers. Gliclazide was detected in all
    samples and the highest concentration was 130 ng/L in influent of sewage treatment plant.
    Matched MeSH terms: Chromatography, Liquid
  5. Xu L, Kaopong R, Nualkaew S, Chullasara A, Phongdara A
    Sains Malaysiana, 2017;46:1491-1498.
    soflavonoids are the main compound in White Kwao Krua (Pueraria mirifica), which is an effective folk medicinal plant endemic to Thailand. It has been widely used for improving human physical and treating diseases. There are substances with estrogenic activities have been isolated from P. mirifica, such as puerarin, daidzein and genistein. Isoflavone synthase (IFS) is one of the key enzymes in Leguminous plants to convert liquiritigenin, liquiritigenin C-glucoside and naringenin chalcone to isoflavonoids. The aim of this research was to enhance the production of isoflavonoids by metabolic engineering. Transgenic plants were constructed by introducing P450 gene (EgP450) which is similar to IFS from oil palm (Elaeis guineensis), into P. mirifica by a biolistic method. After the transgenic plants had proved successfully, isoflavonoids of each group plants were determined by HPLC. The contents of daidzein and genistein in transgenic plants were higher than the control plants
    Matched MeSH terms: Chromatography, High Pressure Liquid
  6. Lee ZS, Chin SY, Cheng CK
    Heliyon, 2019 Jun;5(6):e01792.
    PMID: 31245637 DOI: 10.1016/j.heliyon.2019.e01792
    This study evaluates the effects of subcritical hydrothermal treatment on palm oil mill effluent (POME) and its concomitant formations of solid hydrochar, liquid product and gaseous product. The reactions were carried out at temperatures ranged 493 K-533 K for 2 h. The highest reduction of chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were 58.8% and 62.5%, respectively, at 533 K. In addition, the removal of total suspended solids (TSS) achieved up to 99%, with the pH of POME reaching 6 from the initial pH 4. The gas chromatography coupled with mass spectroscopy (GC-MS) analysis showed that the fresh POME contained n-Hexadecanoic acid as the dominant component, which gradually reduced in the liquid product in the reaction with increased temperature, in addition to the attenuation of carboxyl compounds and elevation of phenolic components. The gaseous products contained CO2, CO, H2, and C3 - C6 hydrocarbons. Traces of CH4 were only found at 533 K. CO2 is the dominant species, where the highest of 3.99 vol% per 500 mL working volume of POME recorded at 533 K. The solid hydrochars showed negligible morphological changes across the reaction temperature. The O/C atomic ratio of the hydrochar range from 0.157 to 0.379, while the H/C atomic ratio was in the range from 0.930 to 1.506. With the increase of treatment temperature, the higher heating value (HHV) of the hydrochar improved from 24.624 to 27.513 MJ kg-1. The characteristics of hydrochar make it a fuel source with immense potential. POME decomposed into water-soluble compounds, followed by deoxygenation (dehydration and decarboxylation) in producing hydrochar with lower oxygen content and higher aromatic compounds in the liquid product. Little gaseous hydrocarbons were produced due to subcritical hydrothermal gasification at low temperature.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  7. Mustafa AM, Yap CG
    JUMMEC, 1998;3:63-64.
    Screening for drugs of abused were conducted by using Gas chromatography-Mass spectrometry (GCMS) fitted with capillary column. Urine samples supplied by Centre of Inmigrant Studies, University of Malaya were processed upon arrival and screened for the following drugs. Amphetamines, methamphetamines, aphedrine, hydroxy-amphetamines, ecstasy, benzamphetamines, codeine, morphine, heroine, cocaine and diazepam. The analysis was done using Shimadzu QP5000 Gas chromatograph-mass spectrometer by selected ion monitoring with BPX35 column, 15 m length, 0.32 ID, helium gas as carrier and quadropole mass detector at 1.60 kV electron gain. Analysis were performed using selected ion monitoring (SIM) mode and quantitations were based on area under the curve of individual standards at various concentrations. The method is sensitive to nanogram levels and are able to detect the presence of these drugs in both urine and plasma. From this study (n-100), none of the urine were found positive for the drugs screened. The major problem encountered were adulterated with water based on the clearness and the colour of the urine. Based on this suspicion we would like to suggest that the testing be done on blood samples as this would be more confirmative and quantitative.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  8. Murugesu S, Khatib A, Ahmed QU, Ibrahim Z, Uzir BF, Benchoula K, et al.
    Toxicol Rep, 2019;6:1148-1154.
    PMID: 31993329 DOI: 10.1016/j.toxrep.2019.10.020
    Clinacanthus nutans, an herbal shrub belonging to the Acanthaceae family, is traditionally used as a functional food to treat various ailments in Malaysia and Indonesia. Although the polar fraction of this plant shows non-toxic effect, the toxicity of the non-polar extract is not reported so far. The present study aimed to assess the toxic effect and determine the lethal concentration of this non-polar fraction using zebrafish embryos. The n-hexane fraction was partitioned from the crude extract of C. nutans obtained using 80% methanolic solution. After spawning of the adult male and female zebrafish, the eggs were collected, transferred into a 96-well plate and incubated with the n-hexane fraction at concentrations of 15.63 μg/ml, 31.25 μg/ml, 62.5 μg/ml, 125 μg/ml, 250 μg/ml and 500 μg/ml in 2% DMSO. The survival and sublethal endpoint were assessed, the mortality and hatchability rates were calculated based on microscopic observation, while the heartbeat rate was measured using DanioScope software. The median lethal concentration (LC50) of the C. nutans n-hexane fraction, which was determined using probit analysis, was calculated to be 75.49 μg/mL, which is harmful. Moreover, gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of palmitic acid, phytol, hexadecanoic acid, 1-monopalmitin, stigmast-5-ene, pentadecanoic acid, heptadecanoic acid, 1-linolenoylglycerol and stigmasterol in the n-hexane fraction.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  9. Hamada T, Harano K, Niihara R, Kitahara H, Yamamoto M, Vairrapan CS, et al.
    J Oleo Sci, 2020;69(6):643-648.
    PMID: 32493886 DOI: 10.5650/jos.ess19296
    Sour citrus are prized for their flavor and fragrance. This work identified the components of the peel oil of Hetsuka-daidai (Citrus sp. hetsukadaidai), a special sour citrus that is native to the southern part of the Osumi peninsula, Kagoshima, Japan. These compounds were compared to those identified from the peels of six other major sour citrus: lime (Citrus latifolia), lemon (Citrus limon), Yuzu (Citrus junos), Kabusu (Citrus aurantium), Kabosu (Citrus sphaerocarpa), and Sudachi (Citrus sudachi). Peel oil contents were analyzed for the duration of four months during harvest season to investigate the differences in peel oil/fragrance during ripening. These results could facilitate the development of preferred flavor and scent profiles using local species.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  10. Ismail NZ, Md Toha Z, Muhamad M, Nik Mohamed Kamal NNS, Mohamad Zain NN, Arsad H
    Molecules, 2020 Apr 29;25(9).
    PMID: 32365508 DOI: 10.3390/molecules25092067
    Clinacanthus nutans is a well-known herb that has been used as an alternative and therapeutic medicine, however more selective C. nutans extracts are needed. In this study, leaves were extracted with 80% methanol and further fractionated with n-hexane, dichloromethane, chloroform, n-butanol, and aqueous residue. Subsequently, the total phenolic content (TPC), total flavonoid content (TFC), antioxidant scavenging activity, and antiproliferative effects on breast cancer (Michigan Cancer Foundation-7 [MCF7]) and normal breast (Michigan Cancer Foundation-10A [MCF 10A]) cells of the extracts were measured. Additionally, molecular docking simulation of the major compounds from C. nutans extracts was conducted. The aqueous residue had the highest TPC and TFC, whereas the crude extract had the highest scavenging activity. Among the extracts, dichloromethane extract (CN-Dcm) was selected as it had the highest selectivity index (SI) (1.48). Then, the chosen extract (CN-Dcm) was proceed for further analysis. The compounds from CN-Dcm were identified using gas chromatography-mass spectrometry (GC-MS). The major compounds from CN-Dcm were further investigated through molecular docking studies. Palmitic acid and linolenyl alcohol were the compounds found in the CN-Dcm extract that exhibited the highest binding affinities with p53-binding protein Mdm-2. These results highlight the potential of C. nutans as a source of anticancer activities.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  11. Subuhi NEAM, Saad SM, Zain NNM, Lim V, Miskam M, Kamaruzaman S, et al.
    J Sep Sci, 2020 Aug;43(16):3294-3303.
    PMID: 32519432 DOI: 10.1002/jssc.201901194
    In this work, a simple, fast, sensitive, and environmentally friendly method was developed for preconcentration and quantitative measurement of bisphenol A in water samples using gas chromatography with mass spectrometry. The preconcentration approach, namely biosorption-based dispersive liquid-liquid microextraction with extractant removal by magnetic nanoparticles was performed based on the formation of microdroplet of rhamnolipid biosurfactant throughout the aqueous samples, which accelerates the mass transfer process between the extraction solvent and sample solution. The process is then followed by the application of magnetic nanoparticles for easy retrieval of the analyte-containing extraction solvent. Several important variables were optimized comprehensively including type of disperser solvent and desorption solvent, rhamnolipid concentration, volume of disperser solvent, amount of magnetic nanoparticles, extraction time, desorption time, ionic strength, and sample pH. Under the optimized microextraction and gas chromatography with mass spectrometry conditions, the method demonstrated good linearity over the range of 0.5-500 µg/L with a coefficient of determination of R2  = 0.9904, low limit of detection (0.15 µg/L) and limit of quantification (0.50 µg/L) of bisphenol A, good analyte recoveries (84-120%) and acceptable relative standard deviation (1.8-14.9%, n = 6). The proposed method was successfully applied to three environmental water samples, and bisphenol A was detected in all samples.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  12. Abdul Rahman M, Mohamad Haron DE, Hollows RJ, Abdul Ghani ZDF, Ali Mohd M, Chai WL, et al.
    PeerJ, 2020;8:e9304.
    PMID: 32547888 DOI: 10.7717/peerj.9304
    Head and neck squamous cell carcinoma (HNSCC) represents a significant world health problem, with approximately 600,000 new cases being diagnosed annually. The prognosis for patients with HNSCC is poor and, therefore, the identification of biomarkers for screening, diagnosis and prognostication would be clinically beneficial. A limited number of studies have used lipidomics to profile lipid species in the plasma of cancer patients. However, the profile and levels of lysophosphatidic acid (LPA) species have not been examined in HNSCC. In this study, a targeted lipidomics approach using liquid chromatography triple quadrupole mass spectrometry (LCMS/MS) was used to analyse the concentration of LPA (16:0 LPA, 18:0 LPA, 18:1 LPA, 18:2 LPA and 20:4 LPA) in the plasma of patients with oral squamous cell carcinoma (OSCC) and nasopharyngeal carcinoma (NPC), together with healthy controls. The levels of three LPA species (18:1 LPA, 18:2 LPA and 20:4 LPA) were significantly lower in the plasma of OSCC patients, whilst the concentrations of all five LPA species tested were significantly lower in plasma from NPC patients. Furthermore, the order of abundance of LPA species in plasma was different between the control and cancer groups, with 16:0 LPA, 18:0 LPA levels being more abundant in OSCC and NPC patients. Medium to strong correlations were observed using all pairs of LPA species and a clear separation of the normal and tumour groups was observed using PCA analysis. In summary, the results of this study showed that the levels of several LPA species in the plasma of patients with OSCC and NPC were lower than those from healthy individuals. Understanding these variations may provide novel insights into the role of LPA in these cancers.
    Matched MeSH terms: Chromatography, Liquid
  13. Kadir R, Awang K, Khamaruddin Z, Soit Z
    An Acad Bras Cienc, 2015 Apr-Jun;87(2):743-51.
    PMID: 26131633 DOI: 10.1590/0001-3765201520140041
    Wood extractives from heartwood of Callophylum inophyllum (bintangor) were obtained by shaker method and analyzed for their constituents by gas chromatography-mass spectrometry (GC-MS). Ten compounds were identified by ethanol (EtOH) solvents, fourteen by methanol (MeOH) and only nine by petroleum ether (PETETHR). Major compounds were contributed by monoterpenes (75.11%, 53.75%) when extracted with EtOH and PETETHR solvents. The anti-termitic assay of the wood extracts was also investigated against Coptotermes curvignathus. The level of concentration for anti-termite activity may be an indication of the dose application of the wood extracts for new development of termiticide.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  14. Lee CC, Neoh KB, Lee CY
    J Econ Entomol, 2014 12;107(6):2154-62.
    PMID: 26470081 DOI: 10.1603/EC14193
    The efficacy of chitin synthesis inhibitors (CSIs) against fungus-growing termites is known to vary. In this study, 0.1% chlorfluazuron (CFZ) cellulose bait was tested against medium and large field colonies of Macrotermes gilvus (Hagen). The termite mounds were dissected to determine the health of the colony. Individual termites (i.e., workers and larvae) and fungus combs were subjected to gas chromatography-mass spectrometry (GC-MS) analysis to detect the presence of CFZ. In this study, 540.0 ± 25.8 g (or equivalent to 540.0 ± 25.8 mg active ingredient) and 680.0 ± 49.0 g (680.0 ± 49.0 mg active ingredient) of bait matrix were removed by the medium- and large-sized colonies, respectively, after baiting. All treated medium-sized colonies were moribund. The dead termites were scattered in the mound, larvae were absent, population size had decreased by 90%, and the queens appeared unhealthy. In contrast, no or limited effects were found in large-sized colonies. Only trace amounts of CFZ were detected in workers, larvae, and fungus combs, and the population of large-sized colonies had declined by only up to 40%. This might be owing to the presence of large amount of basidiomycete fungus and a drastic decrease of CFZ content per unit fungus comb (a main food source of larvae) in the large-sized colonies, and hence reduced the toxic effect and longer time is required to accumulate the lethal dose in larvae. Nevertheless, we do not deny the possibility of CSI bait eliminating or suppressing the higher termite if the test colonies could pick up adequate lethal dose by installing more bait stations and prolonging the baiting period.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry
  15. Atif M, Khalid SH, Onn Kit GL, Sulaiman SA, Asif M, Chandersekaran A
    J Young Pharm, 2013 Mar;5(1):26-9.
    PMID: 24023449 DOI: 10.1016/j.jyp.2013.01.005
    A simple, sensitive and selective HPLC method with UV detection for determination of Glipizide in human plasma was developed. Liquid-liquid extraction method was used to extract the drug from the plasma samples. Chromatographic separation of Glipizide was achieved using C18 column (ZORBAX ODS 4.6 × 150 mm). The mobile phase was comprised of 0.01 M potassium dihydrogen phosphate and acetonitrile (65:35, v/v) adjusted to pH 4.25 with glacial acetic acid. The analysis was run at a flow rate of 1.5 mL/min with an injection volume was 20 μL. The detector was operated at 275 nm. The calibration curve was linear over a concentration range of 50-1600 ng/mL. Intra-day and inter-day precision and accuracy values were below 15%. The limit of quantification was 50 ng/mL and the mean recovery was above 98%. Freeze-thaw, short-term, long-term and post-preparative stability studies showed that Glipizide in plasma sample was stable. The method may be successfully applied to analyze the Glipizide concentration in plasma samples for bioavailability and bioequivalence studies.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  16. Yuen KH, Desmukh AA, Newton JM
    Pharm Res, 1993 Apr;10(4):588-92.
    PMID: 8483843
    A novel multiparticulate sustained-release theophylline formulation, which consisted of spherical drug pellets coated with a rate-controlling membrane, was evaluated in vivo. Two preparations that differ solely in the coat thickness, and hence rate of in vitro drug release, were studied in comparison with a solution of the drug. Both preparations produced serum concentration profiles that are reflective of a slow and sustained rate of absorption. The in vivo release versus time profiles calculated using a deconvolution procedure showed that the two preparations differed in the rate but not the extent of drug release. Satisfactory correlation was also obtained between the in vivo and the in vitro results. When the two preparations were further compared using the parameters, time to reach peak concentration (Tp), peak concentration (Cp), and total area under the serum concentration versus time curves (AUC), a statistically significant difference was observed in the Tp and Cp values but not the AUC values, suggesting that the preparations differed in the rate but not the extent of absorption. In addition, the extent of absorption from both preparations was comparable to that obtained with the drug solution.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  17. Chan KL, Choo CY, Morita H, Itokawa H
    Planta Med, 1998 Dec;64(8):741-5.
    PMID: 17253320 DOI: 10.1055/s-2006-957570
    An analytical method using HPLC with UV detection was developed to investigate the quassinoid content of Eurycoma longifolia Jack (Simaroubaceae) collected from various sources. Eurycomanone (1), longilactone (2), 14,15beta-dihydroxyklaineanone (3), 15beta-acetyl-14-hydroxyklaineanone (4), 6alpha-hydroxyeurycomalactone (5), and eurycomalactone (7) were isolated as reference standards and together with the synthesized 1beta,12alpha,15beta-triacetyleurycomanone (6, internal standard), were identified by NMR, MS, UV and IR spectroscopies. Their coefficient of variation values for 0.50-35 microg ml(-1) concentrations of quassinoids and their retention times measured within- and between-day were small. The recoveries of the spiked quassinoids in E. longifolia samples and their detection limits at 8.5 times signal to noise ratio were 99.75-109.13% and 0.01 microg ml(-1), respectively. From the root samples analysed, 1 had the highest concentration, being about 16.8-39.6 fold higher than the other quassinoids 2, 3, 5, 7 but 145.3 fold higher than 4 which showed the lowest concentration.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  18. Yuen KH, Peh KK, Billa N, Chan KL, Toh WT
    Drug Dev Ind Pharm, 1998 Feb;24(2):193-6.
    PMID: 15605452
    The bioavailability of a generic preparation of acyclovir (Avorax) was compared with the innovator product, Zovirax. Twelve healthy volunteers participated in the study, conducted according to a randomized, two-way crossover design. The preparations were compared using the parameters area under the plasma concentration time curve (AUC(0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the Tmax or the logarithmic transformed AUC(0-infinity) and C(max) values of the two preparations. In addition, the 90% confidence interval for the ratio of the logarithmic transformed AUC(0-infinity) values of Avorax over those of Zovirax was found to lie between 0.85 and 1.06, while that of the logarithmic transformed Cmax values was between 0.95 and 1.25, being within the bioequivalence limit of 0.80-1.25. Moreover, the elimination rate constant (k(e)), elimination half-life (t(1/2)), and apparent volume of distribution (Vd) values obtained with the two preparations were comparable and not significantly different statistically.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  19. Peh KK, Wong CF, Yuen KH
    Drug Dev Ind Pharm, 2000 Apr;26(4):447-50.
    PMID: 10769787
    Lipophilicity was evaluated as a possible mechanism for drug retardation from a glyceryl monostearate matrix system. Lipophilicity of the glyceryl monostearate matrix system was studied using contact angle measurement of water droplets on the surface of compressed disks, extrudate ascension of water, and movement of water through a powder mixture packed in a high-performance liquid chromatographic (HPLC) column. Increase in glyceryl monostearate content resulted in an increase in water droplet contact angle, decrease in the rate of water ascending the extrudate, and increase in the pressure values as a function of flow rate of water moving through the powder mixture. These could be due to the increase in lipophilicity of the matrix, rendering the matrix less wettable. As a result, the rate of water penetration into the matrix decreased, and the drug release could be sustained.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  20. Hassan H, Othman MF, Abdul Razak HR, Zakaria ZA, Ahmad Saad FF, Osman MA, et al.
    Molecules, 2022 Nov 17;27(22).
    PMID: 36432069 DOI: 10.3390/molecules27227969
    [18F]sodium fluoride ([18F]NaF) is recognised to be superior to [99mTc]-methyl diphosphate ([99mTc]Tc-MDP) and 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) in bone imaging. However, there is concern that [18F]NaF uptake is not cancer-specific, leading to a higher number of false-positive interpretations. Therefore, in this work, [18F]AlF-NOTA-pamidronic acid was prepared, optimised, and tested for its in vitro uptake. NOTA-pamidronic acid was prepared by an N-Hydroxysuccinimide (NHS) ester strategy and validated by liquid chromatography-mass spectrometry analysis (LC-MS/MS). Radiolabeling of [18F]AlF-NOTA-pamidronic acid was optimised, and it was ensured that all quality control analysis requirements for the radiopharmaceuticals were met prior to the in vitro cell uptake studies. NOTA-pamidronic acid was successfully prepared and radiolabeled with 18F. The radiolabel was prepared in a 1:1 molar ratio of aluminium chloride (AlCl3) to NOTA-pamidronic acid and heated at 100 °C for 15 min in the presence of 50% ethanol (v/v), which proved to be optimal. The preliminary in vitro results of the binding of the hydroxyapatite showed that [18F]AlF-NOTA-pamidronic acid was as sensitive as [18F]sodium fluoride ([18F]NaF). Normal human osteoblast cell lines (hFOB 1.19) and human osteosarcoma cell lines (Saos-2) were used for the in vitro cellular uptake studies. It was found that [18F]NaF was higher in both cell lines, but [18F]AlF-NOTA-pamidronic acid showed promising cellular uptake in Saos-2. The preliminary results suggest that further preclinical studies of [18F]AlF-NOTA-pamidronic acid are needed before it is transferred to clinical research.
    Matched MeSH terms: Chromatography, Liquid
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