Displaying publications 61 - 80 of 686 in total

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  1. Nurdianah, H.F., Ahmad Firdaus, A.H., Eshaifol Azam, O., Wan Adnan, W.O.
    MyJurnal
    Bee pollen is considered as one of the functional foods due to its complex biochemical
    properties. Bee pollen which is collected from pollen grains from various botanical sources
    contains almost a complete nutrition such as carbohydrates, proteins, amino acids, vitamins
    and minerals. Its beneficial effect on health is thought to be due to the presence of phenolic
    compounds with its antioxidant activity. Antioxidant activities of ethanolic bee pollen extract
    (BPE) from three species of Malaysian stingless bee; Trigona thoracica, Trigona itama and
    Trigona apicalis in this study were measured using DPPH-HPLC method and gallic acid (GA)
    as a standard reference. The percentage of DPPH inhibition by T. apicalis BPE at 1 mg/mL
    showed the highest inhibition (39%, GA equivalent to 0.3 mg/mL) compared with T. itama
    (14.3%, GA equivalent to 0.1 mg/mL) and T. thoracica (6.7%, GA equivalent to 0.05 mg/mL).
    Our result was the first in reporting antioxidant activity of BPE measured using DPPH-HPLC
    method from three different species of Malaysian stingless bee.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  2. Sambanthamurthi R, Tan Y, Sundram K, Abeywardena M, Sambandan TG, Rha C, et al.
    Br J Nutr, 2011 Dec;106(11):1655-63.
    PMID: 21736792 DOI: 10.1017/S0007114511002121
    Waste from agricultural products represents a disposal liability, which needs to be addressed. Palm oil is the most widely traded edible oil globally, and its production generates 85 million tons of aqueous by-products annually. This aqueous stream is rich in phenolic antioxidants, which were investigated for their composition and potential in vitro biological activity. We have identified three isomers of caffeoylshikimic acid as major components of oil palm phenolics (OPP). The 2,2-diphenyl-1-picrylhydrazyl assay confirmed potent free radical scavenging activity. To test for possible cardioprotective effects of OPP, we carried out in vitro LDL oxidation studies as well as ex vivo aortic ring and mesenteric vascular bed relaxation measurements. We found that OPP inhibited the Cu-mediated oxidation of human LDL. OPP also promoted vascular relaxation in both isolated aortic rings and perfused mesenteric vascular beds pre-contracted with noradrenaline. To rule out developmental toxicity, we performed teratological studies on rats up to the third generation and did not find any congenital anomalies. Thus, these initial studies suggest that OPP is safe and may have a protective role against free radical damage, LDL oxidation and its attendant negative effects, as well as vascular constriction in mitigating atherosclerosis. Oil palm vegetation liquor thus represents a new source of phenolic bioactives.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  3. Muchtaridi M, Lestari D, Khairul Ikram NK, Gazzali AM, Hariono M, Wahab HA
    Molecules, 2021 Jun 04;26(11).
    PMID: 34199752 DOI: 10.3390/molecules26113402
    Coffee has been studied for its health benefits, including prevention of several chronic diseases, such as type 2 diabetes mellitus, cancer, Parkinson's, and liver diseases. Chlorogenic acid (CGA), an important component in coffee beans, was shown to possess antiviral activity against viruses. However, the presence of caffeine in coffee beans may also cause insomnia and stomach irritation, and increase heart rate and respiration rate. These unwanted effects may be reduced by decaffeination of green bean Arabica coffee (GBAC) by treatment with dichloromethane, followed by solid-phase extraction using methanol. In this study, the caffeine and chlorogenic acid (CGA) level in the coffee bean from three different areas in West Java, before and after decaffeination, was determined and validated using HPLC. The results showed that the levels of caffeine were reduced significantly, with an order as follows: Tasikmalaya (2.28% to 0.097% (97 ppm), Pangalengan (1.57% to 0.049% (495 ppm), and Garut (1.45% to 0.00002% (0.2 ppm). The CGA levels in the GBAC were also reduced as follows: Tasikmalaya (0.54% to 0.001% (118 ppm), Pangalengan (0.97% to 0.0047% (388 ppm)), and Garut (0.81% to 0.029% (282 ppm). The decaffeinated samples were then subjected to the H5N1 neuraminidase (NA) binding assay to determine its bioactivity as an anti-influenza agent. The results show that samples from Tasikmalaya, Pangalengan, and Garut possess NA inhibitory activity with IC50 of 69.70, 75.23, and 55.74 μg/mL, respectively. The low level of caffeine with a higher level of CGA correlates with their higher levels of NA inhibitory, as shown in the Garut samples. Therefore, the level of caffeine and CGA influenced the level of NA inhibitory activity. This is supported by the validation of CGA-NA binding interaction via molecular docking and pharmacophore modeling; hence, CGA could potentially serve as a bioactive compound for neuraminidase activity in GBAC.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  4. Abubakar BM, Salleh FM, Shamsir Omar MS, Wagiran A
    Pharm Biol, 2018 Dec;56(1):368-377.
    PMID: 30058427 DOI: 10.1080/13880209.2018.1479869
    CONTEXT: Eurycoma longifolia Jack (Simaroubaceae) commonly known as Tongkat Ali is one of the most important plants in Malaysia. The plant extracts (particularly roots) are widely used for the treatment of cough and fever besides having antimalarial, antidiabetic, anticancer and aphrodisiac activities.

    OBJECTIVES: This study assesses the extent of adulteration of E. longifolia herbal medicinal products (HMPs) using DNA barcoding validated by HPLC analysis.

    MATERIALS AND METHODS: Chloroplastic rbcL and nuclear ITS2 barcode regions were used in the present study. The sequences generated from E. longifolia HMPs were compared to sequences in the GenBank using MEGABLAST to verify their taxonomic identity. These results were verified by neighbor-joining tree analysis in which branches of unknown specimen are compared to the reference sequences established from this study and other retrieved from the GenBank. The HMPs were also analysed using HPLC analysis for the presence of eurycomanone bioactive marker.

    RESULTS: Identification using DNA barcoding revealed that 37% of the tested HMPs were authentic while 27% were adulterated with the ITS2 barcode region proven to be the ideal marker. The validation of the authenticity using HPLC analysis showed a situation in which a species which was identified as authentic was found not to contain the expected chemical compound.

    DISCUSSION AND CONCLUSIONS: DNA barcoding should be used as the first screening step for testing of HMPs raw materials. However, integration of DNA barcoding with HPLC analysis will help to provide detailed knowledge about the safety and efficacy of the HMPs.

    Matched MeSH terms: Chromatography, High Pressure Liquid/methods
  5. Anwar S, Madkor HR, Ahmed N, Wagih ME
    Indian J Pharmacol, 2018 9 1;50(3):108-115.
    PMID: 30166747 DOI: 10.4103/ijp.IJP_660_16
    OBJECTIVE: Silymarin, extracted from the seeds of Silybum marianum L. (Milk thistle), is traditionally used for treating various illnesses such as diabetes, cancer, inflammation, hepatitis, liver cirrhosis, and renal problems. Acute cytotoxicity and genotoxicity studies have been reported with ambiguous outcomes; however, its relevant anticlastogenic potential is not yet evaluated. This study was aimed to evaluate in vivo subacute anticlastogenic properties of silymarin to validate its use as a medicinal agent.

    MATERIALS AND METHODS: Silymarin was isolated from seeds of milk thistle. Various genotoxicity bioassays of silymarin were performed using mice. First, the bone marrow cell proliferation was estimated by calculating mitotic index. Second, the chromosomal abnormalities in mice bone marrow cells were studied. Third, micronucleated polychromatic erythrocytes (MPE) test and in vivo activation of sister chromatid exchanges (SCEs) were carried out in mice bone marrow cells. Finally, primary spermatocytes were analyzed to estimate genotoxic effect of silymarin on germ cells.

    RESULTS: We found that silymarin is capable of inducing a significant increase (P ≤ 0.05) in cell proliferation of bone marrow cells. There is no increase in chromosomal aberrations following silymarin treatments. Results clearly showed that it significantly (P ≤ 0.05) decreased the MPE. Likewise, it was found to be a negative inducer of SCEs. It decreased in total abnormal metaphase, SCEs, MPE, and aberrant diakinesis.

    CONCLUSION: The results demonstrated that silymarin has a strong anticlastogenic activity upon mice genome in somatic and germ cells, indicating its safe use as a medicinal substance. Furthermore, it is not only safe but also has protective effect from clastogens.

    Matched MeSH terms: Chromatography, High Pressure Liquid
  6. Wen Min Yun, Yu Bin Ho, Eugenie Sin Sing Tan, Vivien How
    MyJurnal
    Bisphenol A (BPA) is a controversial plastics ingredient used mainly in the production of polycarbonate plastics (PC) and epoxy resins that widely used nowadays in food and drink packaging. Even though BPA is not involved in polyethylene terephthalate (PET) manufacturing, recent study had reported the present of BPA in PET water bottle. This study was conducted to investigate effects storage conditions on release of BPA from PC and PET bottled water as well as to assess health risks associated with consumption. Methods: Solid phase extraction (SPE) was used to extract the samples, followed by analysis using ultra high performance liquid chromatography with fluorescence detector (UHPLC-FLD). The possibility of developing chronic non-carcinogenic health risk among consumers of bottled water was evaluated using hazard quotient (HQ). Results: Results showed that BPA migrated from PC and PET water bottles at concentrations ranging from 9.13 to 257.67 ng/L and 11.53 ng/L to 269.87 ng/L respectively. Concentrations of BPA were higher in PET bottled water compared to PC bottled water across all storage conditions. Higher storage temperature and longer storage duration increased BPA concentrations in PC and PET bottled water. Concentrations of BPA in bottled water which were kept in a car and were exposed to sunlight were higher than control samples which were stored indoor at room temperature. Conclusion: No significant chronic non-carcinogenic health risks were calculated for daily ingestion of BPA-contaminated bottled water; calculated HQ was less than one.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  7. Nur Azura AB, Yusoff M, Tan GY, Jegadeesh R, Appleton DR, Vikineswary S
    J Ind Microbiol Biotechnol, 2016 Apr;43(4):485-93.
    PMID: 26721619 DOI: 10.1007/s10295-015-1724-4
    Actinomycete strain AUM 00500 was 99.5 % similar to Streptomyces sanglieri NBRC 100784(T) and was evaluated for antagonistic activity towards Ganoderma boninense, the causative fungus of basal stem rot of oil palm. The strain showed strong antifungal activity towards G. boninense in in vitro and SEM analysis showed various modes of inhibition of the fungus. Ethyl acetate extracts of single culture and inhibition zone of cross-plug culture by HPLC indicated that strain AUM 00500 produced two different antibiotics of the glutarimide group namely cycloheximide and actiphenol. In greenhouse trials, oil palm seed treated with spores of S. sanglieri strain AUM 00500 at 10(9) cfu/ml showed significant (P 
    Matched MeSH terms: Chromatography, High Pressure Liquid
  8. Saiman MZ, Mustafa NR, Verpoorte R
    Methods Mol Biol, 2018;1815:437-455.
    PMID: 29981141 DOI: 10.1007/978-1-4939-8594-4_31
    The plant Catharanthus roseus is a rich source of terpenoid indole alkaloids (TIA). Some of the TIA are important as antihypertensive (ajmalicine) and anticancer (vinblastine and vincristine) drugs. However, production of the latter is very low in the plant. Therefore, in vitro plant cell cultures have been considered as a potential supply of these chemicals or their precursors. Some monomeric alkaloids can be produced by plant cell cultures, but not on a level feasible for commercialization, despite extensive studies on this plant that deepened the understanding of the TIA biosynthesis and its regulation. In order to analyze the metabolites in C. roseus cell cultures, this chapter presents the method of TIA, carotenoids, and phytosterols analyses. Furthermore, an NMR-based metabolomics approach to study C. roseus cell culture is described.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  9. Iqbal MS, Bahari MB, Darwis Y, Iqbal MZ, Hayat A, Venkatesh G
    J AOAC Int, 2013 6 19;96(2):290-4.
    PMID: 23767352
    A simple and selective RP-HPLC-UV method with SPE was developed and validated for the quantification of cefotaxime in all-in-one total parenteral nutrition (AIO-TPN) admixtures. Chromatographic separation was achieved on a 5 pm particle size C18 DB column (250 x 4.6 mm id) using the mobile phase ammonium acetate (25 mM, pH 4.0)-50% acetonitrile in methanol (80 + 20, v/v). The flow rate was 0.9 mL/min and the detection wavelength was 254 nm. The analyte was extracted from AIO-TPN admixtures by means of an SPE method. The cefotaxime calibration curve was linear over a concentration range of 100-1400 microg/mL with a correlation coefficient of > or = 0.9994. The intraday accuracy and precision for cefotaxime were < or = -3.15 and < or = 3.08%, respectively, whereas the interday accuracy and precision were < or = -2.48 and < or = 2.25%, respectively. The method was successfully applied to stability studies of cefotaxime in the presence of micronutrients together with low and high concentrations of macronutrients in AIO-TPN admixtures. Cefotaxime was degraded by 13.00 and 26.05% at room temperature (25 +/- 2 degrees C) after 72 h in low and high macronutrient concentration formulations of AIO-TPN admixtures, respectively. The values of cefotaxime degradation rates for low and high macronutrient concentration formulations of AIO-TPN admixtures were -0.164 and -0.353, respectively. These results indicated that there was a higher rate of degradation in the AIO-TPN admixture formulations containing high concentrations of macronutrients.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods*
  10. Anas SS, Vasikaran SD
    Ann. Clin. Biochem., 2010 Nov;47(Pt 6):554-8.
    PMID: 20926470 DOI: 10.1258/acb.2010.010131
    BACKGROUND: Measurement of plasma-free metanephrine plus normetanephrine (PFM) is the best screening test for phaeochromocytoma. While clearly raised levels are diagnostic, borderline increases may be associated with factors such as stress and medications, and should prompt a repeat study after interfering factors are withdrawn.
    METHODS: PFM results reported by a teaching hospital laboratory over a 12-month period were extracted from the laboratory information system. All borderline raised results were examined for a subsequent repeat test (as recommended by attached interpretative comment) and those not repeated were followed up by examination of case-notes or questionnaires to doctors.
    RESULTS: Of 111 patients with borderline increased PFM which did not normalize on repeat measurement, 33 were from the hospital and 78 from outside locations. Hospital notes for 27 out of 33 hospital-patients (82%) could be reviewed, and 49 completed questionnaires (63% of 78 sent out) were received from outside locations. Of these 76 patients thus followed up, the test was not repeated in 55 (72%) cases with borderline increased PFM. Of 10 patients with an adrenal mass and borderline PFM, only three had PFM repeated. Of another nine patients with undetermined final diagnosis and borderline PFM, only three had the test repeated.
    CONCLUSION: Seventy-two per cent of borderline increased PFM results were not followed up with appropriate repeat testing, potentially leading to missed detection of phaeochromocytoma. A stronger interpretative comment may encourage appropriate repeat testing in more cases with borderline increased PFM and suspected phaeochromocytoma.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  11. Loke MF, Chua EG, Gan HM, Thulasi K, Wanyiri JW, Thevambiga I, et al.
    PLoS One, 2018;13(12):e0208584.
    PMID: 30576312 DOI: 10.1371/journal.pone.0208584
    Colorectal cancer (CRC) is ranked the third most common cancer in human worldwide. However, the exact mechanisms of CRC are not well established. Furthermore, there may be differences between mechanisms of CRC in the Asian and in the Western populations. In the present study, we utilized a liquid chromatography-mass spectrometry (LC-MS) metabolomic approach supported by the 16S rRNA next-generation sequencing to investigate the functional and taxonomical differences between paired tumor and unaffected (normal) surgical biopsy tissues from 17 Malaysian patients. Metabolomic differences associated with steroid biosynthesis, terpenoid biosynthesis and bile metabolism could be attributed to microbiome differences between normal and tumor sites. The relative abundances of Anaerotruncus, Intestinimonas and Oscillibacter displayed significant relationships with both steroid biosynthesis and terpenoid and triterpenoid biosynthesis pathways. Metabolites involved in serotonergic synapse/ tryptophan metabolism (Serotonin and 5-Hydroxy-3-indoleacetic acid [5-HIAA]) were only detected in normal tissue samples. On the other hand, S-Adenosyl-L-homocysteine (SAH), a metabolite involves in methionine metabolism and methylation, was frequently increased in tumor relative to normal tissues. In conclusion, this study suggests that local microbiome dysbiosis may contribute to functional changes at the cancer sites. Results from the current study also contributed to the list of metabolites that are found to differ between normal and tumor sites in CRC and supported our quest for understanding the mechanisms of carcinogenesis.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  12. Suriyanti SN, Usup G
    Toxicon, 2015 Dec 15;108:257-63.
    PMID: 26541573 DOI: 10.1016/j.toxicon.2015.10.017
    Screening of the occurrence of potentially toxic diatoms was carried out at two sites of cage cultures in Tebrau Straits, Johor. Phytoplankton samples from Sungai Pendas and Teluk Sengat were collected using a 20 μm mesh plankton net and salinity was recorded in-situ. Nitzschia and Pseudo-nitzschia cells were isolated and established into clonal cultures. All cultures were tested for domoic acid using HPLC-UV analysis and verified by LC-MS analysis. Three Nitzschia spp. and one Pseudo-nitzschia sp. were identified from these locations. Toxic and non-toxic strains of Nitzschia navis-varingica are found at the cage culture areas. Cellular toxin content in the toxic strain of N. navis-varingica is 1.8 pg cell(-1). This is a new record from Malaysia and this species was isolated from estuarine water with salinity 28 PSU. The discovery of toxic Nitzschia species in Tebrau Straits indicates the potential for domoic acid accumulation in seafood.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  13. Ahmad N, Ahmad R, Alam MA, Ahmad FJ, Amir M, Pottoo FH, et al.
    Int J Biol Macromol, 2019 May 01;128:825-838.
    PMID: 30690115 DOI: 10.1016/j.ijbiomac.2019.01.142
    BACKGROUND: Daunorubicin hydrochloride (DAUN·HCl), due to low oral bioavailability poses the hindrance to be marketed as an oral formulation.

    AIM OF THE STUDY: To develop a natural biodegradable macromolecule i.e. Chitosan (CS)-coated-DAUN-PLGA-poly(lactic-co-glycolic acid)-Nanoparticles (NPs) with an aim to improve oral-DAUN bioavailability and to develop as well as validate UHPLC-MS/MS (ESI/Q-TOF) method for plasma quantification and pharmacokinetic analysis (PK) of DAUN.

    RESULTS: A particle size (198.3 ± 9.21 nm), drug content (47.06 ± 1.16 mg/mg) and zeta potential (11.3 ± 0.98 mV), consisting of smooth and spherical shape was observed for developed formulation. Cytotoxicity studies for CS-DAUN-PLGA-NPs revealed; a comparative superiority over free DAUN-S (i.v.) in human breast adenocarcinoma cell lines (MCF-7) and a higher permeability i.e. 3.89 folds across rat ileum, as compared to DAUN-PLGA-NPs (p 

    Matched MeSH terms: Chromatography, High Pressure Liquid
  14. Zubair M, Anwar F, Ashraf M, Uddin MK
    Int J Mol Sci, 2012;13(4):4608-4622.
    PMID: 22605998 DOI: 10.3390/ijms13044608
    The present study reports the composition and variation of fatty acids, sterols, tocopherols and γ-oryzanol among selected varieties namely Basmati Super, Basmati 515, Basmati 198, Basmati 385, Basmati 2000, Basmati 370, Basmati Pak, KSK-139, KS-282 and Irri-6 of Pakistani rice (Oryza sativa L). Oil content extracted with n-hexane from different varieties of brown rice seed (unpolished rice) ranged from 1.92% to 2.72%. Total fatty acid contents among rice varieties tested varied between 18240 and 25840 mg/kg brown rice seed. The rice tested mainly contained oleic (6841-10952 mg/kg) linoleic (5453-7874 mg/kg) and palmitic acid (3613-5489 mg/kg). The amounts of total phytosterols (GC and GC-MS analysis), with main contribution from β-sitosterol (445-656 mg/kg), campesterol (116-242 mg/kg), Δ(5)-avenasterol (89-178 mg/kg) and stigmasterol (75-180 mg/kg) were established to be 739.4 to 1330.4 mg/kg rice seed. The content of α-, γ- and δ-tocopherols as analyzed by HPLC varied from 39.0-76.1, 21.6-28.1 and 6.5-16.5 mg/kg rice seed, respectively. The amounts of different γ-oryzanol components (HPLC data), identified as cycloartenyl ferulate, 24-methylene cycloartanyl ferulate, campesteryl ferulate and β-sitosteryl ferulate, were in the range of 65.5-103.6, 140.2-183.1, 29.8-45.5 and 8.6-10.4 mg/kg rice seed, respectively. Overall, the concentration of these bioactives was higher in the Basmati rice cultivars showing their functional food superiority. In conclusion, the tested varieties of Pakistani rice, especially the Basmati cultivars, can provide best ingredients for functional foods.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  15. Najmul Hejaz Azmi S, Aqib Nasir Al Rawahi W, Ibrahim Al Yahyai A, Ali Al Qasimi A, Saif Al Fuliti K, Said Al Qalhati O, et al.
    PMID: 38309045 DOI: 10.1016/j.jchromb.2024.124035
    A UV-HPLC method optimized by Box-Behnken design model was developed to determine caffeine in pharmaceutical preparations and urine samples. The chromatographic conditions followed were mobile phase: methanol/water/ citrate buffer (pH 4.6) (40:25:35, v/v/v),AcclaimTMDionex C18 column (ODS 100A˚, 5 µm; 4.6 × 250 mm),flow rate (0.9 mL min-1), column temperature (30 °C) and UV-detection wavelength (204 nm). The chromatographic variables: pH (A), % methanol fraction (B), flow rate(C) and column temperature (D) were optimized at 50 μg mL-1caffeine using BBD model. The chromatogram resulted in the asymmetry factor (1.23), theoretical plate 13,786 and retention time (5.79 min). The proposed HPLC method's greenness point was assessed byAnalytical Eco-scale and found to be 78 (as per guidelines, ranked as excellent). The linearity was ranged from2.0 to 70 µg mL-1 with coefficient of correlation (r = 0.999) and detection limit of 0.19 µg mL-1. The proposedmethod was developed successfully and applied for the assay of active caffeine in pharmaceutical preparations and urine samples. The % recovery obtained by both (proposed and reference) methods ranged from 99.98 to 100.05 % followed the compliance (100 ± 2 %) with Canadian Health Protection regulatory guidelines. The performance of the proposed method was compared with published papers and found to be acceptable and superior. The proposed method was quite effective as the reference method, and hence can be used as an alternative method for the assay of active caffeine in pharmaceutical preparations and urine samples.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods
  16. Durani LW, Hamezah HS, Ibrahim NF, Yanagisawa D, Makpol S, Damanhuri HA, et al.
    Biochem Biophys Res Commun, 2017 11 25;493(3):1356-1363.
    PMID: 28970069 DOI: 10.1016/j.bbrc.2017.09.164
    We have recently shown that age-dependent regional brain atrophy and lateral ventricle expansion may be linked with impaired cognitive and locomotor functions. However, metabolic profile transformation in different brain regions during aging is unknown. This study examined metabolic changes in the hippocampus, medial prefrontal cortex (mPFC) and striatum of middle- and late-aged Sprague-Dawley rats using ultrahigh performance liquid chromatography coupled with high-resolution accurate mass-orbitrap tandem mass spectrometry. Thirty-eight potential metabolites were altered in hippocampus, 29 in mPFC, and 14 in striatum. These alterations indicated that regional metabolic mechanisms in lated-aged rats are related to multiple pathways including glutathione, sphingolipid, tyrosine, and purine metabolism. Thus, our findings might be useful for understanding the complexity of metabolic mechanisms in aging and provide insight for aging and health span.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods
  17. Chia, Yoke Yin, Ton, So Ha
    Malays J Nutr, 2006;12(1):67-78.
    MyJurnal
    The objective of the study was to quantify and to profile the amino acids content in urine samples. The amino acids content in urine was determined in 162 individuals (62 young non-vegetarians aged 15-45 years, 24 elderly non-vegetarians aged 46-70 years, 40 young vegetarians and 36 elderly vegetarians) by high performance liquid chromatography (HPLC). The most common amino acids detected in the young and elderly individuals on vegetarian and non-vegetarian diets were phenylalanine, threonine, arginine and asparagine, while leucine, aspartic acid and alanine were not found in any urine samples in both groups. Isoleucine was not detected in the urine of vegetarians. The concentrations of the majority of essential amino acids were between 0.10 - 2.00 mgl24hrs except for histidine which had a range of 4.1 - 5.0 mgl24hrs. The concentrations of non-essential amino acids varied. Proline, glycine and tyrosine concentrations were between 0.10 - 1.00 mg/24hrs, while cysteine, glutamine, glutamic acid and cystine concentrations were between 11.0 - 21.0 mg124hrs. Asparagine and hydroxy-proline had a range of 0.10 - 5.00 mg/24hrs, while serine and arginine ranged between 31.0 - 50.0 mg124hrs. Isoleucine and serine were not detected in elderly vegetarians while histidine, glycine, glutamic acid and hydroxy-proline were not detected in elderly non-vegetarians. Isoleucine, glycine and hydroxy proline were detected in young non-vegetarians but not in young vegetarians. The levels of amino acids showed no significant statistical differences between young vegetarians and non-vegetarians as well as between elderly vegetarians and non-vegetarians. Phenylalanine, threonine and trypthophan were commonly detected in the lacto-ovo and lacto vegetarians, while valine, cysteine, arginine and asparagine were commonly detected in vegans. In conclusion, except for isoleucine, general differences were seen in urinary amino acid excretions between vegetarians and non-vegetarians even though the differences were statistically not significant. Therefore lacto-ovo diets could be nutritionally adequate as the nutrients were substituted by dairy or plant products.
    Matched MeSH terms: Chromatography, High Pressure Liquid
  18. Yuen KH, Wong JW, Billa N, Julianto T, Toh WT
    Int J Clin Pharmacol Ther, 1999 Jul;37(7):319-22.
    PMID: 10442505
    The bioavailability of a generic preparation of metformin (Diabetmin from Hovid Sdn Bhd) was evaluated in comparison with a proprietary product (Glucophage from Lipha Pharma Ltd., UK).
    Matched MeSH terms: Chromatography, High Pressure Liquid
  19. 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
  20. Chan KL, Yuen KH, Jinadasa S, Peh KK, Toh WT
    Planta Med, 1997 Feb;63(1):66-9.
    PMID: 9063097
    A high-performance liquid chromatography assay equipped with a glassy carbon electrode for electrochemical detection (HPLC-ECD) was developed at reductive mode for the analysis of artemisinin, the antimalarial drug from Artemisia annua (Asteraceae) in human plasma. This method was selective, sensitive, and produced satisfactory recovery, precision, and accuracy. Analysis of plasma samples from 8 male volunteers given 10 mg kg-1 of artemisinin orally as an aqueous suspension showed a mean peak plasma concentration (Cmax) of 580.89 ng ml-1 +/- 88.64 SD at 2.5 h +/- 0.5 SD after dosing, and the mean area under the plasma concentration-time curve (AUC0-infinity) was 2227.57 ng h ml-1 +/- 677.22 SD. In addition, the elimination rate constant (Ke), elimination half-life (t1/2), and apparent volume of distribution (Vd) were calculated to be 0.2971 h-1 +/- 0.0644 SD, 2.42 h +/- 0.46 SD, and 16.26 l kg-1 +/- 3.44 SD, respectively.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods*
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