Papers by Jantanee Wattanarangsan
Aristolochic acid (AA) and its derivatives, found in Aristolochia spp. have been reported to be n... more Aristolochic acid (AA) and its derivatives, found in Aristolochia spp. have been reported to be nephrotoxic and car- cinogenic agents. Dried root of Aristolochia tagala Cham. (ATC) is a crude drug used in many Thai traditional herbal recipes. A simple and reliable ultra-high performance liquid chromatography technique (UHPLC) for quantitative analysis of AA-I in ATC was established in this study. The method was validated for linearity, limit of detection (LOD), limit of quantitation (LOQ), precision, repeatability, and accuracy. The most appropriate mobile phase was the mixture of 2% acetic acid and ace- tonitrile (62:38) and the suitable detection was at 395 nm. The calibration curve showed excellent linearity with R2 equal to 0.9999. LOD and LOQ were determined to be 0.8 and 2.0 µg/mL, respectively. The recovery was 101.7%. Relative standard deviations (RSDs) of intra-day and inter-day precision were less than or equal to 1.37. RSD of the repeatability test was less than or equal ...
Dihydrofolate reductase (DHFR) and thymidylate synthase (TS) are crucial enzymes catalysing seque... more Dihydrofolate reductase (DHFR) and thymidylate synthase (TS) are crucial enzymes catalysing sequential reactions in the biosynthesis of thymidylate, which is required for DNA synthesis. Inhibition of either enzyme disrupts the dTMP cycle and results in DNA-strand fragmentation and cell death. Thus, these enzymes serve as attractive targets for many drugs including anti-malarial antifolates [1-3]. Two widely used antifolates, pyrimethamine (PYR) and cycloguanil (CYC), selectively bind to and effectively inhibit Plasmodium falciparum DHFR (pfDHFR) [4-7]. Unfortunately, severe resistance to these drugs has developed rapidly through stepwise mutations of amino acids at positions 16, 51, 59, 108 and 164 located in the active site of the enzyme [5-9]. As a result, binding strength of the enzyme to the drugs is greatly reduced [8]. In addition to biochemical and structural studies of the mutations and mode of binding of the drugs, identification of the limit of the parasite to accumulate mutations will greatly benefit the design and development of "resistance-proof" antifolate analogs [10].
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Papers by Jantanee Wattanarangsan