Yodhathai Thebtaranonth

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Azaphilone pigments, monascusones A (1) and B (2), together with two known azaphilones, monascin (3) and FK17-P2b2 (4), were isolated from the CH2Cl2 extract of a yellow mutant of the fungus M. kaoliang grown on rice. Structures of the isolated compounds were elucidated by analyses of spectroscopic data. Monascusone A (1), the major metabolite of M.(More)
Aigialomycins A-E (2-6), new 14-membered resorcylic macrolides, were isolated together with a known hypothemycin (1) from the mangrove fungus, Aigialus parvus BCC 5311. Structures of these compounds, including absolute configuration, were elucidated by spectroscopic methods, chemical conversions, and X-ray crystallographic analysis. Hypothemycin and(More)
The terpenoid lactone nimbolide, the structure of which has been unambiguously established, was found to inhibit Plasmodium falciparum in culture with a moderate potency. The EC50 against the parasite line K1 from Thailand was approximately 2.0 microM (0.95 microgram/ml). The EC50 of crude aqueous extract of Azadirachta indica var. siamensis (Sadao tree),(More)
The nature of the interactions between Plasmodium falciparum dihydrofolate reductase (pfDHFR) and antimalarial antifolates, i.e., pyrimethamine (Pyr), cycloguanil (Cyc) and WR99210 including some of their analogues, was investigated by molecular modeling in conjunction with the determination of the inhibition constants (Ki). A three-dimensional structural(More)
Bioassay-guided fractionation of the extract from the fermentation broth of Streptomyces spectabilis BCC 4785 led to the isolation of three principle antimalarial agents, metacycloprodigiosin, bafilomycin A(1), and spectinabilin. Metacycloprodigiosin exhibited potent in vitro activity against Plasmodium falciparum K1, with a 50% inhibitory concentration of(More)
A novel secondary metabolite, pughiinin A, together with pycnidione, mevalonolactone, and 7-hydroxy-2-methylchromanone, was isolated from the seed fungus Kionochaeta pughii BCC 3878. The chemical structure was established by spectroscopic methods and by single crystal X-ray crystallography. Pughiinin A and pycnidione exhibited in vitro antiplasmodial(More)
The C-4 sulfated isoflavonoid, torvanol A (1), and the steroidal glycoside, torvoside H (3), together with the known glycoside, torvoside A (2), were isolated from a MeOH extract of Solanum torvum fruits. Upon enzymatic hydrolysis with beta-glucosidase, torvoside A (2) and torvoside H (3) yielded the corresponding acetal derivatives 4 and 5, respectively.(More)
The reduced binding of pyrimethamine to Ser108Asn (S108N) mutants of parasite dihydrofolate reductase (DHFR), which forms the basis of resistance of Plasmodium falciparum to pyrimethamine, is largely due to steric constraint imposed by the bulky side chain of N108 on Cl of the 5-p-Cl-phenyl group. This and other S108 mutants with bulky side chains all(More)
Bioassay-guided fractionation of the extracts from the insect pathogenic fungus Cordyceps nipponica BCC 1389 led to the isolation of N-hydroxy- and N-methoxy-2-pyridones, cordypyridones A-D (1-4). Structures of these compounds, including absolute configuration, were determined by spectroscopic methods, chemical conversions and single-crystal X-ray(More)
[reaction: see text] An unusually bridged epidithiodiketopiperazine, pretrichodermamide A (3), was isolated from the fungus Trichoderma sp. BCC 5926. During the extensive effort to crystallize 3 for X-ray crystallographic analysis, conversion of this compound to trichodermamide A with coproduction of S(8) occurred.