RESUMEN
The natural product 9-methoxystrobilurin G (9MG) from Favolaschia spp basidiomycetes is a potent and selective antimalarial. The mechanism of action of 9MG is unknown. We induced 9MG resistance in Plasmodium falciparum 3D7 and Dd2 strains and identified mutations associated with resistance by genome sequencing. All 9MG-resistant clones possessed missense mutations in the cytochrome b (CYTB) gene, a key component of mitochondrial complex III. The mutations map to the quinol oxidation site of CYTB, which is also the target of antimalarials such as atovaquone. In a complementary approach to identify protein targets of 9MG, a photoactivatable derivative of 9MG was synthesized and applied in chemoproteomic-based target profiling. Three components of mitochondrial complex III (QCR7, QCR9, and COX15) were specifically enriched consistent with 9MG targeting CYTB and complex III function in P. falciparum. Inhibition of complex III activity by 9MG was confirmed by ubiquinone cytochrome c reductase assay using P. falciparum extract. The findings from this study may be useful for developing novel antimalarials targeting CYTB.
RESUMEN
Investigation of cultures of the basidiomycete Favolaschia minutissima TBRC-BCC 19434 led to the isolation of two undescribed ß-methoxyacrylate metabolites, 9-methoxystrobilurins R (1) and S (2), and a degraded aldehyde derivative, favodehyde E (3). 9-Methoxystrobilurin derivatives 1 and 2 exhibited significant antimalarial activity against Plasmodium falciparum K1 (multidrug-resistant strain) with IC50 values of 0.12 and 0.21 µM, respectively.
Asunto(s)
Antimaláricos , Plasmodium falciparum , Estrobilurinas , Antimaláricos/farmacología , Antimaláricos/aislamiento & purificación , Antimaláricos/química , Plasmodium falciparum/efectos de los fármacos , Estrobilurinas/farmacología , Estrobilurinas/química , Concentración 50 Inhibidora , Basidiomycota/química , Basidiomycota/metabolismo , Acrilatos/farmacología , Acrilatos/química , Estructura MolecularRESUMEN
Five undescribed polyketide metabolites, oudemansins E (1), M (2), P (3), and Q (4), and 9-methoxystrobilurin I (5), were isolated from cultures of basidiomycete Favolaschia minutissima TBRC-BCC 19434. A γ-lactone derivative (6) of noroudemansin A (8), which was previously reported as a semisynthetic compound, was also isolated. The absolute configuration of the isoprene-derived moiety of the known cometabolite 9-methoxystrobilurin E (9) was determined to be 2'R,6'S by comparison of the experimental and calculated ECD data, which was correlated to the new derivative 1. These compounds exhibited antimalarial activity against Plasmodium falciparum K1 (multidrug-resistant strain). A putative minor natural product, namely 9-methoxystrobilurin P (13), was prepared by semisynthesis, which exhibited significant antimalarial activity (IC50 0.086 µM).
Asunto(s)
Antimaláricos , Basidiomycota , Antimaláricos/farmacología , Butadienos , Plasmodium falciparumRESUMEN
Plasmodium falciparum dihydrofolate reductase (PfDHFR), a historical target for antimalarials, has been considered compromised due to resistance inducing mutations caused by pyrimethamine (PYR) overexposure. The clinical candidate P218 has demonstrated that inhibitors could efficiently target both PYR-sensitive and PYR-resistant parasites through careful drug design. Yet, P218 clinical development has been limited by its pharmacokinetic profile, incompatible with single dose regimen. Herein, we report the design of new PfDHFR inhibitors using fragment-based design, aiming at improved lipophilicity and overall drug-like properties. Fragment-based screening identified hits binding in the pABA site of the enzyme. Using structure-guided design, hits were elaborated into leads by fragment linking with 2,4-diaminopyrimidine. Resulting compounds display nM range inhibition of both drug-sensitive and resistant PfDHFR, high selectivity against the human isoform, drug-like lipophilicity and metabolic stability. Compound 4 and its ester derivative 3 kill blood stage TM4/8.2 parasite at nM concentrations while showing no toxicity against Vero cells.
RESUMEN
The isolation of lanostane triterpenoids possessing significant anti-tuberculosis (anti-TB) activity from mycelial cultures of the basidiomycete Ganoderma australe strain TBRC-BCC 22314 was previously reported. To demonstrate the potential of the dried mycelial powder for utilization in anti-TB medicinal products, its authentic chemical analysis was performed. Considering the possibility of the changes in the lanostane compositions and anti-TB activity by sterilization, both autoclave treated and non-autoclaved mycelial powder materials were chemically investigated. The study led to the identification of the lanostanes responsible for the activity of the mycelial extract against Mycobacterium tuberculosis H37Ra. The anti-TB activity of the extracts from autoclaved and non-autoclaved mycelial powders were the same (MIC 3.13 µg/mL). However, the analytical results revealed several unique chemical conversions of the lanostanes under the sterilization conditions. The most potent major lanostane, ganodermic acid S (1), was shown to be significantly active also against the extensively drug-resistant (XDR) strains of M. tuberculosis.
Asunto(s)
Ganoderma , Mycobacterium tuberculosis , Polvos , Estructura Molecular , Pruebas de Sensibilidad Microbiana , Antituberculosos/farmacología , Ganoderma/químicaRESUMEN
Fourteen new cytochalasans, brunnesins A-N (1-14), along with eleven known compounds, were isolated from the culture extracts of the insect pathogenic fungus Metarhizium brunneum strain TBRC-BCC 79240. The compound structures were established by spectroscopy, X-ray diffraction analysis, and electronic circular dichroism. Compound 4 exhibited antiproliferative activity against all cell lines tested (mammalian), with 50% inhibition concentration (IC50) values ranging from 2.09 to 16.8 µg mL-1. Compounds 6 and 16 were shown to be bioactive only against non-cancerous Vero cells (IC50 4.03 and 0.637 µg mL-1, respectively) whereas compounds 9 and 12 were bioactive only against NCI-H187 small-cell lung cancer cells (IC50 18.59 and 18.54 µg mL-1, respectively). Compounds 7, 13, and 14 showed cytotoxicity against NCI-H187 and Vero cell lines with IC50 values ranging from 3.98-44.81 µg mL-1.
RESUMEN
In the quest for bioactive compounds from Ganoderma, artificially cultivated fruiting bodies of Ganoderma cf. mastoporum, strain TBRC-BCC 47851 were chemically investigated. The study led to the isolation of three undescribed lanostane triterpenoids (1-3) together with twelve known compounds. The structures were elucidated on the basis of NMR spectroscopic and mass spectrometry data. The new compounds were inactive in the antimalarial and antitubercular activity assays.
RESUMEN
Eight new angucyclic quinones, miaosporones A to H (1-8), along with the previously described metabolites 8-hydroxy-3-methylbenz[a]anthraquinone (9), tetrangulol (10), 5,6-dihydro-1,8-dihydroxy-3-methybenz[a]anthracene-7,12-quinone (11), and SF2315A (12), were isolated from the terrestrial actinomycete Actinomadura miaoliensis TBRC 5172 obtained from sediment collected from the Huai Yang reservoir, Prachuap Khiri Khan Province, Thailand. The relative and absolute configurations of the new compounds were determined from analysis of NMR spectroscopic and X-ray crystallographic data. Miaosporone A exhibited antimalarial activity against Plasmodium falciparum K1 and antibacterial activity against Mycobacterium tuberculosis with respective IC50 values of 2.5 and 2.4 µM and displayed cytotoxic activities against both cancerous (MCF-7 and NCI-H187) and nonmalignant (Vero) cells.
Asunto(s)
Actinomadura/metabolismo , Antiinfecciosos/aislamiento & purificación , Antineoplásicos/aislamiento & purificación , Quinolonas/aislamiento & purificación , Antiinfecciosos/farmacología , Antineoplásicos/farmacología , Línea Celular Tumoral , Humanos , Espectroscopía de Resonancia Magnética , Mycobacterium tuberculosis/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Quinolonas/química , Quinolonas/farmacologíaRESUMEN
Antitubercular lanostane triterpenoids isolated from mycelial cultures of the basidiomycete Ganoderma australe were structurally modified by semisynthesis. One of the synthetic compounds, named GA003 (9), showed more potent activity against Mycobacterium tuberculosis H37Ra than the lead natural lanostane (1). GA003 was also significantly active against the virulent strain (H37Rv) as well as extensively drug-resistant tuberculosis strains.
Asunto(s)
Antituberculosos/química , Antituberculosos/farmacología , Ganoderma/química , Triterpenos/química , Animales , Antituberculosos/toxicidad , Chlorocebus aethiops , Ganoderma/crecimiento & desarrollo , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Mycobacterium tuberculosis/efectos de los fármacos , Relación Estructura-Actividad , Triterpenos/síntesis química , Triterpenos/farmacología , Células VeroRESUMEN
Decagram scale synthesis of favipiravir was performed in 9 steps using diethyl malonate as cheap starting material. Hydrogenation and bromination steps were achieved by employing a continuous flow reactor. The synthetic process provided a total of 16% yield and it is suitable for larger-scale synthesis and production.
RESUMEN
Five new compounds, iranginins A-E (1-5), together with sixteen known compounds were isolated from the insect pathogenic fungus Ophiocordyceps irangiensis BCC 2728. The structures and the absolute configurations of the new compounds were established by spectroscopic analyses, the application of modified Mosher's method (for 2), ECD calculation (for 5), and X-ray crystallographic analysis (for 4). LL-Z1640-5 and mucorisocoumarin C were active against Mycobacterium tuberculosis (MIC 41.7 and 85.0 µM, respectively), while peyroisocoumarin D exhibited cytotoxic activity (IC50 65.6 µM).
Asunto(s)
Antineoplásicos , Hormigas , Hypocreales , Policétidos , Animales , Estructura MolecularRESUMEN
A series of flexible diaminodihydrotriazines or cycloguanil (Cyc) analogues are developed and shown to inhibit P. falciparum dihydrofolate reductase (PfDHFR) of the wild type or those carrying either single (S108N), double (C59R + S108N and A16V + S108T), triple (N51I + C59R + S108N and C59R + S108N + I164L) or quadruple (N51I + C59R + S108N + I164L) mutations, responsible for antifolate resistance. The flexibility of the side chain at position N1 has been included in the design so as to avoid unfavourable steric interaction with the side chain of residue 108 of the resistant mutants. The inhibition constants of many inhibitors for the mutant enzymes are in the low nanomolar region. Regaining of drug binding efficacies was achieved with both A16V and S108N series of mutants. X-ray studies of some enzyme-inhibitor complexes designed for optimal interaction with the mutant enzymes reveal the modes of binding in line with the Ki values. A number of these compounds show excellent antimalarial activities against resistant P. falciparum bearing the mutant enzymes, and exhibit low cytotoxicity to mammalian cells, making them good candidates for further development as antimalarial drugs.
Asunto(s)
Antimaláricos/química , Antimaláricos/farmacología , Antagonistas del Ácido Fólico/química , Antagonistas del Ácido Fólico/farmacología , Proteínas Protozoarias/antagonistas & inhibidores , Triazinas/química , Triazinas/farmacología , Antimaláricos/metabolismo , Antagonistas del Ácido Fólico/metabolismo , Simulación del Acoplamiento Molecular , Mutación , Unión Proteica , Conformación Proteica , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Tetrahidrofolato Deshidrogenasa/química , Tetrahidrofolato Deshidrogenasa/genética , Tetrahidrofolato Deshidrogenasa/metabolismo , Triazinas/metabolismoRESUMEN
Fourteen new compounds, oudemansins 1-4, oudemansinols 5-7, favolasins 8-10, favolasinin (12), polyketides 13-15, and (R,E)-2,4-dimethyl-5-phenyl-4-pentene-2,3-diol (16), together with nine known compounds were isolated from the basidiomycete fungus Favolaschia sp. BCC 18686. Two new compounds, favolasin E (11) and 9-oxostrobilurin E (17), were isolated from the closely related organism Favolaschia calocera BCC 36684 along with nine ß-methoxyacrylate-type derivatives. Compounds in the class of oudemansins and strobilurins exhibited moderate to strong antimalarial activity with relatively low cytotoxicity against Vero cells (African green monkey kidney fibroblasts). Potent antimalarial activity was demonstrated for 9-methoxystrobilurins G, K, and E (IC50 values 0.061, 0.089, and 0.14 µM, respectively). The structure-activity relationships (SAR) for antimalarial activity is proposed on the basis of the activity of the new and several known ß-methoxyacrylate derivatives in combination with the data from previously isolated compounds. Furthermore, several compounds showed specific cytotoxicity against NCI-187 cells (human small-cell lung cancer), although the SAR was different from that for antimalarial activity.
Asunto(s)
Agaricales/química , Antimaláricos/química , Antimaláricos/farmacología , Policétidos/química , Policétidos/farmacología , Estrobilurinas/química , Estrobilurinas/farmacología , Acrilatos/química , Acrilatos/farmacología , Animales , Antibióticos Antineoplásicos/farmacología , Línea Celular Tumoral , Chlorocebus aethiops , Ensayos de Selección de Medicamentos Antitumorales , Fermentación , Humanos , Espectroscopía de Resonancia Magnética , Estructura Molecular , Plasmodium falciparum/efectos de los fármacos , Espectrometría de Masa por Ionización de Electrospray , Relación Estructura-Actividad , Células VeroRESUMEN
The series of des-Cl (unsubstituted) and m-Cl phenyl analogues of PYR with various flexible 6-substituents were synthesized and studied for the binding affinities with highly resistant quadruple mutant (QM) DHFR. The derivatives carrying 4 atoms linker with a terminal carboxyl substituted on the aromatic ring exhibited good inhibition to the QM enzyme and also showed effective antimalarial activities against resistant P. falciparum bearing the mutant enzymes with relatively low cytotoxicity to mammalian cells. The X-ray crystallographic analysis of the enzyme-inhibitor complexes suggested that the hydrophobic substituent at 6-position was accommodated well in the hydrophobic pocket and the optimal length of the flexible linker could effectively promote the binding of the terminal carboxyl group to the key amino acid residues, Arg59 and Arg122.
Asunto(s)
Antimaláricos/farmacología , Plasmodium falciparum/efectos de los fármacos , Pirimetamina/análogos & derivados , Animales , Antimaláricos/química , Chlorocebus aethiops , Diseño de Fármacos , Resistencia a Medicamentos , Antagonistas del Ácido Fólico/química , Antagonistas del Ácido Fólico/farmacología , Modelos Moleculares , Estructura Molecular , Conformación Proteica , Pirimetamina/química , Pirimetamina/farmacología , Tetrahidrofolato Deshidrogenasa/química , Tetrahidrofolato Deshidrogenasa/metabolismo , Células VeroRESUMEN
Five new anthraquinones, morakotins A-E (1-5), together with seven known compounds, lunatin (6), rheoemodin (7), YM187781 (8), bislunatin (9), 6-(1-hydroxypentyl)-4-methoxypyran-2-one, 9,11-dehydoergrosterol peroxide, and cerevisterol, were isolated from the insect pathogenic fungus Cordyceps morakotii BCC 56811. The morakotin structures were elucidated from NMR spectroscopic and mass spectrometric data. The absolute configurations of bianthraquinone compounds, morakotins C-E (3-5), were determined by application of the exciton chirality method. Compounds 3, 7, 8, and 9 showed weak to moderate antimycobacterial and antifungal activities. Compounds 4 and 8 exhibited antibacterial activity against both Bacillus cereus and Staphylococcus aureus (MIC 3.13-25 µg ml-1), whereas compounds 3 and 9 were active against B. cereus (MIC 12.5 and 3.13 µg ml-1, respectively), and compound 7 was active against Acinetobacter baumannii (MIC 12.5 µg ml-1).
Asunto(s)
Antraquinonas/aislamiento & purificación , Antraquinonas/farmacología , Antiinfecciosos/aislamiento & purificación , Antiinfecciosos/farmacología , Bacterias/efectos de los fármacos , Cordyceps/metabolismo , Medios de Cultivo/química , Animales , Antraquinonas/química , Antiinfecciosos/química , Hormigas/microbiología , Cordyceps/crecimiento & desarrollo , Cordyceps/aislamiento & purificación , Hongos/efectos de los fármacos , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Pruebas de Sensibilidad MicrobianaRESUMEN
F-THENA is designed as an alternative fluorine-containing chiral derivatizing agent (CDA). The fluorine atom functions exclusively as a reporter which can directly sense an anisotropic effect from an aromatic substituent of a chiral alcohol. In combination with chemical shift differences from both 19F NMR and 1H NMR, the F-THENA method can successfully be used for determining the absolute configuration of chiral secondary aromatic alcohols with a self-validating system.
RESUMEN
BACKGROUND: There is an urgent need for the discovery of new anti-malarial drugs. Thus, it is essential to explore different potential new targets that are unique to the parasite or that are required for its viability in order to develop new interventions for treating the disease. Plasmodium serine hydroxymethyltransferase (SHMT), an enzyme in the dTMP synthesis cycle, is a potential target for such new drugs, but convenient methods for producing and assaying the enzyme are still lacking, hampering the ability to screen inhibitors. METHODS: Production of recombinant Plasmodium falciparum SHMT (PfSHMT) and Plasmodium vivax SHMT (PvSHMT), using auto-induction media, were compared to those using the conventional Luria Bertani medium with isopropyl thio-ß-D-galactoside (LB-IPTG) induction media. Plasmodium SHMT activity, kinetic parameters, and response to inhibitors were measured spectrophotometrically by coupling the reaction to that of 5,10-methylenetetrahydrofolate dehydrogenase (MTHFD). The identity of the intermediate formed upon inactivation of Plasmodium SHMTs by thiosemicarbazide was investigated by spectrophotometry, high performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC-MS). The active site environment of Plasmodium SHMT was probed based on changes in the fluorescence emission spectrum upon addition of amino acids and folate. RESULTS: Auto-induction media resulted in a two to three-fold higher yield of Pf- and PvSHMT (7.38 and 29.29 mg/L) compared to that produced in cells induced in LB-IPTG media. A convenient spectrophotometric activity assay coupling Plasmodium SHMT and MTHFD gave similar kinetic parameters to those previously obtained from the anaerobic assay coupling SHMT and 5,10-methylenetetrahydrofolate reductase (MTHFR); thus demonstrating the validity of the new assay procedure. The improved method was adopted to screen for Plasmodium SHMT inhibitors, of which some were originally designed as inhibitors of malarial dihydrofolate reductase. Plasmodium SHMT was slowly inactivated by thiosemicarbazide and formed a covalent intermediate, PLP-thiosemicarbazone. CONCLUSIONS: Auto-induction media offers a cost-effective method for the production of Plasmodium SHMTs and should be applicable for other Plasmodium enzymes. The SHMT-MTHFD coupled assay is equivalent to the SHMT-MTHFR coupled assay, but is more convenient for inhibitor screening and other studies of the enzyme. In addition to inhibitors of malarial SHMT, the development of species-specific, anti-SHMT inhibitors is plausible due to the presence of differential active sites on the Plasmodium enzymes.
Asunto(s)
Antimaláricos/farmacología , Inhibidores Enzimáticos/farmacología , Glicina Hidroximetiltransferasa/antagonistas & inhibidores , Glicina Hidroximetiltransferasa/metabolismo , Plasmodium falciparum/enzimología , Plasmodium vivax/enzimología , Cromatografía Líquida de Alta Presión , Glicina Hidroximetiltransferasa/aislamiento & purificación , Humanos , Cinética , Espectrometría de Masas , Metilenotetrahidrofolato Deshidrogenasa (NADP)/metabolismo , Espectrofotometría/métodosRESUMEN
Two strobilurins, 9-methoxystrobilurin B (1) and 9-methoxystrobilurin G (2), two monochlorinated 2,3-dihydro-1-benzoxepin derivatives, 3 and 4a, and butenolide 5, together with four known compounds, strobilurin B, 9-methoxystrobilurin A, and oudemansins A and B, were isolated from culture BCC 18689 of the fungus Favolaschia tonkinensis. 9-Methoxystrobilurins A, B (1), and G (2) and oudemansins A and B exhibited antimalarial, antifungal, and cytotoxic activities, while compounds 3, 4a, and 5 displayed only cytotoxic activity.
Asunto(s)
Basidiomycota/química , Citotoxinas/aislamiento & purificación , Citotoxinas/farmacología , Ácidos Grasos Insaturados/aislamiento & purificación , Ácidos Grasos Insaturados/farmacología , Metacrilatos/aislamiento & purificación , 4-Butirolactona/análogos & derivados , 4-Butirolactona/química , 4-Butirolactona/aislamiento & purificación , Animales , Antifúngicos/aislamiento & purificación , Antifúngicos/farmacología , Antimaláricos/farmacología , Benzoxepinas/química , Benzoxepinas/aislamiento & purificación , Candida albicans/efectos de los fármacos , Chlorocebus aethiops , Citotoxinas/química , Ensayos de Selección de Medicamentos Antitumorales , Ácidos Grasos Insaturados/química , Femenino , Humanos , Células KB , Metacrilatos/química , Metacrilatos/farmacología , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Plasmodium falciparum/efectos de los fármacos , Pirazoles , Pirimidinas , Estrobilurinas , Tailandia , Células VeroRESUMEN
Three new isocoumarin glucosides (1, 3, and 4), 6,8-dihydroxy-3-methylisocoumarin (2), and 6,8-dihydroxy-3-hydroxymethylisocoumarin (5) were isolated from the scale insect pathogenic fungus Torrubiella tenuis BCC 12732. Structures of these compounds were elucidated using NMR spectroscopic and MS spectrometric analyses. Compound 5 exhibited moderate anti-HSV-1 and antimycobacterial activities with IC(50) and MIC values of 50 and 25 microg/mL, respectively.
Asunto(s)
Antituberculosos/aislamiento & purificación , Antivirales/aislamiento & purificación , Glucósidos/aislamiento & purificación , Hypocreales/química , Insectos/microbiología , Isocumarinas/aislamiento & purificación , Animales , Antituberculosos/química , Antituberculosos/farmacología , Antivirales/química , Antivirales/farmacología , Chlorocebus aethiops , Glucósidos/química , Glucósidos/farmacología , Herpesvirus Humano 1/efectos de los fármacos , Humanos , Isocumarinas/química , Isocumarinas/farmacología , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Mycobacterium tuberculosis/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacosRESUMEN
Malaria continues to be a major infectious disease of the developing world and the problem is compounded not only by the emergence of drug resistant strains but also from a lack of a vaccine. The situation for tuberculosis (TB) infection is equally problematic. Once considered a "treatable" disease for which eradication was predicted, TB has re-emerged as highly lethal, multi-drug resistant strains after the outbreak of AIDS. Worldwide, the disease causes millions of deaths annually. Similarly, treatments for chronic inflammatory diseases such as arthritis have been impeded due to the potentially lethal side effects of the new and widely prescribed non-steroidal anti-inflammatory compounds. Thais have utilized bioresources from plants and some microorganisms for medicine for thousands of years. Because of the need for new drugs to fight malaria and TB, with radically different chemical structures and mode of actions other than existing drugs, efforts have been directed towards searching for new drugs from bioresources. This is also true for anti-inflammatories. Although Thailand is considered species-rich, only a small number of potential bioresources has been investigated. This article briefly describes the pathogenesis of 2 infectious diseases, malaria and TB, and modern medicines employed in chemotherapy. Diversities of Thai flora and fungi and their chemical constituents with antagonistic properties against these 2 diseases are described in detail. Similarly, anti-inflammatory compounds, mostly cyclooxygenase (COX) inhibitors, are also described herein to demonstrate the potential of Thai bioresources to provide a wide array of compounds for treatment of diseases of a different nature.