RESUMEN
The pentacyclic triterpene 3ß,6ß,16ß-tri-hydroxilup-20(29)-ene is a natural product produced by the Brazilian medicinal plant Combretum leprosum. Its cytotoxicity has been previously reported against breast cancer cell lines. The low water solubility of this natural product, that hampers its bioavailability, motivated the investigation of a new nanoparticle formulation containing the triterpene in order to improve its bioactivity. The triterpene was encapsulated in polycaprolactone (PCL) polymer by nanoprecipitation, producing homogenic nanoparticles with nanometer sizes (122.7 ± 2.06 nm), which were characterized by FT-IR, SEM imaging and DSC. The cytotoxicity (MTT method) of the nanoparticle containing the triterpene 1, besides the free natural product and the nanoparticle control (without 1), was assayed against three human tumor cell lines [human colon carcinoma line (HCT116), prostate (PC3) and glioblastoma (SNB19)] and the normal epithelial embryo kidney human cell line (Hek293T). The nanocarrier produced a significative effect in the cytotoxicity of the natural product in the nanoformulation (IC50 0.11-0.26 µg mL-1) when compared with its free form (IC50 1.07-1.44 µg mL-1). Additionally, higher selectivity of the triterpene to the tumor cells was found when it was encapsulated (SI 1.92-4.54) than in its free form (SI 0.42-0.56). In this case, the nanoencapsulated triterpene was more selective to PC3 (SI 3.33) and SNB19 (SI 4.54) tumor cells.
Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Productos Biológicos/farmacología , Combretum/química , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Productos Biológicos/química , Productos Biológicos/aislamiento & purificación , Cápsulas , Línea Celular , Proliferación Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Estructura Molecular , Hojas de la Planta/química , Relación Estructura-ActividadRESUMEN
Annonalide (3ß,20-epoxy-3α,16-dihydroxy-15-oxo-7-pimaren-19,6ß-olide, C20H26O6, 1) is the major (9ßH)-pimarane diterpene isolated from tubers of Cassimirella ampla, and it exhibits cytotoxic properties upon interaction with ctDNA. We have prepared new derivatives of 1 by modification of the (9ßH)-pimarane backbone and report here the semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9ßH)-pimarane. Our approach was the reduction of the carbonyl groups of 1 with sodium borohydride, at positions C15 (no stereoselectivity) and C3 (stereoselective reduction), followed by rearrangement of the 6,19-γ-lactone ring into the six-membered 19,20-δ-lactone ring in 4a (3ß,6ß,16-trihydroxy-7-pimaren-19,20ß-olide monohydrate, C20H30O6·H2O). The absolute structure of the new compound, 4a, was determined unambiguously with a Flack parameter x of -0.01â (11), supporting the stereochemistry assignment of 1 redetermined here. Besides the changes in the pattern of covalent bonds caused by reduction and lactone rearrangement, the conformation of one of the three fused cyclohexane rings is profoundly different in 4a, adopting a chair conformation instead of the boat shape found in 1. Furthermore, the intramolecular hydrogen bond present in 1 is lost in new compound 4a, due to hydrogen bonding between the 3-OH group and the solvent water molecule.
RESUMEN
The cytotoxic activity of the pimarane diterpene annonalide (1) and nine of its semisynthetic derivatives (2-10) was investigated against the human tumor cell lines HL-60 (leukemia), PC-3 (prostate adenocarcinoma), HepG2 (hepatocellular carcinoma), SF-295 (glioblastoma) and HCT-116 (colon cancer), and normal mouse fibroblast (L929) cells. The preparation of 2-10 involved derivatization of the side chain of 1 at C-13. Except for 2, all derivatives are being reported for the first time. Most of the tested compounds presented IC50s below 4.0⯵M, being considered potential antitumor agents. The structures of all new compounds were elucidated by spectroscopic analyses including 2D NMR and HRMS. Additionally, the interaction of annonalide (1) with ctDNA was evaluated using spectroscopic techniques, and the formation of a supramolecular complex with the macromolecule was confirmed. Competition assays with fluorescent probes (Hoechst and ethidium bromide) and theoretical studies confirmed that 1 interacts preferentially via DNA intercalation with stoichiometric ratio of 1:1 (1:ctDNA). The ΔG value was calculated as -28.24â¯kJâ¯mol-1, and indicated that the interaction process occurs spontaneously. Docking studies revealed that van der Walls is the most important interaction in 1-DNA and EB-DNA complexes, and that both ligands (1 and EB) interact with the same DNA residues (DA6, DA17 and DT19).
Asunto(s)
Ciclooctanos/química , ADN/química , Cetonas/química , Animales , Sitios de Unión , Bovinos , Línea Celular Tumoral , Supervivencia Celular , Ciclooctanos/síntesis química , Ciclooctanos/toxicidad , ADN/metabolismo , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Cetonas/síntesis química , Cetonas/toxicidad , Simulación del Acoplamiento Molecular , Conformación de Ácido Nucleico , Espectrofotometría , Electricidad Estática , Termodinámica , Temperatura de TransiciónRESUMEN
The cytotoxic activities of extracts (50â µg/ml) from 48 fungal strains, recovered from sediments of Pecém's offshore port terminal (Northeast coast of Brazil), against HCT-116 colon cancer cell lines were investigated. The most promising extract was obtained from strain BRF082, identified as Dichotomomyces cejpii by phylogenetic analyses of partial RPB2 gene sequence. Thus, it was selected for bioassay-guided isolation of the cytotoxic compounds. Large-scale fermentation of BRF082 in potato dextrose broth, followed by chromatographic purification of the bioactive fractions from the liquid medium, yielded gliotoxin (4) and its derivatives acetylgliotoxin G (3), bis(dethio)bis(methylsulfanyl)gliotoxin (1), acetylgliotoxin (5), 6-acetylbis(dethio)bis(methylsulfanyl)gliotoxin (2), besides the quinazolinone alkaloid fiscalin B. All isolated compounds were tested for their cytotoxicities against the tumor cell lines HCT-116, revealing 4 and 3 as the most cytotoxic ones (IC50 0.41 and 1.06â µg/ml, resp.).
Asunto(s)
Antineoplásicos/química , Antineoplásicos/farmacología , Productos Biológicos/química , Productos Biológicos/farmacología , Hongos/química , Sedimentos Geológicos/microbiología , Antineoplásicos/aislamiento & purificación , Productos Biológicos/aislamiento & purificación , Brasil , Neoplasias del Colon/tratamiento farmacológico , Hongos/genética , Gliotoxina/análogos & derivados , Gliotoxina/química , Gliotoxina/aislamiento & purificación , Gliotoxina/farmacología , Células HCT116 , Humanos , Indoles/química , Indoles/aislamiento & purificación , Indoles/farmacología , Filogenia , Quinazolinas/química , Quinazolinas/aislamiento & purificación , Quinazolinas/farmacologíaRESUMEN
The basidiomycete Lentinus strigellus was cultivated in three different culture media and the secondary metabolites produced under different culture conditions were isolated and identified. When cultivated in a liquid medium with peptone, L. strigellus afforded the benzopyrans, 2,2-dimethyl-6-methoxychroman-4-one, 4-hydroxy-2,2-dimethyl-6-methoxychromane and (3R,4S)-3,4-dihydroxy-2,2-dimethyl-6-methoxychromane. The indole alkaloid echinuline and the anthraquinone fiscione, both unprecedented for the genus Lentinus, were isolated from the mycelium of the fungus. When cultured in Czapek medium enriched with potato broth, the fungus afforded the same benzopyrans except (3S,4S)-3,4-dihydroxy-2,2-dimethyl-6-methoxychromane. Panepoxydone and isopanepoxydone were also isolated when the microorganism was grown in Czapek medium.
Asunto(s)
Basidiomycota/química , Lentinula/química , Espectroscopía de Resonancia Magnética , Estructura MolecularRESUMEN
Recent advances in the control of molecular engineering architectures have allowed unprecedented ability of molecular recognition in biosensing, with a promising impact for clinical diagnosis and environment control. The availability of large amounts of data from electrical, optical, or electrochemical measurements requires, however, sophisticated data treatment in order to optimize sensing performance. In this study, we show how an information visualization system based on projections, referred to as Projection Explorer (PEx), can be used to achieve high performance for biosensors made with nanostructured films containing immobilized antigens. As a proof of concept, various visualizations were obtained with impedance spectroscopy data from an array of sensors whose electrical response could be specific toward a given antibody (analyte) owing to molecular recognition processes. In addition to discussing the distinct methods for projection and normalization of the data, we demonstrate that an excellent distinction can be made between real samples tested positive for Chagas disease and Leishmaniasis, which could not be achieved with conventional statistical methods. Such high performance probably arose from the possibility of treating the data in the whole frequency range. Through a systematic analysis, it was inferred that Sammon's mapping with standardization to normalize the data gives the best results, where distinction could be made of blood serum samples containing 10(-7) mg/mL of the antibody. The method inherent in PEx and the procedures for analyzing the impedance data are entirely generic and can be extended to optimize any type of sensor or biosensor.
Asunto(s)
Técnicas Biosensibles/métodos , Leishmaniasis/diagnóstico , Anticuerpos Antiprotozoarios/sangre , Antígenos de Protozoos , Enfermedad de Chagas/diagnóstico , Impedancia Eléctrica , NanoestructurasRESUMEN
The need for reliable, fast diagnostics is closely linked to the need for safe, effective treatment of the so-called "neglected" diseases. The list of diseases with no field-adapted diagnostic tools includes leishmaniasis, shigella, typhoid, and bacterial meningitis. Leishmaniasis, in particular, is a parasitic disease caused by Leishmania spp. transmitted by infected phlebotomine sandfly, which remains a public health concern in developing countries with ca. 12 million people infected and 350 million at risk of infection. Despite several attempts, methods for diagnosis are still noneffective, especially with regard to specificity due to false positives with Chagas' disease caused by Trypanosoma cruzi . Accepted golden standards for detecting leishmaniasis involve isolation of parasites either microscopically, or by culture, and in both methods specimens are obtained by invasive means. Here, we show that efficient distinction between cutaneous leishmaniasis and Chagas' disease can be obtained with a low-cost biosensor system made with nanostructured films containing specific Leishmania amazonensis and T. cruzi antigens and employing impedance spectroscopy as the detection method. This unprecedented selectivity was afforded by antigen-antibody molecular recognition processes inherent in the detection with the immobilized antigens, and by statistically correlating the electrical impedance data, which allowed distinction between real samples that tested positive for Chagas' disease and leishmaniasis. Distinction could be made of blood serum samples containing 10(-5) mg/mL of the antibody solution in a few minutes. The methods used here are generic and can be extended to any type of biosensor, which is important for an effective diagnosis of many other diseases.