RESUMEN
Leaf and root essential oils of two closely related but ecologically distant Philodendron species were extracted in natural conditions in French Guiana and analysed by GC/MS to i) describe the blends of volatile organic compounds (VOCs) produced by those species and ii) analyse species and environment-based variations in extracts composition. A total of 135 VOCs were detected with a majority of aliphatic sesquiterpenes. P. fragrantissimum produced mainly ß-bisabolene (on average 29.12% of the extract) as well as α- and ß-selinene (14.52% and 17.50%, respectively) while in P. melinonii, four aliphatic sesquiterpenes could alternatively be the main component: (E)-ß-farnesene (up to 91.42% of the extract), germacrene-D (73.74%), ß-caryophyllene (51.63%) and trans-α-bergamotene (41.26%). A significant effect of species and organs on extracts composition was observed while the environment (sun exposure) only affected the relative proportions of monoterpenes and sesquiterpenes in roots of P. melinonii. These results are discussed in the light of the potential role of leaf and root terpenes in Philodendron species.
Asunto(s)
Philodendron/química , Compuestos Orgánicos Volátiles/análisis , Guyana Francesa , Monoterpenos/análisis , Monoterpenos/efectos de la radiación , Aceites Volátiles/análisis , Hojas de la Planta/química , Raíces de Plantas/química , Raíces de Plantas/efectos de la radiación , Sesquiterpenos/análisis , Sesquiterpenos/efectos de la radiación , Luz SolarRESUMEN
Guaiazulene (GA) is widely used as a natural ingredient in many health care products and solutions. Although it has been reported to have interesting biological effects, GA and azulene derivatives have been proven to be cytotoxic against normal human cells and human tumor cells; moreover, guaiazulene has shown photomutagenic properties on bacterial strains. Therefore, we evaluated and compared the cytotoxicity of GA at different concentrations on human gingival fibroblast (HGF) cell cultures under normal conditions and under UV irradiation (UV-A dose: 6.4 J/cm(2)). The compound tested was found to significantly reduce cell viability (dose-dependent trend, IC(50) 72.1 µM), decrease protein procollagen α1 type I synthesis, a marker for HGF protein, and COL1A1 mRNA expression. The cytotoxic effects were accompanied by activation of an intrinsic apoptotic pathway, studied using transmission electron microscopy (TEM) and caspase-3 activation. The light exposure of the cell culture treated decreased GA-induced cell death (IC(50) 128.9 µM), suggesting a photoprotective effect due to the photodegradation of the toxic agent, guaiazulene. Furthermore, the products of the photodegradation reaction of GA proved not to be toxic against HGFs.
Asunto(s)
Apoptosis/efectos de los fármacos , Azulenos/efectos de la radiación , Azulenos/toxicidad , Encía/efectos de los fármacos , Oxidantes Fotoquímicos/efectos de la radiación , Oxidantes Fotoquímicos/toxicidad , Sesquiterpenos/efectos de la radiación , Sesquiterpenos/toxicidad , Rayos Ultravioleta , Biomarcadores/metabolismo , Caspasa 3/metabolismo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Cadena alfa 1 del Colágeno Tipo I , Fibroblastos/citología , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Fibroblastos/ultraestructura , Regulación de la Expresión Génica/efectos de los fármacos , Encía/citología , Encía/metabolismo , Encía/ultraestructura , Humanos , Concentración 50 Inhibidora , Fotólisis , ARN Mensajero/metabolismo , Sesquiterpenos de GuayanoRESUMEN
(+) and (-) alpha-methylene-hexahydrobenzofuranone derivatives with a stereochemically pure cis ring junction were used as models of sesquiterpene lactones to study their photoreactivity toward thymidine. After 313 nm irradiation of a deoxygenated acetone solution of lactone models and thymidine, six [2+2] photoadducts were isolated for each enantiomer and fully characterized by a combination of NMR experiments. A common syn regioselectivity and exo stereoselectivity were observed for photoadducts. This high photoreactivity of alpha-methylene-gamma-butyrolactone ring toward thymidine could be an explanation of the progressive evolution of allergic contact dermatitis toward chronic actinic dermatitis.
Asunto(s)
4-Butirolactona/análogos & derivados , Trastornos por Fotosensibilidad/etiología , Sesquiterpenos/química , Sesquiterpenos/efectos de la radiación , Timidina/química , Rayos Ultravioleta/efectos adversos , 4-Butirolactona/química , Dermatitis Alérgica por Contacto/etiología , Humanos , Lactonas/química , Espectroscopía de Resonancia Magnética , Trastornos por Fotosensibilidad/inducido químicamenteRESUMEN
Secondary organic carbon (SOC) concentrations in steady-state aerosol were measured in a series of alpha-pinene/NOx and one series of beta-caryophyllene/NOx irradiation experiments. The acidity of the inorganic seed aerosol was varied while the hydrocarbon and NOx concentrations were held constant in each series of experiments. Measurements were made for acidity levels and SOC concentrations much closer to ambient levels than had been previously achieved for alpha-pinene, while there are no previous measurements for SOC increases due to acidity for beta-caryophyllene. The observed enhancement in SOC concentration linearly increases with the measured hydrogen ion concentration in air for each system. For the conditions of these studies, SOC increased by 0.04% per nmol H+ m(-3) for alpha-pinene under two conditions where the organic carbon concentration differed by a factor of 5. For alpha-pinene, this level of response to acidic aerosol was a factor of 8 lower than was reported by Surratt et al. for similar series of experiments for SOC from the photooxidation of isoprene/NOx mixtures. By contrast, SOC from beta-caryophyllene showed an increase of 0.22% per nmol H+ m(-3), roughly two-thirds of the response in the isoprene system. Mass fractions for SOC particle-phase tracers for alpha-pinene decreased slightly with increasing aerosol acidity, although remaining within previously stated uncertainties. Below 200 nmol H+ m(-3), the mass fraction of beta-caryophyllenic acid, the only identified tracer for beta-caryophyllene SOC, was constant although beta-caryophyllenic acid showed a substantial decrease for acidities greater than 400 nmol H+ m(-3).
Asunto(s)
Contaminantes Atmosféricos/química , Monoterpenos/química , Óxidos de Nitrógeno/química , Sesquiterpenos/química , Aerosoles , Contaminantes Atmosféricos/efectos de la radiación , Monoterpenos Bicíclicos , Concentración de Iones de Hidrógeno , Monoterpenos/efectos de la radiación , Óxidos de Nitrógeno/efectos de la radiación , Sesquiterpenos Policíclicos , Sesquiterpenos/efectos de la radiación , Rayos UltravioletaRESUMEN
Rapid and efficient [2 + 2 + 2] cyclotrimerization reactions were discovered through the application of microwave irradiation in conjunction with a Ni(CO)(2)(PPh(3))(2) catalyst. This enables the facile construction of highly substituted indane, isoindoline, and tetraline core structures. The developed microwave-mediated Ni-catalyzed cyclotrimerization reaction was employed as the key step in a concise synthesis of the isoquinoline natural product illudinine. This represents the first example of a Ni-catalyzed cyclotrimerization reaction in total synthesis.
Asunto(s)
Microondas , Níquel/química , Níquel/efectos de la radiación , Compuestos Organometálicos/química , Compuestos Organometálicos/efectos de la radiación , Sesquiterpenos/síntesis química , Sesquiterpenos/efectos de la radiación , Catálisis , Ciclización , Estructura Molecular , Sesquiterpenos/química , EstereoisomerismoRESUMEN
Artemisinin is an antimalarial drug containing an internal endoperoxide linkage in its structure. A simple, selective and sensitive high-performance liquid chromatography (HPLC)-peroxyoxalate chemiluminescence (PO-CL) method for the determination of artemisinin was developed. This method is based on the fact that endoperoxide in artemisinin structure can be converted to hydrogen peroxide (H(2)O(2)) under ultraviolet (UV) irradiation and the generated hydrogen peroxide can be measured using PO-CL detection. The HPLC-PO-CL system was optimized on a mobile phase, post column chemiluminescence reagent, UV source and irradiation time. In addition, the system was combined with simple liquid-liquid extraction using n-hexane that allowed selective and sensitive determination of artemisinin in serum. The limit of detection using 0.5 mL of blood was 0.062 micromol/L (17.5 ng/mL) at a signal-to-noise ratio of 3. Calibration curve obtained for artemisinin in human serum 4-80 micromol/L (1.1-22.6 microg/mL) showed a good linearity (r = 0.999).
Asunto(s)
Artemisininas/sangre , Cromatografía Líquida de Alta Presión/métodos , Sesquiterpenos/sangre , Artemisininas/efectos de la radiación , Humanos , Mediciones Luminiscentes , Sistemas en Línea , Oxalatos/química , Sesquiterpenos/efectos de la radiación , Rayos UltravioletaRESUMEN
In an attempt to explore the biogenetic relationship of furanoeremophilane derivatives and eremophilan-8alpha,12-olides, produced in Ligularia and their structure-activity relationship, we studied the photosensitized oxidation of furanoeremophilane-type sesquiterpenes. Under the condition of several solvents solution Irradiation with a 200 W incandescent lamp of furanoeremophilan-14beta,6alpha-olide isolated from Ligularia vellerea, in various solutions with methylene blue, rose bengal, toluidine blue and safranine T gave several products. The products were isolated by chromatographic procedure and their structures were elucidated as eremophilan-14beta,6alpha,8alpha,12-diolide derivatives by NMR, IR and MS methods. A reaction mechanism has been proposed.
Asunto(s)
Asteraceae/química , Sesquiterpenos/síntesis química , Animales , Hepatocitos/efectos de los fármacos , Luz , Espectroscopía de Resonancia Magnética , Ratones , Estructura Molecular , Oxidación-Reducción , Raíces de Plantas/química , Sesquiterpenos/metabolismo , Sesquiterpenos/farmacología , Sesquiterpenos/efectos de la radiación , Oxígeno SingleteRESUMEN
The aim was to obtain information on the one-electron reduction of the antimalarial natural drug artemisinin (ART). The pulse radiolysis of ART in H(2)O/ethanol (EtOH) (1:1 v/v) solution was studied in the absence and presence of the so-called redox indicators N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), Fe(CN)6(4-), 1,1'-dimethyl-4,4'-bipyridinium dichloride (methyl viologen, MV(2+)) and Fe(CN)6(3-). In an argon-purged solution, ART reacts with solvated electrons (es(-)) with k=4.4 x 10(9) dm(3) mol(-1) s(-1) generating an absorption band rising in the ultraviolet region similar to the spectrum of the CH3(*)CHOH radical. The species originating from the reaction between ART and es(-) do not show any appreciable reactivity toward Fe(CN)6(4-), TMPD, MV(2+) and Fe(CN)6(3-). The experiments performed in the presence of ART and MV(2+) have provided strong support to the idea that the first species obtained from the addition of the electron, which is believed to occur at the endoperoxide group level, undergoes a rapid (k on the order of 10(8) s(-1) or higher) intramolecular rearrangement to give species, most likely carbon-centred radicals, that show some reactivity towards the methyl viologen radical cation (MV(*+)).
Asunto(s)
Artemisininas/efectos de la radiación , Sesquiterpenos/efectos de la radiación , Artemisininas/química , Radicales Libres , Oxidación-Reducción , Radiólisis de Impulso , Sesquiterpenos/químicaRESUMEN
Fourier transform infrared spectra are reported for the Fe(III)- and Fe(II)-mediated activation of the antimalarial agents artemisinin 1 and its simplified synthetic analogue, trioxane alcohol 2. By monitoring the frequencies of the newly established marker lines in the FTIR spectra, the products of the Fe(II) and Fe(III) reactions have been characterized. In both reactions, artemisinin is activated giving a product mixture of a ring-contracted tetrahydrofuran acetatal 3, C(4)-hydroxy deoxyartemisinin 4, and deoxyartemisinin 5. These data illustrate that the oxidation state of the iron places no restrictions on the endoperoxide reduction mechanism. The FTIR difference (light - dark) spectra indicate that the endoperoxide moiety of artemisinin is photolabile and that the resulted products have the same vibrational characteristics as those observed in the reactions with Fe(II) and Fe(III). The use of 18O-18O enriched endoperoxide in 2 has allowed us to identify two oxygen sensitive modes in the reactions with Fe(II). The reduction of the peroxide bond by Fe(II) in trioxane alcohol 2 follows both the C-C cleavage and 1,5-H shift pathways and produces a ring-contracted tetrahydrofuran acetal 6 which is converted to tetrahydrofuran aldehyde 7 and C(4)-hydroxy deoxytrioxane alcohol 8, respectively. The cleavage of the O-O bond in 1 and 2 by iron and the ability to correlate vibrational properties of the reaction products with structural properties of the isolated products suggest that infrared spectroscopy is an appropriate tool to study the mode of action of antimalarial endoperoxides.
Asunto(s)
Alcoholes/química , Antimaláricos/química , Artemisininas , Compuestos Férricos/química , Compuestos Ferrosos/química , Lactonas/química , Sesquiterpenos/química , Lactonas/efectos de la radiación , Oxidación-Reducción , Fotólisis , Sesquiterpenos/efectos de la radiación , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
The photoreactivity of isoalantolactone, a natural sesquiterpene lactone, toward thymine was studied. After 313 nm irradiation of a deoxygenated acetone solution of isoalantolactone (2 x 10(-3) M) and thymine (4 x 10(-3) M), two intermolecular [2 + 2] photoadducts, 3 and 4, were isolated with respective yields of 30% and 18%. The structures of these two photoadducts were determined by a combination of NMR experiments. Compound 3 was identified as a cis-syn-exo intermolecular [2 + 2] photoadduct involving the 5,6 double bond of thymine and the exomethylenic double bond of the lactone, while compound 4 was identified as an intermolecular [2 + 2] photoadduct involving the same bonds but with the cis-syn-endo conformation. This high photoreactivity of sesquiterpene lactones toward thymine could be an explanation of the progressive evolution of allergic contact dermatitis toward chronic actinic dermatitis.