RESUMEN
Prenylated and hydroxyprenylated piceatannol, resveratrol and pinosylvin derivatives were isolated from resin produced by three Australian Lepidosperma Labill. Species (Cyperaceae). From L. congestum R.Br. one known compound, 3',5'-bis-prenyl-E-resveratrol, and five undescribed compounds were isolated, 3'-O-prenyl-5'-prenyl-E-piceatannol, 5',6'-bis-prenyl-E-piceatannol, 5'-prenyl-E-piceatannol, 3',5'-bis(3-hydroxy-3-methylbutyl)-E-resveratrol and 3',5'-bis-E-hydroxyprenyl-E-resveratrol. From L. gunnii Boeckeler one undescribed compound was isolated, 3'-E-hydroxyprenyl-5'-Z-hydroxyprenyl-E-resveratrol. From L. laterale R.Br. six undescribed compounds were isolated, 3-O-prenyl-E-pinosylvin, 3-O-Z-hydroxyprenyl-E-pinosylvin, 3'-Z-hydroxyprenyl-E-resveratrol, 3-O-Z-hydroxyprenyl-E-resveratrol, 3-O-Z-hydroxyprenyl-4'-O-methyl-E-resveratrol, and 3-O-prenyl-3'-δ,δ'-dihydroxyprenyl-E-resveratrol. Compounds, including a reference compound 3-O-prenyl-3'-O-methyl-E-piceatannol, were screened in an assay for melatoninergic binding to MT1 and MT2 receptors and binding to QR2/MT3 enzyme, and for inhibition of QR2/MT3 in a functional assay. Strong binding was observed for 3-O-Z-hydroxyprenyl-E-resveratrol with a Ki of 0.022 nM and the strongest inhibition of QR2/MT3 observed was for the reference compound, 3-O-prenyl-3'-O-methyl-E-piceatannol, with an inhibition of 61% at 1 µM and 95% at 10 µM. The three most active binders and inhibitors of QR2/MT3 were found to have a common substructure corresponding to 3-O-prenylresveratrol.
Asunto(s)
Cyperaceae , Quinona Reductasas , Estilbenos , Australia , Neopreno , Quinona Reductasas/metabolismo , Resveratrol , Estilbenos/química , Estilbenos/farmacologíaRESUMEN
The endemic Australian plants Lepidosperma sp. Flinders Chase (Cyperaceae), Lepidosperma viscidum (Cyperaceae) and Dodonaea humilis (Sapindaceae) were found to be the botanical origin of three propolis types found on Kangaroo Island identified by TLC and 1H NMR matching of propolis and plant resin analytical profiles. Resin samples extracted from the plant, Lepidosperma sp. Flinders Chase, were chromatographically fractionated to give: methyl 3-phenyl-2-(E-cinnamoyloxy)propanoate (1), 3-(E-8-methoxy-8-oxo-3,7-dimethyloct-2-enyl)-4-hydroxy-E-cinnamic acid (2), 3-(E-6,7-dihydroxy-3,7-dimethyloct-2-enyl)-4-hydroxy-E-cinnamic acid (3), previously undescribed; and the known stilbenes, 2-prenyl-3,5-dihydroxy-E-stilbene (6) and 2-prenyl-3-methoxy-5-hydroxy-E-stilbene (7). The resin from L. viscidum gave: 5'-(E-4-hydroxy-3-methylbut-2-enyl)-4,2',4'-trihydroxydihydrochalcone (4); 5'-(E-4-hydroxy-3-methylbut-2-enyl)-4'-methoxy-4,2'-dihydroxydihydrochalcone (5), previously undescribed; and three known flavanones, farrerol (8), 5,7,3',5'-tetrahydroxy-6,8-dimethylflavanone (9) and 5,7,3',5'-tetrahydroxy-6-methylflavanone (10). The major constituent in the propolis identified as being sourced from D. humilis was identified as 6,8-diprenyl-5,7,3',4'-tetrahydroxyflavanone (11), a known compound identified in several unrelated plant species.
Asunto(s)
Cyperaceae , Própolis , Sapindaceae , Estilbenos , AustraliaRESUMEN
Anxiolytics and anticonvulsants generally positively modulate the action of GABA, whereas many convulsants (including the chloride channel blocker picrotoxinin) negatively modulate the action of GABA on GABAA receptors. Like picrotoxinin, bilobalide and ginkgolide B, active constituents of Ginkgo biloba, have been shown to negatively modulate the action of GABA at α1ß2γ2L GABAA receptors. However, unlike picrotoxinin, bilobalide and ginkgolide B are not known to cause convulsions. We have assessed the action of bilobalide, ginkgolide B and picrotoxinin on a range of GABAA modulators (etomidate, loreclezole, propofol, thiopentone sodium, diazepam, and allopregnanolone), using two-electrode voltage clamp electrophysiology at recombinant α1ß2γ2L GABAA receptors expressed in Xenopus oocytes. The results indicate that bilobalide and ginkgolide B differ from picrotoxinin in their ability to inhibit the actions of a range of these structurally diverse GABAA positive modulators consistent with these modulators acting on a multiplicity of active sites associated with GABAA receptors. In the presence GABA, ginkgolide B was more potent than bilobalide in inhibiting the GABA-potentiating effect of propofol, equipotent against loreclezole and allopregnanolone, and less potent against etomidate, diazepam, and thiopentone sodium. This indicates that in comparison to picrotoxinin, bilobalide and ginkgolide B differ in their effects on the different modulators.
Asunto(s)
Ciclopentanos/farmacología , Furanos/farmacología , Moduladores del GABA/química , Moduladores del GABA/farmacología , Ginkgólidos/farmacología , Lactonas/farmacología , Picrotoxina/análogos & derivados , Receptores de GABA-A/metabolismo , Animales , Relación Dosis-Respuesta a Droga , Fenómenos Electrofisiológicos/efectos de los fármacos , Ginkgo biloba/química , Humanos , Picrotoxina/farmacología , Sesterterpenos , Terpenos/química , Terpenos/farmacología , Xenopus laevisRESUMEN
Propolis samples from Kangaroo Island, South Australia, were investigated for chemical constituents using high-field nuclear magnetic resonance spectral profiling. A type of propolis was found containing a high proportion of prenylated hydroxystilbenes. Subsequently, the botanical origin of this type of propolis was identified using a beehive propolis depletion method and analysis of flora. Ligurian honey bees, Apis mellifera ligustica Spinola, were found to produce propolis from resin exuded by the Australian native sedge plant Lepidosperma sp. Montebello (Cyperaceae). The plants, commonly known as sword sedge, were found to have resin that matched with the propolis samples identified as the most abundant propolis type on the island containing C- and O-prenylated tetrahydroxystilbenes (pTHOS) in addition to a small amount of prenylated p-coumarate. The isolation of five pTHOS not previously characterized are reported: (E)-4-(3-methyl-2-buten-1-yl)-3,4',5-trihydroxy-3'-methoxystilbene, (E)-2,4-bis(3-methyl-2-buten-1-yl)-3,3',4',5-tetrahydroxystilbene, (E)-2-(3-methyl-2-buten-1-yl)-3-(3-methyl-2-butenyloxy)-3',4',5-trihydroxystilbene, (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,3',5,5'-tetrahydroxystilbene and (E)-2,6-bis(3-methyl-2-buten-1-yl)-3,4',5-trihydroxy-3'-methoxystilbene. A National Cancer Institute 60 human cell line anticancer screen of three of these compounds showed growth inhibitory activity. The large Australasian genus Lepidosperma is identified as a valuable resource for the isolation of substances with medicinal potential.
Asunto(s)
Antineoplásicos/aislamiento & purificación , Cyperaceae/química , Própolis/química , Estilbenos/aislamiento & purificación , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , Australia , Abejas , Cumarinas/química , Cumarinas/aislamiento & purificación , Macropodidae , Prenilación , Estilbenos/químicaRESUMEN
The terpenoid lactones from Ginkgo biloba, bilobalide and ginkgolides, have been shown to act as negative modulators at α1ß2γ2L GABAA receptors. They have structural features similar to those of the chloride channel blocker picrotoxinin. Unlike picrotoxinin, however they are not known to produce convulsant effects. Using two-electrode voltage clamp electrophysiology, this study compared the effect of mutation of 2', 6' and 15' pore facing M2 domain residues to cysteine on the action of picrotoxinin, bilobalide and ginkgolides at α1ß2γ2L GABAA receptors expressed in Xenopus oocytes. Picrotoxinin was affected by mutation differently from the ginkgo terpenoid lactones. Although some of these compounds were affected by the mutation at same position and/or subunit, the changes in their potency were found to be dissimilar. The results suggest that the intracellular pore binding site for picrotoxinin, bilobalide, ginkgolide A, ginkgolide B and ginkgolide C is comprised of 2'ß-6'ß6'γ, 2'α2'ß-6'α6'ß, 2'α2'ß2'γ-6'ß6'γ, 2'α, 2'ß2'γ-6'ß and 2'α2'ß, respectively. Unlike bilobalide and ginkgolides, the inhibitory action of picrotoxinin was not affected by mutations at 15' position. It is proposed that 15'α15'ß, 15'ß, 15'α15'ß and 15'α15'ß15'γ forms an extracellular pore binding site for bilobalide, ginkgolide A, ginkgolide B and ginkgolide C, respectively. The lack of convulsant effects of bilobalide, and ginkgolide A and B may be associated in part with their different binding locations within the chloride channel.
Asunto(s)
Bilobálidos/farmacología , Cisteína , Antagonistas de Receptores de GABA-A/farmacología , Ginkgo biloba/química , Ginkgólidos/farmacología , Mutación , Receptores de GABA-A/metabolismo , Animales , Secuencia de Bases , Bilobálidos/metabolismo , Sitios de Unión , Relación Dosis-Respuesta a Droga , Antagonistas de Receptores de GABA-A/metabolismo , Ginkgólidos/metabolismo , Humanos , Unión Proteica , Receptores de GABA-A/química , Receptores de GABA-A/genética , Compuestos de Sulfhidrilo/metabolismo , Ácido gamma-Aminobutírico/farmacologíaRESUMEN
Synthesis of the naturally occurred C- and O-prenylated tetrahydroxystilbenes and O-prenylated cinnamates was carried out by decarbonylative Heck reaction and selenium dioxide catalysed oxidation, respectively. In the decarbonylative Heck synthetic route, fusion of benzoyl chloride and styrene derivatives was catalysed by an N-heterocyclic carbene system generated in situ by palladium acetate and 1,3-bis(2,6-diisopropylphenyl)imidazolinium chloride to form a E-tetrahydroxystilbene derivative. Formation of allyl ether was subsequently carried out by reaction of the deprotected OH in the A phenyl ring of the stilbene with 3,3-dimethylallyl bromide and a base (sodium hydride) to form O-prenylated tetrahydroxystilbene derivatives. [1,5]-Rearrangement of the isoprenyl unit from O- to C-position in the A ring was carried out at elevated temperature in the presence of magnesium silicate (Florisil) to form the corresponding C-prenylated tetrahydroxystilbene. Formation of O-prenylated cinnamate was first carried out by base catalysed allyl ether formation between 3,3-dimethylallyl bromide and hydroxycinnamic acid methyl ester. The methyl group of the isoprenyl unit was subsequently oxidized using selenium dioxide to form a terminal hydroxyl group. The prenylated tetrahydroxystilbenes and cinnamate synthesized in this study were novel derivatives of piceatannol and methyl 4-(3'-methylbut-2'-enyloxy)cinnamate isolated from propolis in Kangaroo Island, South Australia. The synthetic compounds were tested against K562 cancer cells and potent growth inhibitory activity was observed for E-1-[5-hydroxy-3-methoxy-2-(3-methyl-2-butenyl)phenyl]-2-[4-hydroxy-3-methoxyphenyl]ethene, IC50 = 0.10 µM.
Asunto(s)
Antineoplásicos/síntesis química , Cinamatos/síntesis química , Estilbenos/síntesis química , Antineoplásicos/química , Antineoplásicos/farmacología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Cinamatos/química , Cinamatos/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Concentración 50 Inhibidora , Células K562 , Modelos Químicos , Estructura Molecular , Prenilación , Própolis/química , Estilbenos/química , Estilbenos/farmacología , Relación Estructura-ActividadRESUMEN
Honey bees, Apis mellifera var ligustica, on Kangaroo Island, Australia, were found to collect propolis from the sticky exudate on the stem shoots and seed pods of an Australian endemic plant, Acacia paradoxa. Extracts of the plant stem shoots and seed pods, the propolis carried on the legs of bees and freshly collected propolis in hives contained major flavonoid components consisting of 2',3',4'-trimethoxychalcone, 2'-hydroxy-3',4'-dimethoxychalcone, 2',4'-dihydroxy-3'-methoxychalcone, 5,7-dihydroxy-2,3-dihydroflavonol 3-acetate (pinobanksin 3-acetate) and 5,7-dihydroxy-6-methoxy-2,3-dihydroflavonol 3-acetate, a substance not previously characterized. HPLC and (1)H NMR analyses of the propolis and plant extracts indicated smaller amounts of other flavonoids. A survey of propolis samples from 47 apiary sites widely distributed on Kangaroo Island showed that 15 samples from 6 sites were largely sourced from A. paradoxa.
Asunto(s)
Acacia/química , Abejas/química , Chalconas/aislamiento & purificación , Própolis/química , Animales , Australia , Chalconas/química , Cromatografía Líquida de Alta Presión , Flavonoides/química , Flavonoides/aislamiento & purificación , Frutas/química , Espectroscopía de Resonancia Magnética , Extractos Vegetales/química , Tallos de la Planta/químicaRESUMEN
The diterpene lactones of Ginkgo biloba, ginkgolides A, B and C are antagonists at a range of Cys-loop receptors. This study examined the effects of the ginkgolides at recombinant human ρ(1) GABA(C) receptors expressed in Xenopus oocytes using two-electrode voltage clamp. The ginkgolides were moderately potent antagonists with IC(50)s in the µM range. At 10 µM, 30 µM and 100 µM, the ginkgolides caused rightward shifts of GABA dose-response curves and reduced maximal GABA responses, characteristic of noncompetitive antagonists, while the potencies showed a clear dependence on GABA concentration, indicating apparent competitive antagonism. This suggests that the ginkgolides exert a mixed-type antagonism at the ρ(1) GABA(C) receptors. The ginkgolides did not exhibit any obvious use-dependent inhibition. Fitting of the data to a number of kinetic schemes suggests an allosteric inhibition as a possible mechanism of action of the ginkgolides which accounts for their inhibition of the responses without channel block or use-dependent inhibition. Kinetic modelling predicts that the ginkgolides exhibit saturation of antagonism at high concentrations of GABA, but this was only partially observed for ginkgolide B. It also suggests that there may be different binding sites in the closed and open states of the receptor, with a higher affinity for the receptor in the closed state.
Asunto(s)
Ginkgólidos/farmacología , Receptores de GABA/efectos de los fármacos , Algoritmos , Animales , Relación Dosis-Respuesta a Droga , Antagonistas del GABA/farmacología , Ginkgólidos/antagonistas & inhibidores , Ginkgólidos/química , Humanos , Cinética , Modelos Moleculares , Oocitos/metabolismo , Técnicas de Placa-Clamp , Receptores de GABA/biosíntesis , Proteínas Recombinantes , Relación Estructura-Actividad , Xenopus laevisRESUMEN
A prenylated cinnamic acid derivative as well as six prenylated tetrahydroxystilbenes were isolated from the ethyl acetate extract of propolis that originated from Kangaroo Island, Australia. Furthermore, six known stilbenes and two known flavanones were also identified from the same sample. Stilbenes are not common in propolis; therefore, Kangaroo Island propolis is considered a unique type of propolis that is rich in prenylated stilbenes. Stilbene propolis from Kangaroo Island showed a stronger scavenging activity towards DPPH free radical than Brazilian green propolis. This strong activity can be explained by the presence of large number of stilbenes, most of them showed strong free radical scavenging activity.
Asunto(s)
Antioxidantes/química , Cinamatos/química , Própolis/química , Estilbenos/química , Antioxidantes/aislamiento & purificación , Antioxidantes/farmacología , Australia , Compuestos de Bifenilo/química , Fraccionamiento Químico , Cinamatos/aislamiento & purificación , Cinamatos/farmacología , Radicales Libres/química , Resonancia Magnética Nuclear Biomolecular , Picratos/química , Prenilación , Estilbenos/aislamiento & purificación , Estilbenos/farmacologíaRESUMEN
Flavonoids are components of plant foods and of many herbal medicines taken in combination with anticancer drugs. We have examined the potential of flavonoids to affect the accumulation and cytotoxicity of 3 cytotoxic drugs [vinblastine (VLB), daunorubicin (DNR), and colchicine (COL)] that are substrates for the ABC transporter, P-glycoprotein in a vinblastine-resistant T-cell leukemia, CEM/VBL(100), that overexpresses P-glycoprotein. The effects of the flavonoids on accumulation and cytotoxicity of these drugs were different depending on the P-gp substrate used. Most of the 30 flavonoids tested decreased DNR accumulation in the VBL-resistant, but not sensitive, leukemia cells. By contrast, flavonoids that inhibited DNR accumulation enhanced the accumulation of fluorescently labeled vinblastine. None of these flavonoids affected COL accumulation. The effects of the flavonoids on the cytotoxicities of these drugs paralleled their effects on accumulation; the same flavonoids decreased DNR cytotoxicity but increased VLB cytotoxicity and had no effect on COL. Verapamil reversed the accumulation deficit and cytotoxicity of all three P-gp substrates. These effects correlated with the effects of flavonoids on P-gp-ATPase activity. Flavonoids that decreased DNR accumulation stimulated DNR-activated P-gp ATPase, whereas flavonoids that increased fluorescently labeled VLB accumulation inhibited VBL-stimulated P-gp ATPase activity, thereby accounting for the decrease or increase in cancer drug accumulation in resistant cells. We conclude that flavonoids often ingested by cancer patients may have different effects on anticancer drugs and that these findings should be considered in designing future combination treatments for cancer patients.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Adenosina Trifosfatasas/metabolismo , Antineoplásicos/farmacología , Flavonoides/farmacología , Interacciones de Hierba-Droga , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Análisis de Varianza , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Colchicina/farmacología , Daunorrubicina/farmacología , Resistencia a Antineoplásicos , Humanos , Verapamilo/farmacología , Vinblastina/farmacologíaRESUMEN
Extracts from the Ginkgo biloba tree are widely used as herbal medicines, and include bilobalide (BB) and ginkgolides A and B (GA and GB). Here we examine their effects on human 5-HT(3)A and 5-HT(3)AB receptors, and compare these to the effects of the structurally related compounds picrotin (PTN) and picrotoxinin (PXN), the two components of picrotoxin (PTX), a known channel blocker of 5-HT(3), nACh and GABA(A) receptors. The compounds inhibited 5-HT-induced responses of 5-HT(3) receptors expressed in Xenopus oocytes, with IC(50) values of 470 µM (BB), 730 µM (GB), 470 µM (PTN), 11 µM (PXN) and >1mM (GA) in 5-HT(3)A receptors, and 3.1mM (BB), 3.9 mM (GB), 2.7 mM (PTN), 62 µM (PXN) and >1mM (GA) in 5-HT(3)AB receptors. Radioligand binding on receptors expressed in HEK 293 cells showed none of the compounds displaced the specific 5-HT(3) receptor antagonist [(3)H]granisetron, confirming that they do not act at the agonist binding site. Inhibition by GB at 5-HT(3)A receptors is weakly use-dependent, and recovery is activity dependent, indicating channel block. To further probe their site of action at 5-HT(3)A receptors, BB and GB were applied alone or in combination with PXN, and the results fitted to a mathematical model; the data revealed partially overlapping sites of action. We conclude that BB and GB block the channel of the 5-HT(3)A receptor. Thus these compounds have comparable, although less potent, behaviour than at some other Cys-loop receptors, demonstrating their actions are conserved across the family.
Asunto(s)
Ciclopentanos/metabolismo , Furanos/metabolismo , Ginkgólidos/metabolismo , Lactonas/metabolismo , Picrotoxina/metabolismo , Receptores de Serotonina 5-HT3/metabolismo , Antagonistas del Receptor de Serotonina 5-HT3/metabolismo , Animales , Sitios de Unión/efectos de los fármacos , Sitios de Unión/fisiología , Ciclopentanos/farmacología , Relación Dosis-Respuesta a Droga , Femenino , Furanos/farmacología , Ginkgólidos/farmacología , Células HEK293 , Humanos , Lactonas/farmacología , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/metabolismo , Extractos Vegetales/farmacología , Antagonistas del Receptor de Serotonina 5-HT3/aislamiento & purificación , Antagonistas del Receptor de Serotonina 5-HT3/farmacología , Xenopus laevisRESUMEN
GABA(C) receptors play a role in myopia, memory-related disorders and circadian rhythms signifying a need to develop potent and selective agents for this class of receptors. Guanidino analogs related to glycine, beta-alanine and taurine were evaluated at human rho(1)GABA(C) receptors expressed in Xenopus oocytes using 2-electrode voltage clamp methods. Of the 12 analogs tested, 8 analogs were active as antagonists and the remaining were inactive. (S)-2-guanidinopropionic acid (IC(50) = 2.2 microM) and guanidinoacetic acid (IC(50) = 5.4 microM; K (B) = 7.75 microM [pK (B) = 5.11 +/- 0.06]) were the most potent being competitive antagonists at this receptor. In contrast, the beta-alanine and GABA guanidino analogs showed reduced activity, indicating the distance between the carboxyl carbon and terminal nitrogen of the guanidino group is critical for activity. Substituting the C2-position of guanidinoacetic acid with various alkyl groups reduced activity indicating that steric effects may impact on activity. The results of this study contribute to the structure-activity-relationship profile required in developing novel therapeutic agents.
Asunto(s)
Antagonistas del GABA/farmacología , Glicina/análogos & derivados , Guanidinas/farmacología , Propionatos/farmacología , Receptores de GABA/metabolismo , Animales , Relación Dosis-Respuesta a Droga , Femenino , Antagonistas del GABA/síntesis química , Antagonistas del GABA/metabolismo , Glicina/síntesis química , Glicina/metabolismo , Glicina/fisiología , Guanidinas/síntesis química , Guanidinas/metabolismo , Humanos , Oocitos/química , Oocitos/metabolismo , Propionatos/síntesis química , Propionatos/metabolismo , Receptores de GABA/biosíntesis , Receptores de GABA/genética , Proteínas Recombinantes/antagonistas & inhibidores , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Taurina/análogos & derivados , Taurina/síntesis química , Taurina/metabolismo , Xenopus laevis , beta-Alanina/metabolismoRESUMEN
Allylic hydroxylated derivatives of the C18 unsaturated fatty acids were prepared from linoleic acid (LA) and conjugated linoleic acids (CLAs). The reaction of LA methyl ester with selenium dioxide (SeO(2)) gave mono-hydroxylated derivatives, 13-hydroxy-9Z,11E-octadecadienoic acid, 13-hydroxy-9E,11E-octadecadienoic acid, 9-hydroxy-10E,12Z-octadecadienoic acid and 9-hydroxy-10E,12E-octadecadienoic acid methyl esters. In contrast, the reaction of CLA methyl ester with SeO(2) gave di-hydroxylated derivatives as novel products including, erythro-12,13-dihydroxy-10E-octadecenoic acid, erythro-11,12-dihydroxy-9E-octadecenoic acid, erythro-10,11-dihydroxy-12E-octadecenoic acid and erythro-9,10-dihydroxy-11E-octadecenoic acid methyl esters. These products were purified by normal-phase short column vacuum chromatography followed by high-performance liquid chromatography (HPLC). Their chemical structures were characterized by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR). The allylic hydroxylated derivatives of LA and CLA exhibited moderate in vitro cytotoxicity against a panel of human cancer cell lines including chronic myelogenous leukemia K562, myeloma RPMI8226, hepatocellular carcinoma HepG2 and breast adenocarcinoma MCF-7 cells (IC(50) 10-75 microM). The allylic hydroxylated derivatives of LA and CLA also showed toxicity to brine shrimp with LD(50) values in the range of 2.30-13.8 microM. However these compounds showed insignificant toxicity to honeybee at doses up to 100 microg/bee.
Asunto(s)
Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Ácido Linoleico/química , Ácido Linoleico/farmacología , Ácidos Linoleicos Conjugados/síntesis química , Ácidos Linoleicos Conjugados/farmacología , Animales , Antineoplásicos/química , Artemia/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Humanos , Hidroxilación , Dosificación Letal Mediana , Ácido Linoleico/síntesis química , Ácidos Linoleicos Conjugados/química , Compuestos de Selenio/química , Óxidos de SelenioRESUMEN
Methyl esters of C18 polyunsaturated fatty acids, including gamma-linolenic acid, alpha-linolenic acid and stearidonic acid, were epoxidised using m-chloroperbenzoic acid. Nine monoepoxides were obtained by normal-phase HPLC, identified using LC-MS and NMR, and characterized by NMR spectroscopy and mass spectrometry. This study is focused on structural characterization using LC-MS and LC/APCI/MS/MS. The elution profiles of these monoepoxides in RP-HPLC are determined as 12,13->9,10->6,7-epoxy, 9,10->15,16->12,13-epoxy and 15,16->12,13->9,10-epoxy derivatives of gamma-linolenic, alpha-linolenic and stearidonic acid methyl esters, respectively. The major diagnostic fragmentations in MS/MS identified are postulated to be induced by cleavages of the epoxide ring and alpha-bond cleavage to the epoxy group from [M+H]+ and/or [M+H-MeOH]+.
Asunto(s)
Bioquímica/métodos , Biofisica/métodos , Compuestos Epoxi/química , Ácidos Grasos/química , Espectrometría de Masas/métodos , Clorobenzoatos/química , Cromatografía Liquida/métodos , Iones , Modelos Químicos , Conformación Molecular , Peso Molecular , Oxígeno/química , Factores de TiempoRESUMEN
Methyl esters of gamma-linolenic acid, alpha-linolenic acid and stearidonic acid were epoxidised using m-chloroperbenzoic acid to achieve nine cis-monoepoxy-C18 fatty acid methyl esters (FAMEs), including novel methyl cis-monoepoxy derivatives of stearidonic acid and a cis-6,7-epoxy derivative of gamma-linolenic acid. These nine monoepoxy FAMEs were purified by normal-phase HPLC, identified by LC-MS, 1H and 13C NMR, and characterized by mass spectrometry and NMR spectroscopy. This study is focused on structural characterization of these C18 monoepoxy FAMEs using techniques in NMR spectroscopy including 1H, 13C, 1H-1H correlated spectroscopy (COSY) and 1H-13C heteronuclear correlation (HETCOR). The proton and carbon NMR chemical shifts of the epoxide, the double bonds, and the interrupted methylenes are assigned. Also discussed is an interpretation of the 1H and 13C NMR spectra of these monoepoxides including the changes in the 13C resonance of the olefinic carbons on the neighboring double bonds resulting from epoxide formation.
Asunto(s)
Ésteres/química , Ácidos Grasos/química , Espectroscopía de Resonancia Magnética/métodos , Ácido Benzoico/química , Carbono/química , Isótopos de Carbono/química , Química Física/métodos , Compuestos Epoxi/química , Ácidos Grasos Omega-3/química , Lípidos/química , Modelos Químicos , Ácido alfa-Linolénico/química , Ácido gammalinolénico/químicaAsunto(s)
Agonistas del GABA/farmacología , Preparaciones de Plantas/farmacología , Receptores de GABA/fisiología , Animales , Flavonoides/química , Flavonoides/farmacología , Agonistas del GABA/química , Humanos , Estructura Molecular , Preparaciones de Plantas/química , Transmisión Sináptica/efectos de los fármacos , Transmisión Sináptica/fisiologíaRESUMEN
Literature indicates that herb-drug interaction of St. John's wort is largely due to increased metabolism of the co-administered drugs that are the substrates of cytochrome P450 (CYP) 3A4 enzyme, alteration of the activity and/or expression of the enzyme. The major St. John's wort constituents, acylphloroglucinols, were evaluated for their effects on CYP3A4 enzyme activity to investigate their roles in herb-drug interaction. Hyperforin and four oxidized analogues were isolated from the plant and fully characterized by mass spectral and NMR analysis. These acylphloroglucinols inhibited activity of CYP3A4 enzyme potently in the fluorometric assay using the recombinant enzyme. Furoadhyperforin (IC(50) 0.072 microM) was found to be the most potent inhibitor of CYP3A4 enzyme activity, followed by furohyperforin isomer 1 (IC(50) 0.079 microM), furohyperforin isomer 2 (IC(50) 0.23 microM), hyperforin (IC(50) 0.63 microM) and furohyperforin (IC(50) 1.3 microM). As the acylphloroglucinols are potent inhibitors of the CYP3A4 enzyme, their modulation of the enzyme activity is unlikely to be involved in increased drug metabolism by St. John's wort.
Asunto(s)
Inhibidores Enzimáticos del Citocromo P-450 , Hypericum/química , Floroglucinol/análogos & derivados , Terpenos/química , Terpenos/farmacología , Compuestos Bicíclicos con Puentes/química , Compuestos Bicíclicos con Puentes/aislamiento & purificación , Compuestos Bicíclicos con Puentes/farmacología , Citocromo P-450 CYP3A , Sistema Enzimático del Citocromo P-450/metabolismo , Humanos , Estructura Molecular , Floroglucinol/química , Floroglucinol/aislamiento & purificación , Floroglucinol/farmacología , Terpenos/aislamiento & purificaciónRESUMEN
Preparations of Harpagophytum procumbens, known as devil's claw, are used as an adjunctive therapy for the treatment of pain and osteoarthritis. Pharmacological evaluations have proven the effectiveness of this herbal drug as an anti-inflammatory and analgesic agent. The present study has investigated the mechanism of action of harpagoside, one of the major components of Harpagophytum procumbens, using human HepG2 hepatocarcinoma and RAW 264.7 macrophage cell lines. Harpagoside inhibited lipopolysaccharide-induced mRNA levels and protein expression of cyclooxygenase-2 and inducible nitric oxide in HepG2 cells. These inhibitions appeared to correlate with the suppression of NF-kappaB activation by harpagoside, as pre-treating cells with harpagoside blocked the translocation of NF-kappaB into the nuclear compartments and degradation of the inhibitory subunit IkappaB-alpha. Furthermore, harpagoside dose-dependently inhibited LPS-stimulated NF-kappaB promoter activity in a gene reporter assay in RAW 264.7 cells, indicating that harpagoside interfered with the activation of gene transcription. These results suggest that the inhibition of the expression of cyclooxygenase-2 and inducible nitric oxide by harpagoside involves suppression of NF-kappaB activation, thereby inhibiting downstream inflammation and subsequent pain events.
Asunto(s)
Inhibidores de la Ciclooxigenasa 2/farmacología , Ciclooxigenasa 2/biosíntesis , Glicósidos , Lipopolisacáridos/farmacología , FN-kappa B/antagonistas & inhibidores , Óxido Nítrico Sintasa de Tipo II/antagonistas & inhibidores , Piranos , Animales , Línea Celular , Inhibidores de la Ciclooxigenasa 2/aislamiento & purificación , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación Enzimológica de la Expresión Génica/fisiología , Lipopolisacáridos/antagonistas & inhibidores , Ratones , FN-kappa B/metabolismo , Óxido Nítrico Sintasa de Tipo II/biosíntesis , Extractos Vegetales , Raíces de PlantasRESUMEN
The effects of the enantiomers of a number of flexible and cis-constrained GABA analogues were tested on GABA(C) receptors expressed in Xenopus laevis oocytes using two-electrode voltage-clamp electrophysiology. (1S,2R)-cis-2-Aminomethylcyclopropane-1-carboxylic acid ((+)-CAMP), a potent and full agonist at the rho1 (EC(50) approximately 40 microM, I(max) approximately 100%) and rho 2 (EC(50) approximately 17 microM, I(max) approximately 100%) receptor subtypes, was found to be a potent partial agonist at rho3 (EC(50) approximately 28 microM, I(max) approximately 70%). (1R,2S)-cis-2-Aminomethylcyclopropane-1-carboxylic acid ((-)-CAMP), a weak antagonist at human rho1 (IC(50) approximately 890 microM) and rho2 (IC(50) approximately 400 microM) receptor subtypes, was also found to be a moderately potent antagonist at rat rho3 (IC(50) approximately 180 microM). Similarly, (1R,4S)-4-aminocyclopent-2-ene-1-carboxylic acid ((+)-ACPECA) was a full agonist at rho1 (EC(50) approximately 135 microM, I(max) approximately 100%) and rho2 (EC(50) approximately 60 microM, I(max) approximately 100%), but only a partial agonist at rho3 (EC(50) approximately 112 microM, I(max) approximately 37%), while (1S,4R)-4-aminocyclopent-2-ene-1-carboxylic acid ((-)-ACPECA) was a weak antagonist at all three receptor subtypes (IC(50)>>300 microM). 4-Amino-(S)-2-methylbutanoic acid ((S)-2MeGABA) and 4-amino-(R)-2-methylbutanoic acid ((R)-2MeGABA) followed the same trend, with (S)-2MeGABA acting as a full agonist at the rho1 (EC(50) approximately 65 microM, I(max) approximately 100%), and rho2 (EC(50) approximately 20 microM, I(max) approximately 100%) receptor subtypes, and a partial agonist at rho3 (EC(50) approximately 25 microM, I(max) approximately 90%). (R)-2MeGABA, however, was a moderately potent antagonist at all three receptor subtypes (IC(50) approximately 16 microM at rho1, 125 microM at rho2 and 35 microM at rho3). On the basis of these expanded biological activity data and the solution-phase molecular structures obtained at the MP2/6-31+G* level of ab initio theory, a rationale is proposed for the genesis of this stereoselectivity effect.
Asunto(s)
Receptores de GABA/efectos de los fármacos , Ácido gamma-Aminobutírico/análogos & derivados , Ácido gamma-Aminobutírico/farmacología , Animales , Humanos , Modelos Moleculares , Estructura Molecular , Ratas , Proteínas Recombinantes/efectos de los fármacos , Xenopus laevisRESUMEN
Liver X receptors (LXR) play an important role in cholesterol homeostasis by serving as regulatory sensors of cholesterol levels in tissues. The present study reports a novel LXR-alpha activator, (20S)-2alpha, 3beta, 12beta, 24(S)-pentahydroxydammar-25-ene 20-O-beta-d-glucopyranoside (TR1), a dammarane-type gynosaponin, isolated from the herbal medicine, Gynostemma pentaphyllum. Gynosaponin TR1 demonstrated greater selectivity toward activation of the LXR-alpha isoform than LXR-beta in HEK293 cells. TR1 selectively enhanced LXR-mediated transcriptional activation and protein expression of ABCA1 and apoE gene expression and secretion in THP-1-derived macrophages. The selectivity of TR1 for LXR-alpha was consistent with ligand docking studies, which showed favourable interaction of TR1 in the LXR-alpha-binding domain, whereas the presence of the sugar substituent interfered with binding to the LXR-beta site. Findings from the present study may provide insight into the development of pharmaceutical agents for treating atherosclerosis.