RESUMO
Nematode parasitosis causes significant mortality and morbidity in humans and considerable losses in livestock and domestic animals. The acquisition of resistance to current anthelmintic drugs has prompted the search for new compounds for which the free-living nematode Caenorhabditis elegans has emerged as a valuable platform. We have previously synthetized a small library of oxygenated tricyclic compounds and determined that dibenzo[b,e]oxepin-11(6H)-one (doxepinone) inhibits C. elegans motility. Because doxepinone shows potential anthelmintic activity, we explored its behavioral effects and deciphered its target site and mechanism of action on C. elegans. Doxepinone reduces swimming rate, induces paralysis, and decreases the rate of pharyngeal pumping required for feeding, indicating a marked anthelmintic activity. To identify the main drug targets, we performed an in vivo screening of selected strains carrying mutations in Cys-loop receptors involved in worm locomotion for determining resistance to doxepinone effects. A mutant strain that lacks subunit genes of the invertebrate glutamate-gated chloride channels (GluCl), which are targets of the widely used antiparasitic ivermectin (IVM), is resistant to doxepinone effects. To unravel the molecular mechanism, we measured whole-cell currents from GluClα1/ß receptors expressed in mammalian cells. Glutamate elicits macroscopic currents whereas no responses are elicited by doxepinone, indicating that it is not an agonist of GluCls. Preincubation of the cell with doxepinone produces a statistically significant decrease of the decay time constant and net charge of glutamate-elicited currents, indicating that it inhibits GluCls, which contrasts to IVM molecular actions. Thus, we identify doxepinone as an attractive scaffold with promising anthelmintic activity and propose the inhibition of GluCls as a potential anthelmintic mechanism of action.
RESUMO
BACKGROUND/AIM: This study examined the potential role of natural triterpenoids lupeol, calenduladiol and heliantriol B2, and a set of 19 derivatives, as antiproliferative and antimetastatic agents against prostate cancer cells. MATERIALS AND METHODS: Natural triterpenoids were isolated from Chuqiraga erinaceae. Analogs were obtained by transformations of lupeol and calenduladiol. The effects of compounds on PC-3 and LNCaP cells were determined using the MTT assay. Compounds with half-maximal inhibitory concentration <70 µM were evaluated as antimetastatic agents by a wound-healing assay. RESULTS: Lupeol-3ß-sulfate, a new semisynthetic lupane, was the most active compound. In general, sulfated derivatives displayed higher activity than the lead against both cell lines. A new analog, calenduladiol-3ß-monosulfate, inhibited the migration of PC-3 cells; heliantriol B2 and 3ß-aminolupane inhibited the migration of LNCaP cells in a concentration-dependent manner. CONCLUSION: Our study provides novel agents with cytotoxic effects on prostate cancer cells, which may represent a potential new therapeutic approach for prostate cancer.
Assuntos
Antineoplásicos/farmacologia , Neoplasias da Próstata/tratamento farmacológico , Triterpenos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Masculino , Cicatrização/efeitos dos fármacosRESUMO
A set of triterpenoids with different grades of oxidation in the lupane skeleton were prepared and evaluated as cholinesterase inhibitors. Allylic oxidation with selenium oxide and Jones's oxidation were employed to obtain mono-, di- and tri-oxolupanes, starting from calenduladiol (1) and lupeol (3). All the derivatives showed a selective inhibition of butyrylcholinesterase over acetylcholinesterase (BChE vs. AChE). A kinetic study proved that compounds 2 and 9, the more potent inhibitors of the series, act as competitive inhibitors. Molecular modeling was used to understand their interaction with BChE, the role of carbonyl at C-16 and the selectivity towards this enzyme over AChE. These results indicate that oxidation at C-16 of the lupane skeleton is a key transformation in order to improve the cholinesterase inhibition of these compounds.
Assuntos
Butirilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Triterpenos/farmacologia , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Butirilcolinesterase/química , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Relação Dose-Resposta a Droga , Humanos , Simulação de Acoplamento Molecular , Estrutura Molecular , Oxirredução , Relação Estrutura-Atividade , Torpedo , Triterpenos/síntese química , Triterpenos/químicaRESUMO
A set of twenty one lupane derivatives (2-22) was prepared from the natural triterpenoid calenduladiol (1) by transformations on the hydroxyl groups at C-3 and C-16, and also on the isopropenyl moiety. The derivatives were tested for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and some structure-activity relationships were outlined with the aid of enzyme kinetic studies and docking modelization. The most active compound resulted to be 3,16,30-trioxolup-20(29)-ene (22), with an IC50 value of 21.5µM for butyrylcholinesterase, which revealed a selective inhibitor profile towards this enzyme.
Assuntos
Acetilcolinesterase/metabolismo , Butirilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Triterpenos/farmacologia , Animais , Butirilcolinesterase/sangue , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Relação Dose-Resposta a Droga , Enguias , Cavalos , Cinética , Modelos Moleculares , Conformação Molecular , Relação Estrutura-Atividade , Triterpenos/síntese química , Triterpenos/químicaRESUMO
A bioactivity-guided approach was taken to identify the acetylcholinesterase (AChE) inhibitory agents in the ethanolic extract of Chuquiraga erinacea D. Don. subsp. erinacea leaves using a bioautographic method. This permitted the isolation of the pentacyclic triterpenes calenduladiol (1), faradiol (2), heliantriol B2 (3), lupeol (4), and a mixture of alpha-and beta-amyrin ( 5A and 5B) as active constituents. Pseudotaraxasterol (6) and taraxasterol (7) were also isolated from this extract and showed no activity at the same analytical conditions. Compound 1 showed the highest AChE inhibitory activity with 31.2 % of inhibition at 0.5 mM. Looking forward to improve the water solubility of the active compounds, the sodium sulfate ester of 1 was prepared by reaction with the (CH3)3N.SO3 complex. The semisynthetic derivative disodium calenduladiol disulfate (8) elicited higher AChE inhibition than 1 with 94.1 % of inhibition at 0.5 mM (IC (50) = 0.190 +/- 0.003 mM). Compounds 1, 2, 3, 5, 6, and 7 are reported here for the first time in C. erinacea. This is the first report of AChE inhibition from calenduladiol (1) as well as from a sulfate derived from a natural product.
Assuntos
Asteraceae/química , Inibidores da Colinesterase/química , Inibidores da Colinesterase/farmacologia , Triterpenos/química , Triterpenos/farmacologia , Estrutura MolecularRESUMO
A literatura registra 8 casos publicados de afasia lentamente progressiva, dois dos quais progrediram em período de anos para demência generalizada. Tomografia por emissäo de pósitrons demonstrou metabolismo diminuído de glicose na regiäo peri-silviana esquerda em dois casos. Descrevemos o caso de um paciente que teve afasia lentamente progressiva e desenvolveu demência generalizada de tipo Alzheimer, 7 anos após a apresentaçäo inicial. Näo foi encontrada evidência clínica ou laboratorial de doença concomitante. Tomografia computadorizada mostrou atrofia generalizada mais marcada na regiäo peri-silviana esquerda tardiamente no processo, quando EEG mostrou lentificaçäo generalizada, mais claramente na mesma área. Afasia lentamente progressiva da idade avançada deve ser considerada entidade em separado até que estudos elucidem sua relaçäo com demência de Alzheimer