Estudo QuÃmico e BiolÃgico de Margaritopsis carrascoana Wright (Rubiaceae).

Margaritopsis carrascoana is a small shrub belonging to the Rubiaceae family and endemic from northeastern of Brazil flora growing in the sandy soils of the region of Ibiapaba and Araripe plateaus â Cearà state. The absence of reports of phytochemical studies related to this species, combined with occurrence of bioactive alkaloids in the genus, motivated us to perform chemical study. The plant specimen was collected in Araripe plateu, in MoreilÃndia-PE county. The phytochemical investigation of the ethanolic extract from the stems yielded the alkaloids calycosidine, hodgkinsine, N-8â-formyl-calycosidine and N-8â-methyl-N-1â-desmethylisocalycosidine, besides neolignan dihydrodehydrodiconiferyl alcohol 4-O-β-D-glucopyranoside, the flavonol luteolin 7-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl, the triterpenes lupeol and ursolic acid, and the mixture of β-sitosterol and stigmasterol steroids, as aglycones and glycosylated. From the ethanolic extract of the leaves were isolated the flavonoid luteolin 7-O-[β-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside, chrysoeriol 7-O-[β-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside, luteolin 7-O-{β-D-apiofuranosyl-(1→6)-[β-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranosyl} and luteolin 7-O-{α-L-rhamnopyranosyl-(1→6)-[β-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranosyl}. The alkaloids N-8"-formyl-calycosidine, N-8â-methyl-N-1â-desmethylisocalycosidine, luteolin 7-O-{β-D-apiofuranosyl-(1→6)-[β-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranosyl} and luteolin 7-O-{α-L-rhamnopyranosyl-(1→6)-[β-L-rhamnopyranosyl-(1→2)]-β-D-glucopyra-nosyl}, are being reported for the first time in the literature, and the other secondary metabolites are unprecedented in the genus Margaritopsis. The secondary metabolites were isolated using classical chromatography techniques; including adsorption chromatography on silica gel, exclusion chromatography on Sephadex LH-20, reverse phase chromatography (C-18), and high performance liquid chromatography (HPLC). For structural characterization were used infrared spectroscopy, mass spectrometry and nuclear magnetic resonance techniques including uni (1H NMR and 13C NMR and DEPT 135) and two-dimensional experiments (HMBC, HSQC, COSY and NOESY), and comparison with the literature data. In addition, the flavonoids flavonol luteolin 7-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl, luteolin 7-O-[β-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside, luteolin 7-O-{β-D-apiofuranosyl-(1→6)-[β-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranosyl} and luteolin 7-O-{α-L-rhamnopyranosyl-(1→6)-[β-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranosyl, sho-wed antioxidant activity greater than the BHT and quercetin standards, while ethanol extracts of stems and leaves showed inhibitory activity on the acetylcholinesterase enzyme. On the other hand, hodgkinsine showed potent cytotoxic activity against ovary, glioblastoma and colon cancer cells lines. The ethanol extract of the leaves and its alkaloidal fraction were submitted to nociception test and yielded good results. The ethanolic extract of the leaves was subjected to gastric antiulcer activity test, leading to a significant reduction in gastric lesions induced by ethanol in mice.Margaritopsis carrascoana à um pequeno arbusto pertencente à famÃlia Rubiaceae e endÃmico da flora do Nordeste brasileiro, que cresce em solos arenosos do planalto da Ibiapaba e serra do Araripe - CearÃ. A ausÃncia de relatos acerca de estudos fitoquÃmicos relacionados à espÃcie, aliada a ocorrÃncia de alcalÃides bioativos no gÃnero, nos motivou ao seu estudo quÃmico. Desta forma, o espÃcimen vegetal foi coletado na chapada do Araripe, municÃpio de MoreilÃndia-PE. A investigaÃÃo fitoquÃmica do extrato etanÃlico dos talos resultou no isolamento dos alcalÃides calicosidina, hodgkinsina, N-8â-formilcalicosidina e N-8â-metil-N-1â-desmetilisocalicosidina, da neolignana Ãlcool 4-O-β-D-glicopiranosil-di-hidro-desidrodiconiferÃlico, do flavonÃide 7-O-[α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil luteolina, dos triterpenos lupeol e o Ãcido ursÃlico, e da mistura de esterÃides β-sitosterol e estigmasterol, como agliconas e nas formas glicosiladas. A partir do estudo do extrato etanÃlico das folhas foram isolados os flavonÃides 7-O-[β-D-glicopiranosil-(1→6)-β-D-apiofuranosil] luteolina, 7-O-[β-D-glicopiranosil-(1→6)-β-D-apiofuranosil] crisoeriol, 7-O-{β-D-apiofuranosil-(1→6)-[α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil} luteolina e 7-O-{α-L-ramnopiranosil - (1→6) - [α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil} luteolina. Os alcalÃides N-8â-formilcalicosidina e N-8â-metil-N-1â-desmetilisocalicosidina, e os flavonÃides 7-O-{β-D-apiofuranosil-(1→6)-[α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil} luteolina e 7-O-{α-L-ramnopiranosil-(1→6)-[α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil} luteolina, estÃo sendo relatados pela primeira vez na literatura, enquanto todas as demais substÃncias possuem carÃter inÃdito no gÃnero Margaritopsis. O isolamento dos metabÃlitos secundÃrios foi conduzido atravÃs de tÃcnicas cromatogrÃficas clÃssicas, incluindo cromatografia de adsorÃÃo em gel de sÃlica, cromatografia por exclusÃo molecular em Sephadex LH-20, cromatografia de fase reversa (C-18) e cromatografia lÃquida de alta eficiÃncia (CLAE). Para a caracterizaÃÃo estrutural foram utilizadas tÃcnicas espectroscÃpicas utilizando infravermelho, espectrometria de massas e ressonÃncia magnÃtica nuclear, incluindo tÃcnicas uni (RMN 1H e RMN 13C e DEPT 135) e bidimensionais (HMBC, HSQC, COSY e NOESY), alÃm de comparaÃÃo com dados descritos na literatura. Em adiÃÃo, os flavonÃides 7-O-[α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil luteolina, 7-O-[β-D-glicopiranosil-(1→6)-β-D-apiofuranosil] luteolina, 7-O-{β-D-apiofuranosil-(1→6)-[α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil} luteolina e 7-O-{α-L-ramnopiranosil-(1→6) - [α-L-ramnopiranosil-(1→2)-β-D-glicopiranosil} luteolina apresentaram atividade antioxidante maior que os padrÃes BHT e quercetina, enquanto os extratos etanÃlicos dos talos e folhas apresentaram atividade inibidora da enzima acetilcolinesterase. Por outro lado, o alcaloide hodgkinsina apresentou potencial citotÃxico frente Ãs cÃlulas de ovÃrio, glioblastoma e colon. No teste de nocicepÃÃo, realizado com o extrato etanÃlico das folhas e a fraÃÃo alcalÃidica, foram observados resultados positivos para ambas as fraÃÃes. O extrato etanÃlico das folhas foi submetido a teste de atividade antiÃlcera gÃstrica, levando a uma reduÃÃo significativa da Ãrea de lesÃo gÃstrica induzida pelo etanol em camundongos