RESUMO
Investigation of the Australian rainforest plant Croton insularis revealed seven new cis-, two new trans-cyclopropane casbanes, and the first trans-cyclopropane seco-casbane. The relative configuration of the cyclopropane moiety for all compounds (EBC-182, 217, 218, 220, 343, 357, 358, 361, 365, 373; EBC=EcoBiotics Compound) was assigned using 13 Câ NMR data. Comparison of the experimental electronic circular dichroism (ECD) spectra with the theoretical curves, calculated by TD-DFT at the B3LYP/6-31+G**//B3LYP/6-31+G** level, in conjunction with NOE data afforded the absolute configuration. EBC-180, 181 and 220 displayed potent activity against cervical carcinoma (HeLa cells).
RESUMO
Investigation of the Australian rainforest plant Croton insularis led to isolation of the first casbane hydroperoxide diterpenes EBC-304 and EBC-320. Extensive DFT and electronic circular dichroism (ECD) calculations in combination with 2D NMR spectroscopy determined the absolute configurations. EBC-304 and EBC-320 both display significant cytotoxicity.
Assuntos
Croton/química , Diterpenos/química , Peróxidos/química , Austrália , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Dicroísmo Circular , Croton/metabolismo , Diterpenos/isolamento & purificação , Diterpenos/toxicidade , Humanos , Espectroscopia de Ressonância Magnética , Conformação Molecular , Peróxidos/isolamento & purificação , Peróxidos/toxicidade , Floresta ÚmidaRESUMO
Investigation of Croton insularis afforded the first in class seco-casbane diterpene, EBC-329. A highly oxidised casbane, EBC-324, was also isolated. The structural motif within EBC-324, which consists of an epoxidised hemi-acetal endoperoxide, is new to the casbane family.
Assuntos
Croton/química , Diterpenos/química , Peróxidos/química , Diterpenos/isolamento & purificação , Espectroscopia de Ressonância Magnética , Peróxidos/isolamento & purificaçãoRESUMO
EBC-162 isolated from Croton insularis, obtained from the northern rainforest of Australia, was structurally affirmed as crotofolinâ C (4). Novel oxidative degradation products, EBC-233 and EBC-300, which are the first crotofolane endoperoxides, were also isolated. Both endoperoxides were found to be stable intermediates, which are proposed to undergo an unprecedented homo-Baeyer-Villiger biosynthetic rearrangement to give a new class of 1,14-seco-crotofolane diterpenes. Prolonged storage of all isolates assisted in authenticating their natural product status. Anticancer activities of reported compounds are presented.
Assuntos
Croton/química , Diterpenos/química , Diterpenos/isolamento & purificação , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Oxirredução , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificaçãoRESUMO
EBC-219 (4), isolated from Croton insularis (Baill), was established by spectroscopic and DFT methods as the first member of a new diterpene skeletal class, uniquely defined by the presence of a bicyclo[10.2.1] bridgehead olefin. The proposed biogenetic pathway to 4 from the co-isolated natural products EBC-131 (1), EBC-180 (2) and EBC-181 (3) is highly likely. EBC-180 (2) and EBC-181 (3) showed moderate to strong cytotoxic activity against various cancer cell lines.
