RESUMO
AIM: 6,7-dehydroroyleanone (DHR) is a cytotoxic abietane present in the essential oil of Plectranthus madagascariensis. METHODS/RESULTS: Different extraction parameters were tested, and its extraction optimization was accomplished with a Clevenger apparatus-based hydrodistillation. After isolation, its effect on microtubules, P-glycoprotein and caspases was assessed on several cell lines and the compound was coupled with hybrid nanoparticles. The results show that DHR does not interfere with microtubule formation, but evades the resistance mechanisms of P-glycoprotein. Strong activation of caspases-3 and -9 indicates that DHR is able to induce apoptosis by triggering the intrinsic cell death pathway. Moreover, the assembly of DHR with hybrid nanoparticles was able to potentiate the effect of DHR in cancer cells. CONCLUSION: DHR seems to be a promising starting material with anticancer properties to further be explored.
Assuntos
Abietanos/química , Antineoplásicos Fitogênicos/química , Subfamília B de Transportador de Cassetes de Ligação de ATP/química , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Abietanos/isolamento & purificação , Abietanos/farmacologia , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Nanopartículas/química , Óleos Voláteis/química , Extratos Vegetais/química , Plectranthus/química , Plectranthus/metabolismoRESUMO
Paclitaxel (PTX) is currently used as a front-line chemotherapeutic agent for several types of cancer, including ovarian carcinoma; however, PTX-resistance frequently arises through multiple mechanisms. The development of new strategies using natural compounds and PTX in combination has been the aim of several prior studies, in order to enhance the efficacy of chemotherapy. In this study, we found the following: (i) gallic acid (GA), a phenolic compound, potentiated the capacity of PTX to decrease proliferation and to cause G2/M cycle arrest in the PTX-resistant A2780AD ovarian cancer cell line; (ii) GA exerted a pro-oxidant action by increasing the production of reactive oxygen species (ROS), and co-treatment with the antioxidant agent Nacetyl-Lcysteine (NAC) prevented GA+PTX-induced cell proliferation inhibition and G2/M phase arrest; (iii) PTX stimulated ERK phosphorylation/activation, and co-treatment with the MEK/ERK inhibitor PD98049 potentiated the proliferation inhibition and G2/M phase arrest; (iv) and finally, GA abrogated the PTX-induced stimulation of ERK phosphorylation, a response that was prevented by co-treatment with NAC. Taken together, these results indicate that GA sensitizes PTX-resistant ovarian carcinoma cells via the ROSmediated inactivation of ERK, and suggest that GA could represent a useful co-adjuvant to PTX in ovarian carcinoma treatment.
Assuntos
Regulação para Baixo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Ácido Gálico/farmacologia , Neoplasias Ovarianas/metabolismo , Paclitaxel/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Acetilcisteína/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sinergismo Farmacológico , Ativação Enzimática , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Pontos de Checagem da Fase G2 do Ciclo Celular , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Neoplasias Ovarianas/tratamento farmacológicoRESUMO
Four natural analogues of podophyllotoxin obtained from the Mexican medicinal plant Bursera fagaroides, namely, acetyl podophyllotoxin (2), 5'-desmethoxy-ß-peltatin A methyl ether (3), 7',8'-dehydro acetyl podophyllotoxin (4), and burseranin (5), have been characterized, and their interactions with tubulin have been investigated. Cytotoxic activity measurements, followed by immunofluorescence microscopy and flow cytometry studies, demonstrated that these compounds disrupt microtubule networks in cells and cause cell cycle arrest in the G2/M phase in the A549 cell line. A tubulin binding assay showed that compounds 1-4 were potent assembly inhibitors, displaying binding to the colchicine site with Kb values ranging from 11.75 to 185.0 × 10(5) M(-1). In contrast, burseranin (5) was not able to inhibit tubulin assembly. From the structural perspective, the ligand-binding epitopes of compounds 1-3 have been mapped using STD-NMR, showing that B and E rings are the major points for interaction with the protein. The obtained results indicate that the inhibition of tubulin assembly of this family of compounds is more effective when there are at least two methoxyl groups at the E ring, along with a trans configuration of the lactone ring in the aryltetralin lignan core.
Assuntos
Bursera/química , Podofilotoxina/farmacologia , Tubulina (Proteína)/metabolismo , Ciclo Celular/efeitos dos fármacos , Colchicina/farmacologia , Humanos , Lactonas/química , Lactonas/farmacologia , Lignanas/farmacologia , Microtúbulos/efeitos dos fármacos , Estrutura Molecular , Podofilotoxina/análogos & derivados , Podofilotoxina/química , Ligação Proteica , Moduladores de Tubulina/química , Moduladores de Tubulina/farmacologiaRESUMO
Three fluorescent probes 3a,3b, and 4 have been synthesized through conjugation of fluorescein and difluorescein groups to the 7-OH of C-2 modified paclitaxel and cephalomannine derivatives with very high affinity to microtubules. All these probes exhibited potent tubulin assembly promotion and tumor cell killing activities, thus may be useful as tools for the determination of thermodynamic parameters and exploration of ligand-microtubule interactions.