RESUMO
A new diketosteroid, (E)-stigmasta-24(28)-en-3,6-dione (1), along with three known steroids (2-4) was isolated from marine alga Tydemania expeditionis collected in China Sea. Their structures were elucidated by extensive spectroscopic methods. Comparison of the chemical constituents revealed significant diversity among different locations. The biological activities of 1, 3 and 4 were evaluated on the prostate cancer cell lines and androgen receptor. Compound 1 exhibited moderate inhibitory activities against the prostate cancer cells DU145, PC3 and LNCaP with IC(50) values of 31.27±1.50, 40.59±3.10 and 19.80±3.84 µM, respectively. Compound 3 showed more potent activities with IC(50) values of 12.38±2.47, 2.14±0.33 and 1.38±0.07 µM, respectively. However, compound 4 showed only weak inhibitory activities on LNCaP cells and was inactive on DU145 and PC3 cells. A competitive binding assay showed that compound 1 exhibited significant affinity to the androgen receptor with an IC(50) value of 7.19±0.45 µM, while 3 and 4 were inactive. The fact that the inhibitory properties of 1 and 3 against the prostate cancer cells were inconsistent with their affinities to the androgen receptor suggested that there might be other mechanism of action involved in the cytotoxic activity.
Assuntos
Antineoplásicos Fitogênicos/uso terapêutico , Clorófitas/química , Cetosteroides/uso terapêutico , Fitoterapia , Neoplasias da Próstata/tratamento farmacológico , Receptores Androgênicos/metabolismo , Esteroides/uso terapêutico , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Linhagem Celular Tumoral , Humanos , Concentração Inibidora 50 , Cetosteroides/isolamento & purificação , Cetosteroides/farmacologia , Masculino , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Esteroides/isolamento & purificação , Esteroides/farmacologiaRESUMO
Column chromatography of the alcoholic extract of Piper betle roots furnished aristololactam A-II and a new phenyl propene, characterized as 4-allyl resorcinol, while the petroleum-ether extract yielded a diketosteroid, viz. stigmast-4-en-3,6-dione. All these compounds were characterized by spectroscopic means. Isolation of these compounds from this source is being reported here for the first time.