RESUMO
The present study investigated the chemical composition of ethylacetate extracts from an endophytic actinomycete Streptomyces sp. A0916 and its host Polygonum cuspidatum. A comparative analysis of the antimicrobial and antioxidant properties of the extracts was also conducted. 32 compounds of P. cuspidatum and 23 compounds of Streptomyces sp. A0916 were isolated and identified by GC/MS. Antimicrobial activities of the extracts were evaluated using eight microbial strains (3 Gram-positive bacteria, 3 Gram-negative bacteria, and 2 fungi). The Streptomyces sp. A0916 extracts showed a wide range of antimicrobial activities and presented greater antimicrobial effectiveness than the P. cuspidatum extracts. The minimum inhibitory concentration (MIC) of Streptomyces sp. A0916 extracts against the ampicillin-resistant strain Enterococcus faecium SIIA843 was 32 µg·mL(-1). Furthermore, the extracts had greater antimicrobial effect against Gram-positive bacteria than Gram-negative bacteria. Finally, the antioxidant activity of the Streptomyces sp. A0916 extracts was equal to that of the P. cuspidatum extracts. In conclusion, our results suggest that the endophytic actinomycetes of the medicinal plants are an important source of bioactive substances.
Assuntos
Anti-Infecciosos/química , Antioxidantes/química , Fallopia japonica/química , Fallopia japonica/microbiologia , Extratos Vegetais/química , Streptomyces/química , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/farmacologia , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Bactérias/efeitos dos fármacos , Fungos/efeitos dos fármacos , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Streptomyces/classificação , Streptomyces/genética , Streptomyces/isolamento & purificaçãoRESUMO
Cercosporenes A-F (1-6, respectively), six new guanacastane diterpenes, including a homodimer (5) and a heterodimer (6), were isolated from the crude extract of the fungus Cercospora sp., endophytic to the medicinal plant Fallopia japonica. The structures of 1-6 were elucidated by nuclear magnetic resonance experiments, and 4 and 5 were further confirmed by X-ray crystallography. The absolute configuration of 1 and 3 was assigned by electronic circular dichroism calculations, whereas that of 6 was deduced by the application of the circular dichroism exciton chirality method. In addition to its cytotoxicity against a panel of five human tumor cell lines, HeLa, A549, MCF-7, HCT116, and T24, heterodimer 6 also induced autophagy in HCT116 cells.