Strepolyketide D, a new SEK15-derived polyketide compound from salt-lake-derived Streptomyces sp. DBC5.

A new SEK15-derived polyketide compound, strepolyketide D (1), was isolated from salt-lake-derived Streptomyces sp. DBC5, together with two known analogues (2-3). Their structures were elucidated based on spectroscopic analysis of IR, MS, 1 D and 2 D NMR. Compound 2 elicited moderate antioxidation with IC50 value of 39.26 µg/ml. The results of the study revealed that salt-lake actinomycetes of Lake Dabancheng appear to have immense potential as a source of polyketide compounds.

[Protective effect of raspberry extract on ConA-induced acute liver injuryin mice].

In this experiment,the antioxidant capacity of raspberry extract and the protective effect on liver injury induced by ConA in mice were investigated. Balb/C male mice were randomly divided into six groups: normal group,model group,bicyclol control group( 200 mg·kg~(-1)),low-dose raspberry extract group( 200 mg·kg~(-1)),middle-dose raspberry extract group( 400 mg·kg~(-1)),and highdose raspberry extract group( 800 mg·kg~(-1)). Each group was intragastrically administered with drugs according to the body weight once a day. Seven days later,all of the groups except for the normal group were treated with ConA( 20 mg·kg~(-1)) through tail vein injection to establish the acute liver injury model. The mice were put to death 8 hours later. The organ indexes were calculated. These rum levels of ALT,AST and LDH and the activities of SOD,CAT,GSH and MDA in liver tissue were detected. HE staining was used to observe the pathological changes of liver tissue in mice. Western blot was used to detect the expressions of Bax,Bcl-2,Nrf2 and Keap-1. The antioxidant capacity of raspberry extract was measured by CAA assay. The results showed that,raspberry extract had a strong antioxidant capacity. Simultaneously,compared with the model group,raspberry extract can significantly improve the pathological conditions of liver,and significantly reduce ALT,AST and LDH activities in serum of liver injury mice( P<0. 01). The activities of SOD,CAT in liver homogenate supernatant were significantly increased in the high-dose group,the content of GSH increased,while the content of MDA was sharply declined in the high-dose group( P<0. 01). Meanwhile,raspberry extract down-regulated the expressions of Bax and Keap-1 and up-regulated the expressions of Bcl-2 and Nrf2. CAA showed that the compound raspberry extract had a strong antioxidant capacity. Therefore,raspberry extract has an obvious protective effect on acute liver injury induced by ConA in mice.