Isolation, Characterization, Antioxidant, Antimicrobial and Cytotoxic Effect of Marine Actinomycete, Streptomyces Carpaticus MK-01, against Fish Pathogens

ABSTRACT Present study aim to evaluate the antimicrobial, antioxidant and cytotoxic potential of crude extract of Marine Streptomyces carpaticus MK-01 isolated from seawater collected from Daejeong-cost of Jeju Island. About 24 actinomycetes strains were isolated and subjected to morphological and molecular analysis that confirmed the isolate as S. carpaticus MK-01. Crude ethyl acetate extract of MK-01 strain showed extensive antibacterial activity against Gram-positive fish pathogenic bacteria namely Streptococcus iniae and S. parauberis with a maximum zone of inhibition (0.92±0.03mm) was recorded against S. parauberis at the minimum extract concentration (3.12µg/ml). The MK-01 ethyl acetate extract shows dose dependant significant increase in antioxidant activity. The 50% cytotoxic concentration (CC50) of MK-01 ethyl acetate extract was attained at 53.71 μg/ml and the effective concentration 50 (EC50) against virus-infected Epithelioma papulosum cyprini cell lines was 8.72 μg/ml of S. carpaticus MK-01 crude ethyl acetate extract.

Selenium acts as an insulin-like molecule for the down-regulation of diabetic symptoms via endoplasmic reticulum stress and insulin signalling proteins in diabetes-induced non-obese diabetic mice.

To investigate whether selenium (Sel) treatment would impact on the onset of diabetes,we examined serum biochemical components including glucose and insulin,endoplasmic reticulum (ER) stress and insulin signalling proteins, hepatic C/EBP-homologous protein (CHOP) expression and DNA fragmentation in diabetic and non- diabetic conditions of non-obese diabetic (NOD) mice. We conclude that (i) Sel treatment induced insulin-like effects in lowering serum glucose level in Sel-treated NOD mice, (ii) Sel-treated mice had significantly decreased serum biochemical components associated with liver damage and lipid metabolism, (iii) Sel treatment led to the activation of the ER stress signal through the phosphorylation of JNK and eIF2 protein and insulin signal mechanisms through the phosphorylation of Akt and PI3 kinase, and (iv) Sel-treated mice were significantly relieved apoptosis of liver tissues indicated by DNA fragmentation assay in the diabetic NOD group. These results suggest that Sel compounds not only serve as insulin-like molecules for the downregulation of glucose level and the incidence of liver damage, but may also have the potential for the development of new drugs for the relief of diabetes by activating the ER stress and insulin signalling pathways.