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Eom S.-H.,Korea Food Research Institute | Moon S.-Y.,Pukyong National University | Lee D.-S.,National Marine Biodiversity Institutes of Korea | Kim H.-J.,Pukyong National University | And 6 more authors.
Algae | Year: 2015

This research was conducted to develop effective and safe marine-derived antiviral compounds against norovirus. The ethyl acetate (EtOAc)-extract from Eisenia bicyclis exhibited strong antiviral activity against murine norovirus (MNV) as a norovirus surrogate. Among the phlorotannins from E. bicyclis, dieckol (DE) and phlorofucofuroeckol-A (PFF) were known to possess the strongest antibacterial activity. In this study, DE and PFF were evaluated for antiviral activity against MNV DE and PFF exhibited strong anti-MNV activity with 50% effective concentration (EC50) of 0.9 pM. However, PFF ex­hibited more effective antiviral activity against MNV with higher selective index (668.87) than that of DE (550.60), due to its lower cell toxicity against RAW 264.7. This is the first report on the anti-MNV activity of phlorotannins from seaweed. The results obtained in this study suggest that the phlorotannins could be used as a potential source of natural antiviral agents. © 2015 The Korean Society of Phycology.

Eom S.-H.,Korea Food Research Institute | Jung Y.-J.,Pukyong National University | Lee D.-S.,National Marine Biodiversity Institutes of Korea | Yim M.-J.,National Marine Biodiversity Institutes of Korea | And 9 more authors.
Journal of Environmental Biology | Year: 2016

Traditional medicinal plants contain a wide variety of chemicals that have potent antibacterial activity. To find an alternative agent of overcoming the problems of methicillin-resistant Staphylococcus aureus (MRSA), the antibacterial mechanism of Ponciruss trifoliata against MRSA was investigated. Ethyl acetate (EtOAc)-soluble extract of P. trifoliata methanolic extract was evaluated for antibacterial activity using minimum inhibitory concentration (MIC). An EtOAc sub-fraction 08 (EA08) from silica-gel open column chromatography exhibited strong anti-MRSA activity. Apart from the study to isolate single compound from EA08, a synergistic antibacterial effect between the sub-fraction and β-lactam antibiotics against MRSA was determined. In order to elucidate the antibacterial restoring mechanism of EA08 on MRSA, mRNA expression of mecA gene and production penicillin-binding protein 2a (PBP2a) encoded by mecA gene were monitored. EA 08 showed the strongest antibacterial activity with MIC value of256μgml-1. MIC of oxacillin against MRSA was dramatically reduced from 512 to 16μgml-1 in combination with 256 μg ml-1 of EA08. The fractional inhibitory concentration index of oxacillin was measured at 0.53 in combination with EA08 against MRSA, suggesting that EA08-oxacillin combinations exert synergetic effect against MRSA. The analysis of RT-PCR and Western blotting profiles revealed that EA08 inhibited mRNA expression of mecA gene and production PBP2a, which is a key determinant for β-lactam antibiotic resistance, in a dose-dependent manner. These results indicated that EA08 eventually led to the reduction or inhibition of PBP2a production through translational inhibition in MRSA. © Triveni Enterprises, Lucknow (India).

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