The Screening and Evaluation of Fucus serratus and Fucus vesiculosus Extracts against Current Strains of MRSA Isolated from a Clinical Hospital Setting.

Antimicrobial resistant strains of infection are afflicting clinical settings, driving the search for novel antimicrobial compounds. Naturally sourced bioactives, for instance those from seaweeds, have the potential to ameliorate this issue. As such, solvent extracts from the edible Irish seaweeds Fucus serratus and Fucus vesiculosus were screened for antimicrobial activity against 28 clinically isolated strains of MRSA, including one GISA (glycopeptide intermediate S. aureus) and two mecC gene containing strains. The water extract of F. vesiculosus was the most promising extract went on to be tested for biofilm prevention and disruption activity. The disk diffusion method was used to investigate the inhibition of the bacterial pathogens tested while MIC, MBC and biofilm disruption and prevention analyses were performed spectroscopically and by plate counts, respectively. Solvent extracts were found to have a wide array of antimicrobial activity against the strains tested, with the water extract from Fucus vesiculosus being the most promising. This extract was also found to both prevent and disrupt MRSA biofilms indicating the potential extract as new antimicrobials, and raising the possibility of their possible use in therapeutics.

Development of a novel antimicrobial seaweed extract-based hydrogel wound dressing.

The objective of this study was to develop a novel antimicrobial seaweed wound dressing. The seaweed extract was active against nine clinically-relevant wound pathogens. A hydrogel formulation was prepared using polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), followed by addition of 1% seaweed extract. The antimicrobial properties of the novel dressing were tested using agar diffusion assays, with release-profiles examined using gel leaching and gel transfer assays. The dressing was found to be effective against the same microbial strains as the seaweed extract, with similar efficacy to the commonly used silver-based dressing, Acticoat(®). Antimicrobial release-profile assays revealed that the dressing was effective in inhibiting 70-90% of the bacterial population within the first 30 min, followed by a long, sustained released up to 97 h, without leaving a residue following five subsequent transfers of the dressing. Antimicrobial activity was stable for up to 6 months of storage at 4 °C, but activity was reduced slightly after 15 weeks. Following autoclave sterilization, the dressing displayed a slower release profile compared to a non-autoclaved counterpart. Hence, the seaweed dressing may have commercial applications, potentially competing with silver-based dressings at a lower cost per-application. This is the first report of development of a seaweed-based antimicrobial dressing.

Standardised herbal extract of chlorogenic acid from leaves of Etlingera elatior (Zingiberaceae).

BACKGROUND: Chlorogenic acid (CGA) or 5-caffeoylquinic acid, was found to be the dominant phenolic compound in leaves of Etlingera elatior (Zingiberaceae). The CGA content of E. elatior leaves was significantly higher than flowers of Lonicera japonica (honeysuckle), the commercial source. In this study, a protocol to produce a standardised herbal CGA extract from leaves of E. elatior using column chromatography was developed. MATERIALS AND METHODS: Freeze-dried leaves of E. elatior were extracted with 30% ethanol, and sequentially fractionated using Diaion HP-20 and Sephadex LH-20. RESULTS: The CGA fractions, which yielded extracts of 10% and 40% w/w purity, possessed antioxidant, tyrosinase inhibition, and antibacterial properties. The entire fractionation process took only 6.5 hours, using gravity flow. From 50 g of leaves, the final yield of CGA extract was 0.2 g (0.4%). The CGA content of the standardised herbal extract from leaves of E. elatior (40%) is 1.6 times that of commercial extracts from honeysuckle flowers (25%). CONCLUSION: With high CGA content, the standardised herbal extract has a great potential to be developed into functional food and other health products. Leaves of E. elatior, which currently have no economic value, could serve as an alternative source of CGA. Leaves are large, available in abundance, and harvesting is non-destructive to the plants.

Antioxidative, tyrosinase inhibiting and antibacterial activities of leaf extracts from medicinal ferns.

Leaf extracts of five medicinal ferns, Acrostichum aureum L. (Pteridaceae), Asplenium nidus L. (Aspleniaceae), Blechnum orientale L. (Blechnaceae), Cibotium barometz (L.) J. Sm. (Cyatheaceae) and Dicranopteris linearis (Burm.) underwood var. linearis (Gleicheniaceae), were investigated for their total phenolic content (TPC), and antioxidative, tyrosinase inhibiting and antibacterial activities. The antioxidative activity was measured by assays for radical scavenging against 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric ion reducing power (FRP), beta-carotene bleaching (BCB) and ferrous ion chelating (FIC). The results revealed B. orientale to possess the highest amount of total polyphenols and strongest potential as a natural antioxidative, tyrosinase inhibiting and antibacterial agent as demonstrated by its strong activities in all related bioassays. The other ferns with antioxidative potential were C. barometz and D. linearis. Except for A. aureum, all ferns showed antibacterial activity which may justify their usage in traditional medicines.