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Macroalgal extracts as an alternative for the control of Paenibacillus larvae

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Abstract

The present study evaluated the potential use of methanolic extracts from two seaweeds from the Argentine Patagonian coasts, Macrocystis pyrifera and Undaria pinnatifida, as natural alternatives against Paenibacillus larvae. We carried out a detailed characterization of both seaweeds, comparing vegetative and reproductive thallus portions. We also assessed their phenolic content and antioxidant activity and evaluated the in vitro antibacterial action. Based on the minimal inhibitory concentration results, extracts from sporophyll of Undaria (US) and basal thallus portion of Macrocystis (MB) are strong inhibitors. US showed the best activity against P. larvae strain CMM(B)35 (12.2 μg/mL), and MB showed the same activity for strains CMM(B)35 and MAR1 (18.6 μg/mL). Antioxidant activity was higher in US, followed by MB, and a positive correlation was found with phenolic content. Taken together, our results indicate the role of specific chemical compounds present in algal extracts on antioxidant properties and antibacterial activity against P. larvae. We conclude that these seaweeds are promising alternatives against P. larvae.

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Chapter
In this chapter data on the composition of proteins, peptides and amino acids from macro and microalgae are presented. The specific chemical and physico-chemical methods of protein and amino acid analysis are discussed. Information on the variability in the contents and activities caused by seasonal and environmental factors is described. In addition, the biological activities and the potential applications as functional food ingredients are discussed.
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Products of browning reaction of glucosamine were prepared from glucosamine-HCl by incubating it at 37°C for 0-30 days, and the antioxidative activity, reducing power, degree of browning, aminosugar contents, pH, moisture and total nitrogen contents of the products were measured. In addition, the brown products prepared from glucosamine by incubation at 37°C for 0, 15 and 30 days were fractionated by gel filtration using Sephadex G-15, and the antioxidative activity, reducing power, degree of browning and pH of each fraction were also measured. The results obtained were as follows: 1) When white powder of free glucosamine was allowed to stand for 3 days at 37°C, it transformed to a brown paste. 2) The strongest antioxidative activity was observed in the product obtained after incubation between 20 and 30 days. 3) The increase in antioxidative activity of the products of browning reaction was accompanied by the increase in the degree of browning. 4) The brown products prepared from glucosamine by long incubation were fractionated into fractions according to their molecular weights. Antioxidative activity was detected in the fractions corresponding to intermediate molecular weight.
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Several brown algal (Phaeophyta) taxa or seaweeds such as Laminaria japonica, Hizikia fusiformis and Undaria pinnatifida are widely used as food staples, particularly in Japan, China and Korea due to their high nutritional values. An additional brown algal genus, Sargassum, abundant in tropical waters, is found to be rich in a variety of nutrients. In the present study Sargassum wightii, common to the Indian coastline has been investigated for its nutritional value. S. wightii's chemical properties were found to fluctuate as a function of seasonality and vegetative parts. Significant correlations between environmental factors and S. wightii chemical composition were determined. Carbohydrate and protein concentrations were highest in March collected samples and minimal values were recorded from July through September collections. Both protein and carbohydrates were found to be negatively correlated with ash content. Maximum and minimum ash contents were recorded from July (22.3 ± 0.12%) to November (16.2 ± 0.08%) collections, respectively.
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Propolis plays an important role in the exogenous defense of honeybee colony against pathogens. However, the studies dealing with the activity of propolis against bee pathogens are scarce. Poplar propolis extracts demonstrated promising activity against Paenibacillus larvae, the causative agent of American foulbrood. From the same propolis, five individual components and a mixture of caffeates were isolated, and their structures confirmed by spectroscopic data. Among the isolated propolis constituents are flavonoids, ferulic acid esters, and the oxylipin 9-oxo-10(E)-12(Z)-octadecadienoic acid, newly identified as propolis component. These substances were tested for their activity against P. larvae strains. The most active constituents were pinocembrin, 3-O-acetyl pinobanksin, and the caffeate mixture. This is the first communication of antimicrobial activity of individual propolis constituents against P. larvae; their important advantage is the fact that they are naturally present in the hive.
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Brown seaweeds are rich in sulfated polysaccharides that could potentially be exploited as functional ingredients for human health. Over the years, sulfated polysaccharides with potential pharmacological, nutraceutical, functional food and cosmeceutical properties have been isolated from brown seaweeds. In the present review, attempts have been made to discuss the functional properties of brown algal fucoidans and fucose rich sulfated polysaccharides. Anticoagulant, antithrombotic, immunomodulation, anticancer and anti-proliferative activities are the most extensively studied biological activities of fucoidans. The profound functional properties of fucoidans have proven to be invaluable and could be employed in the potential industrial applications as natural functional ingredients to obtain possible health benefits. For such applications, the reviewed literature in this communication may provide valuable basic information.