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In research on anti-human immunodeficiency virus (HIV) agents from natural sources, thirty two extracts of Vietnamese plants and twenty five isolated compounds were screened for their inhibitory effect against the ribonuclease H (RNase H) activity of HIV-1 reverse transcriptase and the cytopathic effect of the HIV virus. At a concentration of 50 μg/mL, eleven plant extracts and five isolated compounds inhibited over 90 percent of RNase H enzymatic activity. Of these, the methanol extracts from the leaves of Phyllanthus reticulatus and Aglaia aphanamixis highly inhibited RNase H activity by 99% and 98%, respectively. Several fucoidans isolated from seaweeds Sargassum kuetzingii, Sargassum polycystum, and Gelidiella acerosa, as well as epigallocatechin-3-gallate isolated from Camellia chinensis also showed strong inhibitory effects over ninety percent. Sixteen plant extracts with inhibition of over seventy five percent in the RNase H assay were tested in a cellular model of HIV-1 cytopathicity; four extracts showed modest activity in protecting against the cytopathic effect of the HIV virus.

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Sulfated fucans are among the most widely studied of all the sulfated polysaccharides of plant origin that exhibit biological activities in mammalian systems. In this report fucoidans from some Vietnamese Sargassum species such as S. polycystum, S. oligocystum, S. mcclurei, S. swartzii and denticaprum were extracted and fractionated on a DEAE-Sephadex A-25 column.On the basis of chemical and spectral analyses, the fucoidan fractions obtained were found to be the sulfated fucogalactans containing sulfate ester groups and uronic acid, and composed essentially of fucose and galactose, as well as a minor amount of other sugars. The polysaccharide fractions were tested for anticancer activity. The primarily obtained results showed that all fucoidan fractions isolated from S. swartzii demonstrate bioactivity effects against cancer cells, while fraction F5 with a highest sulfate content exhibits the strongest antiinvasion activity. This indicates that sulfate content plays an important role in the anticancer activity of the brown algal fucoidans.A laboratory scale pilot for fucoidan production from Vietnamese brown seaweeds has been set with a capacity of 500 g of crude fucoidan per day.

Introduction: β-D-glucans (beta-Glucan), a water-soluble polysaccharide with diversity physiological activities for applications in food and pharmaceutical industries. Methods: In this paper, we report the use of ionic liquid 1-butyl-3-methyl-imidazolium chloride [BMIM]Cl on the extraction and isolation of β-glucan from baker's yeast Saccharomyces cerevisiae. The β-D-glucans precipitated by adding water into the solution and obtained by filtration or centrifugation were pure, cleaned, and free of cell membranes. Results: The beta-glucan was obtained as white precipitates after adding water into the mixed solution. The 1D and 2D-NMR spectrum and titration methods applied for qualitative and quantitative determination showed that the beta-glucan product contained 78.2% 1,3-β-D glucan with 98.4% purity. Conclusion: This method can be used to prepare purified beta-glucan from baker’s yeast.