Inhibitory action of natural carrageenans on Herpes simplex virus infection of mouse astrocytes

Innovative natural functional ingredients from microalgae

Nowadays, a wide variety of compounds such as polyphenols, polyunsaturated fatty acids (PUFA), or phytosterols obtained, for example, from wine, fish byproducts, or plants are employed to prepare new functional foods. However, unexplored natural sources of bioactive ingredients are gaining much attention since they can lead to the discovery of new compounds or bioactivities. Microalgae have been proposed as an interesting, almost unlimited, natural source in the search for novel natural functional ingredients, and several works have shown the possibility to find bioactive compounds in these organisms. Some advantages can be associated with the study of microalgae such as their huge diversity, the possibility of being used as natural reactors at controlled conditions, and their ability to produce active secondary metabolites to defend themselves from adverse or extreme conditions. In this contribution, an exhaustive revision is presented involving the research for innovative functional food ingredients from microalgae. The most interesting results in this promising field are discussed including new species composition and bioactivity and new processing and extraction methods. Moreover, the future research trends are critically commented.

Subcritical water extraction and characterization of bioactive compounds from Haematococcus pluvialis microalga

In this work, extraction and characterization of compounds with antioxidant and antimicrobial activity from Haematococcus pluvialis microalga in red phase have been carried out. To do this, subcritical water extraction (SWE) has been combined with analytical techniques such as HPLC-DAD, HPLC-QqQ-MS and GC-MS and in vitro assays (i.e., for antioxidant and antimicrobial activity). The effect of the extraction temperature (50, 100, 150 and 200 degrees C) and solvent polarity has been studied in terms of yield and activity of the extracts. Results demonstrate that the extraction temperature has a positive influence in the extraction yield and antioxidant activity. Thus, the extraction yield achieved with this process was higher than 30% of dry weight at 200 degrees C as extraction temperature. Moreover, the extract obtained at 200 degrees C presented the highest antioxidant activity by far, while temperature does not seem to significatively affect the antimicrobial activity. Chemical composition was determined by HPLC-DAD, HPLC-QqQ-MS and GC-MS. Short chain fatty acids turned out to be responsible of the antimicrobial activity, whereas the antioxidant activity was correlated to vitamin E (present exclusively in the 200 degrees C extract), together with simple phenols, caramelization products and possible Maillard reaction products obtained during the extraction at high temperatures.

Identification of natural compounds with anti-hepatitis B virus activity from Rheum palmatum L. ethanol extract

BACKGROUND

Hepatitis B virus (HBV) infection is a severe health problem in the world; however, there is still no satisfactory therapeutic strategy for the HBV infection. In search for new anti-HBV agents with higher efficiency and less side effects, the anti-HBV activities of traditional Chinese medicine Rheum palmatum L. ethanol extract (RPE) and isolated anthraquinones were evaluated.

METHODS

The anti-HBV activities of RPE and isolated anthraquinones were demonstrated in a stable HBV-producing cell line HepG2 2.2.15 by using real-time polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA) and Southern blot analysis.

RESULTS

RPE could inhibit HBV-DNA production and HBsAg expression in a dose-dependent manner. The concentration of 50% HBV-DNA inhibition (IC(50)) of RPE was calculated at 212.36 +/- 11 microg/ml. Six anthraquinones were isolated from RPE by using RP-HPLC. Five free anthraquinones showed weakly or slightly inhibitory activities against HBV. The only combined anthraquinone chrysophanol 8-O-beta-D-glucoside exhibited significant activity against HBV DNA production and antigens expression with an IC(50) value of 36.98 +/- 2.28 microg/ml on HBV DNA inhibition. Endogenous HBV DNA polymerase activity assay indicated that chrysophanol 8-O-beta-D-glucoside might be a potential inhibitor of the HBV DNA polymerase.

CONCLUSIONS

The results suggested that RPE could effectively inhibit HBV. The combined anthraquinone chrysophanol 8-O-beta-D-glucoside is the major active compound in RPE and could be a promising candidate for the development of new anti-HBV drugs in the treatment of HBV infection.

Intermediate filament integrity is required for Junin virus replication

The role of the cytoskeletal framework in Junin virus (JUNV) replication has already been demonstrated with compounds interfering with the microfilament (MF) and microtubule (MT) networks. In this work, we evaluated the role of intermediate filaments (IF) during JUNV infection. We tested the effect of acrylamide, a compound that selectively disrupts IF, in culture of three different cell types: Vero cells, murine astrocytes and human foreskin fibroblasts. Perturbation of intermediate filaments had an inhibitory effect on JUNV production within a range of acrylamide concentration of 0.5-3mM in a dose-dependent manner, without cell viability modification. Recovery experiments showed that viral production was partially increased when medium containing acrylamide was replaced by normal maintenance medium (MM). The adsorption and internalization steps were not affected by IF disruption. The expression of JUNV proteins was highly reduced in the presence of 2mM acrylamide while immunofluorescence staining of IF showed network disruption with the formation of cytoplasmic aggregates containing vimentin or glial fibrillary acidic protein (GFAP). We conclude that the IF network may play a role in the early step of JUNV multiplication, subsequent to virus entry and that its integrity is a necessary condition for the normal replication of JUNV in neural and fibroblast cells as well as in the Vero cell line.

Herpes simplex virus type 1 variants arising after selection with an antiviral carrageenan: lack of correlation between drug susceptibility and syn phenotype

Natural carrageenans of diverse structural types isolated from the red seaweed Gigartina skottsbergii were recently identified as potent and selective inhibitors of herpes simplex virus types 1 and 2 (HSV-1 and -2). The mu/nu-carrageenan 1C3 was tested in vitro for its ability to select resistant variants. After serial passages of HSV-1 strain F in Vero cells in the presence of increasing concentrations of 1C3, viruses emerged that were approximately 2- to 10-fold more resistant to 1C3 inhibition than parental virus; these viruses formed large plaques with an altered syncytial phenotype (1C3-syn). Plaque-purified syncytial variants isolated from passages 13 and 14 have shown variable levels of resistance to 1C3, as well as to the other antiviral carrageenans isolated from G. skottsbergii and to other sulfated polysaccharides with known antiviral activity, such as heparin and dextran sulfate 8000, but all the clones were susceptible to acyclovir. The syn phenotype was not related to polysaccharide resistance. All the 1C3-syn variants formed large syncytia in Vero and CV-1 cells but did not induce fusion in other cell types. The growth efficiency in Vero cells, as well as the virulence for mice by intracerebral or intraperitoneal inoculation of 1C3-syn variants, showed no significant alterations in comparison with the parental virus. The syncytial properties were not affected by cyclosporine or melittin, suggesting that an alteration on glycoprotein gB could be responsible for the syn phenotype induced by 1C3.