Upgrading of residues of bracts, stems and hearts of Cynara cardunculus L. var. scolymus to functional fractions enriched in soluble fiber.

Since only the central portion of the immature flowers of artichoke (Cynara cardunculus L. var. scolymus) is consumed (<20%) it is interesting to upgrade its residues to render value added products. In this research, bracts (B), hearts (H) or stems (S) were used to isolate fractions enriched in soluble fiber. Extraction was performed in citrate buffer with or without hemicellulase. Additionally, the effect of preheating (70 °C - 5 min) prior to extraction was also tested. Polysaccharides were precipitated with ethanol and the fractions obtained were freeze-dried. The presence of the enzyme increased fiber yields and preheating produced an additional increment, especially from stems (≈21%). Isolated fibers were constituted by 70-84% of carbohydrates and 2-25% of proteins, and contained phenolics (2.1-8.2 g/100 g). Carbohydrates included uronic acids (12-25%) and neutral sugars (NS, 4-55%) of pectins, and inulin (13-55%). The lowest protein and NS contents and the highest inulin content were obtained with the enzyme and preheating. The behavior of fractions isolated with higher yields was characterized, observing a pseudoplastic behavior in water and gelation with Ca(2+). They also showed antioxidant activity and an inhibitory effect against herpes simplex virus type 1 without cytotoxicity. The isolated fractions retaining bioactive compounds can be useful as functional food ingredients.

Virucidal activity and chemical composition of essential oils from aromatic plants of central west Argentina.

The essential oils of seven aromatic plants from central west Argentina were isolated by steam distillation and analyzed by a gas chromatography/mass spectrometry technique. The oils were screened for cytotoxicity and in vitro inhibitory activity against herpes simplex virus type 1 (HSV-1), dengue virus type 2 (DENV-2) and Junin virus (JUNV). The oils showed a variable virucidal action according to the virus. JUNV was the least susceptible virus in comparison with HSV-1 and DENV-2. The better relationship between cytotoxicity and inhibitory activity was observed for the essential oil of Lantana grisebachiii (Seckt.) var. grisebachii against DENV-2 and HSV-1 with IC50 (inhibitory concentration 50%) values of 21.1 and 26.1 ppm, respectively. This effect was specific since the selectivity indices (ratio cytotoxicity/virucidal activity) were > 23.7 and > 19.1 for DENV-2 and HSV-1, respectively. Furthermore, the oil from L. grisebachii was also an effective inhibitor of HSV-2 and acyclovir resistant variants of herpes virus. This study demonstrates the effective and selective inhibitory activity of the essential oil from Lantana grisebachii against HSV and DENV by direct virus inactivation.

An algal-derived DL-galactan hybrid is an efficient preventing agent for in vitro dengue virus infection.

The DL-galactan hybrid C2S-3, isolated from the red seaweed Cryptonemia crenulata (Halymeniaceae, Halymeniales), is a potent and selective inhibitor of the multiplication of diverse strains of DENV-2 in Vero cells with higher effectiveness than the reference polysaccharide heparin. The presence of the compound either only at virus adsorption or at virus internalization exerted a significant and dose-dependent inhibition in DENV-2 plaque number. The compound failed to inactivate DENV-2 directly by incubation of virus before cell infection as well as to induce a refractory state by cell pretreatment. Thus, the inhibitory effect was exclusively exerted through a blockade in virus multiplication during the infectious process. When the entry of DENV-2 particles into the cell is bypassed, as occurs in virus RNA transfection, the polysaccharide C2S-3 failed to block the completion of the multiplication cycle. Furthermore, the antiviral properties of C2S-3 are not correlated with anticoagulant activity.

Galactans from cystocarpic plants of the red seaweed Callophyllis variegata (Kallymeniaceae, Gigartinales).

The polysaccharide extracted from cystocarpic Callophyllis variegata was fractionated with potassium chloride yielding three small fractions that precipitated in the ranges of 0-0.05 M KCl, 1.20-1.25 M KCl, and 1.80-2.00 M KCl, and a main product soluble in 2.00 M KCl. These fractions were analyzed, and as the first one contained very high amounts of protein, it was not studied further. Structural analysis of the rest of the fractions (F1-F3) was carried out by methylation, desulfation-methylation, IR, and 13C NMR spectroscopy. The results are consistent for F1 with a carrageenan-type backbone mainly constituted by beta-D-galactose 2-sulfate linked to alpha-D-galactose 2,3,6-trisulfate and beta-D-galactose 2,4-disulfate linked to 3,6-anhydro-D-galactose 2-sulfate as dominant diads. In F2 these diads are present together with low amounts of beta-D-galactose 2-sulfate linked to 3,6-anhydro-D-galactose 2-sulfate, whose contribution becomes higher in F3. In addition, minor but significant amounts of L-galactose were detected. F1-F3 showed potent antiviral activity against herpes simplex types 1 and 2 and dengue type 2.

Evaluation of chemical and antiviral properties of essential oils from South American plants.

The essential oils of seven aromatic plants from Córdoba, San Luis and San Juan Provinces (Argentina) were isolated by steam distillation and analysed by a gas chromatography/mass spectrometry technique. The oils were screened for cytotoxicity and in vitro inhibitory activity against herpes simplex virus type 1 (HSV-1), dengue virus type 2 (DENV-2) and Junin virus (JUNV) by a virucidal test. The oils showed a variable virucidal action according to the virus. The better relationship between cytotoxicity and antivirus action was observed with the essential oils of Heterothalamus alienus and Buddleja cordobensis against JUNV, with virucidal concentration 50% (VC50) values of 44.2 and 39.0 ppm and therapeutic indices (cytotoxicity to virucidal activity ratio) of 3.3 and 4.0, respectively. The inhibitory action was exerted by a direct interaction of virions with the oils. Virions inactivated with B. cordobensis and H. alienus essential oil were not affected in their ability to bind to the host cell. The therapeutic indices shown by these essential oils in toto were very modest, but given the complexity of their chemical composition the future identification of the precise active principle may allow the elimination of cytotoxic components and increase the selectivity of the effective compound.

Anti-herpes simplex virus activity of sulfated galactans from the red seaweeds Gymnogongrus griffithsiae and Cryptonemia crenulata.

This study presents the chemical composition and antiviral activity against herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) of sulfated galactan crude extracts and main fractions obtained from two red seaweeds collected in Brazil, Gymnogongrus griffithsiae and Cryptonemia crenulata. Most of the eighteen tested products, including homogeneous kappa/iota/nu carrageenan and DL-galactan hybrid, exhibited antiherpetic activity with inhibitory concentration 50% (IC50) values in the range 0.5-5.6 microg/ml, as determined in a virus plaque reduction assay in Vero cells. The galactans lacked cytotoxic effects and showed a broad spectrum of antiviral activity against HSV-1 and HSV-2. No direct virus inactivation was observed after virion treatment with the galactans. The mode of action of these compounds could be mainly ascribed to an inhibitory effect on virus adsorption. Most importantly, a significant protection against a murine vaginal infection with HSV-2 was afforded by topical treatment with the sulfated galactans.