Antiviral activity of south Brazilian medicinal plant extracts.

Brazilian plants are potential sources of useful edible and medicinal plants. Hydromethanolic extracts prepared from 54 medicinal plants used in folk medicine to treat infections were screened for antiviral properties against five different viruses (HSV-1, HSV-2, poliovirus type 2, adenovirus type 2 and VSV). Fifty-two percent of the plant extracts exhibited antiviral against one or more tested viruses. More specifically, 42.6% showed activity against HSV-1 (herpes simplex virus type 1), 42.6% against HSV-2 (herpes simplex virus type 2), 26% against poliovirus and 24% against VSV (vesicular stomatitis virus). None of the extracts was active against adenovirus. Trixis praestans (Vell.) Cabr. and Cunila spicata Benth. extracts were further characterized for antiviral activity.

Mechanism of antiviral activity of triterpenoid saponins.

Triterpenoid saponins are naturally occurring sugar conjugates of triterpenes possessing various biological activities, including antiviral action. Two substances isolated from natural sources were tested against herpes simplex virus type 1 replication. They did not show evidence of cytotoxicity under antiviral test conditions. The triterpenoid saponin, isolated from a Brazilian plant (s21), represents the oleanane group and inhibited herpes simplex virus type 1 DNA synthesis. The triterpenoid saponin, isolated from a Chinese plant (s17), represents the ursane group and seemed to inhibit viral capsid protein synthesis of herpes simplex virus type 1.

Antipoliovirus structure-activity relationships of some aporphine alkaloids.

A series of 18 aporphinoids have been tested in vitro against human poliovirus. The aporphines (+)-glaucine fumarate (1), (+)-N-methyllaurotetanine (4), (+)-isoboldine (7), and (-)-nuciferine, HCl (10) were found to be active with selectivity indices > 14. The nature of the 1, 2-substituents of the isoquinoline moiety appeared to be critical for antipoliovirus activity. An SAR study demonstrated the importance of a methoxyl group at C-2 on the tetrahydroisoquinoline ring for the induction of antipoliovirus activity. Molecular modeling of some compounds in this series revealed the close similarities between the three-dimensional conformational features of the inactive 1,2-substituted derivatives (+)-boldine (6) and (+)-laurolitsine (5) with derivatives containing the 1,2-(methylenedioxy) moiety, which were generally found to be inactive as exemplified by (+)-cassythicine (9).

Anti-herpes virus activity of aporphine alkaloids.

We evaluated, in cell cultures, the action of a series of 19 aporphine alkaloids against Herpes simplex virus type 1 (HSV-1). On the basis of viral titre reduction, six alkaloids were found to be active. The mode of action of the three most potent inhibitors, oliverine HCl, pachystaudine, and oxostephanine, was studied. These compounds did not have any virucidal or prophylactic effect but they were shown to interfere with the viral replicative cycle. Although DNA synthesis was reduced, their exact target remains to be elucidated. In the discussion, some structure-activity relationships are considered.

Mutagenic and membranal effect of a phytotoxic molecule isolated from olive leaves parasitized by the fungus Cycloconium oleaginum Cast.

A phytotoxic substance (C23H44O3) which is named 'Substance A', was purified from olive leaves infected with Cycloconium oleaginum Cast. The mutagenic effect of this substance was detected using TA 100 and TA 102 strains of Salmonella in the Ames test using Bacillus subtilis strains M45 rec-, H17 rec+ in the rec assay. Another substance manifesting the mutagenic effect was found in the extract from the Cycloconium oleaginum culture. This substance was not detected in the extract from contaminated olive leaves. Substance A increased electrolytes leakage from tissue of olive leaves, thus manifesting its phytotoxicity.

Comparison of the anti-herpes simplex virus activities of propolis and 3-methyl-but-2-enyl caffeate.

The in vitro activity against herpes simplex virus type 1 of 3-methyl-but-2-enyl caffeate isolated from poplar buds or prepared by synthesis was investigated. Under conditions of one or multiple multiplication cycles, this compound, which is a minor constituent of propolis, was found to reduce the viral titer by 3 log10, and viral DNA synthesis by 32-fold.

Synergistic effect of flavones and flavonols against herpes simplex virus type 1 in cell culture. Comparison with the antiviral activity of propolis.

The in vitro activity against herpes simplex virus type 1 of the major flavonoids identified in propolis was investigated. Flavonols were found to be more active than flavones, the order of importance being galangin, kaempferol, and quercetin. The efficacy against HSV-1 of binary flavone-flavonol combinations has been also investigated. The synergy demonstrated by all combinations could explain why propolis is more active than its individual compounds.

Search for "in vitro" antiviral activity of a new isoflavonic glycoside from Ulex europaeus.

Extracts from Ulex europaeus L. (Fabaceae) were tested for antiviral activity against HSV-1 and poliovirus. It was found that the n-butanolic extract significantly inhibited the replication of these viruses, as shown by inhibition of cytophathic effects and reduction of plaques; the extract has neither a prophylactic nor a virucidal activity. From this extract has been isolated and identified by chromatographic, chemical, and spectroscopic methods, the 5-O-methylgenistein 7-O-beta D-glucopyranoside. This isoflavonic glycoside has not been previously described and it is responsible at least partially for the antiviral activity.

[The effect of modification of the intracellular distribution of polyamines on the proliferation of hepatocytes treated with 2-methyl-9-hydroxyellipticine]. / Influence d'une modification de la repartition intracellulaire des polyamines sur la proliferation d'hepatocytes traites par la methyl-2-hydroxy-9 ellipticine.

2-Methyl-9-hydroxyellipticine (MHE) added to tumoral hepatocyte cultures (400 ng MHE/ml medium) is responsible for a cytostatic effect. This decrease of cellular proliferation and of DNA synthesis is accompanied by an increase of intracellular free spermidine levels. We could not attribute this result to a deviation of this polyamine metabolism. These increased concentrations of free spermidine are connected to a decrease of the amount of nuclear bound polyamines, mainly joined with the RNA fraction. Thus, the cytostatic effect observed with this drug might be related to a decrease in the amount of spermidine connected to RNA; therefore, its intercalating effect is only indirectly responsible for the cellular proliferation decrease.

[Inhibitory effects of some crude and semi-purified extracts of indigenous French plants on the multiplication of human herpesvirus 1 and poliovirus 2 in cell culture]. / Effets inhibiteurs de quelques extraits bruts et semi purifiés de plantes indigènes françaises sur la multiplication de l'herpesvirus humain 1 et du poliovirus humain 2 en culture cellulaire.

Within a valorization program of natural regional resources, 50 ethanolic extracts of 41 indigenous plants have been subjected to chemical tests and antiviral screening. Four plants: Bryonia dioìca, Anthyllis vulneraria, Matricaria chamomilla, and M. inodora inhibit the growth of poliovirus. Furthermore, three (A. vulneraria, M. Chamomilla, and M. inodora) have an antiherpetic effect.

[Behavior of alpha-tocopherol during the autoxidation of linoleic acid in aqueous solution]. / Comportement de l'alpha-tocophérol au cours de l'autoxydation de l'acide linoléique en milieu aqueux.

Addition of great quantity of alpha-tocopherol to an aqueous solution containing linoleic acid dispersed with twen 20 conduce to an important augmentation of the rate of formation of linoleic hydroperoxides. In these particular conditions, alpha-tocopherol have a prooxidant effect. In the same time, alpha-tocopherol is rapidly transformed into tocopherylquinone and a dimer of alpha-tocopherol. Transitorily there is formation of a dihydroxydimer of alpha-tocopherol. Comparison of these compounds behaviour on the oxydation rate of linoleic acid in the same conditions show a near relation between a prooxidant effect and chemical structure of these compounds as well as alpha-tocopherol. So, alpha-tocopherol and its dihydroxydimer are both prooxidant and both have a free hydroxyl on carbon 6. Dimer of alpha-tocopherol and tocopherylquinone are both antioxidant and they have neither free hydroxyl on carbon 6. alpha-tocopherol acetate in the same conditions have an antioxidant comportment. This confirms the importance of free hydroxyl on carbon 6 to obtain a prooxidant effect.