[Use of cell culture for the research of cytotoxic and antiviral effects of a natural extract of Amaryllidaceae]. / Utilisation des cultures cellulaires pour la recherche des effets cytotoxiques et antiviraux d'un extrait naturel d'Amaryllidaceae.

The use of tissue culture for evaluation of antiviral agents can provide rapid information on the toxicity induced by drugs. Toxicity is assessed through 4 different tests: observation through a light microscope, colorimetric evaluation of living cells stained with MTT (Methyl Thiazol Tetrazolium), colorimetric evaluation of fixed cells stained with crystal violet, inhibition of incorporation of radioactive labelled precursors specific to the synthesis under study. These tests allowing evaluation of effects on cell morphological changes (1), of modifications of mitochondrial and enzymatic activities in the cytoplasm (2), of effects on cell growth (3) and on their major synthesis [ADN, ARN, proteins] (4). This design of experiments has been applied to an hydroalcoolic extract from Haemanthus albiflos (Amaryllidaceae) tested for its antiviral properties towards Poliovirus type 1 propagated on monkey kidney cells line (MA 104). The maximum tolerated dose by the cell and the inhibition of virus replication were determined according to tests 2 and 3. The sensitive step of the virus replication cycle was investigated using test 4. Concentration of 7 microliters/ml plant extract showed: 20% cytotoxicity (MTT test). At 7 microliters/ml plant extract the inhibition of replication virus is 4.5 log units (microplates assay) and inhibition of proteins viral synthesis is 97% compared with the control.

[Study of antiviral action of total alkaloids from Haemanthus albiflos]. / Etude de l'action antivirale des alcaloïdes totaux d'Haemanthus albiflos.

Investigations were undertaken on the antiviral action level of an alkaloïd extract from Haemanthus albiflos bulb, earlier reported as efficient against RNA viruses. Rotavirus propagated on MA 104 cells with different concentrations of the extract was used in the assays. Incidence on cellular and viral RNA synthesis was evaluated by measuring the radioactivity incorporated using labelled precursors. An inhibition of 42% and 79% of the cellular RNA synthesis was observed when respectively 25 microliters/ml and 50 microliters/ml concentrations of the alkaloïd extract were tested. After 20 h incubation a decrease of the viral RNA synthesis was observed. It was of 46%, 36% and 27% compared to the control when respectively 25 microliters/ml, 50 microliters/ml and 100 microliters/ml concentrations of the extract were tested. Besides, the maximum viral production was delayed parallelly to the increase of the extract concentration. A similar viral synthesis inhibition was obtained after only 4 hours incubation suggesting that the extract interfere in the early events of the viral cycle.

[Plants as a source of research in antiviral activity. Example of the Haemanthus albiflos bulb]. / Les plantes comme source de recherche d'activité antivirale. Exemple du bulbe d'haemanthus albiflos.

The antiviral potency of an hydroalcoholic extract from Haemanthus albiflos (AMARYLLIDACEAE) bulb was investigated. Experimentations were conducted on continuous cell lines (BGM, MA 104, Hep 2) seeded in microplates. Three viruses from the RNA group (Poliovirus type I, Vesicular Stomatitis Virus type 11 and Simian Rotavirus SA 11) and two from the DNA group (Adenovirus type 5, Herpes Simplex Virus type 1) were tested. Important reduction in yield of viral infectivity was observed with the RNA group (respectively 6,4 and 4,5 logarithmic units order of magnitude).

[Antiviral effect of Haemanthus albiflos leaves extract on herpes virus, adenovirus, vesicular stomatitis virus, rotavirus and poliovirus]. / Effet antiviral d'un extrait de feuilles d'Haemanthus albiflos sur le virus de l'herpès, l'Adénovirus, le virus de la stomatite vésiculeuse, le Rotavirus et le Poliovirus.

An hydro-alcoholic extract from Haemanthus albiflos leaves (Amaryllidaceae) was tested for its potential antiviral activity against two DNA viruses: herpes simplex virus type I, Adenovirus type 5 and three RNA viruses: poliovirus type I, vesicular stomatitis virus, simian Rotavirus SA 11. Positive results were obtained against herpes virus and all the RNA viruses tested.