[Use of cell culture for the research of cytotoxic and antiviral effects of a natural extract of 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.