Forty-seven plant extracts of 10 species of the genus
Euphorbia
(
Euphorbia
ceae) used by Colombian traditional healers for the treatment of ulcers,
cancers, tumors, warts, and other diseases, were tested in vitro for their
potential antitumour (antiproliferative and cytotoxic) and antiherpetic
activity. To evaluate the capacity of the extracts to inhibit the lytic
activity of herpes simplex virus type 2 (HSV-2) and the reduction of viability
of infected or uninfected cell cultures, the end-point titration technique
(EPTT) and the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide] colorimetric assay were used, respectively. The therapeutic index
of the positive extracts for the antiviral activity was determined by calculating
the ratio CC
50
(50% cytotoxic concentration) over IC
50
(50% inhibitory concentration of the viral effect). Five of the 47 extracts
(11%) representing 3 out of 10
Euphorbia
species (30%) exhibited antiherpetic action; the highest activity was found
in the leaf/stem water-methanol extracts from
E.
cotinifolia
and
E.
tirucalli
. The therapeutic indexes of these two plant species were > 7.1; these extracts
exhibited no cytotoxicity. Six extracts (13%) representing 4 plant species
(40%) showed cytotoxic activity. The highest cytotoxicity was found in the
dichloromethane extract obtained from
E. cotinifolia
leaves and the CC
50
values for the most susceptible cell lines, HEp-2 and CHO, were 35.1 and
18.1 mg/ml, respectively.
