RESUMO
<p><b>OBJECTIVE</b>To investigate the effects of total alkaloids of Tripterygium hypoglaucum Hutch (THH) on the tk gene of mouse lymphoma cells.</p><p><b>METHOD</b>L5178Y cells were infected with total alkaloids of THH with different concentrations and put into single-cell wells at different time phases. Then the numbers of positive wells were counted and the cell plating efficiency, relative suspension growth and mutation frequency were determined.</p><p><b>RESULT</b>Total alkaloids of THH (0.1-2.0 g x L(-1)) induced tk locus mutation with mutation frequency 2-9 times higher than that of spontaneous mutation frequency of L5178Y cells. There were two different phenotypes of mutation colonies, large colony and small colony, but the main colony was large colony. This phenomenon might be related with the mutagenesis of THH.</p><p><b>CONCLUSION</b>Total alkaloids of THH can exert toxicity and mutagenic effects on tk gene in L5178Y cells, and there may be range limit in gene mutation.</p>