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Updated: Jun 27, 2026

Functionalized Spirocyclic Heterocycle Synthesis and Cytotoxicity Assay
Published on: February 9, 2021
2,3-dehydrosilybin is a better DNA topoisomerase I inhibitor than its parental silybin
Piyanut Thongphasuk1, Wolfgang Stremmel, Walee Chamulitrat
1Department of Gastroenterology and Infectious Diseases, University Hospital Heidelberg, Im Neuenheimer Feld 345 EG, Heidelberg, Germany.
Background:
We have shown that compared with silybin, 2,3-dehydrosilybin (DHS) exhibits more potent in vitro anticancer activities alone or in combination with tumor necrosis factor (TNF)-alpha. Since TNF-alpha sensitization is related to DNA topoisomerase (topo) inhibition, DHS may be a potent topo inhibitor.
Methods:
Under significant apoptosis induction by DHS, we measured specific topo I activity in nuclear extracts or purified enzyme.
Results:
Treatment of more transformed FIB cells with 30 microM DHS for 24 h caused significant decreases in topo I activity in nuclear extracts while silybin did not have any effects. Less transformed EPI cells were more resistant against DHS-induced topo I inhibition. Inhibitory effects of topo I activity by DHS were also found in cell-free assays using purified topo I, whereas silybin again did not have any effects.
Conclusion:
DHS is a potent topo I inhibitor rendering its ability to sensitize TNF-alpha for enhanced cytotoxicity.
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