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Published on: February 7, 2018
Pharmacodynamic characterization and evaluation of oxidative stress effects of digitoxigenin derivatives on HeLa
Jessica M M Valadares1, Pedro Azalim-Neto2, Xiaofan Liu3
1Laboratório de Bioquímica Celular, Universidade Federal de São João del-Rei (UFSJ), Divinópolis, Brazil.
Abstract:
Cancer is a leading cause of death worldwide and its treatment is hampered by the lack of specificity and side effects of current drugs. Cardiotonic steroids (CTS) interact with Na+/K+-ATPase (NKA) and induce antineoplastic effects, but their narrow therapeutic window is key limiting factor. The synthesis of digitoxigenin derivatives with glycosidic unit modifications is a promising approach to develop more selective and effective antitumor agents. This study aimed to compare the pharmacological properties as well as the cytotoxic effects of digitoxigenin-α-L-amiceto-pyranoside and digitoxigenin-α-L-rhamno-pyranoside and to evaluate the mechanism of these derivatives in oxidative conditions in HeLa cells. The rhamnose derivative increased the binding affinity and inhibitory effect of digitoxigenin by approximately 5-15 times, unlike the amicetose derivative. Despite this difference, both compounds similarly increased H2O2 levels, induced membrane lipid peroxidation, and reduced GSH levels and SOD activity at nanomolar concentrations. This study highlights the importance of the sugar moiety in CTS structure for NKA binding and demonstrates that a primary mechanism of cytotoxicity of digitoxigenin derivatives may involve cellular oxidative stress, underscoring their potential as therapeutic agents for cancer treatment.
Insights
Modified cardiotonic steroids show promise for cancer treatment. The rhamnose derivative enhanced binding affinity, while both compounds induced oxidative stress and cytotoxicity in cancer cells.
Area of Science:
- Biochemistry
- Pharmacology
- Oncology
Background:
- Cancer remains a leading cause of death globally, with current treatments facing limitations due to lack of specificity and side effects.
- Cardiotonic steroids (CTS) exhibit antineoplastic effects by interacting with Na+/K+-ATPase (NKA), but their clinical use is restricted by a narrow therapeutic window.
- Modifying the glycosidic unit of digitoxigenin derivatives offers a potential strategy for developing more selective and effective anticancer agents.
Purpose of the Study:
- To compare the pharmacological properties and cytotoxic effects of two digitoxigenin derivatives: digitoxigenin-α-L-amiceto-pyranoside and digitoxigenin-α-L-rhamno-pyranoside.
- To investigate the mechanism underlying the cytotoxic effects of these derivatives, particularly in the context of oxidative stress in HeLa cells.
Main Methods:
- Synthesis and characterization of digitoxigenin-α-L-amiceto-pyranoside and digitoxigenin-α-L-rhamno-pyranoside.
- Evaluation of NKA binding affinity and inhibitory effects.
- Assessment of cytotoxic effects on HeLa cells.
- Measurement of intracellular reactive oxygen species (H2O2), lipid peroxidation, glutathione (GSH) levels, and superoxide dismutase (SOD) activity under oxidative conditions.
Main Results:
- The rhamnose derivative demonstrated a 5-15 fold increase in binding affinity and inhibitory effect compared to digitoxigenin, whereas the amicetose derivative did not show similar enhancement.
- Both digitoxigenin derivatives significantly increased intracellular H2O2 levels and induced membrane lipid peroxidation at nanomolar concentrations.
- Treatment with both compounds led to a reduction in GSH levels and SOD activity, indicating increased cellular oxidative stress.
Conclusions:
- The sugar moiety of CTS plays a crucial role in NKA binding affinity and inhibitory potency.
- Cellular oxidative stress, including increased H2O2 production and lipid peroxidation, is a primary mechanism contributing to the cytotoxicity of these digitoxigenin derivatives.
- These findings underscore the potential of modified digitoxigenin derivatives as therapeutic agents for cancer treatment, warranting further investigation.
