Modulation of oxidative stress by doxorubicin loaded chitosan nanoparticles Ankita Leekha, Vijay Kumar, Imran Moin, Bahadur Singh Gurjar, Anita Kamra Verma Journal of Cancer Research and Practice 2019 6(2):76-84 Purpose of the Research: Chitosan nanoparticles (CHNP) are being used to modulate the generation of reactive oxygen species (ROS), as unwarranted generation of ROS can damage proteins, lipid membranes, and DNA of host cells. CHNP possess exceptional abilities to modulate antioxidants and suppress oxidative stress damage caused by the CHNP themselves in normal cells. Methods and Results: CHNP were prepared by ionic gelation in the size range of ~115 nm, with a polydispersity index of 0.365. Doxorubicin (DOX) was encapsulated in CHNP with entrapment efficiency ~48%. The modulation of free radicals and antioxidative enzymes by DOX-loaded CHNP (DLCHNP) was evaluated. The glutathione s-transferase and glutathione levels induced by DLCHNP were lower in Ehrlich ascites carcinoma cells(EACs) cells (6.60 ± 0.02 nM/min/mg protein and 0.92 ± 0.05 nM/min/mg protein, respectively) compared to void CHNP and DOX per se decreased levels of nitric oxide and superoxide dismutase (0.03 ± 0.001 nMoles and 28.84 ± 0.016 Unit/mg protein), elevated levels of GSSG (11.69 ± 0.004 nM/min/mg protein), marginally reduced levels of GSH reductase (1.87 ± 0.002 Unit/mg protein), reduced levels of GPx (31.35 ± 0.022 Unit/mg protein) and significantly enhanced levels of LPO (1.56 ± 0.01 nMoles/mg protein) indicated cellular damage. As observed in DNA fragmentation assay, void nanoparticles did not show any DNA damage whereas DLCHNP caused significant damage. Enhanced gene expressions of Cyt. C and p21 on EACs cells was observed in DLCHNP-treated cells compared to DOX per se. Conclusion: CHNP were not efficient in generating remarkable oxidative stress, but when coupled with a drug (i.e., DLCHNP) severe damage was caused to the cancer cells compared to the free drug. This indicated the potential of our encapsulated nanoparticles in drug delivery.