antioxidants Article Implications of Oxidative Stress in Glioblastoma Multiforme Following Treatment with Purine Derivatives Marta Orlicka-Płocka 1,† , Agnieszka Fedoruk-Wyszomirska 1,† , Dorota Gurda-Wo´zna 1 , Paweł Pawelczak 1 , Patrycja Krawczyk 2, Małgorzata Giel-Pietraszuk 1, Grzegorz Framski 1 , Tomasz Ostrowski 1 and Eliza Wyszko 1,* 1 Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland;
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[email protected] † Equally contributed as the first author. Abstract: Recently, small compound-based therapies have provided new insights into the treatment of glioblastoma multiforme (GBM) by inducing oxidative impairment. Kinetin riboside (KR) and newly designed derivatives (8-azaKR, 7-deazaKR) selectively affect the molecular pathways crucial for cell growth by interfering with the redox status of cancer cells. Thus, these compounds might serve as potential alternatives in the oxidative therapy of GBM. The increased basal levels of reactive oxygen species (ROS) in GBM support the survival of cancer cells and cause drug resistance. The simplest Citation: Orlicka-Płocka, M.; approach to induce cell death is to achieve the redox threshold and circumvent the antioxidant Fedoruk-Wyszomirska, A.; defense mechanisms. Consequently, cells become more sensitive to oxidative stress (OS) caused by Gurda-Wo´zna,D.; Pawelczak, P.; exogenous agents.