Research Article For reprint orders, please contact: reprints@future-science.com Enhancing anticancer activity through the combination of bioreducing agents and triterpenes Barbara Bednarczyk-Cwynar 1 , Piotr Ruszkowski 2 , Tomasz Jarosz 3,4 & Katarzyna Krukiewicz* ,3 1 Department of Organic Chemistry, Poznan University of Medical Sciences, 60-780 Poznan, Poland 2 Department of Pharmacology, Faculty of Pharmacy, Poznan University of Medical Sciences, 60-806 Poznan, Poland 3 Department of Physical Chemistry & Technology of Polymers, Silesian University of Technology, 44-100 Gliwice, Poland 4 Department of Inorganic, Analytical Chemistry & Electrochemistry, Silesian University of Technology, 40-100 Gliwice, Poland * Author for correspondence: Tel.: +48 32 237 1305, katarzyna.krukiewicz@polsl.pl Aim: Triterpenes are natural compounds, whose wide biological activity predestines them for application as promising new chemotherapeutics. In this paper, we report the results of our investigations into the substitution of oleanolic acid with aromatic and nitroaromatic moieties acting as bioreducing agents. Results: The process of reduction of nitro groups was investigated through cyclic voltammetry, UV–Vis and electron paramagnetic resonance spectroelectrochemistry. The cytotoxic activity against selected cancer cell lines was determined, showing a signifcant increase in cytotoxicity when the triterpene is equipped with a nitroaromatic moiety. Conclusion: We believe this approach to the functionalization is promising in terms of enhancing anticancer activity. We also indicate electrochemical techniques as advantageous preclinical screening methods for the identifcation of cytotoxic agents. Graphical abstract: -20 E / V vs Fc/Fc + I / μA -2.0 10 -15 -10 -5 0 5 -1.8 -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 0.0 l / nm Absorbance 0.7 0.1 0.2 0.3 0.4 0.5 0.6 700 300 400 500 600 B / mT 336 337 338 339 340 341 0 Cell line IC 50 / μM HeLa 120 20 40 60 80 100 KB MCF-7 A-549 HDF * ** *** * ** *** * ** *** * ** *** * ** *** -2.0 V -1.9 V -1.8 V -1.7 V -1.6 V -1.5 V -1.4 V -1.3 V -1.2 V -1.1 V 0 V Oleanolic acid BzOMe DiNO 2 OMe O 2 N O O N O O CH 3 O 2 N NO 2 First draft submitted: 4 July 2017; Accepted for publication: 22 November 2017; Published online: 9 February 2018 Keywords: anticancer activity • bioreducing agents • triterpenes Triterpenes are naturally derived compounds that exhibit a wide range of biological activities; they show anticancer, antiviral, antibacterial, antioxidant, anti-inflammatory and analgesic effects [1]. Their cytotoxic properties result Future Med. Chem. (Epub ahead of print) ISSN 1756-8919 10.4155/fmc-2017-0154 C  2018 Newlands Press