Biological activity of orange peel extracts obtained by natural deep eutectic solvents

Preradom naranče, kao jednog od najviše korištenih agruma u svijetu, stvara se velika količina otpada, primarno u obliku kore. Kora naranče predstavlja veliku količinu biomase bogate biološki aktivnim spojevima koji bi se mogli izdvojiti te koristiti u prehrambenoj i farmaceutskoj industriji. U skladu s načelima zelene kemije, ključno je pronaći proces ekstrakcije bioaktivnih komponenti iz biljnih izvora koji je ekonomski održiv i prihvatljiv za okoliš. U tom smislu su se eutektička otapala pokazala kao dobra zamjena za organska otapala konvencionalno korištena u procesima ekstrakcije, koja su često hlapiva i štetna za okoliš. U ovom radu ispitano je citotoksično djelovanje ekstrakta kore naranče pripravljenog u euteltičkom otapalu kolin-klorid:glicerol s različitim udjelima vode te je istražen tip stanične smrti na HeLa i HaCaT stanicama. Najjače djelovanje pokazao je ekstrakt pripremljen u ChClGly s 30 % (v/v) vode, u odnosu na ekstrakte u puferu i ChClGly s 80 % (v/v) vode, koji nisu pokazali značajni učinak na rast stanica. Djelovanje ekstrakta pripremljenog u ChClGly s 30 % (v/v) vode ovisno je o dozi i vremenu trajanja tretmana, a može se povezati s indukcijom nekroze kod HeLa stanica te apoptoze kod HaCaT stanica. Jača citotoksičnost ekstrakata kod HeLa stanica u odnosu na HaCaT stanice ukazuje na potencijalno antitumorsko djelovanje ekstrakta kore naranče, čija je biološka aktivnost izraženija u prirodnom eutektičkom otapalu nego u konvencionalnom otapalu. As one of the most used citrus fruits in the world, orange produces a large amount of waste, mostly in the form of peels. Orange peel represents a large amount of biomass rich in bioactive compounds that could be reused in the food and pharmaceutical industry. According to green chemistry principles, it is essential to invent an extraction process that is economically acceptable and safe for the environment. According to this, deep eutectic solvents have shown to be an excellent substitute to commonly used organic solvents in extractions that are often volatile and harmful to the environment. In this paper, the cytotoxic ability of orange peel extract prepared in choline-chloride:glycerol with different water ratios has been explored, as well as the type of cell death on HeLa and HaCaT cell cultures. The extract prepared in ChClGly with 30 % (v/v) water has shown the strongest antiproliferative effects compared to the ones prepared in buffer solution and ChClGly with 80 % (v/v) water. The effect of the extract in ChClGly with 30 % (v/v) water is dose- and time-dependent, and could be connected with the induction of necrosis in HeLa cells, and apoptosis in HaCaT cells. Extracts prepared in buffer solution and ChClGly with 80 % (v/v) water have shown no significant results. The cytotoxic effect that was stronger on HeLa cells than on HaCaT cells could imply potential antitumor properties of orange peel extract whose biological activity has also been enhanced in natural deep eutectic solvents in comparison to conventional solvents.