Anti- and pro-oxidant potential of lettuce (Lactuca sativa L.) biofortified with iodine by KIO(3), 5-iodo- and 3,5-diiodosalicylic acid in human gastrointestinal cancer cell lines

Vegetables are particularly rich sources of micronutrients and phytochemicals such as polyphenols and vitamins. These plant-derived bioactive compounds provide antitumor and antioxidant properties due to their capacity to interact with reactive oxygen species (ROS). The objective of this study was to determine the effect of iodine biofortification (potassium iodate/KIO(3)/, 5-iodosalicylic acid/5-ISA/, and 3,5-diiodosalicylic acid/3,5-diISA/) on the antioxidant activity of lettuce (Lactuca sativa L. capitata) cv. ‘Melodion’. In this work, HPLC analysis was used to identify polyphenolic compounds while the antioxidant activity of iodine-enriched vegetables was determined by using DPPH, ABTS and FRAP methods. The content of the water-soluble vitamins was analyzed by using the LC-MS/MS technique. The impact of extracts from iodine-biofortified lettuce on production of reactive oxygen species (ROS) in gastrointestinal cancer cells was also evaluated. The results from this research indicate that application of iodine compounds improves the antioxidant potential of lettuce by increasing the concentration of some vitamins, antioxidant enzymes and polyphenolic compounds in the enriched plants. Moreover, the study has shown that iodine-biofortified lettuce induces production of ROS in cancer cells, resulting in an anticancer effect by the induction of programmed cancer cell death.