Effect of Harvesting at Different Times on Antioxidant Potential and Phytochemical Contents of <i>Kickxia lanigera</i> and <i>Kickxia spuria</i> subsp. <i>integrifolia</i> : In Vitro and In Silico Studies

ABSTRACT Thanks to the various biological effects of the secondary metabolites it contains, plants have been used to treat various diseases. Free radicals, generated by psychological and biochemical processes, cause disease in the human body, as well as oxidation, decomposition, and microbial reactions in food all of which have negative effects. Various Kickxia species are used to treat different diseases in traditional medicine. This study investigated the content analysis (HPLC‐DAD) and antioxidant activities (total antioxidant, reducing power, H 2 O 2 scavenging and DPPH • scavenging) of methanol‐chloroform extracts of K. lanigera and K. spuria subsp. integrifolia harvested at different time points. Additionally, molecular dynamics were employed to determine the interaction and binding energy of the primary components (as identified by HPLC‐DAD analysis) of Kickxia species with antioxidant enzymes, such as glutathione peroxidase and human erythrocyte catalase. HPLC‐DAD analysis revealed that the main components were gallic acid and trans‐ferulic acid. Although the results of the antioxidant activity tests varied according to the time of harvest and the type of activity, the extracts generally showed greater activity than the standards in the H 2 O 2 scavenging tests. According to the molecular docking results, gallic acid (−6.80 kcal/mol) was found to have a higher binding energy than trans‐ferulic acid (−5.90 kcal/mol). MM/PBSA analysis revealed that the binding energies of gallic acid and trans‐ferulic acid with catalase were −9.08 and −28.73 kcal/mol, respectively.