DNA protection, molecular docking, molecular dynamic, enzyme inhibition, and kinetics studies of apigenin isolated from <i>Nepeta baytopii</i> Hedge &amp; Lamond by bioactivity-guided fractionation

Plant-derived bioactive substances have demonstrated significant qualities that suggest they may be crucial in preventing various chronic diseases. Flavonoids, which include apigenin, are the biggest group of polyphenols. In our study, we aimed to obtain the methanol-chloroform (1:1) extract from the aerial parts of <i>Nepeta baytopii</i> Hedge & Lamond and purify the apigenin using bioactivity-guided isolation to separate the active fraction. The current <i>in vitro</i> study provides updated knowledge on apigenin regarding its previously unresearched DNA protection activity and enzyme inhibition, enzyme inhibition kinetics, and enzyme-apigenin interactions. In this context, these studies will be the first and will contribute to the literature. Apigenin had high urease (IC₅₀-5.00 ± 0.00 µM), butyrlcholinesterase (BChE:IC₅₀-10.48 ± 0.00 µM), and tyrosinase (IC₅₀-177.82 ± 14.40 µM) inhibition activities, while inhibition binding constants were high in urease (K<i>_i</i>-0.05 mM), tyrosinase (K<i>_i</i>-0.06 mM), and carbonic anhydrase (K<i>_i</i>-0.08 mM). The binding affinities and constants of the interaction were also ascertained to be high for BChE (-9.50 kcal/mol, and K<i>_i</i>-0.11 µM), and tyrosinase (-8.80 kcal/mol, and K<i>_i</i>, 0.62 µM) with apigenin. In summary, apigenin can be used as an inhibitor for five enzymes. These results will give priority to further studies. Apigenin showed high DNA protection activity with a Form I value of 67.37%. These data demonstrated that the interaction formed by BChE-apigenin gave the best results regarding enzyme inhibition and enzyme-molecule interaction. The stability of this complex was evaluated using molecular dynamics modeling.