## 4 Conclusions  
The variation in ultrasound-assisted extraction (UAE) parameters exhibited a positive impact on soluble phenols (TSP) and flavonoids (FLA) extracted from native Mexican pigmented corn kernel powder. By using response surface methodology, the UAE conditions were successfully optimized. The results showed that the combination of extraction time and pulse cycle had the most significant influence on the extraction of TSP. In contrast,  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{2}{c}{**Total Soluble Phenols (mg GAE/g)**} & \multicolumn{2}{c}{**Total Flavonoids (mg CE/g)**} \\ \cline{2-5}  & **Predicted** & **Experimental** & **Predicted** & **Experimental** \\ \hline Extraction time (min) & 3.158 & 3.158 & 4.188 & 4.188 \\ Pulse cycle (s) & 1.58 & 2 & 3 & 3 \\ Ultrasound power (\%) & 100 & 100 & 80 & 80 \\ Optimal response & 35.07 & 34.06 & 27.51 & 27.04 \\ \(-\)99\% confidence level & 33.98 & 33.57 & 26.52 & 26.61 \\ +99\% confidence level & 36.17 & 34.54 & 28.52 & 27.47 \\ \multicolumn{5}{c}{**Antioxidant activity**} \\ DPPH (mmol TE/g) & 80.86 \(\pm\) 0.16 & 2 & 79.77 \(\pm\) 0.33 & 2 \\ ABTS (mmol TE/g) & 43.78 \(\pm\) 0.28 & 2 & 31.31 \(\pm\) 0.19 & 2 \\ FRAP (mmol TE/g) & 59.43 \(\pm\) 0.32 & 2 & 54.65 \(\pm\) 0.60 & 2 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Predicted TSP and FLA contents and antioxidant activity of native Mexican native pigmented corn kernel powder at optimal ultrasound-assisted extraction conditions.  
extraction time was critical for FLA extraction. Additionally, the ultrasound power significantly affected the recovery yield; 100% ultrasound power was required for TSP extraction, while 80% ultrasound power was sufficient for FLA extraction. This study highlights that employing statistical tools along with ultrasound can enhance the extraction of compounds with antioxidant properties from a native Mexican pigmented corn kernel powder, which could be potentially used in functional or nutraceuticalal foods and beverages, as well as in pharmaceutical and cosmetics applications. Further studies are needed to evaluate the potential biological activities of native pigmented corn kernel extracts, as well as to evaluate their toxicological effects. Furthermore, the impact of different solvents and solid-liquid ratios in extracting bioactive from this or other native colored corn materials could be assessed.  
Conceptualization, L.M.A.-E.; methodology, S.H.-E., L.A.H.-V, V.M.G.-R., H.R.-V, N.R.-B. and Z.V.; software, H.R.-V. and J.M.R.-G.; validation, S.G.-T. and E.M.-G.; formal analysis, L.M.A.-E., S.H.-E., H.R.-V. and J.M.R.-G.; investigation, S.H.-E., L.M.A.-E. and L.A.H.-V.; resources, L.M.A.-E., S.G.-T. and V.M.G.-R.; data curation, L.M.A.-E.; writing--original draft preparation, L.M.A.-E., S.G.-T., Z.V., N.R.-B. and E.M.-G.; writing--review and editing, L.M.A.-E., S.G.-T., Z.V. and E.M.-G.; visualization, L.M.A.-E.; supervision, L.M.A.-E. and S.G.-T. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The dataset used and/or analyzed during the current study is available from the corresponding author on reasonable request.  
[PERSON] (CVU: 1319414) and [PERSON] (CVU: 629990) gratefully acknowledge the financial support for the scholarship from CONAHCYT-Mexico. Thanks to the Subcommittee of Microbial and Invertebrate Genetics Resources for Food and Agriculture, especially to the Macro-Network of the Food Industry. This work is part of the RED TEMATICA CONACYT 12.3 activities to Reduce and Valorize Food Losses and Waste Towards Sustainable Food Systems (294768). We would also like to thank [PERSON] and [PERSON] for technical support as part of their activities in the \"Early Incorporation into Research Program\" from the Centro Universitario de Los Altos of the University of Guadalajara.  
The authors declare no conflicts of interest.