## 4 Conclusions  
Overall, the results of this study show that the seeds of three different cultivars of _O. ficus-indica_ from the Souk Ahras area of Algeria represent a valuable source of nutrients and bioactive compounds. An oil rich in essential fatty acids can be extracted that can be potentially used as table or cooking oil. Moreover, the results show that these seeds contain significant levels of antioxidants. The concentration of total phenolic compounds was higher in the yellow cultivar, while flavonoid and tannin contents were higher in the orange one. The antioxidant activity of seed extracts is significant, but a variability that depends on the cultivar was observed in the different assays performed. The green and orange cultivars had a higher reducing power, while yellow and green cultivars had higher anti-radical activity. Positive and negative correlations were observed between the different activities and the concentrations of antioxidants measured, indicating that these compounds participate, according to the concentration, in antioxidant and antiradical effects. Also, these observations indicate that the concentration factor alone does not explain the results obtained. Therefore, it would be desirable to purify and identify the compounds present in seed extracts, apply more experimental protocols, and carry out the test on other varieties of prickly pear.  
Finally, for a complete valorization of this plant species in Algeria, the current study should be integrated with analyses of other parts of the fig tree that are considered as waste in the future, and with further bioactivity tests on whole extracts and isolated chemical constituents.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app1303144/s1](https://www.mdpi.com/article/10.3390/app1303144/s1)]([https://www.mdpi.com/article/10.3390/app1303144/s1](https://www.mdpi.com/article/10.3390/app1303144/s1)), Figure S1: Chromatogram of the standard phenols mixture; Figure S2: Representative HPLC chromatograms of _O. ficus-indica_ seed extract at 280 nm.  
Conceptualization, A.B. and F.B.; methodology, A.B., F.B., H.B., H.M. and G.P.; software, A.B.; validation, G.P., H.B. and A.B.; formal analysis, A.B.; investigation, G.P.; resources, A.B.; data curation, G.P.; writing--original draft preparation, A.B.; writing--review and editing, G.P.; visualization, A.B.; supervision, H.B.; project administration, A.B.; funding acquisition, A.B. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Antioxidants** & \multicolumn{2}{c}{**Antioxidant Activities**} \\ \hline  & **EC\({}_{50}\) RP** & **EC\({}_{50}\) DPPH** \\ \hline TPC & 0.261 & 0.890 * \\ TFC & \(-0.657\)* & \(-0.520\) \\ TC & 0.742 * & \(-0.320\) \\ EC\({}_{50}\) RP & - & 0.042 \\ \hline \hline \end{tabular}  
* \(p\leq 0.05\). RP: reducing power; TPC: total phenolic content; TFC: total flavonoid content; TC: tannin content.  
\end{table}
Table 6: Results of the correlation analysis between measured antioxidant activities of prickly pear seeds and the classes of antioxidants monitored.  
**Acknowledgments:** The authors are grateful to [PERSON] (Ankara Gazi University, Department of Biology, Developmental Biology and Biotechnology, Turkey) for the plant identification. They want also to acknowledge the Ministry of Higher Education and Scientific Research (MHESR, Algeria) for the financial support. Finally, thanks also to the Laboratory of Science and Techniques for Living, Department of Agricultural Sciences, Institute of Agriculture and Veterinary Sciences, University of Souk Ahras, and NOPALTEC Algeria Cooperative, Sidi-Fredj, Souk Ahras region, Algeria.  
**Conflicts of Interest:** The authors declare no conflict of interest.