## 3 Results and Discussion  
Identification and Quantification of Flavonoids with Antiproliferative Potential in the Polyphenol Extract of Mexican Oregono L. gravelopens  
For the analysis and identification of flavonoids, the molecular ion and the fragments obtained in each peak found in the spectra of polyphenol extract (Figure 1) were taken as a reference and compared with the compounds' data reported for other oregano species as well as in the database Massbank of North America (MoNA). The flavonoid concentration was calculated using the reference standards of each compound. The data obtained can be seen in Table 1.  
According to the literature, among the main flavonoids reported with antiproliferative activity in cells of different types of cancer are luteolin, quercetin, naringenin, and apigenin [34; 46; 47; 48; 49]. These have been reported to exert this activity by interacting with \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**MS** & **[M-H]-** & **Fragmentation Pattern** & **Flavonoid** & **Concentration (\(\mu\)g/g)** \\ \hline
302.04 & 301.03 & 302.03, 303.04 & Quercetin & 250.23 \(\pm\) 18.15 \\
286.04 & 285.04 & 151.00, 286.04 & Luteolin & 38.24 \(\pm\) 1.12 \\
272.06 & 271.06 & 151.00, 177.02, 269.04 & Naringenin & 7758.71 \(\pm\) 32.15 \\
270.05 & 269.04 & 151.00, 270.05 & Apigenin & 122.60 \(\pm\) 10.65 (EQ) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Flavonoids with antiproliferative potential identified in the polyphenic extract of Mexican oregano _L. gravelopens_. Figure 1: Molecular ions and fragments obtained for each flavonoid found in the spectra of the polyphenol extract of Mexican oregano _Lippia gravelopens_. different cell signaling pathways [50; 51]. Some of the chemical characteristics of these phenolic compounds that have been identified with antiproliferative properties are the presence of double bonds between C2 and C3, the presence of an -OH group at the 3'-position of the B-ring of quercetin, unsubstituted allylic hydrogen at C3 and two adjacent -OH groups on the B-ring, the presence of the ortho-dihydroxy group on the B-ring at the 1' and 2' positions of trihydroxylfavone derivatives, the presence of amino side chains of the N-heterocyclic ring in the apigenin derivatives, which increases their antiproliferative activity, and the ortho functional group at position 4 and a double bond at C2-C3 [52; 53; 54; 55]. In our oregano extract, we were able to identify the presence of these compounds, finding the highest concentration naringenin at 7758.71 \(\pm\) 32.15 \(\upmu\)g/g extract, followed by quercetin and apigenin at 250.23 \(\pm\) 18.15 and 122.60 \(\pm\) 10.65 (EQ) \(\upmu\)g/g extract, respectively; the compound with the lowest concentration in our extract was luteolin at 38.24 \(\pm\) 1.12 \(\upmu\)g/g extract. It is important to mention that the total phenol content of this polyphenonic extract is 143.87 \(\pm\) 1.29 mg of GAE/g, which was already reported in our previous work with this species of oregano. In addition, we were able to identify the presence of other phenolic acids and flavonoids of importance in anticancer research, such as rosmarinic acid, caffeic acid, gallic acid, eriodictylol, and baicalin, among others [29]. The compounds of our polyphenol extract coincide with the data reported for other oregano species, such as _Origanum dictamus, Origanum marjorana_, and _Lippia micromen_[56; 57; 58; 59]. In addition, some species of oregano with a similar content of flavonoid compounds have shown antiproliferative activity in breast cancer cells [11; 12; 60; 61]. Identifying and quantifying the presence of these compounds in our extract allowed us to guide our research towards the elucidation of the mechanism of action of the same, in this case, to know if the inhibition of proliferation in breast cancer cells was by activating the apoptosis pathway, one of the most studied and important in the research and development of new drugs for the treatment of this type of disease.