## 4 Discussion
As with the PAM, the knee perimeter is an essential measure to confirm experimental OA, as this test, by measuring the knee perimeter, measures oedema and indirectly inflammation [22; 31]. Previous studies showed that K/C-induced osteoarthritis causes inflammation and swelling in the knee [20; 32]. Our outcomes are in line with previous results, since, after OA induction, the knee perimeter of rats increased [20]. Similarly, to what was observed in the PAM test, both the extract treatments and the nonsteroidal anti-inflammatory drug treatment decreased knee perimeter in OA animals. Furthermore, both extract concentrations displayed identical efficiency. The phytochemical characterization of _P. tridentatum_ demonstrated its richness in phenolic compounds, which are frequently associated with anti-inflammatory activity [11; 33; 34]. In the present study, the HPLC-DAD analysis of _P. tridentatum_ leaves methanolic extract demonstrated the presence of various phytochemical compounds, predominantly quercetin, quercetin derivates, isoquercetin, and genistein. These outcomes agree with the phytochemical studies found in the literature, which describe the occurrence of these types of compounds in extracts of _P. tridentatum_[25; 35; 36]  
Phenolic compounds can act alone or by synergy to protect against damage caused by oxidative stress. In their structure, phenolic compounds display an aromatic ring that presents one or more hydroxyl substitutes, including their functional derivates. This aromatic feature in association with a highly conjugated system with multiple hydroxyl groups makes these compounds good electron or hydrogen atom donors and enhances their ability to neutralize free radicals and other reactive oxygen species [37]. As previously shown, isoquercetin and genistein, phenolic compounds present in _P. tridentatum_ extracts, could be linked to the scavenging of reactive oxygen species [38; 39; 40]. Nevertheless, our results in molecular docking analysis showed isoquercetin can also act as an agonist of PPAR\(\alpha\) and PPARV, inhibiting NF-\(\kappa\)B signaling and activation of macrophages, consequently decreasing inflammatory cytokine production (tumor necrosis factor-alpha (TNF-\(\alpha\)), interleukin (IL)-6, and II-1\(\beta\)[41]. Furthermore, isoquercetin showed an important capability to inhibit 5-LO, which decreases TNF-\(\alpha\), IL-6, and MCP-1 production, and it is also involved in inflammation [42]. Additionally, isoquercetin and genistein demonstrated very strong molecular interactions with CK2\(\alpha\), which is known to inhibit NF-\(\kappa\)B activation in macrophages and subsequently IL-1, IL-6, and IL-10 cytokine secretion [43; 44]. Finally, the inhibition of COX-1 by quercetin and genistein can act by decreasing the levels of arachidonic acid, thus decreasing the production of bioactive prostanoids [45; 46]. In the literature, studies about the effect of _P. tridentatum_ on inflammation are scarce and do not identify the mechanism of action, but some reports support our results. [PERSON] et al. [11] evaluated the anti-inflammatory activity of _P. tridentatum_ (methanolic, petroleum ether, and ethyl acetate extracts), and their results demonstrated the inhibition of TNF-\(\alpha\) levels in human monocytes. Likewise, [PERSON] et al. [47] assessed the anti-inflammatory activity of _P. tridentatum_ ethanolic extracts and demonstrated a downregulation of the Nos2 gene, along with a decrease in the transcription of the pro-inflammatory genes IL1b, IL6, and PtgS2.