In Vivo Assessment of Anti-Inflammatory Effects of Aqueous Extracts of Nepeta nuda ssp. nuda L. in Experimental Model of Peripheral Inflammation in Male Long Evans Rats

<b>Background</b>: Recently various plants have attracted considerable scientific interest as potential therapeutic alternatives to known drugs used in anti-inflammatory therapy. Therefore, we have investigated the possible anti-inflammatory and analgesic effects of aqueous extracts from flowers of the medical plant <i>Nepeta nuda</i> ssp. <i>nuda</i> L. (naked catmint) in a model of acute peripheral inflammation induced by intraplantar injection of λ-carrageenan in the hind paw of Long Evans rats. <b>Methods</b>: Two routes of <i>N. nuda</i> extract application were used: locally by intraplantar injections at dosages of 2.5 mg/kg and 25 mg/kg and systemically by intraperitoneal administration at dosages of 50 mg/kg and 200 mg/kg, respectively. Paw volume was measured prior to the carrageenan application and 1, 2, 3, and 4 h after carrageenan injection. Spontaneous locomotor activity of the rats was assessed 3 h after carrageenan injection, corresponding to the peak of acute paw inflammation. <b>Results</b>: Local application of the higher <i>N. nuda</i> dose led to a marked reduction in inflammatory paw edema at the 4th hour after carrageenan injection, comparable to the effect of the positive control diclofenac sodium. Interestingly, a similar anti-inflammatory effect was observed at the 1st hour when both extract doses were administered intraperitoneally. Only the higher intraplantar dose of <i>N. nuda</i> extract significantly enhanced the vertical activity in comparison to the group treated with carrageenan alone. <b>Conclusions</b>: Our data indicate that the aqueous <i>N. nuda</i> extract possesses potent anti-inflammatory effects following both local and systemic administration in rats. Furthermore, when administered locally the extract exerts significant analgesic activity in inflammatory pain.