Cell experiment:

Human U937 cells are cultured in RPMI1640 supplemented with 10% fetal bovine serum. To differentiate U937 cells, 2×106 cells/mL are treated with phorbol 12-myristate 13-acetate (PMA) of 20 ng/mL for 24 h. The PMA is removed by washing and adherent cells are then allowed to recuperate for 40 h. The recuperated cells are subsequently incubated with lipopolysaccharide of 1 μg/mL for 6 h with Cynaropicrin and positive control drugs. Supernatants are harvested and assayed by ELISA kit for human TNF-α[1].

Animal experiment:

Male Swiss mice are used in this study. Mice are housed at a maximum of 8 per cage and kept in a conventional room at 20 to 24℃ under a 12 h to 12 h light-dark cycle. The animals are provided with sterilized water and chow ad libitum. Infection is performed by i.p. injection of 104 or 5×103 bloodstream trypomastigotes. The animals (18 to 21 g) are divided into the following groups (at least five mice per group): uninfected (noninfected and untreated), untreated (infected with T. cruzi but treated only with vehicle), and treated (infected and treated i.p. with 0.5 to 50 mg/kg/day compound (including Cynaropicrin) or 100 mg/kg/day benznidazole). Mice receive 0.1 mL (i.p.) at 5 and 8 days postinfection (dpi), or at 11, 12, and 13 dpi for the dose of 25 mg/kg, twice a day (b.i.d.)[3].

Cynaropicrin is a sesquiterpene lactone which can inhibit tumor necrosis factor (TNF-α) release with IC50s of 8.24 and 3.18 μM for murine and human macrophage cells, respectively. Cynaropicrin also inhibits the increase of cartilage degradation factor (MMP13) and suppresses NF-κB signaling.

Cynaropicrin strongly inhibits lipopolysaccharide-induced TNF-α release from either murine or human macrophage cells in a dose-dependent manner with the IC50 values of 8.24 and 3.18 μM, respectively. Cynaropicrin shows significant inhibitory effects toward all mitogenic signals with the IC50 values of 1.20 (concanavalin A), 1.02 (phytohemagglutinin) and 0.90 μM (lipopolysaccharide), respectively. Cynaropicrin suppresses CTLL-2 cell proliferation in a dose-dependent manner and the 50% inhibitory concentration (IC50) of Cynaropicrin for CTLL-2 cell growth is 0.91 μM[1]. The increased mRNA expression of MMP13 induced by TNF-α is similarly inhibited in a concentration-dependent manner by Cynaropicrin. The increased mRNA expression of HIF-2α induced by IL-1β in SW1353 is inhibited in a concentration-dependent manner by Cynaropicrin[2].

[1]. Cho JY, et al. In vitro anti-inflammatory effects of cynaropicrin, a sesquiterpene lactone, from Saussurea lappa. Eur J Pharmacol. 2000 Jun 23;398(3):399-407. [2]. Masutani T, et al. Cynaropicrin is dual regulator for both degradation factors and synthesis factors in the cartilage metabolism. Life Sci. 2016 Aug 1;158:70-7. [3]. da Silva CF, et al. Activities of psilostachyin A and cynaropicrin against Trypanosoma cruzi in vitro and in vivo. Antimicrob Agents Chemother. 2013 Nov;57(11):5307-14.