Anti-inflammatory effects of ethanolic extracts from Micromeria species

Micromeria species are traditionally used as expectorant, antispasmodic and stimulant agents as well as condiments [1]. Our study aimed to evaluate in vitro modulation effects of three Micromeria ethanolic extracts on interleukin-6 (IL-6) production in comparison with hydroxycinnamic acids. IL-6 is a cytokine with various essential biological activities. It plays important roles in the regulation of immune response and inflammation [2]. Total contents of hydroxycinnamic acids were spectrophotometrically determined in aerial plant parts of M. croatica (6.8%), M. juliana (5.4%) and M. thymifolia (5.3%). TLC analysis showed the presence of caffeic, chlorogenic and rosmarinic acids in studied plant extracts. Modulation of IL-6 production in LPS-stimulated male Balb/C mice splenocytes by plant extracts (18.75–300 μg/mL), as well as caffeic acid, chlorogenic acid and rosmarinic acid (125-2000 μM) was exhibited using enzyme-linked immunosorbent assay (ELISA). None of the investigated samples showed cytotoxic effect or inhibition of cell growth of human THP-1 and HepG2 cell lines, as well as on mouse splenocytes (where we observed increased absorbance) by MTS citotoxicity test. In tested concentrations, all extracts and hydroxycinnamic acids inhibited production of IL-6 in the range of 9.5-100% and 30.6-100%, respectively. Among the extracts, the activity decreased in order M. juliana > M. croatica > M. thymifolia, percentages of inhibition were 56.6%, 54.3% and 42.1% at concentration of 75 μg/mL. These findings suggest that Micromeria ethanolic extracts possess anti-inflammatory activity, which could be attributed to the presence of hidroxycinnamic acids. References: 1. Vladimir-Kneževic, S. et al. (2000) Farm. Glas. 56:301–312. 2. Nishimoto, N., Kishimoto, T. (2004) Curr. Opin. Pharmacol. 4:386–391.