Inhibitory effect of eugenol on rat ileal motility in vitro

Abstract

Eugenol, an essential oil of clove oil possesses several different pharmacological properties, including antimicrobial, antifungal, insecticidal and antihelmintic. With regard to the digestive tract, eugenol has shown spasmolitic and relaxant effects. To elucidate some of the mechanisms involved, the effects of eugenol on contractions of isolated rat ileum induced by electrical field stimulation (EFS) were investigated. Eugenol (100 µM) significantly and reversibly reduced EFS induced contractions by approximately 80%. Control contractions were 2.00±0.18 g, while contractions in the presence of eugenol decreased to 0.40±0.02 g (n=7; P=0.0001), respectively. Moreover, eugenol (100 µM) reversibly decreased ileal basal tonus from 0.88±0.04 g to 0.65±0.04 g (n=7; P=0.0002). After incubation with the nitric oxide synthase inhibitor nitro-Larginine methyl ester (L-NAME), eugenol (100 µM) still significantly inhibited ileum contractions (reduction by 75.30%), from 1.70±0.09 g to 0.42±0.08 g (n=6; P=0.0001), respectively. Likewise, incubation with L-NAME did not alter the eugenol relaxant effect on ileal basal tonus. Mean control basal tonus was 0.84±0.07 g and significantly decreased after the addition of eugenol (100 µM), to 0.37±0.09 g (n=6; P=0.0003). After incubation with 300 µM of L-NAME mean basal tonus was 0.85±0.08 g, while eugenol significantly relaxed ileal preparations in the presence of L-NAME to 0.34±0.11 g (n=6; P=0.0003). Our results suggest that eugenol reversibly inhibits contractions caused by EFS and induces relaxation of rat ileum via a mechanism largely independent of NO activity.

Eugenol, aktivni princip ulja karanfilića, poseduje različita farmakološka svojstva, kao što su antimikrobno, antimikotičko, insekticidno i antihelmintičko. U digestivnom traktu deluje spazmolitički i relaksantno. U cilju bližeg upoznavanja mehanizma dejstva eugenola, ispitan je njegov efekt na kontrakcije iziolovanog ileuma pacova izazvane spoljnom stimulacijom (electrical field stimulation-EFS). Eugenol (100 µM) signifikantno, reverzibilno redukuje kontrakcije ileuma izazvane EFS za oko 80%. Kontrolne kontrakcije iznosile su 2,00 ± 0,18 g, dok su kontrakcije u prisutvu eugenola bile 0,40 ± 0,02 g (n=7; P=0,0001). Eugenol (100 µM), takođe signifikantno smanjuje i bazalni tonus izolovanog ileuma sa 0,88 ± 0,04 g na 0,65 ± 0,04 g (n=7; P=0,0002). Posle inkubacije sa ihibitorom sintaze azotnog oksida L-NAME, eugenol i dalje signifikantno redukuje kontrakcije ileuma (za 75,30%) sa kontrolnih 1,70 ± 0,09 g na 0,42±0,08 g (n=6; P=0,0001). Isto tako, inkubacija sa L-NAME ne utiče na relaksantni efekt eugenola na bazalni tonus ileuma. Kontrolna srednja vrednost bazalnog tonusa bila je 0,84 ± 0,07 g i signifikantno je smanjena posle dodavanja eugenola (100 µM) na 0,37 ± 0,09 g (n=6; P=0,0003). Posle inkubacije sa 300 µML-NAME, srednji bazalni tonus bio je 0,85±0,08 g, dok je eugenol i u prisustvu L-NAME relaksirao izolovani ileum na 0,34 ± 0,11 g (n=6; P=0,0003). Dobijeni rezultati ukazuju da eugenol reverzibilno inhibiše kontrakcije ileuma izazvane spoljnom stimulacijom i dovodi do relaksacije izolovanog ileuma pacova mehanizmom nezavisnim od aktivnosti azotnog oksida.