Effects of the essential oil of Croton zehntneri and its major components, anethole and estragole, on the rat corpora cavernosa.

AIMS: The effects of the essential oil of Croton zehntneri (EOCz) and its major components anethole, estragole and methyl eugenol were evaluated in phenylephrine precontracted rat corpora cavernosa (RCC). MAIN METHODS: RCC strips were mounted in 5 ml organ baths for isometric recordings of tension, precontracted with 10 µM phenylephrine and exposed to test drugs. KEY FINDINGS: All major compounds relaxed RCC. The order of potency was estragole>anethole>methyl eugenol. The maximal relaxation to EOCz and methyl eugenol was 62.67% (IC50 of 1.67 µM) and 45.8% (IC50 of 1.7 µM), respectively. Estragole relaxed RCC with an IC50 of 0.6 µM (maximal relaxation-76.6%). The maximal relaxation to estragole was significantly reduced by L-NAME (43.46%-IC50 of 1.4 µM), ODQ (53.11%-IC50 of 0.83 µM) and indomethacin (24.41%-IC50 of 1.3 µM). On the other hand, anethole relaxed RCC by 66.73% (IC50 of 0.96 µM) and this relaxation was blunted by indomethacin (35.65%-IC50 of 1.6 µM). Both estragole and anethole increased the relaxation achieved upon electrical stimulation. Both compounds increased the levels of cAMP (estragole by 3-fold and anethole by 2-fold when compared to controls). Estragole also increased the levels of cGMP (0.5-fold). SIGNIFICANCE: The higher potency of these compounds to relax corpora cavernosa smooth muscle may form the pharmacological basis for the use of such substances as leading compounds in the search of alternative treatments of erectile dysfunction.