Effect of eucalyptol on matrix metalloproteinase-9 and its tissue inhibitor in hypertensive rats

Effects of eucalyptol, a key component of eucalyptus globules, on matrix metalloproteinase-9 (MMP-9) and its tissue inhibitor (TIMP-1), compared with lisinopril, were investigated in a model of hypertension induced by chronic intraperitoneal (IP) injection of low dose nicotine in rats. The hypertensive rats were randomly allocated to 4 groups (n=8): Positive control (PC, untreated), eucalyptol-treated group (1.0 mg/kg, IP), lisinopril-treated group (10 mg/kg, IP), and eucalyptol+lisinopril-treated group. Systolic blood pressure and plasma levels of MMP-9 and TIMP-1 were measured. All treatments decreased the elevated blood pressure and plasma levels of MMP-9 and TIMP-1 most significantly with the combination group which showed non-significant differences from the normal control group. Lisinopril reduced plasma levels of MMP-9 and TIMP-1 more significantly than eucalyptol. In conclusion, eucalyptol significantly decreased the increased plasma levels of MMP-9 and TIMP-1 in nicotine-induced hypertension in rats. Moreover, its combination with lisinopril exerted more significant effects compared to each drug alone. This makes this combination particularly useful in hypertension and related cardiovascular disorders where suppression of MMP-9 and TIMP-1 activities decreases the related complications and improves the overall morbidity and mortality. To our knowledge, the current data are novel, and may open the way for development of a co-delivery system of both drugs which could be beneficial in treatment of hypertension in chronic smokers.