Pharmacological Study Of Clove Oil And Its Main Constituents

Clove oil is derived from Caryophyllus aromaticus. It has been used traditionally as carminative, antiemetic, hypotensive, toothache remedy and counter irritant. Eugenol which is a simple phenolic compound and forms the major constituent of clove oil has a wide spread therapeutic application in dentistry for the treatment of toothache. However, these uses have not been well studied on scientific basis. This work aimed to study the scientific evidence of safety and efficacy of clove oil and its major constituent eugenol.Adult albino mice were used to test the acute toxicity of intraperitoneal injection of both clove oil and eugenol. Also, the effects of both agents were tested on different vascular beds and on mammalian heart preparations isolated from rabbits. In addition, clove effects were studied on isolated rabbit’s jejunum, guinea pig’s tracheal spiral strip, frog’s rectus abdominis muscle and rat’s uterus. Male rats were used to detect the effect of both clove oil and eugenol on some cardiovascular parameters including blood pressure and heart rate.The results were tabulated and statistically analyzed using the SPSS. The results were also presented in forms of histograms.The present work proved that there is no significant difference between the toxic doses of intraperitoneal injection of both clove oil and eugenol denoting that eugenol is the most toxic constituent of clove oil.Our work demonstrated that both clove oil and eugenol produced concentration-dependant depressant effect on cardiac contractility. However, the -ve inotropic effect of eugenol was more profound than that of clove oil. This could explained by K+ channel blocking activity of one of the constituents of clove oil.Also, both agents caused reduction in the adrenaline induced +ve inotropic action. The reduction mediated by eugenol was significantly different from that of clove oil. This is due to the ability of one constituent of clove oil to inhibit Na+/K+ ATPase with subsequent increase in the intracellular Ca++.As regard the effects of both clove oil and eugenol on different vascular beds, both agents have vasodilating effect as they decrease the amplitude of contraction induced by NA. On comparing the effects of both agents, this work showed that clove oil is more potent than eugenol as vasodilator agent. This referred to the presence of other constituents of clove oil which potentiate its vasodilating effect as - caryophyllene.Clove oil has concentration related reduction of the amplitude of rhythmic contraction of isolated rabbit’s jejunum and on the amplitude of contraction induced by both histamine and ACh in guinea pig’s tracheal spiral strip and on ACh-induced contraction of rat uterus.This work showed that clove oil (in low concentrations) produced concentration-dependant reduction in ACh-induced contraction of frog’s rectus abdominis muscle. However, in high concentration, it increased the height of contraction induced by ACh.As regard the effects of both clove oil and eugonl on MAP and HR of anaesthetized normotensive and pithed normotensive rats, this work showed that both agents have hypotensive effect and bradycardia. But the hypotnesion and bradycardia resulted from clove oil administration showed significant difference from that induced by eugenol.