Physiological Effects of Eucalyptus camaldulensis Dehn Fractions on Isolated Aorta and Trachea in Male Albino Rats: PhD Thesis

Abstract The aim of the present study was to identify the chemical composition of essential oil of Eucalyptus camaldulensis, collected from Kurdistan region of Iraq. The current study represents the first qualitatively and quantitatively detailed documentation study using different methods for the determination of essential oil constituents. The current study also aimed to investigate the effect of E. camaldulensis leaves extracts on isolated aortic and tracheal rings. Eucalyptus camaldulensis leave oils obtained by hydrodistillation (EOS, EOW, EOA and EOAr) showed a different ratio and constituents in oil composition of samples that varied qualitatively and quantitatively. The major constituents of essential oils obtained from all the samples were monoterpenese, except in EOF in which the major constituents were sesquiterpense. The major content of monoterpense percentages in EOS, EOW, EOAr, EOA, EOE, EOD and EOF were about 88%, 85%, 77%, 83%, 95%, 96% and 19%, respectively. On the other hand, sesquiterpenese percentage were 9%, 13%, 7%, 12%, <1%, <4% and 79%, respectively. The main component of monoterpene, 1,8-cineole percentage in EOS, EOW, EOA, EOE and EOD ranged from 53.4 to 89.25%. On the other hand, its percentages in EOAr and EOF ranged only from 2.98 to 10.1%. The percentage of other main compounds were also variable, such as alpha-terpinol (0.4-17.3%), o-cymene (0.16-12.09%), terpinen-4-ol (0.18-3.86%) and aromadendrene (0.15-3.97%). Moreover the ratios of other compounds that were not identified in all samples were also variable, such as crypton ranged from (0.16 to 13.9%), valencen (0.2 to 12.55%), spathulenol (1.65 to 10.52%) and globulol (0.18 to 10.25). Furthermore, the essential oil obtained from Medium Performance Liquid Chromatography (MPLC) fraction showed higher amounts of sesquiterpense; such as valencen, spathulol, globulol and other main compounds, and it showed a lower amount of monoterpense; such as 1,8-cineole, carvacrol and alpha-terpinol. The results showed that solvent extraction with ethyl acetate and MPLC technique was a useful method for obtaining sesquiterpense. On the other hand, for obtaining monoterpense, it is more useful to use hydrodistillation to obtain essential oils of the plant, and it is better to use more than one method to get detailed documentation. The results of the current study demonstrated that aqueous extract (AE) (10-2- 3mg/ml) and hydromethanolic extract (HME) (10-2- 3mg/ml) produced a relaxation in phenylphrine (PE) precontracted aortic rings. The cumulative addition of the plant extract caused vasorelaxation in concentration-dependent manner in precontracted aortic rings, in both AE and HME, with percentage of relaxation 68.017% and 60.75%, respectively. Pretreatment of aortic rings with nifedipine, significantly decreased the vasodilatory response in the mode of both AE and HME with the percentage of relaxation 15.002% and 22.352%, respectively. On the other hand, K+ channel blockers tetraethylammonium (TEA) (1mM), glibenclamide (GLIB) (10-5), barium chloride (BaCl2) (1mM) and 4-aminopyridine (4-AP) (1mM) did not alter vasodilation in aortic rings. Furthermore, the vasoactive substances which are released from endothelium, NO and cyclooxygenase pathway did not play a role in the vasodilation induced by HME in PE precontracted aortic rings. Methanolic extract (ME) (10-2- 3mg/ml) produced a vasorelaxation in aortic rings on PE-induced contractions, with percentage of relaxation 82.246%. The relaxant effect in thoracic aortic rings was inhibited significantly by using GLIB (10-5), and 4-AP (1mM), with percentage of relaxation of 46.979% and 59.59 %, respectively. Pretreatment with nifedipine, inhibited the percentage of relaxation to 31.38%. Ethyl acetate extract (EA) (10-2- 3mg/ml) E produced a vasorelaxation in aortic rings on PE-induced contractions, with percentage of relaxation 87.265%.