Cardiovascular activities of loranthus ferrugineus roxb. "methanol extract and its fractions
| dc.contributor.author | Ameer, Omar Ziad | |
| dc.date.accessioned | 2015-07-30T03:10:02Z | |
| dc.date.available | 2015-07-30T03:10:02Z | |
| dc.date.issued | 2009 | |
| dc.description.abstract | Loranthus ferrugineus Roxb. is a hemiparasitic shrub traditionally used for treatment of hypertension. In the present study, the cardiovascular effects-guided fractionation of L. ferrugineus was performed in an attempt to identify the active fraction and determine its mechanism of action. The plant was dried, pulverized and successively extracted with petroleum ether, chloroform, ethyl acetate, methanol and water. Each extract was dried under reduced pressure and freeze-dried. The effect of each extract was examined on isolated rat aortic ring and anesthetized rat preparations. The methanol extract (LFME) was found to be the most potent in shifting the log concentration response curve of noradrenaline (NA) to the right with reduced maximum response. It suggests that the extract acts as a non-competitive inhibitor to NA. The methanol extract was also found to be the most potent in lowering blood pressure of anesthetized rats. Similar to acetylcholine (Ach), pretreatment with atropine significantly (P<0.05) decreased the blood pressure lowering effect of LFME which suggests that LFME acts as cholinergic agonist. Similarly, pretreatment with Nmnitro- L-arginine methyl ester (L-NAME, 10 mg/kg) significantly (P<0.05) inhibited the reduction in mean arterial pressure (MAP) induced by LFME. Conversely, no significant (.?>0.05) changes in MAP were seen following intravenous injections of neostigmine (40 J.Lg/kg), hexamethonium (30 mg/kg), propranolol (2 mg/kg) and prazosin (50 J.Lg/kg). By means of solvent-solvent extraction, the aqueous LFME solution was successively fractionated using chloroform, ethyl acetate and n-butanol. The effects of the freeze-dried fractions were then investigated in anesthetized rat preparation. Among the four fractions, then-butanol fraction of LFME (NBF-LFME) was found to cause the largest and longest lowering of blood pressure. The NBF-LFME (l.OOE-5-3.00 mg/mL) also caused the largest inhibition of phenylephrine (PE)- and high K+ -induced aortic ring contraction. Removal of the endothelium of the aortic ring completely abolished the vascular relaxing properties of NBF-LFME. Pretreatment with atropine (1 11M), L-NAME (10 11M), indomethacin (10 11M) and methylene blue (10 )lM) significantly (?<0.001-0.05) blocked NBFLFME- mediated relaxation. NBF-LFME (0.05, 0.1 and 0.3 mg/rnL) did not significantly (.?>0.05) alter the concentration-dependent contractile effect induced by cumulative additions of calcium (3.00E-03-3.00E-02M) in high K+ (80 mM) depolarized aortic rings incubated in calcium-free Kreb's solution. Endothelium-dependent and -independent relaxations induced by Ach and sodium nitroprusside (SNP), respectively, were significantly (?<0.001-0.05) enhanced in aortic rings pretreated with NBF-LFME (0.3 mg/rnL). On the contrary, glibenclamide (10 )lM), propranolol (1 )lM) and prazosin (0.01 )lM) did not (.?>0.05) alter NBF-LFME-induced relaxation. In guinea-pig ileum preparation, NBF-LFME (0.065-4 mg/rnL) induced concentration-dependent contraction. This contraction was significantly (P<O.OOl) inhibited by atropine (1 ~tM) but potentiated by neostigmine (0.05 )lM). Hexamethonium (100 )lM) had no effect on NBF-LFME-induced contraction. The results suggest that L. ferrugineus induced its cardiovascular effects by stimulating cardiovascular muscarinic receptor, activating the endothelium-derived nitric oxidecGMP- relaxant pathway, promoting prostacyclin release and/or possibly through its ability to lengthen the released nitric oxide half life. Chemical analysis of NBF-LFME using UV and IR spectroscopies, thin layer chromatography, column chromatography and HPLC indicated the presence ofterpenoids in the J\il3F-LFME. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/945 | |
| dc.language.iso | en | en_US |
| dc.subject | Loranthus ferrugineus | en_US |
| dc.subject | Methanol extract | en_US |
| dc.title | Cardiovascular activities of loranthus ferrugineus roxb. "methanol extract and its fractions | en_US |
| dc.type | Thesis | en_US |
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