title: Chemical composition and vascular and intestinal smooth muscle relaxant effects of the essential oil from Psidium guajava fruit.
abstract: BACKGROUND
  Psidium guajava L. (Myrtaceae) is widely used in traditional medicine for the treatment of various ailments including cardiovascular and gastrointestinal disorders.
  
  
  OBJECTIVE
  The current study investigated the chemical composition and cardiovascular and gastrointestinal effects of the essential oil of P. guajava.
  
  
  METHODS
  The chemical composition of the essential oil was investigated using gas chromatography-mass spectrometry (GC-MS) technique. The biological activity of the essential oil was tested on rabbit aorta and jejunum. All changes in isometric tension were recorded through a force transducer coupled with a bridge amplifier data acquisition system.
  
  
  CONCLUSIONS
  GC-MS analysis showed the presence of butanoic acid methyl ester, 3-methyl glutaric anhydride, 1-butanol, 3-hexenal, cinnamyl alcohol, 1-hexanol and hexane as the major components. In isolated rabbit aorta preparations, the essential oil showed vasorelaxation at doses of 3-10 mg/mL against high K+and phenylephrine pre-contractions with EC50values of 5.52 (5-6.04) and 6.23 mg/mL (5.0-7.46). The essential oil inhibited spontaneous and high K+induced contractions in isolated rabbit jejunum with EC50values of 0.84 (0.3-1.38) and 0.71 mg/mL (0.3-1.12) and shifted Ca+2concentration curves to the right, similar to verapamil, suggesting spasmolytic activity mediated possibly through Ca+2channel blockade.
  
  
  CONCLUSIONS
  In summary, the data indicated the presence of seven different phytoconstituents in the essential oil of P. guajava and calcium channel blocking activity, which provides a pharmacological base to the traditional use of P. guajava in cardiovascular and gastrointestinal disorders. Further studies are suggested to explore the molecular nature of these effects.
authors.affiliation: a Department of Pharmacy , COMSATS Institute of Information Technology , Abbottabad , Pakistan.
authors.forename: Hafiz Majid
authors.initials: HM
authors.lastname: Rasheed
authors.affiliation: a Department of Pharmacy , COMSATS Institute of Information Technology , Abbottabad , Pakistan.
authors.forename: Taous
authors.initials: T
authors.lastname: Khan
authors.affiliation: b Biotechnology Program, Department of Environmental Sciences , COMSATS Institute of Information Technology , Abbottabad , Pakistan.
authors.forename: Fazli
authors.initials: F
authors.lastname: Wahid
authors.affiliation: c Institute of Chemical Sciences, University of Peshawar , Peshawar , Pakistan.
authors.forename: Rasool
authors.initials: R
authors.lastname: Khan
authors.affiliation: a Department of Pharmacy , COMSATS Institute of Information Technology , Abbottabad , Pakistan.
authors.forename: Abdul Jabbar
authors.initials: AJ
authors.lastname: Shah
mesh_terms: D000818:Animals; D005638:Fruit / Q000737:chemistry; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009822:Oils, Volatile / Q000032:analysis / Q000494:pharmacology*; D010276:Parasympatholytics / Q000494:pharmacology*; D031647:Psidium / Q000737:chemistry*; D011817:Rabbits
chemical_list: D009822:Oils, Volatile; D010276:Parasympatholytics
keywords: Guava fruit; Myrtaceae; spasmolytic; vasorelaxant