title: Inhibition of angiotensin-converting enzyme by aqueous extract of tomato.
abstract: OBJECTIVE
  To investigate the presence of anti-angiotensin converting enzyme (ACE) factors in aqueous extract of tomato.
  
  
  METHODS
  The bio-guided fractionation of the aqueous extract of tomato produced a sugar-free, heat-stable fraction with molecular mass <1,000 Da from tomatoes. The sugar-free tomato extract (TE) was tested for its anti-ACE activity using human plasma and rabbit lung pure ACE. In addition, its effect on human platelet aggregation induced by ADP, collagen or arachidonic acid was determined. The mechanism of platelet inhibitory action of TE was investigated by measuring platelet factor 4 (PF4) release and cAMP synthesis by platelets.
  
  
  RESULTS
  Typically, 100 g tomatoes produced 72.2 ± 4.7 mg of TE. This extract inhibited both platelet aggregation and plasma ACE activity in a dose-dependent manner. It inhibited platelet aggregation in response to ADP, collagen or arachidonic acid, and inhibitory action was mediated in part by reducing platelet PF4 release and by stimulating cAMP synthesis. The IC50 value of TE for ADP-induced platelet aggregation was 0.4 ± 0.02 mg/ml, whereas the IC50 value for ACE enzyme inhibition was 1.40 ± 0.04 mg/ml. Both the TE and commercially available sugar-free TE, Fruitflow(®)-2 had similar amount of catechin, and also had equal inhibitory potencies against platelet aggregation and plasma ACE activity.
  
  
  CONCLUSIONS
  Together these data indicate that aqueous extract of tomatoes contain anti-ACE factors in addition to previously described anti-platelet factors.
authors.affiliation: Department of Nutrition, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, PO Box 1046, Blindern, 0316, Oslo, Norway.
authors.forename: Dipankar
authors.initials: D
authors.lastname: Biswas
authors.forename: Md Main
authors.initials: MM
authors.lastname: Uddin
authors.forename: Lili L
authors.initials: LL
authors.lastname: Dizdarevic
authors.forename: Aud
authors.initials: A
authors.lastname: Jørgensen
authors.forename: Asim K
authors.initials: AK
authors.lastname: Duttaroy
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D062385:Hydroxybenzoates / Q000032:analysis / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000737:chemistry*; D007703:Peptidyl-Dipeptidase A / Q000097:blood*; D010936:Plant Extracts / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011817:Rabbits
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D062385:Hydroxybenzoates; D010936:Plant Extracts; D010975:Platelet Aggregation Inhibitors; D016718:Arachidonic Acid; D003094:Collagen; D000242:Cyclic AMP; D007703:Peptidyl-Dipeptidase A; C017616:phenolic acid