title: Identification of flavonoids with trypsin inhibitory activity extracted from orange peel and green tea leaves.
abstract: BACKGROUND
  Orange peel (Citrus sinensis) and green tea (Camellia sinensis) leaves, rich sources of food flavonoids, were analyzed for their trypsin inhibitory potential. Hesperetin, rutin and hesperidin from orange peel, and catechin from green tea leaves, were isolated and their chemical structures were analyzed. All four compounds were evaluated for their trypsin inhibitory potential.
  
  
  RESULTS
  Among all the isolated compounds, rutin exhibited the highest protease inhibition activity (75.4 ± 0.9%) with IC50 = 16 ± 2 µmol L(-1), followed by catechin (65.3 ± 1.4%; IC50 = 83 ± 9 µmol L(-1)), hesperetin (62.1 ± 1.3%; IC50 = 104 ± 12 µmol L(-1)) and hesperidin (59.7 ± 1.1%; IC50 = 127 ± 14 µmol L(-1)). Lineweaver-Burk and Dixon plots and their secondary replots indicated that all four compounds possessed non-competitive inhibition. The Ki values of hesperetin, rutin, hesperidin and catechin were calculated as 90.2 ± 1.1, 17.5 ± 0.6, 84.2 ± 1.5 and 65.1 ± 1.5 µmol L(-1) respectively.
  
  
  CONCLUSIONS
  The present results suggest that the four isolated flavonoids can be used as a supplement in food for the treatment of pathologies associated with the degradation of a specific protein.
authors.affiliation: Department of Chemistry, Government College University, Lahore, Pakistan. drdshahwar@yahoo.com
authors.forename: Durre
authors.initials: D
authors.lastname: Shahwar
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Raza
authors.lastname: Atta-Ur-Rahman
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000302:isolation & purification / Q000494:pharmacology; D032084:Citrus sinensis / Q000737:chemistry*; D019587:Dietary Supplements; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology*; D005638:Fruit / Q000737:chemistry*; D006569:Hesperidin / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D018515:Plant Leaves / Q000737:chemistry*; D012431:Rutin / Q000302:isolation & purification / Q000494:pharmacology; D014357:Trypsin / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D005419:Flavonoids; D014361:Trypsin Inhibitors; D012431:Rutin; D002392:Catechin; D006569:Hesperidin; D014357:Trypsin; C013015:hesperetin
keywords: enzyme inhibition; enzyme kinetics; medicinal plants; phenolic compounds