title: Screening for phosphodiesterase inhibitory activity of Thai medicinal plants.
abstract: BACKGROUND
  Phosphodiesterases (PDEs) are a group of enzymes that have powerful effects on cellular signaling because they regulate the second messenger, cAMP or cGMP. PDE inhibitors have been used for treatment of many indications such as cardiovascular diseases, chronic obstructive pulmonary diseases, erectile dysfunction and pulmonary hypertension.
  
  
  OBJECTIVE
  The aim of the study was to search for sources of PDE inhibitors from Thai biodiversity.
  
  
  METHODS
  Some Thai medicinal plants used as aphrodisiac and neurotonic agents together with plants from Leguminosae collected from the North of Thailand were screened for PDE inhibitory activity using a radioassay.
  
  
  RESULTS
  Seven from nineteen aphrodisiac and neurotonic plants as well as three from twelve Leguminosae plants showed potent PDEs inhibitory activity. The concentrations that could inhibit 50% PDE activity (IC(50)) of the active extracts were determined in comparison to the standard inhibitor, 3-isobutyl-1-methylxanthine (IBMX). Betula alnoides, Hiptage benghalensis, Leea indica and Senna surrattensis showed IC(50) values in the range of microgram per milliliter while IBMX standard showed an IC(50) value of 0.68+/-0.13 microg/ml.
  
  
  CONCLUSIONS
  Thai biodiversity was the great sources of PDE inhibitors.
authors.affiliation: Department of Pharmaceutical Chemistry and Pharmacognosy, Faculty of Pharmaceutical Sciences, Naresuan University, Phitsanulok 65000, Thailand.
authors.forename: Prapapan
authors.initials: P
authors.lastname: Temkitthawon
authors.forename: Jarupa
authors.initials: J
authors.lastname: Viyoch
authors.forename: Nanteetip
authors.initials: N
authors.lastname: Limpeanchob
authors.forename: Wittaya
authors.initials: W
authors.lastname: Pongamornkul
authors.forename: Chawlada
authors.initials: C
authors.lastname: Sirikul
authors.forename: Anchana
authors.initials: A
authors.lastname: Kumpila
authors.forename: Khanit
authors.initials: K
authors.lastname: Suwanborirux
authors.forename: Kornkanok
authors.initials: K
authors.lastname: Ingkaninan
mesh_terms: D044822:Biodiversity; D020128:Inhibitory Concentration 50; D008518:Medicine, East Asian Traditional; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D012588:Scintillation Counting / Q000379:methods; D013785:Thailand
chemical_list: D010726:Phosphodiesterase Inhibitors