title: Kaempferia parviflora, a plant used in traditional medicine to enhance sexual performance contains large amounts of low affinity PDE5 inhibitors.
abstract: OBJECTIVE
  A number of medicinal plants are used in traditional medicine to treat erectile dysfunction. Since cyclic nucleotide PDEs inhibitors underlie several current treatments for this condition, we sought to show whether these plants might contain substantial amounts of PDE5 inhibitors.
  
  
  METHODS
  Forty one plant extracts and eight 7-methoxyflavones from Kaempferia parviflora Wall. ex Baker were screened for PDE5 and PDE6 inhibitory activities using the two-step radioactive assay. The PDE5 and PDE6 were prepared from mice lung and chicken retinas, respectively. All plant extracts were tested at 50 μg/ml whereas the pure compounds were tested at 10 μM.
  
  
  RESULTS
  From forty one plant extracts tested, four showed the PDE5 inhibitory effect. The chemical constituents isolated from rhizomes of Kaempferia parviflora were further investigated on inhibitory activity against PDE5 and PDE6. The results showed that 7-methoxyflavones from this plant showed inhibition toward both enzymes. The most potent PDE5 inhibitor was 5,7-dimethoxyflavone (IC(50) = 10.64 ± 2.09 μM, selectivity on PDE5 over PDE6 = 3.71). Structure activity relationship showed that the methoxyl group at C-5 position of 7-methoxyflavones was necessary for PDE5 inhibition.
  
  
  CONCLUSIONS
  Kaempferia parviflora rhizome extract and its 7-methoxyflavone constituents had moderate inhibitory activity against PDE5. This finding provides an explanation for enhancing sexual performance in the traditional use of Kaempferia parviflora. Moreover, 5,7-dimethoxyflavones should make a useful lead compound to further develop clinically efficacious PDE5 inhibitors.
authors: Department of Pharmaceutical Chemistry and Pharmacognosy, Faculty of Pharmaceutical Sciences and Center of Excellence for Innovation in Chemistry, Naresuan University, Phitsanulok 65000, Thailand.
authors: Prapapan
authors: P
authors: Temkitthawon
authors: Thomas R
authors: TR
authors: Hinds
authors: Joseph A
authors: JA
authors: Beavo
authors: Jarupa
authors: J
authors: Viyoch
authors: Khanit
authors: K
authors: Suwanborirux
authors: Wittaya
authors: W
authors: Pongamornkul
authors: Pattara
authors: P
authors: Sawasdee
authors: Kornkanok
authors: K
authors: Ingkaninan
mesh_terms: D000818:Animals; D002645:Chickens; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000378:metabolism*; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6 / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000201:enzymology; D008297:Male; D051379:Mice; D015394:Molecular Structure; D010410:Penile Erection / Q000187:drug effects*; D058986:Phosphodiesterase 5 Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010946:Plants, Medicinal; D012160:Retina / Q000201:enzymology; D027343:Rhizome; D013329:Structure-Activity Relationship; D030521:Zingiberaceae / Q000737:chemistry
chemical_list: D058986:Phosphodiesterase 5 Inhibitors; D010936:Plant Extracts; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6