Comparative pharmacology of chemically distinct NADPH oxidase inhibitors.
OBJECTIVE
Oxidative stress [i.e. increased levels of reactive oxygen species (ROS)] has been suggested as a pathomechanism of different diseases, although the disease-relevant sources of ROS remain to be identified. One of these sources may be NADPH oxidases. However, due to increasing concerns about the specificity of the compounds commonly used as NADPH oxidase inhibitors, data obtained with these compounds may have to be re-interpreted.


METHODS
We compared the pharmacological profiles of the commonly used NADPH oxidase inhibitors, diphenylene iodonium (DPI), apocynin and 4-(2-amino-ethyl)-benzolsulphonyl-fluoride (AEBSF), as well as the novel triazolo pyrimidine VAS3947. We used several assays for detecting cellular and tissue ROS, as none of them is specific and artefact free.


RESULTS
DPI abolished NADPH oxidase-mediated ROS formation, but also inhibited other flavo-enzymes such as NO synthase (NOS) and xanthine oxidase (XOD). Apocynin interfered with ROS detection and varied considerably in efficacy and potency, as did AEBSF. Conversely, the novel NADPH oxidase inhibitor, VAS3947, consistently inhibited NADPH oxidase activity in low micromolar concentrations, and interfered neither with ROS detection nor with XOD or eNOS activities. VAS3947 attenuated ROS formation in aortas of spontaneously hypertensive rats (SHRs), where NOS or XOD inhibitors were without effect.


CONCLUSIONS
Our data suggest that triazolo pyrimidines such as VAS3947 are specific NADPH oxidase inhibitors, while DPI and apocynin can no longer be recommended. Based on the effects of VAS3947, NADPH oxidases appear to be a major source of ROS in aortas of SHRs.
Wind
S
S
Rudolf-Buchheim-Institute for Pharmacology, Justus-Liebig-University, Giessen, Germany.
Beuerlein
K
K
Eucker
T
T
Müller
H
H
Scheurer
P
P
Armitage
M E
ME
Ho
H
H
Schmidt
H H H W
HH
Wingler
K
K
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D018938:Caco-2 Cells; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors*; D009861:Onium Compounds / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013450:Sulfones / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology
C553815:3-benzyl-7-(2-oxazolyl)thio-1,2,3-triazolo(4,5-d)pyrimidine; D000098:Acetophenones; D004791:Enzyme Inhibitors; D009861:Onium Compounds; D011743:Pyrimidines; D017382:Reactive Oxygen Species; D013450:Sulfones; D014230:Triazoles; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; C007517:diphenyleneiodonium; C056165:acetovanillone; D019255:NADPH Oxidases