Abstract
Aflatoxin B1 (AFB1) action on cyclic nucleotide phosphodiesterase (PDE) activity has been tested on tissue extracts of various organs. In the presence of 100 μM AFB1 a significant inhibition of cAMP and cGMP hydrolytic activity is observed in all tested tissue extracts. However, cGMP hydrolytic activity appears more sensitive to AFB1 inhibition than cAMP hydrolytic activity and a considerably higher inhibition is observed in lung and spleen, than in liver, brain, kidney, and heart. When cGMP is used as substrate, the inhibitory response reaches 72% in lung and spleen extracts. We have also tested AFB1 effects on lung and liver PDE activity peaks separated by DEAE-cellulose chromatography. These data confirm the poor sensitivity to the toxin of all PDE activities present in liver, while the lung peak (where PDE V in present) shows a higher sensitivity to AFB1. In order to establish whether PDE V is in fact more sensitive to AFB1, we have used mouse neuroblastoma cells, in which cGMP hydrolytic activity has been shown to be due to PDE V only. In this case, the calculated IC50 is 24 μM and Dixon plot analysis shows a competitive inhibitory effect with a Ki of 16.7 μM. We have also used aflatoxin B2 and M2, and they proved to be much less effective than AFB1: AFB2 inhibits PDE V with an IC50 of 117 μM, while AFM2 does not show any effect. These results provide the first evidence of a competitive inhibition of AFB1 on an enzymatic activity and suggest that an alteration of cellular cyclic nucleotide levels may play a role in the mechanism of aflatoxin action. All rights reserved. Copyright (C) 1999 Elsevier Science Inc.
| Original language | English |
|---|---|
| Pages (from-to) | 615-619 |
| Number of pages | 5 |
| Journal | General Pharmacology |
| Volume | 32 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - May 1999 |
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Keywords
- Aflatoxin B
- High affinity cyclic nucleotide phosphodiesterase
- PDE V isoform
ASJC Scopus subject areas
- Pharmacology
Cite this
Aflatoxin B1 is an inhibitor of cyclic nucleotide phosphodiesterase activity. / Bonsi, Paola; Augusti-Tocco, Gabriella; Palmery, Maura; Giorgi, Mauro.
In: General Pharmacology, Vol. 32, No. 5, 05.1999, p. 615-619.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Aflatoxin B1 is an inhibitor of cyclic nucleotide phosphodiesterase activity
AU - Bonsi, Paola
AU - Augusti-Tocco, Gabriella
AU - Palmery, Maura
AU - Giorgi, Mauro
PY - 1999/5
Y1 - 1999/5
N2 - Aflatoxin B1 (AFB1) action on cyclic nucleotide phosphodiesterase (PDE) activity has been tested on tissue extracts of various organs. In the presence of 100 μM AFB1 a significant inhibition of cAMP and cGMP hydrolytic activity is observed in all tested tissue extracts. However, cGMP hydrolytic activity appears more sensitive to AFB1 inhibition than cAMP hydrolytic activity and a considerably higher inhibition is observed in lung and spleen, than in liver, brain, kidney, and heart. When cGMP is used as substrate, the inhibitory response reaches 72% in lung and spleen extracts. We have also tested AFB1 effects on lung and liver PDE activity peaks separated by DEAE-cellulose chromatography. These data confirm the poor sensitivity to the toxin of all PDE activities present in liver, while the lung peak (where PDE V in present) shows a higher sensitivity to AFB1. In order to establish whether PDE V is in fact more sensitive to AFB1, we have used mouse neuroblastoma cells, in which cGMP hydrolytic activity has been shown to be due to PDE V only. In this case, the calculated IC50 is 24 μM and Dixon plot analysis shows a competitive inhibitory effect with a Ki of 16.7 μM. We have also used aflatoxin B2 and M2, and they proved to be much less effective than AFB1: AFB2 inhibits PDE V with an IC50 of 117 μM, while AFM2 does not show any effect. These results provide the first evidence of a competitive inhibition of AFB1 on an enzymatic activity and suggest that an alteration of cellular cyclic nucleotide levels may play a role in the mechanism of aflatoxin action. All rights reserved. Copyright (C) 1999 Elsevier Science Inc.
AB - Aflatoxin B1 (AFB1) action on cyclic nucleotide phosphodiesterase (PDE) activity has been tested on tissue extracts of various organs. In the presence of 100 μM AFB1 a significant inhibition of cAMP and cGMP hydrolytic activity is observed in all tested tissue extracts. However, cGMP hydrolytic activity appears more sensitive to AFB1 inhibition than cAMP hydrolytic activity and a considerably higher inhibition is observed in lung and spleen, than in liver, brain, kidney, and heart. When cGMP is used as substrate, the inhibitory response reaches 72% in lung and spleen extracts. We have also tested AFB1 effects on lung and liver PDE activity peaks separated by DEAE-cellulose chromatography. These data confirm the poor sensitivity to the toxin of all PDE activities present in liver, while the lung peak (where PDE V in present) shows a higher sensitivity to AFB1. In order to establish whether PDE V is in fact more sensitive to AFB1, we have used mouse neuroblastoma cells, in which cGMP hydrolytic activity has been shown to be due to PDE V only. In this case, the calculated IC50 is 24 μM and Dixon plot analysis shows a competitive inhibitory effect with a Ki of 16.7 μM. We have also used aflatoxin B2 and M2, and they proved to be much less effective than AFB1: AFB2 inhibits PDE V with an IC50 of 117 μM, while AFM2 does not show any effect. These results provide the first evidence of a competitive inhibition of AFB1 on an enzymatic activity and suggest that an alteration of cellular cyclic nucleotide levels may play a role in the mechanism of aflatoxin action. All rights reserved. Copyright (C) 1999 Elsevier Science Inc.
KW - Aflatoxin B
KW - High affinity cyclic nucleotide phosphodiesterase
KW - PDE V isoform
UR - http://www.scopus.com/inward/record.url?scp=0032589059&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032589059&partnerID=8YFLogxK
U2 - 10.1016/S0306-3623(98)00282-1
DO - 10.1016/S0306-3623(98)00282-1
M3 - Article
C2 - 10382866
AN - SCOPUS:0032589059
VL - 32
SP - 615
EP - 619
JO - General Pharmacology: The Vascular System
JF - General Pharmacology: The Vascular System
SN - 0306-3623
IS - 5
ER -