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PDE5-004
Question
Answer
General
AOAC Method Number:
PDE5-004
Method Title:
Testing for Phosphodiesterase Type 5 (PDE5) Inhibitors in
Dietary Supplements
Method Author(s):
Reviewer Name:
Jerry Zweigenbaum
Summary of Method
This method utilizes a luminescence quenching to
measure presence and semi-quantitation of PDE5
inhibitor. It requires PDE5 enzyme reaction with cyclic
guanosine monophoshate deactivating PKA which
maintains level of ATP for luminscent reaction. Inhibition
of enzyme allows active PKA to react with ATP and thus
reduces luminescence.
Method Scope / Applicability:
This method identifies the presence of PDE5 inhibitor
and provides a semi-quantitative measurement. The
measurement is of activity and not identification nor
concentration of the molecule responsible for inhibition.
This would be applicable to screening dietary
supplements for PDE5 inhibitors.
General Comments About the
Method:
The method appears to be an excellent screening tool
and provides a quantitative indication of activity. There
is no discussion of possible false positive and negative
results.
Method Clarity
The diagram describing the reactions involved needs a
key as it is difficult to follow. The procedure to perform
the test seems straightforward and clear.
Pros/Strengths
This method appears capable of detecting and measuring
activity of PDE5 inhibitors that have been altered to
escape molecular detection (designer drugs).
Cons/Weaknesses
There is no way to identify the specific molecule
producing inhibition. False positives seem more likely
than false negatives which makes it a potentially
excellent screening method but a confirmatory method