Background: Punica granatum L. (pomegranate) is one of the oldest edible fruits used for
the treatment of countless diseases. The bioactivity of this fruit is mainly related to tannins, especially
elagitannins. P.granatum fruit peel dried extracts (PPDEs) are widely marketed today and the lack
of accessible quality control methods is a key to the variable and questionable quality of these products.
Objective: To develop a miniaturized spectrophotometric method for quantification of tannins in
Method: Spectrophotometric method using Folin-Ciocalteu reagent was developed and validated for
quantification of total polyphenols and polyphenols not adsorbed by hide powder in 17 samples of
commercial PPDEs. Tannins content was calculated by the difference between total polyphenols and
polyphenols not adsorbed by hide powder contents and expressed as pyrogallol. The UV/Visible microplate
spectrophotometer was operated at 760 nm.
Results: The developed miniaturized method was precise, accurate, selective and linear, and has no
rotational or translational matrix effect. This method significantly reduced the cost of the analysis:
82.2% with reagents, 84.7% in electricity consumption, and 56.3% in the total analysis time. The
wide variability in tannins contents in commercial PPDEs (<1% to 14.20%) shows the importance of
quality control, ensuring the therapeutic effect and safety of the extracts.
Conclusion: A miniaturized spectrophotometric method was successfully developed and fully validated,
being appropriate for quantification of tannins of PPDEs in quality control routine analysis, as
it showed to be a simple and cheaper method.