The pomegranate, Punica granatum L., has been the subject of current interest as a medicinal agent with wide-ranging therapeutic indications. In the present study, pomegranate ethanolic seed and hull extracts were tested, in comparison with a commercial sample, for the inhibition of
aldose reductase, an
enzyme involved in the etiology of
diabetic complications. In vitro inhibition of rat lens
aldose reductase was determined by a conventional method. Pomegranate ethanolic hull extract and commercial pomegranate hull extract exhibited similar
aldose reductase inhibitory activity characterized by IC(50) values ranging from 3 to 33.3 μg/ml. They were more effective than pomegranate ethanolic seed extract with IC(50) ranging from 33.3 to 333 μg/ml.
Antioxidant action of the novel compounds was documented in a DPPH test and in a liposomal membrane model, oxidatively stressed by peroxyl radicals. All the
plant extracts showed considerable
antioxidant potential in the DPPH assay. Pomegranate ethanolic hull extract and commercial pomegranate hull extract executed similar protective effects on peroxidatively damaged liposomal membranes characterized by 10<IC(50)<100 μg/ml. Pomegranate ethanolic seed extract showed significantly lower
antioxidant activity compared to both hull extracts studied. Pomegranate extracts are thus presented as bifunctional agents combining
aldose reductase inhibitory action with
antioxidant activity and with potential
therapeutic use in prevention of
diabetic complications.