Phytochemical composition and anti-oxidant, anti-Alzheimer and anti-inflammatory activities of pomegranate fruit as function of variety and ripening

Introduction

Medicinal plants are considered as rich resources of secondary metabolites and have been used for treating diseases. Pomegranate (Punica granatum) is considered ‘a pharmacy unto itself’. The current study aimed to evaluate the effect of ripening and variety factors on the antioxidant activity of pomegranate fruits and their capacity to inhibit three enzymes involved in degenerative diseases.

Methods

The fruits were collected from four Tunisian pomegranate varieties (Espagnoule, Rafrafi, Zaghwani and Zehri) during three maturity stages. Phytochemical content, the antioxidant activity by DPPH and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assays and acetylcholinesterase, butyrylcholinesterase and 15-lipoxygenase inhibition activities were carried out.

Results

The unripe fruits were found to be the richest in terms of total phenolic content. Total flavonoids, tannins, anthocyanins and acetylcholinesterase, butyrylcholinesterase and 15-lipoxygenase inhibition activities varied greatly during ripening process and within varieties. It was found that unripe fruits of Zehri (IC₅₀ = 2.2 µg/ml by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay) and Rafrafi (IC₅₀ = 73.4 µg/ml by 2, 2-diphenyl-l-picrylhydrazyl assay) varieties exhibited the highest antioxidant capacities. The strongest extract against acetylcholinesterase and butyrylcholinesterase was found to be the unripe fruit extract of Espagnoule variety with IC₅₀ values of 86.7 and 58.0 µg/ml, respectively. The ethanolic extract from the unripe fruit of Zehri pomegranate variety inhibited moderately 15-lipoxygenase activity with an IC₅₀ value of 63.0 µg/ml.

Conclusion

The current study supported the popular use of pomegranate fruits, and highlighted also the potential effect of variety and ripening factors on their chemical composition and in vitro biological activities.