Pomegranate leaves, buds, and flowers: phytochemical, antioxidant, and comparative solvent analyzes

Punica granatum L. possesses significant nutritional and medicinal potential. Its pharmacological activities have been investigated, but no comparative evaluation has been reported regarding the effect of different extraction solvents on the phytochemical content and antioxidant activity of its leaf, bud, and flower extracts. This research involved seven various solvents, namely methanol, ethanol, water, acidified methanol, acidified ethanol, acidified water, and hexane. A set of experiments made it possible to define the effect of each of these solvents on the contents of phenolics, flavonoids, flavanols, flavonols, anthocyanins, and tannins, as well as on the antioxidant activity of pomegranate leaf, bud and flower tissues. The research objective was to identify the optimal solvent for the most effective extraction of the abovementioned functional compounds. The antioxidant activity tests involved DPPH free radical scavenging, metal chelating, iron (III) reducing power, and CUPRAC assays. The aqueous extract of P. granatum leaves demonstrated the highest total phenolic content (192.57 mg GAE/g extract) while the greatest flavonoid content belonged to the acidified methanol extract of P. granatum buds (73.93 mg RE/g extract). The HPLC analysis detected such significant phenolic compounds as punicalagin in buds and flowers, as well as gallic acid in leaves. All the extracts showed good antioxidant activity; however, the bud extracts had a better antioxidant profile than the extracts from leaves and flowers. The pomegranate leaf, bud, and flower extracts demonstrated excellent phytochemical and antioxidant properties, which makes it possible to recommend these plant tissues as raw materials to be used in pharmaceutical, food, nutraceutical, and cosmetic industries.