Prunus persica (L.) Batsch leaves as a source of anti-inflammatory, antioxidant, and antimicrobial agents

In this study, waste of leaves of Prunus persica (L.) Batsch was valorized as a source of bioactive compounds. The use of ultrasounds at two different energy levels (35 and 130 kHz) produced 14 extracts from these plant components and using 4 different extraction solvents, that is methanol: water (40:10; v/v; HMe), acetonitrile: water: formic acid (49.5:49.5:1; v/v/v; ANWF), ethyl acetate: water (40:10; v/v; EaW), and pure water (W), all acidified or not (except ANWF). All fractions revealed the presence of phytochemicals, but HMe presented the highest levels of total phenolics (323.31 mg GAE/g DW) and flavonoids (510.58 mg CE/g DW), while ANFW of flavonols (184.97 mg QE/g DW). Thus, HPLC-DAD and GC-MS analyses were carried out on these two specific samples to better characterize their biochemical profile. Twenty-one secondary metabolites were detected in the plant samples, including 5,7-dimethoxycoumarin, quercetin, genistein, and salicylic acid, together with more lipophilic substances, like hexadecanoic acid, 9,12-octadecadienoic acid, 9,12,15-octadecatrienoic acid, phytol, octadecanoic acid, and vitamin E. The study examined the biological activity of HMe and ANFW in vitro, revealing their significant antioxidant, anti-inflammatory, and antimicrobial properties, which effectively reduce inflammation and inhibit bacterial and fungal growth. Therefore, recycling leaves from P. persica trees after fruit harvesting and using them as a novel source for nutraceuticals, and more generally bioactive phytochemicals, could represent a way to exploit the potential of this plant waste in favor of the food, cosmetic, pharmaceutical, and medicinal industries.