Restorative antiaging influence and chemical profile of Prunus domestica L. (European plum) seed extract in a D-galactose-induced rat model

Background
Prunus domestica L., also known as European plums or prunes, is a member of the Rosaceae family. Recently, fruit byproducts like seeds have been used as a novel and affordable source of bioactive compounds that may be an affordable source of substances. These substances hold potential benefit to the food and pharmaceutical industries.
Objective
The study aims to evaluate the chemical composition of P. domestica L. seeds and their safety and efficiency as an antiaging agent.
Materials and methods
The phenolic content in ethanolic seed extract was determined using the Folin–Ciocalteu reagent. Chlorophyll a, chlorophyll b, and β-carotene concentrations were measured by high performance liquid chromatography analysis. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) negative ion mode was carried out to investigate the phytoconstituents, in addition to the isolation of the main active compounds on preparative TLC as well as evaluation of cognitive capabilities, measurement of antioxidants and neurotransmitters and histopathological brain examination.
Results and conclusion
The total phenolic and flavonoid contents of ethanolic extract were 136.55 mg GAE/g and 89 mg CE/g, respectively. Also, high performance liquid chromatography analysis led to the identification of β-carotene as the main natural pigment (59.376 mg/100 g), followed by chlorophyll b (41.745 mg/100 g) and finally chlorophyll a (20.824 mg/100 g). In addition, UPLC/ESI-MS analysis using the negative ion mode led to the identification of 24 compounds, including two flavonols, one flavanone, two flavones, 10 flavonoid-O-glycosides, two methylated flavonoids, one isoflavonoidC-glycosides, two phenolic acids, two aldehydes, one stilbene, and one coumarin. Preparative TLC chromatographic technique for ethanolic P. domestica seed extract resulted in the isolation of γ-tocopherol, kaempferol-3-O-rutinoside, luteolin, and luteolin-7-O-glucoside. The ethanolic extract proved to have a remarkable scavenging effect against 1,1-Diphenyl-2-picryl-hydrazyl in a dose-dependent manner compared with vitamin C. Improvement in behavioral assessment was noticed posttreatment of rats with the extract suggesting amelioration in cognitive ability and spatial memory of rats compared with standard drug. In addition, noticeable improvements were observed in neurotransmitter levels, acetylcholinesterase, noradrenaline, dopamine, and serotonin, in the brain tissue of aged rats. Besides, remarkable improvements in oxidative stress biomarkers (nitric oxide, reduced glutathione and lipid peroxide, total antioxidant capacity) and in histopathological pictures of different brain regions posttreatment of aged rats with the extract compared with donepezil standard drug were recorded.