PhD Scientific Days 2025

Poster Session I. - F: Pharmaceutical Sciences and Health Technologies

Comprehensive Characterization of Phytochemical Composition, Membrane Permeability, and Antiproliferative Activity of Juglans nigra Polyphenols

Name of the presenter

Osztie Rita

Institute/workplace of the presenter

Department of Pharmacognosy

Authors

Dr. Rita Osztie¹

1: Department of Pharmacognosy

Text of the abstract

Introduction: Juglans species are rich sources of bioactive natural products, cytotoxic activity of constituents isolated from walnut species has also been described. However, the comprehensive screening of the phenolic profile of J. nigra has not been performed yet.
Aims: The aim of our study was the detailed polyphenol profiling of Juglans nigra and the characterization of the membrane permeability and antiproliferative properties of its main isolated phenolics.
Methods: We prepared extracts of different plant parts of J. nigra using solvents with different polarities, and analyzed their phenolic composition using UHPLC-Orbitrap-MS. The isolation of the compounds was performed by flash chromatography and reversed-phase semi-preparative HPLC methods. The structures of the isolated compounds were identified by HR-MS and NMR spectroscopy. The in vitro antiproliferative activity was determined by Alamar Blue assay in three human cancer cell lines. The passive diffusion of the compounds across biological membranes was determined using in vitro models (PAMPA-BBB and PAMPA-GI).
Results: We have performed a comprehensive phytochemical screening of J. nigra leaf, bark, and pericarp samples. A total of 161 compounds were tentatively identified: flavonoids, phenolcarboxylic acids, ellagitannins, and naphthoquinones. Additionally, we described several gallotannins, flavonoids, juglone, and tetralone derivatives, and linear and cyclic diarylheptanoids in J. nigra for the first time. Eight compounds, including three flavonol-O-glycosides, juglone, 1,2,3,4-tetrahydro-7,8-dihydroxy-4-oxonaphthalen-1-yl-6-O-galloyl-glucoside, ellagic acid, gallic acid, and ethyl gallate, were isolated from J. nigra pericarp. The in vitro antiproliferative activity of the isolated compounds confirmed that juglone inhibits cell proliferation, and has similar activity as the clinical standards.
Both juglone and ethyl-gallate showed positive results in the blood–brain-barrier-specific PAMPA-BBB study. Juglone also possesses logPe values which indicates that it may be able to cross both the GI and BBB membranes via passive diffusion.
Conclusion: In our work, we provided new data on the chemical and biological characteristics of specialized plant metabolites of J. nigra, which may lay the foundation for the use of the plant as the source of drug candidate compounds.