Chemical composition and oral sub-chronic safety of Algerian propolis with in silico targeting of Keap1-Nrf2 and mitochondrial proteins

Abstract

Algerian propolis has shown promising biological activities, but data on its safety profile remain limited. This study investigated the phytochemical composition and antioxidant activity of an ethanolic extract of Algerian propolis (EEP), as well as its sub-chronic toxicity at an oral dose of 100 mg/kg/day for 30 days in rats. EEP exhibited high levels of total polyphenols and flavonoids with low contents of hydrolysable and condensed tannins. GC–MS analysis identified naringenin (17.48%), pinocembrin (15.62%), 3-(acetylmethyl)-β-pinene (8.23%), 3(Z)-cembrene A (6.36%) and totarol (5.78%) as major constituents. In vitro, EEP effectively scavenged superoxide anion (O 2 - ), DPPH- and H 2 O 2 and showed strong reducing power in the FRAP assay. In vivo, EEP limited superoxide anion generation, inhibited mitochondrial permeability transition pore (mPTP) opening and protected against mitochondrial swelling and apoptosis. It also preserved redox homeostasis by decreasing malondialdehyde (MDA) levels and increasing superoxide dismutase (SOD) and catalase (CAT) activities, as well as glutathione (GSH) content. Histopathological examination revealed normal liver and kidney architecture comparable to controls. In silico analyses indicated favorable pharmacokinetic properties and negative predicted organ toxicity for the main constituents. Molecular docking showed strong binding affinities toward Keap1–Nrf2 and mitochondrial targets, including the bc1 complex, Mn-SOD and cyclophilin D. Overall, these findings support the oral sub-chronic safety profile and mitochondria-protective antioxidant potential of Algerian propolis.