Lipophilic compounds in Pulmonaria rubra and their in vitro activity

Pulmonaria rubra Schott (Boraginaceae) is a scarcely investigated congener of the medicinal species P. officinalis. This study aimed to characterize the lipophilic constituents of the dichloromethane extract from P. rubra aerial parts (PR-DCM) and to evaluate its antioxidant and neuroprotective activity in vitro , as well as its effects on monoamine oxidase (MAO) and major cytochrome P450 (CYP) isoforms. GC–MS analysis after silylation enabled the identification of virtually the entire extract (99.99% of the total peak area), revealing a profile dominated by non-volatile lipids, including unsaturated and saturated fatty acids (notably linolenic and palmitic acids), long-chain aliphatic alcohols, phytol, and phytosterols such as β-sitosterol and campesterol, while steam-distillable volatiles were negligible. In isolated rat brain synaptosomes, mitochondria, and microsomes, PR-DCM (up to 200 μg/mL) did not show intrinsic toxicity or pro-oxidant effects, but significantly counteracted 6-OHDA-, t -BuOOH-, and Fe 2+ /ascorbic acid-induced decreases in reduced glutathione and increases in malondialdehyde. At a concentration of 1 μg/mL, PR-DCM did not significantly inhibit human recombinant MAO-A, MAO-B, CYP1A2, CYP2D6, or CYP3A4. Overall, PR-DCM emerges as a promising source of lipophilic antioxidants with neuroprotective potential and a favorable in vitro safety and interaction profile, warranting further isolation of active components and confirmation in neuronal and in vivo models.