The effects of Siberian pine (Pinus sibirica Du Tour) extract on cell viability and its antioxidant activity

Siberian pine (Pinus sibirica Du Tour) seeds are ascribed a number of medicinal properties and are indicated in traditional medicinal systems for the treatment of different ailments. Despite their potential therapeutic value, little has been published regarding their phytochemistry or biological properties. We have examined the qualitative-quantitative composition, antioxidant activity and cell viability-related properties of a defatted aqueous acetone-soluble P. sibirica seed extract. Reverse-phase chromatographic analysis of the crude extract indicated the presence of a chromatographic hump indicative of the presence of proanthocyanidins. After acid hydrolysis, the presence of hydroxylated benzoic and cinnamic acids, flavanones and flavan-3-ols were confirmed. After thiolysis, (+)-catechin was identified as more abundant than (-)-epicatechin suggesting that this molecule was the main terminal unit of the proanthocyanidins within this extract. The extract demonstrated iron(III) reductive and iron(II) chelating activities and the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radicals. When the effects of P. sibirica extract were assessed in a tumorigenic SH-SY5Y neuroblastoma cell line, it was found that the cell viability was diminished in the presence of P. sibirica extract as indicated by decreased membrane integrity (LDH assay) and mitochondrial metabolic activity (MTT assay) but the level of p53 protein was not changed (Western blot). Further studies (e.g., caspase activity and gene expression) are needed to examine the mechanisms of P. sibirica extract on the cell viability in more detail.