Identification of Oxidative-Stress-Reducing Plant Extracts from a Novel Extract Library-Comparative Analysis of Cell-Free and Cell-Based In Vitro Assays to Quantitate Antioxidant Activity.

Numerous underexplored plant species are believed to possess considerable potential in combating oxidative stress and its associated health impacts, emphasizing the need for a comprehensive methodological screening approach to assess their antioxidant capacity. This study investigated 375 plant extracts, utilizing both cell-free and cellular methods to evaluate their antioxidant properties. Target-based antioxidant capacity was evaluated by the total phenolic content (TPC) and ferric reducing antioxidant power (FRAP) assays. Cell-based assays employed the H2DCF-DA probe to measure reactive oxygen species (ROS) levels and the Griess assay to quantify nitric oxide (NO) levels in stressed Caco-2 and RAW264.7 cells, respectively. The highest TPC and FRAP values were found in extracts of Origanum vulgare and Fragaria × ananassa leaves. Several plant extracts significantly reduced stress-induced ROS or NO levels by at least 30%. Distinctive selectivity was noted in certain extracts, favoring the significant reduction of NO (e.g., Helianthus tuberosus extract), of ROS (e.g., Prunus domestica subsp. Syriaca extract), or of both (e.g., Fragaria × ananassa leaf extract). A strong correlation between TPC and FRAP values and moderate correlations between the results of the cell-free and cell-based assays were evident. These findings highlight the great antioxidant potential of underexplored plant extracts and the diversity of the underlying mechanisms, emphasizing the importance of a multifaceted approach for a comprehensive assessment.

Extracts Prepared from Feed Supplements Containing Wood Lignans Improve Intestinal Health by Strengthening Barrier Integrity and Reducing Inflammation.

Lignans are known to exhibit a broad spectrum of biological activities, indicating their potential as constituents of feed supplements. This study investigated two extracts derived from the feed supplements 'ROI' and 'Protect'-which contain the wood lignans magnolol and honokiol ('ROI'), or soluble tannins additional to the aforementioned lignans ('Protect')-and their impact on selected parameters of intestinal functionality. The antioxidant and anti-inflammatory properties of the extracts were determined by measuring their effects on reactive oxygen species (ROS) and pro-inflammatory cytokine production in vitro. The impact on intestinal barrier integrity was evaluated in Caco-2 cells and Drosophila melanogaster by examining leaky gut formation. Furthermore, a feeding trial using infected piglets was conducted to study the impact on the levels of superoxide dismutase, glutathione and lipid peroxidation. The Protect extract lowered ROS production in Caco-2 cells and reversed the stress-induced weakening of barrier integrity. The ROI extract inhibited the expression or secretion of interleukin-8 (IL-8), interleukin-6 (IL-6), interleukin-1ß (IL-1ß) and tumor necrosis factor α (TNFα). Moreover, the ROI extract decreased leaky gut formation and mortality rates in Drosophila melanogaster. Dietary supplementation with Protect improved the antioxidant status and barrier integrity of the intestines of infected piglets. In conclusion, wood lignan-enriched feed supplements are valuable tools that support intestinal health by exerting antioxidant, anti-inflammatory and barrier-strengthening effects.