To investigate antioxidant activities and life span prolonging effects of the extracts from the roots of Incarvillea younghusbandii Sprague, and to study the correlations between these activities and the polar intensity of the extracts.
Five extracts (IYS1, IYS2, IYS3, IYS4 and YS5) with different polar intensity were prepared. Antioxidant activities in vitro were determined by LPO inhibitory and free radicals scavenging experiments. Life span prolonging effects in vivo were evaluated by feeding Drosophila melanogaster.
Total phenolic content in extracts were solvent-dependent and decreased in the order of IYS4 > IYS1 > IYS3 > IYS5 > IYS2. Organic extracts (IYS1 and IYS4) showed excellent LPO inhibitory activity, O(2)(· -) and ·OH scavenging activity compared to ascorbic acid (or benzoic acid, or BHT), while aqueous extracts (IYS2, IYS3 and IYS5) did not. The antioxidant activities (in vitro) were solvent dependent and decreased in the order of IYS4 > IYS1 > IYS3 > IYS5 ≥ IYS2. Drosophila melanogaster was fed with organic extracts (IYS1 or IYS4) at 5.0 mg mL(-1). The mean life span were increased by 24.4% (IYS1) or 23.0% (IYS4) in female and 15.3% (IYS1) or 16.9% (IYS4) in male; the maximum life span were increased by 8.4% (IYS1) or 11.2% (IYS4) in female and 9.7% (IYS1) or 15.8% (IYS4) in male, and the survival curves were significantly shifted to the right after fifteen days in both sexes survival period. Feeding aqueous extracts (IYS2, IYS3 or IYS5) at 5.0 mg·mL(-1), the significant life span prolonging effects were not achieved. The life span prolonging effects of the extracts were solvent-dependent and decreased in the order of IYS4 ≥ IYS1 > IYS3 > IYS2 > IYS5.
Extracts from the roots of Incarvillea younghusbandii Sprague showed excellent antioxidant activities and significant life span prolonging effects in Drosophila melanogaster. Positive correlations existed between the antioxidant activities and total phenolic content. Life span prolonging effect was positively correlated with the total phenolic content or antioxidant activities. The extracts possess better life span prolonging effect in females than in males.