Summer savory (Satureja hortensis L., Lamiaceae) is used in several regions of the world as a spice and folk medicine. Anti-inflammatory and cytoprotective effects of S. hortensis and of its rosmarinic acid-rich phenolic fraction have been demonstrated in animal trials. However, previous studies of rosmarinic acid in cell models have yielded controversial results. In this study, we investigated the effects of summer savory extracts on H2O2-challenged human lymphoblastoid Jurkat T cells. LC-MS analysis confirmed the presence of rosmarinic acid and flavonoids such as hesperidin and naringin in the phenolic fraction. Adding 25 or 50 µM of H2O2 to the cell culture caused oxidative stress, manifested as generation of superoxide and peroxyl radicals, reduced cell viability, G0/G1 arrest, and enhanced apoptosis. This stress was significantly alleviated by the ethanolic and aqueous extracts of S. hortensis and by the partially purified rosmarinic acid fraction. The application of an aqueous S. hortensis extract doubled the activity of catalase and superoxide dismutase in the cells. The production of IL-2 and IL-10 interleukins was stimulated by H2O2 and was further enhanced by the addition of the S. hortensis extract or rosmarinic acid fraction. The H2O2-challenged Jurkat cells may serve as a model for investigating cellular mechanisms of cytoprotective phytonutrient effects.

The flowers of French marigold (Tagetes patula L.) are widely used in folk medicine, in particular for treating inflammation-related disorders. However, cellular mechanisms of this activity demand further investigation. In the present work, we studied the potential of T. patula compounds to alleviate the oxidative stress in hydrogen peroxide-challenged human lymphoblastoid Jurkat T-cells. Crude extracts of marigold flowers and purified fractions containing flavonoids patuletin, quercetagetin, and quercetin and their derivatives, as well as the carotenoid lutein, were brought in contact with Jurkat cells challenged with 25 or 50 μM H2O2. Hydrogen peroxide caused oxidative stress in the cells, manifested as generation of superoxide and peroxyl radicals, reduced viability, arrested cell cycle, and enhanced apoptosis. The stress was alleviated by marigold ingredients that demonstrated high radical-scavenging capacity and enhanced the activity of antioxidant enzymes involved in neutralization of reactive oxygen species. Flavonoid fraction rich in quercetin and quercetagetin showed the highest cytoprotective activity, while patuletin in high dose exerted a cytotoxic effect associated with its anticancer potential. T. patula compounds enhanced the production of anti-inflammatory and antioxidant interleukin-10 (IL-10) in Jurkat cells. Both direct radical-scavenging capacity and stimulation of protective cellular mechanisms can underlay the anti-inflammatory properties of marigold flowers.