Olive Mill Pomace Impact on the Phytochemical Content and Antioxidant Activity of <i>Rosmarinus officinalis L</i>

Abstract

Sustainable methods for enhancing the quality of medicinal herbs are required to provide high amounts of antioxidants  widely used in the food, pharmaceutical, and cosmetic industry. In this study, the impact of olive pomace (OMP)  addition  on total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of two selected    Rosmarinus officinalis at different proportions 0 and 25% of OMP was examined. The experiments were done in a shade  house at the National Agency of Medicinal and Aromatic Plants in Taounate, Morocco. The various parameters TPC, TFC,  antioxidant activity (DPPH), pH, CEC (meq.100g^-1), EC (μS.cm^-1), macroand micronutrient content (mg.kg^-1), and  nutrient uptake (g. plant^-1) were measured after the samples were extracted by sonication. The results indicated that  rosemary leaves treated with 25% OMP amendment exhibited the highest TPC (68.48 mg GAE g^-1 DW), TFC (6.13 ± 6.103  mg GAE g^-1 DW), and antioxidant activity (1.279± 0.26 mg/mL DW). Additionally, the addition of OMP to the soil  increased the level of macro- and micronutrients, mainly P, K, and Ca, as well as nutrient absorption factors including P,  K, Ca, Cu, and Zn in the rosemary leaves, all of which were increased slightly but significantly. Notably, there was a  positive association between DPPH, TPC, TFC, and soil organic matter. These results show that OMP addition has a great  impact on the nutritional quality of rosemary leaves and directly increases TPC, TFC, and antioxidant activity. This study  emphasizes the positive impacts of OMP on the bioactive qualities and overall nutrient profile of rosemary plants.