Optimization of aqueous enzyme‐assisted extraction of rosmarinic acid from rosemary ( Rosmarinus officinalis L.) leaves and the antioxidant activity of the extract

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Rosemary (Rosmarinus officinalis L.) is a potential source of rosmarinic acid (RA). This study aimed to develop a novel aqueous enzymatic approach for extracting RA from rosemary leaves and evaluate the antioxidant activity of the RA-rich extract. The ability of several enzymes to release RA from plant tissues was investigated. Among the examined enzymes, cellulase A exhibited the highest extraction efficiency. Subsequently, aqueous cellulase A-assisted extraction was optimized. The optimal extraction conditions were as follows: an extraction time of 4.63 hr, a water-to-sample ratio of 28.69 ml/g, an enzyme concentration of 2.56%, and a temperature of 36.6°C, with the maximum RA content of 13.97 mg/g. The RA-rich extract exhibited potent antioxidant activity against the 2,2-diphenyl-1-picrylhydrazyl radical with an IC50 value of 532.01 μg/ml. Aqueous cellulase-assisted extraction is a green approach for RA extraction from rosemary leaves. Furthermore, the rosemary leaf extract is a promising antioxidant agent for future use. Practical applications RA is a potent antioxidant and is widely applied in the food and pharmaceutical industries. This study developed a new method involving the use of enzyme for ecofriendly extracting RA from rosemary leaves. The results indicated that the RA-rich extract is a potential antioxidant agent for future nutraceutical and pharmaceutical applications and the aqueous cellulase-assisted extraction is a practical and green process for RA extraction from rosemary leaves.