Evaluation of Antioxidant Activities of Rosemary (Rosmarinus officinalis L.) Essential Oil and Different Types of Solvent Extractions

Abstract

The evaluation of the antioxidant activity of different solvents of rosemary extract would involve testing the efficacy of various solvents in extracting antioxidants. This can be done by measuring the antioxidant capacity of the extracts using different assays. The solvent that results in the highest antioxidant activity can then be considered the most effective for extraction purposes. This study examined the effects of several solvents on the extract of rosemary leaves, including its total phenolic content, total flavonoid content, total tannin content, and antioxidant activity. Six different in-vitro methods DPPH, ABTS, FRAP, ferric reducing power, total antioxidant activity, and nitric oxide (NO) radical scavenging—were used for the antioxidant activity assessment. The TPC, TFC, TTC, and antioxidant capacity were all highly and considerably impacted by the extraction solvents. In general, the maximum TPC (72.34 GAE mg/g) and TFC (26.81 RE mg/g) were found in the ethanol extract. while aqueous extract had the highest TTA value (20.25 GAE mg/g). In the (NO) radical scavenging assay (86.68 RE mg/g) and DPPH (138.3 GAE mg/g) assays, methanol extract exhibited the best antioxidant activity, the aqueous extract had the highest activity in ABTS (125.33 TE mg/g), and ferric reducing power (144.5 AScE mg/g), in comparison, ethanol extract had the highest activity in FRAP (130.5 AScE mg/g) and total antioxidant activity (178.86 GAE mg/g) of rosemary leaves, also methanol extract shown the highest antibacterial activity. In addition, R2 (The coefficient of determination) values established a significant correlation between the phytochemical content and all antioxidant methods utilized. The highest R2 value was between FRAP assay and TPC and TFC, (0.8814), (0.9878) respectively, as DPPH with the TTC (0.923). R2 values also proved a strong correlation between antioxidant methods used, where the highest R2 was between frap and ferric reducing power (0.8985), and the lowest between DPPH and total antioxidant activity (0.5337).