Extraction of antioxidant compounds from thymbra spicata L. plant using deep eutectic solvents

Within the scope of this thesis, ultrasonic assisted extraction (UAE) process was applied to obtain phenolic compounds using the leaves of zahter (Thymbra spicata L.). Antioxidant capacities were analyzed using conventional solvents and deep eutectic solvents (DES) by optimizing the UAE method. Analysis was performed using CUPRAC, total antioxidant capacity (TAC), DPPH, ABTS, total phenolic content (TPC) and total flavonoid content (TFC) methods. Experimental designs were performed using the Box-Behnken model and analysis results were supported by ANOVA analyses and 3D surface graphic interpretations. Higher results were obtained with ethanol in antioxidant capacity analysis results. In the CUPRAC method, 5.275 mmol TR/g were obtained with DES and 6.084 mmol TR/g with ethanol. When other analysis results were examined, the results of the analyses performed with DES were higher. For ABTS, the analysis result with DES was found as 0.280 mmol TR/g, and the analysis result with ethanol was found as 0.225 mmol TR/g. In DPPH analysis, the results were calculated as 0.302 mmol TR/g for DES and 0.167 mmol TR/g for ethanol. The results obtained in TPC analysis were found as 10.062 mmol gallic acid/g-dry sample for DES and 0.731026861 mmol gallic acid/g-dry sample for ethanol. Finally, in the TFC analysis results, the analysis result of the extraction with DES was found to be 0.412 mmol quercetin/g-dry sample and the analysis result of the extraction with ethanol was found to be 0.348 mmol quercetin/g-dry sample. When the results are examined, ABTS, DPPH, TPC and TFC analysis results were found to be higher in the UAE process performed using DES. When all the findings were evaluated, it was revealed that DES, which is an environmentally friendly, low-cost and non volatile green solvent, is suitable for use as an alternative to traditional solvents and gives better results.