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Title: Synthesis and application of deep eutectic solvents for the extraction of natural products
Authors: Naseem, Zubera
Keywords: Physical Sciences
Issue Date: 2020
Publisher: Synthesis and application of deep eutectic solvents for the extraction of natural products
Abstract: The hazardous organic solvents are widely used for the extraction of natural bioactive compounds from plants in the pharmaceutical, food and cosmetic industries. In the present study, different choline chloride based deep eutectic solvents (DESs) were synthesized using ethylene glycol, malic acid, tartaric acid, glycerol and oxalic acid as hydrogen bond donors. Characterization of synthesized solvents was done by physico-chemical (refractive index, density, viscosity, conductivity, pH) and spectroscopic (FT-IR) methods. These innovative solvents were used for the extraction of bioactive components from Cymbopogon citratus and Mentha arvensis. The extraction was carried out by maceration, ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE) methods with DESs and aqueous methanol. Effects of process parameters like time, temperature, biomass to solvent ratio and microwave power were optimized in preliminary experiments for maximum extraction yield. The deep eutectic solvents showed higher extraction yields in maceration and UAE than aqueous methanol. The evaluation of total phenolic contents (TPC) and total flavonoids contents (TFC) was carried out in addition with 2, 2diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity to determine the antioxidant potential of bioactive ingredients. The optimization of process parameters was done by response surface methodology (RSM) during the evaluation of TPC, TFC and DPPH in all three extraction methods with DESs and aqueous methanol. The DESs extracts showed higher values of TPC, TFC and DPPH (% inhibition) than aqueous methanol in maceration and sonication process but in microwave assisted extraction the aqueous methanol showed comparable results. The antibacterial potential against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) species of plants extracts obtained at optimized conditions was assessed. The antifungal potential of plants extracts against Fusarium solani and Aspergillus niger was also assessed by established biological protocols. It has been observed that DESs extracts showed larger zones of inhibition against bacterial and fungal strains with minimum inhibitory concentration (MIC) values as compared to aqueous methanol. The extracted bioactive ingredients obtained at optimized conditions were identified by HPLC and LC-ESI-MS analysis. The use of DESs could provide an effective and alternate approach for the extraction of bioactive compounds from medicinal plants.
Gov't Doc #: 20284
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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