Li, Cheng (2025) Optimization Extraction Conditions Andcharacterization Ofanti-Hyperpigmentation Polysaccharidefrom From Callisia Repens. Masters thesis, Universiti Sains Malaysia.
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Abstract
Deep eutectic solvents (DESs) are promising green media for extraction. This study aimed to synthesize a novel acidic DES from aspartic acid and citric acid, characterize its physical and chemical traits, assess its phytotoxicity, and explore its suitability for polysaccharide extraction. Two heating methods, i.e., conventional and microwave heating were investigated for DES formation. Only microwave heating at 270 W for 6 min using 3:1 molar ratio (citric acid : aspartic acid) successfully formed the DES. The synthesized DES appears orange, has a density of 1.44 g.ml-1 and high viscosity of 11665 Pa.s. It is soluble in polar solvents, with a dissociation temperature of 119.0 ℃. Interestingly, a Maillard reaction occurred during DES synthesis beyond hydrogen bonding, in which LC-MS analysis confirmed the presence of Maillard by-products. Browning index and pH reduction further confirmed the chemical changes beyond conventional DES formation. This unconventional DES showed no phytotoxicity based on wheat seed germination and provided good polysaccharide-solubilizing properties. Furthermore, the synthesized DES was used to obtain polysaccharides from Callisia repens with anti-tyrosinase activity, sun protection factor (SPF), and antioxidant activity.
| Item Type: | Thesis (Masters) |
|---|---|
| Subjects: | Q Science > Q Science (General) |
| Divisions: | Pusat Penyelidikan Biokimia Analisis (Analytical Biochemistry Research Centre (ABrC)) > Thesis |
| Depositing User: | Mr Aizat Asmawi Abdul Rahim |
| Date Deposited: | 15 Jul 2026 06:42 |
| Last Modified: | 15 Jul 2026 06:42 |
| URI: | http://eprints.usm.my/id/eprint/64645 |
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