Kharsa, Badr EddinBadr EddinKharsa2026-05-062026-05-062026https://studentrepo.iium.edu.my/handle/123456789/34087Diabetes mellitus is a complex metabolic disorder characterized by elevated blood glucose levels and insufficient insulin production. α-amylase and α-glucosidase are key enzymes involved in the breakdown of polysaccharides into glucose during digestion. Inhibiting these enzymes is a promising strategy for managing postprandial hyperglycemia, commonly associated with type 2 diabetes. Free radicals activate cellular signalling pathways and cause oxidative stress, which plays a significant role in the development of diabetes and related complications. Antioxidants mitigate oxidative damage by neutralizing free radicals, chelating metal ions, and preventing lipid peroxidation. Smoothies, which are blended beverages containing fruits, vegetables, yogurt, milk, and honey, are recognized for their beneficial nutritional profiles and health benefits due to the fruit and vegetable components. This study aimed to develop a high-antioxidant smoothie and assess its potential antidiabetic effects by inhibiting the activities of α-amylase and α-glucosidase. The study was conducted in five phases: In the first phase, a high-antioxidant smoothie was formulated using a mixture of carrot, beet, lettuce, pineapple, and banana, optimized through response surface methodology (RSM). The optimal blend was determined as follows: carrot (9.25 g), beet (9.25 g), lettuce (9.5 g), pineapple (25.9 g), and banana (11.1 g). The total phenolic content (TPC), DPPH radical scavenging activity, and FRAP were measured as 21.97 ± 0.99 mg/100 g gallic acid, 36.86 ± 0.76 μmol/100g Trolox, and 52.26 ± 1.52 μmol/100g Trolox, respectively. In the second phase, thermal treatment conditions were optimized using RSM, and the optimum temperature and treatment time for achieving the highest antioxidant activity were 58.45°C and 17.3 minutes, respectively. In the third phase, the percentage of sweeteners was optimized, and formulations 101 (5% honey and 2% sugar) and 201 (5% honey and 5% sugar) were identified as the best formulations. In the fourth phase, sensory evaluation, nutrient analysis, and phenolic and flavonoid quantification by UHPLC-MS/MS were conducted on five formulations (101, 201, 301, 401, and 501). All formulations were generally accepted by consumers, and formulations with higher honey content showed significantly (p < 0.05) higher nutritional values and greater concentrations of phenolic and flavonoid compounds. Among the identified compounds, caffeic acid, coumaric acid, and gallic acid were the most abundant. In the fifth phase, the in vitro antidiabetic potential of the formulations was evaluated by determining their α-amylase and α-glucosidase inhibitory activities. The IC50 values for α-amylase inhibition ranged from 295.84 ± 2.49 to 470.23 ± 12.42 mg/mL, while the IC50 for α-glucosidase inhibition ranged from 238.38 ± 2.53 to 523.87 ± 31.76 mg/mL. Smoothies containing higher levels of Trigona honey exhibited significantly (p < 0.05) stronger inhibitory activity against both enzymes, whereas higher sugar content reduced the inhibitory effects. In conclusion, this study successfully developed a high-antioxidant smoothie with potential antidiabetic properties. The findings suggest that the formulated smoothie may serve as a promising natural dietary intervention for diabetes prevention and management. However, further in vivo studies are required to confirm these effects.enEmbargoedAntioxidant;Response Surface Methodology;AntidibetecDiabetes -- Nutritional aspectsDiabetes -- Alternative treatmentHypoglycemic agentsDoctoral Theses