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Rattanaporn Kanthada. Development of nanoemulsions loaded with combination of green tea and Indian gooseberry extracts with synergistic biological activities. Master's degree(Cosmetic Science). Chiang Mai University. Library. : Chiang Mai University, 2025.
Development of nanoemulsions loaded with combination of green tea and Indian gooseberry extracts with synergistic biological activities
Abstract:
Previous studies have demonstrated that green tea and Indian gooseberry contain a significant content of bioactive compounds, contributing to their strong antioxidant potential. However, limited research has been conducted on the synergistic effects of these extracts and their incorporation into an efficient delivery system. Therefore, this study aimed to investigate the bioactive compounds present in green tea and Indian gooseberry extracts, as well as their individual antioxidant activities using DPPH, ABTS, FRAP, and lipid peroxidation inhibition assays. Subsequently, the synergistic effects of combined extracts were examined at various ratios: 0.5(IC50): 0.5(IC50), IC50: IC50, 2(IC50): 2(IC50), 4(IC50): 4(IC50), 5(IC50): 5(IC50), and 10(IC50): 10(IC50), with IC50 values received from the DPPH and ABTS assays. The combination index (CI) was then calculated to identify the optimal synergistic ratio. The synergistic extract ratio was further evaluated for its tyrosinase inhibition activity and anti-aging potential. The optimal extract ratio was subsequently incorporated into a nanoemulsion formulation, and its physicochemical properties and stability under various conditions were assessed. Quantitative analysis of bioactive compounds revealed that green tea extract exhibited higher total phenolic and total flavonoid contents (611.87 ± 0.00 mg gallic acid equivalent/g extract and 63.80 ± 0.01 mg quercetin equivalent/g extract, respectively) compared to Indian gooseberry extract (65.82 ± 0.01 mg gallic acid equivalent/g extract and 44.04 ± 0.01 mg quercetin equivalent/g extract, respectively). Green tea extract demonstrated superior antioxidant activity, with IC50 values of 6.27 ± 0.11 μg/mL (ABTS assay), 8.20 ± 1.02 μg/mL (DPPH assay), and 1.52 ± 0.06 mg/mL (lipid peroxidation inhibition assay). The FRAP assay further confirmed the stronger ferric-reducing ability of green tea extract (3442.59 ± 111.16 mg ferrous sulfate equivalent/mg extract) compared to Indian gooseberry extract. The combination of green tea and Indian gooseberry extracts exhibited synergistic antioxidant effects at multiple ratios, specifically 5(IC50): 5(IC50), 5(IC50): 10(IC50), 10(IC50): 5(IC50), and 10(IC50): 10(IC50) ratios from the ABTS assay, and 4(IC50): 4(IC50) and 10(IC50): 10(IC50) ratios from the DPPH assay. The extract combination at a ratio of 10(IC50): 10(IC50) (from ABTS assay) showed the highest inhibition of collagenase and hyaluronidase enzymes, whereas the ratio of 4(IC50): 4(IC50) (from DPPH assay) exhibited strong inhibitory effects on elastase and tyrosinase. Based on these findings, the synergistic 4(IC50): 4(IC50) (from DPPH assay) extract ratio at 10% w/w was selected to incorporate into a nanoemulsion system consisting of isopropyl myristate, polyglycerol polyricinoleate, Polysorbate 80, and polyethylene glycol 400. The nanoemulsion was prepared using high-shear homogenization and ultrasonic emulsification. The resulting formulation exhibited a particle size of 319.2 ± 5.12 nm, a polydispersity index (PDI) of 0.421 ± 0.01, and a zeta potential of 22.93 ± 0.3 mV. The nanoemulsions demonstrated efficient encapsulation of green tea and Indian gooseberry extracts, with encapsulation efficiencies of 66.68 ± 0.16% and 69.73 ± 0.65%, respectively. In the stability assessment under accelerated conditions (heating-cooling cycle) and storage at 4°C and 30°C for one month, the nanoemulsions containing green tea and Indian gooseberry extracts exhibited no noticeable physical changes at 4°C. However, an increase in particle size was observed, indicating potential instability over time. Based on these findings, it can be concluded that green tea and Indian gooseberry extracts exhibit a synergistic effect in inhibiting oxidation, as well as possessing skin-brightening and antiaging properties. While the nanoemulsion formulation demonstrated favorable characteristics upon preparation, further optimization is required to enhance its long-term stability.