In vivo anti-aging activity of cream containing niosomes loaded with purple glutinous rice (Oryza sativa Linn.) extract

Objective: To evaluate the anti-aging activity of cream containing the methanolic purple glutinous rice extract loaded in niosomes.

Methods: The in vitro biological activities of the purple glutinous rice extracted by methanol maceration were determined. The extract loaded in niosomes and the cream containing the niosomes were developed. The in vivo anti-aging activity in 20 human volunteers including skin hydration, pigmentation, roughness and elasticity after daily application for 28 days compared to at initial was evaluated by Corneometer, Mexameter, Visiometer and Cutometer, respectively.

Results: The purple glutinous rice extract showed free radical scavenging (SC₅₀ ), lipid peroxidation inhibition (IPC₅₀ ), metal ion chelating (CC₅₀ ) and tyrosinase inhibition (IC₅₀ ) values at 32.31±1.28, 57.40±2.12, 85.05±5.43 and 43.89±2.14 mg/ml which were 0.00031, 0.011, 0.0078 and 0.0016 times of the standards (0.01±0.00, 0.62±0.14, 0.66±0.05 and 0.07±0.01), respectively. The purple glutinous rice extract contained 0.35 µg of anthocyanin/ 1 mg of the extract determined by HPLC. After loaded in niosomes, the solubility of the extract was not only increased in various solvents, but also the chemical stability in different environments (weak base, reducing agent and acid salt) was improved. The cream formulation containing niosomes loaded with 1%w/v of the purple glutinous rice extract indicated the anthocyanin remaining percentages after 6 cycles of heating and cooling test at 52.28% of the initial. For in vivo anti-aging activities, cream containing niosomes loaded with the extract gave significant decreased melanin index and skin roughness reduction of -14.05 and -9.95% of the initial, respectively. The % changes of the increased skin hydration, skin elastic extension and skin elastic recovery when applied on human volunteers' skin with this formulation were +48.73, -24.51 and +35.98%, respectively.

Conclusion: The cream containing niosomes loaded with the 1%w/v methanolic purple glutinous rice extract gave not only the suitable in vitro antioxidant activity and physical stability of the active anthocyanin, but also the superior in vivo anti-aging activity on human skin compared to the cream base and before application which can be further developed as a novel anti-aging cosmeceutical product.

Keywords: antioxidant; cosmeceutical product; in vivo anti-aging efficacy; niosomes; purple glutinous rice; tyrosinase inhibition.