GREEN TEA EXTRACT IN MICROEMULSION: STABILITY, DERMAL SENSITIZATION AND EFFICACY AGAINST UV INDUCED DAMAGES
Objective: To determine the photoprotective effect of epigallocatechin (EGC) extracted from green tea using microemulsions as a carrier system.
Methods: In the present study, EGC was extracted from commercially available branded as well as loose green tea samples. Further, microemulsions (MEs) of these extracts were formulated and were evaluated for their antioxidant and photoprotective effects. MEs were formulated using Capmul MCM as oily phase, Tween 80 as a surfactant and Labrasol as co-surfactant after studying the phase behavior. MEs containing green tea extracts were applied to the rat dorsal skin after exposure to UV radiation (rate of exposure = 9.71 J/cm2, dose = 0.9011 mJ/cm2/sec). The effect of the formulation was evaluated in terms of reduced glutathione level (GSH), radical scavenging activity (DPPH), trans-epidermal water loss (TEWL), irritation potential and histological changes. The EGC content of both types of green tea was estimated using HPTLC and photo-stability of ME formulation was evaluated using FTIR-ATR technique.
Results: The content of EGC in loose and branded tea leaf extracts was found to be 0.00322 % w/w and 0.00468 % w/w, respectively. FTIR studies revealed the instability of formulations prepared with water as aqueous phase after UV exposure. However, in the case of PB (pH 7.4) as the aqueous phase in MEs; no change in the spectra of formulations after UV exposure for different time intervals was observed. Results of TEWL studies indicated that the barrier perturbation was not severe which clearly states the safety aspect of the formulation. The extinction coefficient (EC50) value for loose tea and branded tea leaf extract was found to be 170 Âµg/ml and 79 Âµg/ml, respectively. The yield of the extract was 0.00322Â±0.026 % w/w for loose tea and 0.00468Â±0.150 % w/w for branded tea.
Conclusion: The results of the present investigation indicated that pH of the aqueous phase used for preparing the formulation affected the photo-stability of the formulation. Further, MEs prepared using green tea extracts exhibited photoprotective effects. Hence, the green tea extract containing ME formulations have promising potential to be a cosmeceutical.
Keywords: Efficacy against uv induced damages, Microemulsion, Dermal sensitization
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