Physiological effects of formulation containing tannase-converted green tea extract on skin care: physical stability, collagenase, elastase, and tyrosinase activities

Abstract

Background: Green tea contains numerous polyphenols, which have health-promoting effects. The purpose of this study was to evaluate the effect of tannase-converted green tea extract (TGE) formulation on the physical stability and activities of skin-related enzymes.

Methods: Physical stability was evaluated by measuring the pH, precipitation, and colors at 25 ± 2 °C/ambient humidity and at 40 ± 2 °C/70% ± 5% relative humidity for 4 months. Activities of collagenase, elastase, and tyrosinase as skin-related enzymes were assessed on TGE formulation.

Results: The concentrations of epigallocatechin-3-gallate and epicatechin-3-gallate in green tea extract were greatly decreased to the extent of negligible level when treated with tannase. The formulation containing 5% tannase-converted green tea extract showed relatively stable pH, precipitation, and color features for 16 weeks. When TGE was added to the formulation, there was a significant increase in the inhibition of elastase and tyrosinase activities (p < 0.05) compared with the formulation containing 5% normal green tea extract.

Conclusion: The TGE could be used in cosmetics as skin antiwrinkling or depigmenting agent.

Keywords: elastase; green tea; stability; tannase; tyrosinase.

Fig. 1

High-performance liquid chromatography chromatogram for catechins in green tea extract (A) with or (B) without tannase treatment under optimum extraction conditions. GC, (–)-gallocatechin; EGC, (–)-epigallocatechin; EGCG, (–)-epigallocatechin gallate; EC, (–)-epicatechin; GCG, (–)-gallocatechin gallate; ECG; (–)-epicatechin gallate.

Fig. 2

pH changes of formulation containing 5% tannase-converted green tea extract stored at (A) 25 ± 2 °C/ambient humidity and at (B) 40 ± 2 °C/70% ± 5% relative humidity for 4 months. Values are means ± standard deviation of three determinations. FNGE, formulation containing 5% normal green tea extract; FTGE, formulation containing 5% tannase-converted green tea extract.

Fig. 3

Color changes of formulation containing 5% tannase-converted green tea extract stored at (A) 25 ± 2 °C/ambient humidity and at (B) 40 ± 2 °C/70% ± 5% relative humidity for 4 months. Values are means ± standard deviation of three determinations. Asterisk indicates a significant difference (p < 0.05) between baseline and each week by a paired t test. L (degree of lightness), a (degree of redness), and b (degree of yellowness) are colors of samples; L′, a′, and b′ are colors of base at zero time. FNGE, formulation containing 5% normal green tea extract; FTGE, formulation containing 5% tannase-converted green tea extract.

Fig. 4

Total (A) polyphenol and (B) flavonoid contents in formulation containing 5% tannase-converted green tea extract. Bars are means ± standard deviation of three determinations. Asterisks indicate significant differences (p < 0.05) among samples by Turkey multiple range test. FNGE, formulation containing 5% normal green tea extract; FTGE, formulation containing 5% tannase-converted green tea extract.

Fig. 5

(A) Collagenase and (B) elastase inhibitory activities of formulation containing 5% tannase-converted green tea extract. Collagenase inhibition activity (%) = [(A–B)/A] × 100. (A) With collagenase but without sample; (B) with sample and collagenase. The percentage of elastase inhibition was calculated using the same method used for collagenase inhibition. Bars are means ± standard deviation of three determinations. Asterisks indicate significant differences (p < 0.05) among samples by Turkey multiple range test. FNGE, formulation containing 5% normal green tea extract; FTGE, formulation containing 5% tannase-converted green tea extract.

Fig. 6

Tyrosinase inhibitory activities of formulation containing 5% tannase-converted green tea extract. Tyrosinase inhibition activity (%) = [(A − B) − (C − D)]/(A − B) × 100. (A) With tyrosinase but without sample; (B) without sample and tyrosinase; (C) with sample and tyrosinase; and (D) with sample but without tyrosinase. Bars are means ± standard deviation of three determinations. Asterisks indicate significant differences (p < 0.05) among samples by Turkey multiple range test. FNGE, formulation containing 5% normal green tea extract; FTGE, formulation containing 5% tannase-converted green tea extract.