The Effect of Ultrasound, Oxygen and Sunlight on the Stability of (−)-Epigallocatechin Gallate

Abstract

(−)-Epigallocatechin gallate (EGCG), is the main catechin found in green tea, and has several beneficial effects. This study investigated the stability of EGCG aqueous solution under different stored and ultrasonic conditions to determine whether it can be used with an ultrasonic dental scaler to treat periodontal infection. Four concentrations (0.05, 0.1, 0.15, 2 mg/mL) of EGCG aqueous solution were prepared and stored under four different conditions (A: Exposed to neither sunlight nor air, B: Exposed to sunlight, but not air, C: Not exposed to sunlight, but air, D: Exposed to sunlight and air) for two days. The degradation rate of EGCG was measured by high performance liquid chromatography (HPLC). On the other hand, an ultrasonic dental scaler was used to atomize the EGCG solution under four different conditions (a: Exposed to neither air nor sunlight, b: Not exposed to air, but sunlight, c: Not exposed to sunlight, but air, d: Exposed to air and sunlight), the degradation of EGCG was measured by HPLC. We found that the stability of EGCG was concentration-dependent in water at room temperature. Both sunlight and oxygen influenced the stability of EGCG, and oxygen had a more pronounced effect on stability of EGCG than sunlight. The most important conclusion was that the ultrasound may accelerate the degradation of EGCG due to the presence of oxygen and sunlight, but not because of the ultrasonic vibration. Thus, EGCG aqueous solution has the potential to be used through an ultrasonic dental scaler to treat periodontal infection in the future.

Efficacy of (−)-epigallocatechin gallate delivered by a new-type scaler tip during scaling and root planing on chronic periodontitis: a split-mouth, randomized clinical trial

“…According to microbiological studies, EGCG exhibited better anti-microbial and anti-inflammatory than other main catechins in green tea extract, therefore, we applied a 5 mg/mL EGCG solution as coolants, which was higher than its minimal inhibitory concentration to periodontal pathogens [ 13 ]. The pertinent study applying purified EGCG medication on periodontal disease was absent, while our previous study has proved that the concentration as high as 5 mg/mL could maintain stable under ultrasonic vibration [ 28 ].…”

EGCG regulates CTR1 expression through its pro‐oxidative property in non‐small‐cell lung cancer cells

“…Many antitumor agents based on the antioxidant activities of EGCG targeting oncogenes were used (Cerezo-Guisado et al, 2015). Notably, EGCG is rather stable in range of 2.0-5.5 of pH (Hong et al, 2002), whereas underwent autoxidation (Akagawa, Shigemitsu, & Suyama, 2003), donated hydrogen atoms and led to the generation of superoxide and oxidized products (Zeng et al, 2018) under neutral and alkaline conditions. For example, EGCG exhibited its auto-oxidation effect in HT-29 cells in typical cell culture conditions at pH 7.2-7.4 and caused maximum H 2 O 2 formation at 2 hr in McCoy's 5A medium when 50 μM of EGCG was added (Hong et al, 2002).…”

Great green tea ingredient? A narrative literature review on epigallocatechin gallate and its biophysical properties for topical use in dermatology

“…After 48 hr, the 2 mg mll −1 solution had maintained more than 80% of its EGCG concentration, whereas both the 0.1 and the 0.5 mg mll −1 solution fully degraded (Zeng et al, 2018).…”