Impact of ultrasound-assisted extraction of polyphenols and caffeine from green tea leaves using high-performance thin-layer chromatography.

Tea is the most popular daily drink consumed globally, with a high concentration of caffeine and polyphenols. In this study, the effects of ultrasonic-assisted extraction and quantification of caffeine and polyphenols from green tea were investigated and optimized using 2 -full factorial design and high-performance thin-layer chromatography. Three parameters were optimized to maximize the concentration of caffeine and polyphenols extracted using ultrasound: crude drug-to-solvent ratio (1:10-1:5), temperature (20-40°C), and ultrasonication time (10-30 min). The optimal conditions achieved from the model for tea extraction were as follows: crude drug-to-solvent ratio, 0.199 g/ml; temperature, 39.9°C; and time, 29.9 min; the extractive value was found to be 16.8%. Images from scanning electron microscopy showed that the matrix underwent a physical alteration and cell wall disintegration, which intensified and accelerated the extraction. This process might be simplified using sonication, which results in a higher extractive yield and a significant concentration of caffeine and polyphenols than the traditional approach, with a smaller quantity of solvent and faster analytical times. The result of high-performance thin-layer chromatography analysis proves a significant positive correlation between extractive value and caffeine and polyphenol concentrations.