Evaluation of green tea extract as a safe personal hygiene against viral infections

Lee, Yun Ha; Jang, Yo Han; Kim, Young-Seok; Kim, Jinku; Seong, Baik Lin

Finally, we examined whether GTE treatment affects the morphological properties of the influenza virus. The PR8 virus was treated with 0.1% GTE or PBS and the virus particles were observed under cryoelectron microscope (cryo-EM). As shown Fig. 5a , the treatment of GTE did not result in noticeable changes in particle sizes and the shape of the viruses, as compared with PBS control (Fig. 5) . Furthermore, the size distribution of the virus particles was measured using dynamic light scattering (DLS) system. PR8 virus treated with PBS showed the highest intensity at particle diameter of 97.8 nm (Fig. 5b) . GTE treatment resulted in the highest intensity at particle diameter of 126.2 nm, 113.7 nm, and 121 nm for GTE concentration of 0.01%, 0.05%, and 0.1%, respectively, showing that GTE treatment increased the viral particle sizes to 15.5 − 28.8%. Considering that the influenza virus particles typically have a size of 80 − 120 nm [36] , the increase in the particle sizes by GTE treatment does not appears to be significant. Catechins may also interact with the viral membranes as well as the viral proteins [22] . Whether the observed changes in the particle size may be associated with the membrane fluidity/integrity, crucially important for viral membrane fusion for infection, remains to be further investigated. Fig. 4 Effects of supplements on the kinetics of viral inactivation by GTE. a Chemical stability of green tea catechins. 0.1% GTE and GTE-mix solutions were stored at 25°C for up to 56 days. The samples were obtained at various time-points and catechins concentration was measure by GC. b Kinetics of viral inactivation by GTE and GTE-mix. 0.1% GTE and GTE-mix solutions were incubated at for 24 h at 25°C. After the incubation, the GTE and GTE-mix solutions were mixed with 10 6 PFU of PR8 virus and further incubated at 25°C for 0, 1, 5, 10, 30, 120, and 360 mins for viral inactivation. Residual viral titers at each time-point were determined by plaque assay on MDCK cells. Data are the mean of two independent experiments. Detection limit of plaque assay is 5, and error bars indicate the SD