| dc.description.abstract | Chlorophyll and its derivatives are potential natural sensitizers frequently applied in antimicrobial photodynamic therapy. Chlorophyll
derivatives are formed naturally during tea processing, but they do not contribute to the color of tea infusions and thus are presumably
left in the tea dregs. 'e present study aimed to investigate (i) the chlorophyll remnants in the pigments recovered from dregs of green
and black teas and (ii) the antibacterial activity of pigments extracted from the tea dregs upon illumination using a light-emitting diode
(LED) as the light source. Pigment analysis using high-performance liquid chromatography (HPLC) revealed the presence of main
degradation products of chlorophylls, such as pheophytin and its epimers, pyropheophytin, and pheophorbides. In vitro assays
demonstrated significant reductions in the number of viable bacteria in the presence of the pigments after 30 min of incubation with LED
light irradiation. 'e descending order of bacterial susceptibility was Listeria monocytogenes>Staphylococcus aureus>Escherichia
coli>Salmonella typhi. At an equivalent irradiation intensity, the blue and red LEDs could stimulate a comparable inactivation effect
through photodynamic reactions. 'ese findings demonstrated the valorization potential of tea dregs as a source of chlorophyll
derivatives with visible light-induced antibacterial activity. | en_US |
