Visible Light-Induced Antibacterial Activity of Pigments Extracted from Dregs of Green and Black Teas

Renny Indrawati; Elok Zubaidah; Aji Sutrisno; Leenawaty Limantara; Melisa Megawati Yusuf; Tatas Hardo Panintingjati Brotosudarmo

doi:10.1155/2021/5524468

Visible Light-Induced Antibacterial Activity of Pigments Extracted from Dregs of Green and Black Teas

Scientifica (Cairo). 2021 Jun 12:2021:5524468. doi: 10.1155/2021/5524468. eCollection 2021.

Authors

Renny Indrawati^{1

2

3}, Elok Zubaidah¹, Aji Sutrisno¹, Leenawaty Limantara⁴, Melisa Megawati Yusuf³, Tatas Hardo Panintingjati Brotosudarmo^{2

3}

Affiliations

¹ Department of Food Science and Technology, Faculty of Agricultural Technology, Universitas Brawijaya, Malang 65145, Indonesia.
² Ma Chung Research Center for Photosynthetic Pigments, Universitas Ma Chung, Malang 65151, Indonesia.
³ Chemistry Study Program, Faculty of Science and Technology, Universitas Ma Chung, Malang 65151, Indonesia.
⁴ Center for Urban Studies, Universitas Pembangunan Jaya, South Tangerang 15413, Indonesia.

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. The 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. The 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. These findings demonstrated the valorization potential of tea dregs as a source of chlorophyll derivatives with visible light-induced antibacterial activity.