Wound healing activity of medicinal plants and their application in photodynamic therapy (PDT)

Infected chronic wounds are difficult to treat, and often lead to heavy economic burden on health care systems. Bacterial resistance due to misuse/overuse of antibiotics is a challenge for infection treatment.

Photodynamic therapy works by light activation of a locally applied photosensitizing agent that triggers the release of reactive oxygen species and singlet oxygen, causing oxidative damage on cells and bacteria. Plants are sustainable sources of accessible treatment, especially in low-to-middle income countries. The first photosensitizers were natural compounds, but only few taxa have been explored for PDT application.

Therefore, this project aims to investigate the possible use of medicinal plants in the application of PDT for the treatment of infected wounds. The UV absorbance of crude extracts was assessed firstly. Anti-microbial test proved 4 medicinal plants, Polygalae japonica Houtt., Morinda citrifolia L., Semiaquilegiae adoxoides (DC.) Makino, and Turpiniae arguta Seem, having limited activity against two pathogenic microbes ([Table 1]). In the ultraviolet-visible light (UV/VIS) spectrometry determination, only acetone extracts of M. citrifolia (AEMC) absorbed visible light. Dark cytotoxicity of AEMC was detected at a concentration of 10% on 4 T1 and MRC-5 cells. With light irradiation, the cytotoxicity of AEMC increased on MRC-5 cells (5%). For the first time our study revealed light-activated cytotoxicity of the AEMC on 4 T1 and MRC5 cell lines. Further exploration on the light cytotoxicity to bacteria is essential to study if the light enhances antimicrobial effect of M. citrifolia and its potential in treating infected wounds.

Table 1 The MlCs value of 4 medicinal plants on S. aureus and S. pyogenes.

Plant species	Minimum inhibitory concentration (mg/ml)
	Staphylococcus aureus (ATCC25 923)	Streptococcus pyogenes (ATCC19 615)
Polygalae japonica Houtt	> 1024	512
Morinda citrifolia L.	1024	512
Semiaquilegiae adoxoides (DC.) Makino	1024	512
Turpiniae arguta Seem	> 1024	1024

We have no conflicts to disclose.

Publikationsverlauf

Artikel online veröffentlicht:
12. Dezember 2022