Investigating the active chemical constituents and pharmacology of Nanocnide lobata in the treatment of burn and scald injuries
Authors: Zou Yanlin , Yu Cao , Huang Qian , Tan Xiaorong , Tan Xiaoyan , Zhu Xiaolong , Yi Dongyang , Mao Jingxin 
Published: June 2023

Objective
To identify the most effective fraction of Nanocnide lobata in the treatment of burn and scald injuries and determine its bioactive constituents.

Methods
Chemical identification methods were used to analyze solutions extracted from Nanocnide lobata using petroleum ether, ethyl acetate, n-butanol using a variety of color reactions. The chemical constituents of the extracts were identified by ultra-performance liquid chromatography (UPLC)–mass spectrometry (MS). A total of 60 female mice were randomly divided into the following 6 groups: the petroleum ether extract-treated group; the ethyl acetate extract-treated group; the n-butanol extract-treated group; the model group; the control group; and the positive drug group. The burn/scald model was established using Stevenson’s method. At 24 hours after modeling, 0.1 g of the corresponding ointment was evenly applied to the wound in each group. Mice in the model group did not undergo treatment, while those in the control group received 0.1 g of Vaseline. Wound characteristics, including color, secretions, hardness, and swelling, were observed and recorded. Photos were taken and the wound area calculated on the 1st, 5th, 8th, 12th, 15th, 18th and 21st days. Hematoxylin-eosin (HE) staining was utilized to observe the wound tissue of mice on the 7th, 14th, and 21st days. An enzyme-linked immunosorbent assay (ELISA) kit was used to measure the expression of tumor necrosis factor (TNF)-α, interleukin (IL)-10, vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-β1.

Results
The chemical constituents of Nanocnide lobata mainly include volatile oils, coumarins, and lactones. UPLC–MS analysis revealed 39 main compounds in the Nanocnide lobata extract. Among them, ferulic acid, kaempferitrin, caffeic acid, and salicylic acid have been confirmed to exhibit anti-inflammatory and antioxidant activity related to the treatment of burns and scalds. HE staining revealed a gradual decrease in the number of inflammatory cells and healing of the wounds with increasing time after Nanocnide lobata extract administration. Compared with the model group, the petroleum ether extract-treated group showed significant differences in the levels of TNF-α (161.67±4.93, 106.33±3.21, 77.67±4.04 pg/mL) and IL-10 (291.77±4.93, 185.09±9.54, 141.33±1.53 pg/mL) on the 7th, 14th, and 21st days; a significant difference in the content of TGF-β1 (75.68±3.06 pg/mL) on the 21st day; and a significant difference in the level of VEGF (266.67±4.73, 311.33±10.50 pg/mL) on the 7th and 14th days respectively.

Conclusion
Petroleum ether Nanocnide lobata extract and the volatile oil compounds of Nanocnide lobata might be effective drugs in the treatment of burn and scald injuries, as they exhibited a protective effect on burns and scalds by reducing the expression of TNF-α, IL-10 and TGF-β1 and increasing the expression of VEGF. In addition, these compounds may also exert pharmacological effects that promote wound tissue repair, accelerate wound healing, and reduce scar tissue proliferation, inflammation and pain.