In vivo wound healing and in vitro antioxidant activities of Bletilla striata phenolic extracts

- Antioxidant activity of the residue after BSP extraction was determined.
- Six phenolic compounds were identified in residue after BSP extraction.
- Phenolic extract residue reduced inflammatory factor levels typically increased by burns.
- Phenolic extract residue accelerated the healing rate of cutaneous wounds in mice.
- The economic value of B. striata is currently underpriced.

Bletilla striata has attracted extensive research interest due to the potential uses for its extracts to treat skin burns and inflammatory disorders in a clinical setting. My current research focuses on Bletilla striata polysaccharides (BSP), and often ignores the residues that remain after polysaccharide extraction. It also remains unclear whether the residues have medical value related its traditional clinic function.During this work, we firstly identified the contents of the post-extraction residue by UPLC-Q-Exactive Orbitrap-MS and evaluated its in vivo wound healing and in vitro antioxidant activity. The wound healing activity of the ointment containing residue was assessed for 15 days the scald model was used in mice, followed by histopathology and histomorphological analysis. The in vitro antioxidant effect of Bletilla residue was researched using DPPH, ABTS, Hydroxyl radical scavenging, superoxideanion radical scavenging, and reducing power assays. AUPLC-Q-Exactive Orbitrap-MS analysis identified 6 phenolic compounds: protocatechuic acid, p-hydroxybenzoic acid, caffeic acid, p-hydroxybenzaldehyde, 3-Hydroxycinnamic acid, and ferulic acid. Animals treated with “mixed ointment” experienced inflammatory infiltration, which was lower than that of other groups. Both “BSPG ointment” and “Bletilla phenolic ointment” demonstrated superior tissue repair compared to the control. This study was the first to confirm that the residual liquid after polysaccharide extraction has excellent antioxidant and wound healing activities. In addition to Bletilla striata polysaccharides, the residual liquid can improve skin regeneration after burns and reduce inflammatory marker levels. These results have implications that the residual liquid has potential wound healing medicinal value.

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