NADES-based Extraction of Phenolic Compounds From Spent Mitragyna speciosa Biomass for Wound-healing Spray Gel Formulations

The significant economic value of Mitragyna speciosa alkaloid extract has resulted in an increase in demand for the leaf extract. This industrial process produces abundant underutilized spent M. speciosa biomass (SMB). This exhausted biomass is reported to still contain phenolic compounds that can be further utilized, such as for use as a wound-healing agent. The utilization of SMB for wound-healing has not been previously documented in a scientific report. In this investigation, natural deep eutectic solvent (NADES) was used to extract phenolics from SMB and then formulated into a spray gel with various concentrations of extract of 1%, 5%, and 10% (w/v). These formulas were assessed based on changes in physical and chemical characteristics, specifically organoleptic properties, pH, viscosity, spreadability, adhesiveness, and drying time. Additionally, wound-healing efficacy was assessed by an excisional wound model in male Wistar rats. Results indicated that the NADES-based extract had a total phenolic content of 1.575% (w/v). All developed formulations exhibited appropriate physicochemical properties and no phase separation. The formulation containing 5% of SMB depicted more effective results among the extract-treated groups, with a 68.25% wound area closure rate on Day 14. Histologically, this concentration also significantly decreased polymorphonuclear neutrophil cells, increased epithelial thickness, and had a good fibroblast score. Thus, the spray gel with 5% SMB represents a promising advanced topical therapeutic for tissue regeneration.