Optimizing Burn Wound Healing: pH Modulation and Rheological Considerations in Plant-Based Topical Treatments

A new preclinical study highlights the critical role of wound pH and rheological properties in optimizing the healing of burn injuries using plant-based topical formulations. The research, recently published in Pharmaceutics, demonstrates that oleogels and hydrogels enriched with extracts from medicinal plants such as Boswellia serrata and Ocimum basilicum significantly improve healing outcomes in an experimental rat burn model.

Researchers from Victor Babes University of Medicine and Pharmacy in Romania developed and characterized multiple gel formulations using ethanolic and hydroalcoholic plant extracts. These were applied daily over a 21-day period to second-degree burns induced in Wistar rats using a standardized scald model. The results indicate that formulations with an acidic pH, high viscosity, and enhanced thixotropic behavior not only promoted faster healing but also improved histological indicators such as epithelialization and reduced inflammation.

Of the numerous combinations tested, oleogels containing Boswellia serrata and Ocimum basilicum extracts performed best, significantly reducing wound size and inflammatory markers by days 9 and 21. These improvements were strongly correlated with formulation pH below 6 and favorable rheological behavior that enhanced topical adherence and sustained bioactive release.

“Maintaining a slightly acidic microenvironment at the wound site is essential,” the authors write. “It supports antimicrobial activity, preserves the skin barrier, and fosters regeneration.” This aligns with prior evidence that healthy skin maintains an acidic surface pH of 4.1 to 5.8, whereas elevated pH levels are associated with delayed healing and microbial colonization.

The study’s histological evaluations provide further support: tissue samples from rats treated with acidic oleogels showed reduced fibrosis, more advanced epithelial layers, and better vascularization than those treated with neutral or basic formulations. Interestingly, combinations of multiple extracts in equal proportions (1.25% each of four plants) were less effective than single-extract formulations, possibly due to reduced synergism or competing bioactive interactions.

Beyond pH, rheological characteristics such as viscosity and thixotropy emerged as key performance indicators. High-viscosity gels persisted longer on the wound surface, allowing for controlled release of active compounds like boswellic acids, rosmarinic acid, and rutin—all identified through high-performance liquid chromatography in the formulations.

Temperature monitoring offered additional insights. Most formulations showed a return toward baseline skin temperatures by day 21, suggesting resolution of inflammation. However, a few—such as hydrogels with Ocimum basilicum—maintained slightly elevated temperatures, potentially indicating prolonged inflammatory activity.

The authors emphasize that while their findings are promising, clinical translation will require further human trials. They also note limitations such as the short duration of observation, the absence of detailed microbiological assessments, and the need to explore optimal dosing and extract combinations.

Nonetheless, the study presents a compelling case for a new class of burn treatments rooted in plant pharmacology and physicochemical precision. With further validation, these customized, pH-modulating topical formulations could become valuable tools in both clinical and home burn care settings.