Development and evaluation of a propolis, tea tree oil, and jojoba oil nanoemulgel with enhanced antioxidant, anti-inflammatory, and wound-healing activities

Abstract

The wound healing’s acceleration depends on developing an innovative therapeutic strategy that reduces inflammation, regulates oxidative stress, promotes fibroblast proliferation, and collagen deposition. This study aimed to prepare and evaluate a green nanoemulsion-based formulation containing propolis, tea tree, and jojoba oils to integrate their biological activities for enhanced wound healing efficacy. Nanoemulsion formulations were prepared via a low-energy emulsification approach and characterized by zeta potential, hydrodynamic size (DLS), polydispersity index (PDI), and transmission electron microscopy (TEM). The in vitro antioxidant and anti-inflammatory activities were assessed. In addition, cytotoxicity was assessed using the MTT colorimetric assay against the HSF-1 normal skin cell line. Additionally, NO and IL-1β levels were measured on NHDF-Ad cells. A propolis nanoemulgel (PNEG) was produced using Carbopol 940 as a gelling agent. The in vivo wound healing efficacy of PNEG was tested by evaluating wound closure rate, malondialdehyde, superoxide dismutase, tumor necrosis factor-alpha, and histopathological alterations in healed tissues. The obtained results demonstrated that, the optimized formula displayed a zeta potential of − 28.6 ± 1.91 mV, a DLS of 187.8 ± 3.29 nm, and a 50% cytotoxic concentration (CC50) of 24.82 ± 0.16% and showed a significant antioxidant and anti-inflammatory activities. Furthermore, NO and IL-1β levels were significantly decreased by 35% and 40%, respectively, demonstrating potent anti-inflammatory activity. Additionally, the therapeutic activity was associated with inhibition of IL-1β/NO-driven inflammatory signaling, suppression of NF-κB, activation of the NRF2/HO-1 antioxidant axis, and modulation of BAX/Bcl-2 apoptotic pathways. The in vivo results indicated that PNEG accelerates wound closure significantly compared with both positive and negative control groups. SOD level increased significantly (p < 0.05), whereas MDA and TNF-α levels decreased compared with the control groups (p < 0.05). Furthermore, histopathological examination illustrated infiltration reduction of inflammatory cells, increased collagen deposition, and fast epithelialization. The developed green formula, resulting from both the low-energy, environmentally friendly preparation method and the natural origin of its constituents, was demonstrated to be an antioxidant and inflammatory and to accelerate wound healing, suggesting it could be used as a natural formula for topical wound healing application.