Topical Eucalyptol Ointment Accelerates Wound Healing and Exerts Antioxidant and Anti-Inflammatory Effects in Rats' Skin Burn Model

Abstract

Eucalyptol is a major volatile constituent among well-known wound healing medicinal plants. The current study evaluated eucalyptol wound healing activity in the rat's third-degree skin-burn model. The parameters, i.e., skin-healing, oxidative/antioxidant markers, pro-/anti-inflammatory markers, were evaluated after 1- and 2-weeks of treatment regimens with 5% eucalyptol ointment. Eucalyptol-loaded ointment base of 5% w/w strength was formulated using fusion method and physically evaluated for consistency, stability, and homogeneity. A 25-rats were divided randomly into intact, negative control (untreated), silver sulfadiazine (SS, positive control), 1-week, and 2-weeks treated eucalyptol groups. Using an aluminum cylinder (120℃, 10 second duration), 3^rd-degree skin burns were created on the rat's dorsum. Skin biopsies were collected at the end of the experiment for biochemical and histological investigations. Compared to the negative group; time-dependent wound size reduction and decreased edema were observed in eucalyptol-treated animals. Histopathological examinations demonstrated epidermis integrity, decreased neutrophil, and increased capillaries number in the 2-weeks and SS groups, compared to the negative and 1-week treated eucalyptol groups. Compared to the untreated animals, the 1- and 2-weeks eucalyptol treated groups' demonstrated significantly increased antioxidant superoxide dismutase (SOD, p=0.002 and p=0.003, respectively) and reduced lipid peroxide (LP, p=0.005 and p=0.0006, respectively). However, a significant increment of catalase (CAT, p=0.0009) was found only in the 2-weeks of eucalyptol group at a level of 2.42 ± 0.39 ng/g compared to 1.14 ± 0.04 ng/g in the untreated animals. Also, significant reductions in the cytokines, IL-1b, IL-6, and TNF-α (p < 0.05); and increase in the pro-angiogenic marker, IL-10, were detected in the 2-weeks (p=0.001) and SS (p=0.002) treated animals compared to the negative and 1-week eucalyptol treated groups. The study concluded that eucalyptol induced significant duration-based wound healing properties attributed to its antioxidant and anti-inflammatory effects.

Keywords: 1,8-cineole; angiogenesis; anti-inflammatory; antioxidant; eucalyptol; inflammatory markers; skin wound healing.