Effects of Laurus nobilis Leaf Extract on Healing of Experimentally Induced Wounds in Rabbits

Abstract

Wound or injury can be defined as partial or complete separation of the skin, while the healing of the wounds is defined as the sequences of processes by which the skin heals and returns to its normal appearance. This study aims to evaluate the efficacy of Laurus nobilis leaf extracts on the healing of open wounds in rabbits. Twenty-four healthy rabbits were used, divided randomly into control and treated groups, each consisting of 12 rabbits. The rabbits were caused to experience circular wound defects (2.5 cm) in diameter. All animals in the control (C) group were left without treatment while those in the Laurus nobilis leaf extract group were treated with drops of the aqueous extract of Laurus nobilis in a dose of 200 mg/kg per day for 20 days. The results of macroscopic observation revealed that all animals in both groups showed equitable viability and good appetite, no mortality occurred, and no signs of infection. In the group with the Laurus nobilis extract, we noticed a significant improvement in wound-healing activity and a reduction in the wound area at p ≤ 0.05 compared with the C group. Histopathological results at the end of the study show that the thick epidermal layer covers a mass of granulation with congested blood vessels and the dermis transforms into a denser layer gradually due to the improvements of the cellularity in the C group and also revealed a well-formed skin appearance, widespread of collagen, and fibrosis within the dermis with an appearance near the normal dermis in the group treated with Laurus nobilis leaf extract. In conclusion, the results confirmed that using Laurus nobilis methanolic extract solution in a daily dose of 200 mg/kg promotes healing of open wounds in rabbits.

Keywords: Laurus nobilis; leaf extract; rabbit injury; wound healing.

Figure 1

(a) and (b) The induced full-thickness circular wound: 2.5 cm in diameter in the skin.

Figure 2

(a) and (b) The application of the Laurus nobilis methanolic extract on the wound.

Figure 3

Measurement of the wound contraction by centimeter: (a–d) control group on 5^th, 10^th, 15^th, and 20^th days postoperatively, respectively, and (e–h) LET group on 5^th, 10^th, 15^th, and 20^th days postoperatively, respectively.

Figure 4

Histopathological section of the wound for the control group. (a) and (b) On the 5^th day postwounding shows neutrophils infiltration (blue arrow) and fibrin network formation (red arrows): wide area of hemorrhage (yellow arrow) (a): H&E X10 and (b): Masson's trichrome X40. (c) and (d) On the 10^th day postwounding shows granulation tissue (blue arrow) loose stroma (red arrow) and active angiogenesis (yellow arrow) (c): H&E X10 and (d): Masson's trichrome X40. (e) and (f) On the 15^th day postwounding shows immature granulation tissues (blue arrow) with mononuclear cells infiltration (black arrow). (e) H&E X10 and (f) Masson's trichrome X40. (g) On the 20^th day postwounding shows thick epidermal layer (black arrow) over the granulation tissue (red arrow) which consists of newly formed blood vessels (yellow arrow). Masson's trichrome X10.

Figure 5

Histopathological section of the wound for the LET group. (a) and (b) On the 5^th day postwounding shows granulation tissue replaced most of incision area (green arrows) with congested blood vessels, neutrophils, and mononuclear cells infiltration (yellow arrow). (a): H&E X10 and (b): Masson's trichrome X40. (c) and (d) On the 10^th day postwounding shows large amount of well-organized granulation tissue (black arrow), mononuclear inflammatory cells (red arrow) with dense stroma (blue arrow), and sufficient vascularization (yellow arrow). (c): H&E X10 and (d): Masson's trichrome X40. (e) and (f) On the 15^th day postwounding shows thick epidermal area (black arrow) with mononuclear cells infiltration (red arrow) and presence of dens matures granulation tissue in the incision area (yellow arrow). (e): H&E X10 and (f): H&E X40. (g) On the 20^th day postwounding shows normal epidermal area (black arrow) covering mature granulation tissue (yellow arrow). Masson's trichrome X40.