Potential Use of Essential Oil Isolated from Cleistocalyx operculatus Leaves as a Topical Dermatological Agent for Treatment of Burn Wound

Abstract

Several herbal remedies have been used as topical agents to cure burn wound, one of the most common injuries in worldwide. In this study, we investigated the potential use of Cleistocalyx operculatus essential oil to treat the burn wound. We identified a total of 13 bioactive compounds of essential oil, several of which exhibited the anti-inflammatory and antimicrobial activities. Furthermore, the essential oil showed the antibacterial effect against S. aureus but not with P. aeruginosa. The supportive effect of essential oil on burn wound healing process also has been proven. Among three groups of mice, wound contraction rate of essential oil treated group (100%) was significantly higher than tamanu oil treated (79%) and control mice (71%) after 20 days (0.22 ± 0.03 versus 0.31 ± 0.02 cm², resp., p < 0.05). Histological studies revealed that burn wounds treated with essential oil formed a complete epidermal structure, thick and neatly arranged fibers, and scattered immune cells in burn wound. On the contrary, saline treated burn wound formed uneven epidermal layer with necrotic ulcer, infiltration of immune cells, and existence of granulation tissue. This finding demonstrated Cleistocalyx operculatus essential oil as promising topical dermatological agent to treat burn wound.

Figure 1

GC/MS chromatogram of essential oil extracted from Cleistocalyx operculatus leaves. A total of 13 compounds were identified in CLO: 6-camphenol; isopinocarveol; p-cymen-8-ol; (−)-myrtenol; I-verbenone; cis-carveol; ethaneperoxoic acid, 1-cyano-4,4-dimethyl-1-phenylpentyl ethaneperoxate; (+)-carotol; caryophyllene oxide; (−)-globulol; 2-(4a,8-dimethyl-2,3,4,4a,5,6-hexahydronaphthalen-2-yl)propan-1-; and longipinocarvone. Among them, many bioactive compounds identified in CLO exhibited antimicrobial and/or anti-inflammatory activities. This finding supports the idea of using Cleistocalyx operculatus essential oil as topical agent for treatment of burn wound, at least to prevent the infection and sepsis.

Figure 2

Antimicrobial activity of C. operculatus essential oil. Both CLO and commercial tamanu oil exhibited antibacterial activity against S. aureus whereas they did not inhibit the growth of P. aeruginosa. The diameter of inhibition zones against S. aureus of gentamicin (positive control) was highest (11.37 ± 0.15 mm), followed by tamanu oil (9.03 ± 0.31 mm) and CLO (7.17 ± 0.12 mm). On the contrary, only gentamicin showed the antibacterial activity against P. aeruginosa (12.07 ± 0.15 mm); both tamanu oil and CLO did not affect the growth of P. aeruginosa. This finding implies the potential use of CLO as anti-infective agent for burn wound treatment. The experiments were triplicated, and results were presented as mean ± standard deviation.

Figure 3

Establishment of second-degree burn wound models. Histological analysis showed that injury of burn wound was extended into both epidermis and dermis. In normal skin section, thick squamous epithelium covered the epidermis, and both of epidermis and dermis had the normal structure with several hair follicles and sebaceous glands (a). In burn wound skin section, epidermis and dermis lost their normal structure. Of note, squamous epithelium layer was removed, and epidermis was necrotized. Moreover, the underlying stromal tissue was swollen and congestive (b). These results indicated that the second-degree burn model was successfully established in experimental mice. The arrows indicated the border between the dermis and hypodermis.

Figure 4

Evaluation of the healing rate of burn wound in experimental mice. At the beginning of experiment, all burn wounds were of similar sizes in three groups (a, b, c). In day 10, burn wound areas of tamanu oil (e) and essential oil treated mice (f) were smaller than saline treated group (d), and the significant difference of wound contraction between tamanu oil and essential oil treated mice was observed (p < 0.05). Furthermore, we found that burn wounds of essential oil treated mice were fully recovered (i). Burn wound contraction rate of tamanu oil treated mice (h) was significantly higher than that of saline treated groups (g) after 20 days. These results implied that C. operculatus essential oil has supportive effect on wound healing process and its efficiency was higher than the commercial tamanu oil.

Figure 5

Microscopic changes in burn wounds of experimental mice. Histology studies revealed that burn wounds treated with essential oil developed complete epidermal structure (c). In tamanu oil treated mice, wounds were partially recovered with existence of coagulative necrosis region on epidermis and vascular congestion, swollen stromal tissue, and no matured hair follicles (b). On the contrary, saline treated mice formed uneven epidermal layer with the ulcer on epidermis layer and infiltration of immune cells (a). The highlighted part in (a) pointed out the ulcer region with infiltration of lymphocytes and multinuclear leukocytes.