EVALUATION OF EFFECTIVENESS IN A NOVEL WOUND HEALING OINTMENT-CROCODILE OIL BURN OINTMENT

Abstract

Background: Crocodile oil and its products are used as ointments for burns and scalds in traditional medicines. A new ointment formulation - crocodile oil burn ointment (COBO) was developed to provide more efficient wound healing activity. The purpose of the study was to evaluate the burn healing efficacy of this new formulation by employing deep second-degree burns in a Wistar rat model. The analgesic and anti-inflammatory activities of COBO were also studied to provide some evidences for its further use.

Materials and methods: The wound healing potential of this formulation was evaluated by employing a deep second-degree burn rat model and the efficiency was comparatively assessed against a reference ointment - (1% wt/wt) silver sulfadiazine (SSD). After 28 days, the animals were euthanized and the wounds were removed for transversal and longitudinal histological studies. Acetic acid-induced writhing in mice was used to evaluate the analgesic activity and its anti-inflammatory activity was observed in xylene -induced edema in mice.

Results: COBO enhanced the burn wound healing (20.5±1.3 d) as indicated by significant decrease in wound closure time compared with the burn control (25.0±2.16 d) (P<0.01). Hair follicles played an importance role in the physiological functions of the skin, and their growth in the wound could be revealed for the skin regeneration situation. Histological results showed that the hair follicles were well-distributed in the post-burn skin of COBO treatment group, and the amounts of total, active, primary and secondary hair follicles in post-burn 28-day skin of COBO treatment groups were more than those in burn control and SSD groups. On the other hand, the analgesic and anti-inflammatory activity of COBO were much better than those of control group, while they were very close to those of moist exposed burn ointment (MEBO).

Conclusions: COBO accelerated wound closure, reduced inflammation, and had analgesic effects compared with SSD in deep second degree rat burn model. These findings suggest that COBO would be a potential therapy for treating human burns. Abbreviations: COBO, crocodile oil burn ointment; SSD, silver sulfadiazine; MEBO, moist exposed burn ointment; TCM, traditional Chinese medicine; CHM, Chinese herbal medicine; GC-MS, gas chromatography-mass spectrometry.

Keywords: Anti-inflammatory; Antinociceptive; Burn healing; Chinese herbal medicine; Crocodile oil burn ointment; Hair follicles.

Figure 1

A deep second-degree burn wound of a surface (2.5 cm in diameter) was created; two burns were created on the dorsum of the animal except normal group (Sham group). Scale bar: 1.0 cm.

Figure 2

The healing time on Wistar rat dorsal wound. Values are mean± SE of twelve burns, Values in brackets represent statistic differences: * P < 0.05; ** P < 0.01.

Figure 3

Wound contraction in different groups. Rat dorsal burn wound area photograph on the 3^rd, 7^th, 10^th, 14^th, 21^st, 28^th day after application of different treatments: burn control group (a-f), silver sulfadiazine group (g-l) and crocodile oil burn ointment group (m-r). Photographs were taken from a representative animal of each group. Scale bar: 1 cm. The percentage of wound contraction in different groups on the 3^rd, 7^th, 10^th, 14^th, 21^st, 28^th day (s): Burn control group, Silver sulfadiazine group, and Crocodile oil burn ointment group. Values are mean ± SE of twelve burns. * P < 0.05; ** P <0.01.

Figure 4

Hematoxylin and eosin (HE) staining in the post-burn 28 day rat dorsum biopsies. Cross-sections through the longitudinal aspect of the scarred areas were made. (a) Normal group, (b) Burn control group; (c) Silver sulfadiazine group; (d) Crocodile oil burn ointment group. epi, epidermis; h, hair follicle; Scale bar 200 μm; Original magnification x10.

Figure 5

Sacpic staining in the post-burn 28 day rat dorsum biopsies. Embedded skin samples were sectioned in transverse plane. (A, a) Normal group; (B, b) Burn control group; (C, c) Silver sulfadiazine group; (D, d) Crocodile oil burn ointment group. Pictures (A - D) were taken at original magnification x10, Scale bar: 200 μm; Pictures (a - d) were taken at original magnification x40, Scale bar: 50 μm.

Figure 6

Assessment of the activity and distribution of hair follicles in the post-burn 28 day rat dorsum biopsies. Data were quantified from the samples which were stained with Sacpic. The active follicle was stained in red. The amounts of total follicle or active follicle (a), primary follicle (b), and secondary follicle (c) were measured respectively. All measurements were evaluated by taking average number of follicles in eight high power fields (20xobjective), midway in the post-burn skins. Values are mean ± SE of twelve burns. * P < 0.05; ** P < 0.01.