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Estimation of the healing effects of the topical use of MEBO and hyaluronic acid gel in the burned rats

Safa Mustafa Najim1*, Ammar A. Fadhil1, Muhammed Naeem Abdullah2, Luma Eassa Hammodi3

1Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad, Baghdad, Iraq. 2Department of Surgery, Plastic and Reconstructive Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq. 3Department of Pharmacology and Toxicology, College of Pharmacy, Baghdad, University of Al Turath, Iraq.

Correspondence: Safa Mustafa Najim, Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad, Baghdad, Iraq. [email protected]


Exposing the dorsal superficial skin of rats to partial-depth burn leads to bacterial and microbes Invasion. Topical treatment is required in most superficial burn cases Moist exposed burn ointment (MEBO) protects wounds from infection and enhances healing without any harmful effects of purified chemicals is caused. The topical using of HA gel in rat models with full and partial thickness surgical wounds shows enhancement in wound repair. In this study, we compared the healing efficacy of topical use of hyaluronic acid gel products with MEBO as standard management in rats that were exposed to a partial-thickness burn. The experiment included twenty-four (24) adult albino rats of male sex with weight (150-220 gm) of 3 months’ age divided into four groups. Partial-thickness burn wounds are applied on their shaved dorsal skin by a hot metal plate for 4 seconds. Group I: control group received topically normal saline as a vehicle placebo, group II: are treated topically with MEBO, Groups III & IV: are treated topically with hyaluronic acid gel (Afta Med and Gum Afta Clear) respectively twice daily for 14 days. The burn wound area was daily examined and measuring the diameter of the lesion area was until day 14 and photographs of the lesion area and wound repairs were taken at different time intervals (0,3,5,7, 10, and 14). % of wound contraction also detected. The rats were sacrificed on days 11 and 14, then elevates 5 mm of diameter full-thickness flap of healed and unhealed wound areas. Wound healing occurs faster when using HA gel products topically for treatment of the induced partial-thickness burn when compared with using MEBO and control group which was supported with histological examination and statistical analysis.

Keywords: MEBO, Hyaluronic acid gel, Partial-thickness burn, Wound-healing, Re-epithelialization


The definition of a burn is coagulative necrosis or damage to the skin caused by excessive exposure to heat or caustic chemicals [1].  Burns is a common and hard healthcare issue [2]. The possibility of healing of a burn wound and/or its depth is considered the crucial determining factor in the management protocol of burns [3]. A burn that influences the epidermis and dermis which are the top two layers of skin, is called the partial depth burn (a second-degree burn). This type of thermal injury can continue to change over time and can progress to a full-thickness burn (third-degree), even after initial management. Partial-thickness burns can be serious and life-threatening and have a high risk of mortality and morbidity.

The healing of a burn wound is a dynamic and active operation that commences from the beginning of an injury. Additionally, the major difficulties for health care are delayed healing of burned wounds and this led to a lowered quality of life for patients who have this kind of deep wound [4, 5]. The delay in the initiation of proper burn management can elongate the healing process [6]. Infection is a serious complication of burn injuries and is responsible for 50–75% of the burn mortality rate [7]. So, prophylactically several antimicrobial agents are described to prevent the development of infection, at the same time other medications are intended to kill proliferating microbial cells that are within the burn when an infection has been developed [8]. The selection of the topical treatment should be depended on the ability of an agent to inhibit the recovery of microorganisms from burn wound surveillance cultures [9].

Moist exposed burn ointment (MEBO) is an oil-based natural pure preparation of herbal generally utilized in the Middle East and Asia [10]. In 1989; It was developed at China National Science and Technology Centre. Then, formu­lated in the USA as a burn ointment since 1995 [11]. It is used to treat different burn thicknesses and accomplish good results in clinical pieces of research [12]. In Chinese literature, several experimental and clinical research has demonstrated that the MEBO markedly decreases the evaporation of water from the surface of burn wounds [13].  MEBO consists of sesame oil, berberine oil and beta-sitosterol (is a plant steroid), and other Chinese herbal ingredients.  The oils relieve pain, retain moisture and soften the wounds. Beta-sitosterol stimulates epithelialization [10]. Many studies express that β‑sitosterol has anti-inflammatory effects [14] and berberine shows antimicrobial effects [15]. Different experimental and clinical researches explain the antimicrobial and analgesic effects of MEBO, which also accelerates the timing of burning treatment and wound healing in patients [12, 16, 17]. Additionally, MEBO promotes epithelial repair and debridement effect, with improved quality of scar and decreased treatment costs for patients [12, 17]. Similarly, it exhibits chronic ischemic and neurogenic ulcer healing [18, 19].

Hyaluronic acid (HA), is an essential physiological polysaccharide substance in the body composed of the glycosaminoglycan group which consists of N-Acetyl-D-glucosamine and D-glucuronic acid monosaccharide molecules. It is mostly found in a huge amount of synovial fluid, including cartilages, joints, eyes, and skin tissues [20]. During wound healing, HA has a crucial role in the formation of healthy connective tissues and enhances inflammatory response and attenuating inflammation by decreasing inflammatory cell infiltration and possibly stabilizing granulation tissue, regeneration and angiogenesis, also exhibits scavenging of free radicals which form during wound healing [21-23].

The topical using of hyaluronic acid gel in rat models with full and partial thickness surgical wounds shows enhancing in wound repair and facilitates re-epithelization which led to healthy tissue formation with good elasticity and high microvascular density [24] also by decreasing abscess formation, necrosis, and neutrophil infiltration as well as reduced inflammation in skin wounds in rats. Additionally, the synthesis of collagen, the formation of fibroblasts, and vascularization are also enhanced by HA treatment [25, 26].

The HA action happens through a cluster of differentiation (CD) 44 cell receptors. CD44 and intercellular adhesion molecule-1 are adhesive cell molecules that play a role in cell migration [21, 27]. The molecular weight of the HA plays a vital role in the appearance of these HA effects in wound healing [28]. The healing of wounds of soft tissue is more rapid than bone wounds healing [29] and HA with high molecular weight shows effective healing for infected bone wounds by developing bone formation and enhancing regeneration of bone defects [30]. hyaluronic acid brings moisture to the surface of skin because of the ability of HA to hold a thousand times its weight in water, and not only keep that moisture in skin and joints, but it is also preventing evaporation of all the moisture into the air [31].

The present study aims to compare the healing effect of the topical treatment between MEBO and hyaluronic acid gel products in rats exposed to a partial-thickness burn.  

Materials and Methods


Normal saline (0.9% N.S), lidocaine (1ml/200 gm), Povidone-iodine, MEBO: Gulf Pharmaceutical industries (Juiphar), U.A.E. was purchased from Iraqi Medical Center Pharmacy, Hyaluronic acid gel products (Gum Aftaclear and Afta med). In addition, Sunstar Europe S.A. Made in Italy, Afta med with high molecular weight hyaluronic acid 240 mg/100 g gel is marketed by Pharmaniaga Sdn Bhd, Malaysia, and Gum AftaClear gel.

Experimental animals

Twenty-four male albino rats with a weight of (150-220 g) of age 3 months were obtained by the Animal House of the College of Pharmacy/ University of Baghdad. They are homed under standardized conditions of temperature, humidity, and light/dark cycle in the same location and individual cages about 2 weeks before the experiment. They were nourished with a standard rodent pellet diet and supplied with free water. The local Research Ethics Committee in the College of Pharmacy, University of Baghdad, approved the research protocol [32].


Induction of burn wound

The back of each rat was shaved and washed with povidone-iodine solution. Then, all rats were anesthetized subcutaneously with lidocaine (1ml/200 gm), and 1 by 1.5 cm of partial-thickness burn wounds (2nd- degree burn wounds) < 20% total body surface area were induced on a shaved area of the animals’ dorsal skin, by Smahel method. A steel plate 2 mm thick (1 cm diameter) was heated in boiling water for 7 min and applied firmly and perpendicularly to the skin for 4 seconds, then the medical therapies were applied topically twice a day until 14 days .and then all wounds were exposed to air and checkout daily for evidence of clinical infection [33].

They were divided into 4 groups each one supplies with 6 rats as a following:

Group I: (Negative control) they received topically normal saline solution (as a placebo vehicle) on skin burn twice/day for 14 days.

Group II: (Positive control) they are treated topically with MEBO twice/day for 14 days.

Group III and IV: They are treated with topical hyaluronic acid gel products (AftaMed and Gum AftaClear) respectively twice/day for 14 days.

Measurement of burned wound area

Photographics of each burned lesion area were obtained regularly each day by a camera phone (Canon-Japan) to observe wound surface areas healing and constriction as shown in Figure 1.  also percent (%) of burned wound contraction was calculated according to this formula [34], as shown in Table 1.

% Wound contraction = (Current wound area/wound area at the beginning) × 100