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    This article can be downloaded from www.ijpbs.net P - 63  ISSN 0975-6299 Vol 3/Issue 2/April – June 2012 International Journal of Pharma and Bio Sciences WOUND HEALING ACTIVITY OF TOPICAL APPLICATION OF ALOE VERA GEL IN EXPERIMENTAL ANIMAL MODELS K.C.HARITHA YADAV* 1 , J. RAVI KUMAR  2 , S.ILIAS BASHA 2 , G.R.DESHMUKH 3 , RAVI GUJJULA 4  AND B.SANTHAMMA 1 1 Department of Pharmacology, Kamineni Institute of Medical Sciences, Nalgonda, India. 2 Department of Pharmacology, SVS Medical College, Mahabubnagar, India. 3 Department of Pathology, Aptus Biosciences, Mahabubnagar, India. 4 Department of Chemical Engineering, Indian Institute of Technology, Hyderabad, India. PHARMACOLOGY   RESEARCH ARTICLE ABSTRACT  Aloe vera  gel of 50% and 96.4% were tested for its wound healing activity by topical application in experimental rats. The effect of  Aloe vera  gel on wound healing was evaluated by wound excision model and histopathology was used to study the effect on wound healing. The effect produced by  Aloe vera gel with reference to wound contraction, wound closure, decrease in surface area of wound, tissue regeneration at the wound site and histopathological characteristics were significant in treated rats. The effect of  Aloe vera  gel on biochemical studies revealed significant increase in collagen and decreased hexosamine content and malondialdehyde levels when compared with control. The present study thus provided scientific rationale for the traditional use of  Aloe vera  gel for management of wounds. K.C.HARITHA YADAV Department of Pharmacology, Kamineni Institute of Medical Sciences, Nalgonda, India.    This article can be downloaded from www.ijpbs.net P - 64  ISSN 0975-6299 Vol 3/Issue 2/April – June 2012 KEYWORDS  Aloe vera  gel, wound healing activity, wound excision model, collagen. INTRODUCTION Due to poor hygienic conditions both in developed and developing countries, wound infection has become common disease in recent years 1 . Wounds are physical injuries, which lead to open or broken skin and thus appropriate method for wound healing is essential for the restoration of disrupted anatomical continuity and functional state of the skin. 2  Wound is a break in epithelial integrity of the skin and may be accompanied by an alteration of the structure and function of underlying normal tissue and can also be caused by contusion, haematoma, lacerations or abrasions. 3  Wound healing begins from the time of injury and can continue for varying periods of time, depending on the degree of wounding. Wound healing process can be diversified in to three stages namely inflammatory, proliferative and lastly the remodeling phase which determines the potency and appearance of the healed tissue. 4  Wound healing is a complex mechanism which holds numerous steps involving coagulation, inflammation, granulation tissue formation, matrix formation, connective tissue remodeling, collagenization and wound strength acquisition. 5  Many traditional practitioners worldwide, especially in countries like India and China have valuable information on many lesser known hitherto unknown wild plants for treating wounds and burns. Traditional forms of medicine practiced for centuries in Africa and Asia have been scientifically studied for their potential in the treatment of disorders associated with wounds. 6 Biswas and Mukherjee in their study noticed that 70% of the wound healing ayurvedic drugs are of plant srcin, 20% of mineral srcin and the remaining 10% consisting of animal products and these drugs have been shown to be effective in different circumstances. Among various plant herbs,  Aloe vera  is very popular in both Ayurvedic and traditional Chinese medicine for its vast medicinal properties. 7  In the Ayurvedic traditional Indian medicine Aloe vera is used internally as laxative, haemorrhoid remedy, antihelminthic and menstrual regulator. It is also used topically in combination with licorice root for treating psoriasis and eczema.  Aloe vera has been used for centuries for its wound healing properties and therapeutic potential. Though more than 75 active ingredients were identified, therapeutic effects have not been well correlated with each components. 8  In India  Aloe vera  gel has been evaluated for its wound healing properties. 9,10  Against this backdrop the present study is aimed to determine the wound healing activity of  Aloe vera  gel in experimental animal models. MATERIALS AND METHODS i. Experimental Animals Female Sprague Dawley rats weighing 150-250 gm were obtained from the central animal house of SVS Medical College, Mahabubnagar, Andhra Pradesh and housed under standard conditions of temperature, 12 hour light/dark cycle and fed with standard pellet diet and water ad libitum. . These experimental rats were kept in poly-propylene cages provided with paddy husk bedding and were acclimatized for a week under the aforesaid housing, feeding and other ménage mental conditions. The experimental protocols were approved by the Institutional Animal Ethical Committee (45/2008/IAEC/SVSMC/MBNR). ii. Drugs 96.4%  Aloe vera gel and 50%  Aloe vera  gel (diluted with demineralised water) used in this    This article can be downloaded from www.ijpbs.net P - 65  ISSN 0975-6299 Vol 3/Issue 2/April – June 2012 study were gifted by Bhaskara biotech (Hyderabad, India). iii. Creation of wound The animals were anaesthetized using ether anesthesia. The anesthetized animals were secured to the operation table in the natural position. The fur of the dorsum of each animal was shaved and wound area was created. Ethanol (70%) was applied as an antiseptic for the shaved region before the wound creation. An impression was made on the dorsal interscapular region 5 mm away from the ears using a circular colored rubber stamp of 21 mm diameters as described by Morton and Malone 11 . Full thickness skin from the demarcated area was excised including  panniculus carnosus to get a wound area of approximately 350 mm 2 . The wound was blotted with a cotton swab soaked in normal saline. The treatment included topical application 50% and 96.4%  Aloe vera  gel compared with untreated group. Treatments were continued until complete closure of the wound had occurred. iv. Experimental Protocol After wound creation experimental animals were randomly divided into three groups: group I (n=15) untreated control rats; group II (n=15) rats treated topically with 50% Aloe vera gel and group III (n=15) rats treated with 96.4% Aloe vera gel. Six animals in each group were used for studying progressive changes in morphology of wound. Nine animals in each group were used for histopathalogical and biochemical analysis. v. Assessment of wound healing The physical attributes of wound healing namely, wound closure, epithelialisation time and scar features are studied by tracing the raw wound area on tracing paper on the days 0, 4, 8, 12 and 16. Wound area was calculated by the number of squares of the retraced wound area on a 1mm 2  graph paper from the tracing paper. The degree of wound healing was calculated as percentage closure of the wound area from the srcinal wound area using the Walker and Mason formula 12 : Where Ao is the wound area on the day zero and Ad is the wound area on corresponding days. vi. Biochemical analysis After seventh, ninth and fourteenth day of wounding, animals were sacrificed by over dosage of ether anesthesia. The wound biopsies were collected and stored at -80 0 C   until analysis. Difficulty was encountered in collecting the fourth day wounds thus fourth day sampling was not done. The granulation tissue was subjected for estimation of biochemical parameters. As an indication of total collagen content, hydroxyproline concentration was determined as described by Woessner. 13 To estimate hexosamine the tissue samples were defatted in chloroform:methanol (2:1) and dried in acetone, before use. Hexosamine was estimated by the method of Elson and Morgon respectively 14 . Lipid peroxide levels in granulation tissues were determined by the thiobarbituric acid reaction 15 . vii. Histopathological studies The cross sectional full thickness skin biopsy specimen from each group was collected on days 7, 9 and 14 and the histological evaluation was carried out during the study. The tissues were fixed in 10% buffered formalin and passed through different grades of alcohol and were embedded in paraffin wax. Samples were sectioned (3-5µm) and stained with hematoxylin and eosin. For collagen deposition studies, traces of staining reaction, hyalinization and irregular arrangement of collagen bundles were considered as positive, where as the most intense reaction and compactly arranged collagen bundles were considered as +++. Two areas in each section were counted for neovascularisation and fibroblast proliferation. viii. Statistical analysis For the in vivo study of wound areas on rats, the results were expressed as a mean ± SD. The results were analyzed by one-way analysis of variance (ANOVA) by using SPSS 18.0    This article can be downloaded from www.ijpbs.net P - 66  ISSN 0975-6299 Vol 3/Issue 2/April – June 2012 statistical software package. Tukey post hoc test was used on group comparison. Differences were considered significant at P<0.05. RESULTS i. Wound closure Table 1 Wound healing activity of the Aloe vera gel on wound contraction. Post wounding days Control (n=6) 50%  Aloe vera  gel (n=6) 96.4%  Aloe vera gel (n=6) 0 350.83 ± 1.6 349 ±3.8 350 ± 2.5 4 317.67 ± 4.4 (9.45) 245.83 ± 8.8 (29.56) **  235.17 ± 8.7 (32.82) **  8 224.17 ± 3.9 (36.10) 147.83 ± 7.8 (57.64) **  84.33 ± 6.2 (75.91) ***  12 116.00 ± 6.3 (66.94) 48.83 ± 10.2 (86.00) **  30.33 ± 4.1 (91.33) ***  16 48.83 ± 6.8 (86.07) 4.67 ± 4.7 (98.66)* **  2.83 ±1.7 (99.19) ***  Epithelialisation Period 20.67 ± 1.8 18.33 ± 1.5 16.17 ± 0.7 *   Values are expressed as Mean±SD. *p = 0.05; **p = 0.01; ***p = 0.001. Compared to control. Values in parenthesis are percentage of wound closure A better healing pattern with complete wound closure was observed in rats treated within 16 days for 50% and 96.4%  Aloe vera  gel. The epithelialisation period recorded was very short for 96.4% and 50%  Aloe vera  gel. There was a significant reduction in wound area from day 4 onwards in treated rats and also on later days the closure rate was much faster when compared with control (Table 1). With reference to the percentage of wound closure, the results indicated that  Aloe vera  gel (96.4%) showed nearly 100% wound closure followed by  Aloe vera  gel (50%) which recorded 98.66%. The results clearly indicated that the  Aloe vera  gel influences the wound closure at a greater extent (Table 1). ii. Biochemical parameters Collagen synthesis is an important process that takes place during the wound healing mechanism. The collagen content was measured in control and  Aloe vera  gel treated rats. The results indicated a common pattern of change in collagen content in all the three groups. Maximum collagen levels were found on day 7 of post wounding. In 50%  Aloe vera  gel group, the collagen level was drastically decreased by 9 th  day, where as in control and 96.4% the decrease in collagen levels was at lower rate. The levels continued to decrease later at slower rate in all the three groups (Graph1).
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