ORIGINAL ARTICLE Efficacy of L-proline administration on the early responses during cutaneous wound healing in rats Thangavel Ponrasu • Sankar Jamuna • Arulanandham Mathew • Karuppanan Natarajan Madhukumar • Moorthy Ganeshkumar • Kuttalam Iyappan • Lonchin Suguna Received: 3 August 2012 / Accepted: 5 March 2013 Ó Springer-Verlag Wien 2013 Abstract Proline (Pro) plays a versatile role in cell metabolism and physiology. Pro and hydroxypro are major imino acids present in collagen, an important connective tissue protein, essential for wound healing, which is a primary response to tissue injury. This study explains the role of L-pro on cutaneous wound healing in rats when administered both topically and orally. Open excision wounds were made on the back of rats, and 200 ll (200 mg) of pro was administered topically and orally once daily to the experimental rats until the wounds healed completely. The control wounds were left untreated. Granulation tissues formed were removed after day 4 and 8 of post excision wounding, and biochemical parameters such as total protein, collagen, hexosamine, and uronic acid were estimated. Levels of enzymatic and non-enzymatic antioxidants such as catalase, superoxide dismutase, glu- tathione peroxidase, ascorbic acid, and reduced glutathione were evaluated along with lipid peroxides in the granula- tion tissues. Tensile strength and period of epithelialization were also measured. It was observed that the treated wounds healed very fast as evidenced by augmented rates of epithelialization and wound contraction, which was also confirmed by histological examinations. The results strap- pingly authenticate the beneficial effects of the topical administration of L-proline in the acceleration of wound healing than the oral administration and control. Keywords L-Proline  Collagen  Excision wound  Tensile strength  Epithelialization Introduction Wound healing is a basic response to tissue injury, the end product of which is a dense connective tissue (scar) con- sisting predominantly of collagen. Wounds normally heal in a very orderly and efficient manner characterized by four distinct, but overlapping phases: hemostasis, inflammation, proliferation, and remodeling (Iba et al. 2004). The process of wound healing is promoted by several natural products (Sumitra et al. 2009), plant products (Nayak et al. 2010, 2011a, 2012), Shetty et al. (2008), and biomolecules (Shi et al. 2002, 2003; Aoki et al. 2010, Simon et al. 2012). Nutrition plays a key role in proper wound healing. Biomolecules such as vitamins, amino acids, micro and macro elements are very important for normal wound healing. Vitamin A increases macrophage influx and acti- vation into the wounds, stimulate fibroblast to synthesize collagen, and increases cellular proliferation (Zaidi et al. 2005). Vitamin C or ascorbic acid is an essential S. Jamuna and A. Mathew contributed equally in this paper. T. Ponrasu  M. Ganeshkumar  L. Suguna (&) Department of Biochemistry, Central Leather Research Institute (Council of Scientific and Industrial Research), Adyar, Chennai 600 020, India e-mail: slonchin@yahoo.co.uk S. Jamuna Department of Biochemistry, University of Madras, Chennai, India A. Mathew School of Biotechnology, Vellore Institute of Technology, Vellore, India K. N. Madhukumar Shirmpex Biotech Services, Sozhinganallur, Chennai, India K. Iyappan Chemical Engineering Division, Central Leather Research Institute, (Council of Scientific and Industrial Research), Adyar, Chennai 600 020, India 123 Amino Acids DOI 10.1007/s00726-013-1486-0