Ethnopharmacological communicationsWound healing properties of Carica papaya latex: In vivo evaluation in mice burn model
Introduction
Burns and trauma wounds are very common in both developed and developing countries, however, in developing countries burns constitute a major health problem because the incidence of severe complications is high and financial resources are limited. About 42.0% of the total population of Nepal is lying below the poverty line. Moreover, due to a high dependency on limited resources like electricity, gas and water, most of the people have to rely on firewood for cooking and other household activities and thus are exposed to the open fire which again increases the incidence of burning (Anonymous, 2003). The use of traditional medicinal remedies and plants in the treatment of burns and wounds is an important aspect of health treatment and at the same time a way to reduce the financial burden. Several plants used as traditional healing remedies have been reported to treat skin disorders, including burn wounds (Starley et al., 1999, Biswas and Mukherjee, 2003, Inngjerdingen et al., 2004, Mikhalchik et al., 2004, Muthu et al., 2006, Nayak and Pinto Pereira, 2006, Singh et al., 2006).
Our particular interest was Carica papaya, traditionally used to treat skin disorders (Mikhalchik et al., 2004). For example in Gambia, papaya fruit has been used in full thickness and infected burns and has shown promising results in clinical trials (Starley et al., 1999). Carica papaya (family Caricaceae) is cultivated in tropical and subtropical regions all around the world as fruit due to its palatable taste, nutritive value and easy digestion (Monti et al., 2004). Damaging the papaya tree inevitably severs its laticifers, eliciting an abrupt release of latex (Azarkan et al., 2003). The latex from unripe papaya fruits contains a mixture of cysteine endopeptidases such as papain, chymopapain A and B, papaya endopeptidase II, papaya endopeptidase IV, omega endopeptidase (Azarkan et al., 2003), chinitases, protease inhibitors, linamarase and proteins without known functions (Azarkan et al., 2004, Oloyede, 2005). Although papaya fruit is known to posses wound healing properties, no systematic studies have been carried out up to now on the clinical evaluation of the wound healing potential of Carica papaya latex. Thereof, its effects were investigated using thermal wound models in mice. Papaya latex was applied to the burn wounds using hydrogel as a vehicle system, known to have superior properties such as spreadability, stability and cooling effects (Sankalia et al., 2005).
Section snippets
Plant material
Papaya latex (Carica papaya, Caricaceae) was identified by comparing the authentic sample and confirmed with the help of expert (Professor Dr. Kayashta, Tribhuvan University, Nepal). The voucher specimen is (No. 283) preserved in the Museum of Natural Medicine of The School of Pharmaceutical and Biomedical Sciences, Pokhara University, Nepal. The latex was collected locally in the early mornings (7.00–8.00 am), as the flow of latex is low during the day. Collection was done by making 1–2 mm deep
Hydroxyproline content
The measurement of hydroxyproline can be used as an index for collagen turnover (Nayak and Pinto Pereira, 2006). Increase in hydroxyproline content indicates increased collagen synthesis which in turn leads to enhanced wound healing. In our study, the hydroxyproline content was found to be significantly increased in Group-III (p < 0.05) as compared with the Group-I (Fig. 1). The content was found to be increased in the Group-IV as well, but due to larger variation among animals, the difference
Discussion
Papaya is widely used in hot climate countries as traditional remedy in wound treatment. Its therapeutical value has been proven in several animal and human trials (Starley et al., 1999, Mikhalchik et al., 2004, Nayak et al., 2007, Anuar et al., 2008). Papain and chymopapain are known to be effective in desloughing necrotic tissue, prevention of infection and the antimicrobial and antioxidant properties related to hydroxyl scavenging and iron chelating properties (Anuar et al., 2008). Moreover,
Acknowledgements
The authors are grateful to the Department of Plant Research, Kathmandu for providing the animals. We would also like to acknowledge Department of Pharmaceutics, Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia for providing Carbopol 974P NF and Mr. Niranjan Shrestha for his help in statistical analysis.
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