Healing of burned tissue is a complex process, which involves re-epithelisation, granulation tissue formation and remodeling of extracellular matrix. There is also experimental evidence that indicates the involvement of superoxide radical in the pathogenesis of burn wound [21
]. Earlier studies have shown that there is a close relationship between a lipid peroxidative reaction and secondary pathological changes following thermal injury [13
]. It has been known that severe burning not only affects skin but also internal organs. An attack of biomolecules by ROS can result in an alteration of the structure of biological membranes of tissues. A local burn injury produces oxidant-induced organ changes as evidenced by increased lipid peroxidation in remote organs. The body’s innate mechanism to protect itself from the deleterious effect of free radicals is antioxidants. Glutathione plays an important role in the detoxification of foreign compounds, hydrogen peroxide and free radicals [22
]. There was a significant increase in the glutathione content in all the burned animals, which may be through the triggering of the antioxidant system. This level was further increased by the treatment with the Calendula
extract. Similar results were also found with SOD and catalase, which were increased by treatment with the extract. Results indicate the effectiveness of Calendula officinalis
extract on enhancing the antioxidant defense mechanism thereby decreasing the burn injury.
The significant increase of both hexosamine and hydroxyproline content in the granuloma tissue shows the effectiveness of the extract in enhancing the collagen content in burned tissue. This could be either due to increased synthesis or decreased catabolism of collagen due to presence of flavonoids in the extract which can produce artificial cross linkage between collagen molecules.
The systemic inflammatory response after trauma leads to protein degradation, catabolism, and hyper metabolism. To restore systemic homeostasis, the liver reprioritizes its synthesis from constitutive hepatic proteins toward acute-phase proteins. A prolonged increase in the acute-phase response, however, has been shown to increase morbidity and mortality [4
]. The increased level of the acute phase proteins in thermally injured animals were found to be decreased in Calendula
extract treated animals. The administration of Calendula officinalis
extract significantly decreased the serum level of marker enzymes of tissue damage like ALP, GOT and GPT indicating that Calendula
extract reduce the injury of the internal organs during thermal burning.
Antioxidant therapy in burn injury has been used to prevent the harmful effect of oxygen free radicals [23
]. The anti-inflammatory drugs are reported to be effective against wound healing [24
]. Nitric oxide radical and inflammatory mediators play an important role in thermal injury [25
]. Our previous study has shown that the Calendula
extract is an antioxidant both in vitro
and in vivo
]. This property may be attributed to the effectiveness of Calendula
extract in burn injury. Calendula
extract may be act through modifying the activities of proinflammatory cytokines and inhibits cyclooxygenase-2 enzyme (unpublished data).
The phytochemical constituents of Calendula officinalis
include flavonoids like lupeol, quercetin, protocatechuic acid etc. many alkaloids and triterpinoids [26
]. Flavoxanthin, luteoxanthin, lycopene, auroxanthin, lutein, β-carotene etc. are the major carotenoids present in this flower [27
]. Most of these constituents are reported as free radical scavengers and enhance wound healing by producing artificial cross linkage [28
Biological activity of Calendula officinalis extract could be related to pharmacological activities of these ingredients in the extract.