Indonesian propolis suppressed the expression of cyclooxygenase enzymes on inflamed rat dental pulp in direct pulp capping treatment

Propolis, or bee glue is a natural wax-like resinous substance collected by bees from buds and exudates of the plants (Kuropatnicki et al, 2013). Honey bees used propolis as antibiotic, seal hole or cracks of its combs, and also protect it from insects (Bogdanov (2017). Propolis has been used since long time ago as traditional medicine due to its several biological properties, such as antibacterial (Sforcin et al, 2000), anti-inflamatory (Wang et al, 2014), and immunomodulatory (Sforcin, 2007). Among of its constituents, both flavonoid and non-flavonoid substances of propolis also showed anti-bacterial (Sabir, 2005, Sabir, 2010) and anti-inflammatory activities (Sabir et al, 2005). The chemical composition of propolis is very complex, depends on the collecting location, time, and plant source (Toreti et al, 2013). Commonly, the composition of propolis primarily consists of resinous (50%), wax (30%), essential and aromatics oils (10%), bee pollen (5%), and other substances (5%) (Huang et al, 2014).Recently, propolis, an adhesive substance produced by honeybees has been drawn much attention due to its anti-inflammatory property. Cyclooxygenase (COX) enzymes are responsible for conversion of arachidonic acids to prostaglandins biosynthesis. COX-1 is a constitute expressed in most cells of tissue to maintain homeostatis, while COX-2 is inducible in response to inflammatory reaction including in the pathogenesis of dental pulp inflammation. The aim of the present study is to analysis COX)-1 and COX-2 expressions in inflamed rat dental pulp after propolis application. Propolis was obtained from South Sulawesi Province, Indonesia. Flavonoids and non-flavonoids were purified from an ethanolic extract of propolis (EEP). Eighty male, 8-16 week old Sprague Dawley rats were divided into five groups, each consisting of 16 animals. As a negative control (group I), rats were left without any treatment. A Class I cavity was prepared on the occlusal surface of permanent maxillary right first molar. Dental pulp was exposed and allowed in oral environment for 1 hour, then capped with EEP (group II), propolis flavonoids (group III), non-flavonoids propolis (group IV), or calcium hydroxide (group V). All cavities were filled with glass ionomer cement as permanent filling. The animals were sacrificed at 6 hours, 2, 4 or 7 days after treatment, biopsy samples were obtained, processed for immunostaining of both COX using the biotin-streptoavidin method and viewed under light microscope. Data was statistically analyzed using Friedman and Kruskal-Wallis tests at a significant level of P<0.05. The results showed that COX-1 expression was weak in all groups at all time periods. Except in group IV, COX-2 expression was decreased in group II, III, and V with the longer of observation time periods. In group II and group V, COX-2 expression was weaker than group III and IV at all periods time. However, there was no statistically significant differences (P>0.05) of both COX expressions among groups for each time period. As conclusion, ethanolic extract of propolis as well as calcium hydroxide suppressed COX-2 expression in inflamed rat dental pulp