The Effects of Solvent Fractions of Bee Pollen Crude Extract in an Animal Model of Inflammation

Abstract

BACKGROUND AND OBJECTIVE: Conventional anti-inflammatory drugs, despite their beneficial effects, have serious and irreversible side effects. Due to the remarkable anti-inflammatory properties of bee pollen crude extract, the present study was conducted to investigate the effects of 100% methanol fraction (MF) and dichloromethane fraction (DF) in an air pouch model of inflammation. METHODS: This experimental study was performed on 42 male Wistar rats in 7 groups of six. First, the hairs on the back of the rats were shaved. Subcutaneous injection of sterile air (20 and 10 mL) was performed on the dorsum of anaesthetized rats (day 1 and day 3, respectively). On day 6, inflammation was induced by intra-pouch injection of carrageenan. Group I: Normal saline; Group II, III, and IV: the rats treated with 100, 500 and 2500 μg MF; Group V, VI, and VII: the animals treated with 100, 500 and 2500 μg DF by intra-pouch injection simultaneously with carrageenan after 24 and 48 h. Three days after carrageenan administration, the inflammatory parameters and angiogenesis were measured. FINDINGS: Compared to the control group (5.3±0.5 g), granulation tissue weight was significantly decreased (p<0.001) by approximately 30% and 40% by all three doses of MF and DF, respectively. Inflammatory parameters such as exudate volume and angiogenesis were significantly reduced by DF (p<0.001) and MF (p<0.01), respectively. In both fractions, a dose of 2500 μg increased the number of leukocytes. CONCLUSION: Although different effects were observed in the two fractions of extract due to different amounts of flavonoids, a promising inhibitory effect on granulation tissue and angiogenesis was obtained, which could be considered as a natural source of anti-rheumatoid and anti-cancer agents.