The aqueous and methanolic extracts of Pittosporum mannii (Pittosporaceae) leaves are devoided of anti-inflammatory activity: evidence from in vivo and in vitro testing

Abstract

Objectives: Previous studies demonstrated that aqueous and methanolic extracts from the leaves of Pittosporum mannii possess analgesic but not anti-inflammatory activities. The present work attempted to understand the lack of the anti-inflammatory effects of those extracts. Materials and methods: Plant extracts were given orally at the doses of 75, 150 and 300 mg/kg on inflammation induced by Complete Freund’s Adjuvant (CFA; 100 µL; i.pl.). Equally the acetic acid (0.7%) induced vascular permeability and leukocytes mobilizations were investigated. Extracts (75, 150 and 300 mg/kg) were given orally one hour before inflammation induction. The effects of extracts were also evaluated on stimulated and non-stimulated macrophages at the concentration of 10, 30, 100 and 300 µg/mL for 8 and 24 h..            

Results: Aqueous and methanolic extracts administration have no effects on CFA induced inflammation model. However, both extracts significantly (p<0.05, p<0.01 and p<0.001) increased capillary permeability accentuation induced by acetic acid in rat at dose 75, 150, 300 mg/kg. Both extracts significantly (p<0.05, p<0.01 and p<0.001) inhibited leukocytes, granulocytes and lymphocytes migration in the rat’s peritoneal fluid with high effect for AEPM at the dose of 75 mg/kg. Animals mean platelet volume and in vitro hemolysis of erythrocytes induced by heat were not significantly inhibited by extracts. For the NO production by non-stimulated macrophages and stimulated (using LPS), no significant difference was observed.  Conclusion: These results suggest that, aqueous and methanolic extracts from the leaves of Pittosporum mannii present no anti-inflammatory activities despite their ability to inhibit leukocytes migration.