Apigenin and apigeninidin isolates from the Sorghum bicolor Sorghum bicolor leaf targets inflammation via cyclo‐oxygenase‐2 and prostaglandin‐E 2 2 blockade

摘要

Abstract Aim This study evaluated the anti‐inflammatory properties of a species of Sorghum bicolor leaf (SBL) grown in West Africa. Method Cyclo‐oxygenase (COX)‐2:COX‐1 selectivity assay was carried out by plating isolated peripheral blood mononuclear cells in culture medium with specific SBL fractions: crude extract (J), ethyl‐acetate (JE) and aqueous (JA); secondary compounds from JE (JE5, JE6, JE7 and JE8); purified (P9) and semi‐purified (P8) compounds from JE5 at 5‐200?μg/mL for 1?hour. Test compounds and controls ibuprofen (50?μmol/L) and CAY10404 (1?μmol/L; 10?μmol/L) were added to two sets of plates, one without lipopolyshaccharide (LPS) and the other with LPS (1?μg/mL) for 24?hour. COX‐2IC 50 :COX‐1IC 50 ratio represented 50% inhibition of the activity of COX‐2 to that of COX‐1 using ibuprofen as control. In separate experiments the supernatant of P8 and P9‐treated fractions of SBL and controls were plated with RAW 264.7 macrophage cells to measure prostaglandin (PG)‐E 2 production and cell proliferation activity. Results JA fraction of SBL had the highest ratio of COX‐2IC 50 :COX‐1IC 50 41.214 whereas JE had the lowest ratio COX‐2IC 50 :COX‐1IC 50 1.161 . Interestingly, JE5 derived from JE showed a ratio of COX‐2IC 50 :COX‐1IC 50 0.495 while P8 derived from JE5 showed a dose‐dependent reduction in COX‐2IC 50 :COX‐1IC5 0 ratio and in PG‐E 2 production, which was more effective compared to ibuprofen. A dose‐dependent reduction in RAW 264.7 macrophage cell proliferation was also observed in P8‐treated cells. The phenolic compounds identified in P8 include apigenin and apigeninidin adducts which may explain the exceptional anti‐inflammatory activity and efficacy in COX‐2 targeting.