Effects of Amburoside A and Isokaempferide, Polyphenols from Amburana cearensis, on Rodent Inflammatory Processes and Myeloperoxidase Activity in Human Neutrophils

: The present study evaluated the anti‐inflammatory activity of amburoside A (a phenol glucoside) and isokaempferide (a flavonol) isolated from the trunk bark of Amburana cearensis, a medicinal plant used in northeast Brazil for the treatment of asthma. Animals (male Wistar rats or Swiss mice) pre‐treated with amburoside A (25 and 50 mg/kg) or isokaempferide (12.5, 25 and 50 mg/kg), orally or intraperitoneally, showed a significant inhibition of the paw oedema induced by carrageenan (1%), prostaglandin E2 (30 nmol/paw), histamine (200 µg/paw) or serotonin (200 µg/paw). Histological and morphometric evaluations of the rat paw oedema induced by carrageenan showed that amburoside A and isokaempferide also inhibited the accumulation of inflammatory cells. Amburoside A reduced significantly the paw oedema and the increase in vascular permeability induced by dextran, as related to the control group. Similar results were observed with the isokaempferide pre‐treatment. Furthermore, amburoside A or isokaempferide inhibited both leucocyte and neutrophil migrations, in mouse peritoneal cavity, after the carrageenan injection. The polyphenols were not cytotoxic and blocked N‐formyl‐methyl‐leucyl‐phenylalanine‐induced myeloperoxidase release and activity in human neutrophils. In addition, amburoside A and isokaempferide at 50 and 100 µg/ml concentrations reduced significantly the lipopolysaccharide‐mediated increase in tumour necrosis factor‐α (TNF‐α) levels. These results provide, for the first time, evidence to support the anti‐inflammatory activity of amburoside A and isokaempferide that seems to be related to an inhibition of inflammatory mediators, such as TNF‐α, as well as histamine, serotonin and prostaglandin E2, besides leucocyte infiltration in a dose‐ or concentration‐dependent manner. These anti‐inflammatory effects can be explained, at least in part, by the ability of these compounds to reduce neutrophil degranulation, myeloperoxidase activity, mediators as well as TNF‐α secretion.