Gastroprotective and anti-inflammatory effects of resin from Protium heptaphyllum in mice and rats

The natural resin collected from the trunk wood of Protium heptaphyllum is used in folk medicine to treat inflammatory conditions and to hasten wound repair. In the search of new potential anti-inflammatory agents with gastroprotective property, the present study evaluated its effects in experimental models of gastric ulcer and inflammation. In mice, the resin (200 and 400 mg/kg) significantly attenuated the gastric damage induced by ethanol or acidified ethanol (HCl/ethanol), in a manner similar to N-acetyl-L-cysteine (NAC), a replenisher of sulfhydryls. Unlike NAC the resin failed to restore the ethanol-induced depletion of non-protein sulfhydryl content, indicating a different mechanism of gastroprotection. However, in 4-h pylorus-ligated rats, the resin significantly reduced the total acidity without much change in gastric secretory volume. In rats, at similar doses the resin did not modify the hind-paw edema induced by carrageenan, but effectively reduced the formation of cotton pellet-induced granuloma, suggesting its inhibitory effect on collagen formation but not on acute edema. Furthermore, the vascular permeability increase induced by acetic acid was significantly reduced in mice that received 400 mg/kg resin. The resin demonstrated no overt toxicity in mice up to an oral dose of 5 g/kg. Phytochemical analysis revealed the presence of alpha- and beta-amyrins as principal triterpenoid constituents of resin, which were previously described to have anti-ulcer property. These findings indicate the potential gastroprotective and anti-inflammatory property of P. heptaphyllum resin and further support its popular use in gastrointestinal disorders.