Evaluation of oil-resin activity of Copaifera sp. on gastric emptying in Rattus novergicus

The Copaiba oil-resin (Copaifera sp.) is widely used in folk medicine, especially as a healing, antiinflammatory, antiseptic, to treat ulcers and skin diseases. Increased gastric emptying was observed with oilresin of Copaifera langsdorfii, highlighting those others species from the genus of Copaifera can act over the gastrointestinal tract. This study evaluated the activity of the Copaifera sp oil-resin on gastric emptying in Rattus novergicus. Eighteen male rats were fasted for 24h and orally received Tween-80 and Copaiba oil-resin 100 and 200 mg/kg; one hour later they all received phenol red (PR) 0.5 mg/mL. Then, the parts of gastrointestinal tract (stomach and intestine) were analyzed. The results showed that Copaifera sp oil-resin at 200 mg/kg increased the gastric emptying in Rattus novergicus.

From copaiba tree is possible to obtain its oilresin, a transparent liquid which color ranges from yellow gold to brow, depending on the specie. However, Copaifera langsdorfii oil-reins are redcolored (Francisco, 2005).
This aim of this study was to evaluate the activity of the Copaifera sp oil-resin on gastric emptying in Rattus novergicus.

Materials and Methods
The gastric emptying and small intestinal transit were assessed by the phenol red content assay, modified from the method described by Izbeki et al. (2001). Briefly, three groups of 6 male rats (242-292 g), were fasted for 24 h and orally received Tween-80 1% in water (5 mL/kg, vehicle control-VC) and copaiba oil-resin (100 and 200 mg/kg -experimental groups, Cop100 and Cop 200, respectively. One hour later, they all orally received phenol red 0.5 mg/mL in glucose 5 g% (1.5 mL/animal). After 20 min, the animals were euthanized with an overdose of sodium thiopental (100 mg/kg, i.p.) and the stomach and small intestine were removed. The small intestine was divided in the proximal (40%), medial (30%) and distal (30%) portions and each segment was homogenized in 100 mL of 0.1 N NaOH. Tissue proteins (in 5 mL homogenate) were precipitated with 0.5 mL of 20 g% trichloroacetic acid and centrifuged out (20 min, 3000 rpm). From the supernatant, an aliquot of 3 mL was added to 4 mL of 0.5 N NaOH and the concentration of phenol red was determined by absorbance at 560 nm (Biospectro SP-220 UV-VIS spectrophotometer, EQUIPAR Ltda., Curitiba, Brazil). The content of the dye in each segment was calculated and the retention of the marker was expressed as the percentage of the total amount of phenol red recovered in the four segments.

Statistical analysis
The data were analyzes by ANOVA and Tukey pos-test.
This study was approved by the Ethics Committee for Animal Research at the Federal University of Piauí (085/2010).
The elimination of the copaiba of the human body is made by the lungs, kidneys, sebaceous and sweat glands (Veiga Junior, 2005;Opção Fênix, 2011). In large quantities it can cause side effects like gastrointestinal irritation, vomiting, nausea, salivation, diarrhea, irritative effect in the peritoneum, causing adhesions and abscess formation and cavitary central nervous system depression. In normal doses it has antiinflammatory effects without causing gastric damage. Thus, it becomes an agent clinically safe and potentially useful (Veiga Junior, 2007;Opção Fênix, 2011).
As a drug, the oil-resin of Copaifera sp. is not different. Scientific studies showed that administration of 0.4 ml of the oil-resin via transdiaphragmatic caused diarrhea (Sousa, 2000). Researches with commercial copaiba oil in rats showed the occurrence of diarrhea, weight loss and irritating action on the behavior of rats at doses of 0.63 ml / kg. It is also known that gastrointestinal irritation, diarrhea, drooling and central nervous system depression are adverse effects of high doses of the oil (Veiga Junior, 2005).
Therefore, due to the proven link between the plasma concentration of the drug (which depends directly on the dose) and the proportion of the desired therapeutic effect (Brunton, 2006), the oilresin of Copaifera sp., at 200 mg/kg, increased significantly the speed of gastric emptying in Rattus novergicus, however, at 100 mg/kg no kinetic activity was showed by Copaifera sp. oil-resin.