This study aimed to evaluate the safety of the hydroalcoholic extract (HE) of Syzygium cumini (L.) Skeels, Myrtaceae, leaves in rodents. Acute toxicity was evaluated through the determination of a LD50 in mice and rats (up to 14 days). In mice, the oral administration (p.o.) of the HE (0.1 at 6 g/kg) did not cause any death. When administered by intraperitoneal route (i.p.) the HE (0.1 at 1 g/kg) caused death of the animals (LD50 of 0.489 g/kg). In rats, the HE (0.5, 1 and 2 g/kg, p.o.) did not cause any death, while by i.p., only the 2 g/kg dose was lethal to 67% of the animals. To evaluate chronic toxicity, groups of rats daily received the HE (0.05, 0.1 and 0.25 g/kg) through p.o., during 30, 90 or 180 days and the effects on behavior, body weight, feed consumed were measured. Histology, hematology and biochemical parameters were measured at the end of the treatment. After a 30-day treatment, the HE caused changes in some biochemical parameters. Histological examination of the liver, kidneys, lungs, heart, stomach, intestine and pancreas showed normal architecture suggesting no morphological disturbances. These data may mean that the HE of S. cumini does not exert acute or chronic toxic effects by oral administration.

The gastroprotective action of the aqueous extract (AE) and the hydroalcoholic extract obtained from the leaves of Struthanthus marginatus (Desr.) Blume, Loranthaceae, were performed with in vivo models in rodents using: ethanol, indomethacin or stress-induced ulcers, determination of gastric secretion and the mucus production. The scavenger activity of AE in vitro was tested by the DPPH method. The treatment with the extracts (125-1000 mg/kg) significantly inhibited ulcerative lesions in comparison with the negative control groups in all the models evaluated and demonstrated greater effectiveness of the aqueous extract. Regarding the model of gastric secretion, a reduction in volume of gastric juice and total acidity was observed, as well as an increase in the gastric pH. The treatment of rats raised the gastric mucus production. Significant DPPH scavenging activity was evident in the AE. No sign of toxicity was observed. These results show that S. marginatus possesses gastroprotective activity. There are indications that the mechanisms involved in anti-ulcer activity are related to a decrease in acid secretion and an increase in gastric mucus content. Also, there is evidence for the involvement of antioxidant activity in the gastroprotective mechanism.

The antispasmodic activity of Jatropha gossypiifolia L., Euphorbiaceae, aerial parts was investigated in rodents using the mouse intestinal transit model and acetylcholine (ACh, 10-9 to 10-4 M) and calcium (CaCl2, 10-4 to 10-1 M)-induced contractions of isolated rat jejunum. Similar to atropine (1 mg/kg), oral doses of ethanolic extract (EE) of J. gossypiifolia (500, 1000 and 2000 mg/kg) produced a decrease in intestinal transit (37.6 to 57.1%) when compared with control. The ACh-induced contraction in the jejunum was inhibited by EE (0.5, 1.0 and 2.0 mg/mL), chloroformic (CF) and aqueous fractions (0.1 and 0.5 mg/mL) and methanolic subfraction (0.05 and 0.25 mg/mL), suggesting an antimuscarinic mechanism. CaCl2 - induced responses in jejunum were also attenuated in the presence of CF (0.05 and 0.1 mg/mL) implying a direct interference of CF with the influx of calcium ions in the cells. Only the organic fraction of the extract had a calcium-antagonist effect, whereas both chloroformic and aqueous fractions had anticholinergic effect. These results suggest that the antispasmodic effect of J. gossypiifolia may be due a combination of anticholinergic and calcium antagonist mechanisms.