Evaluation of the toxicity of the hydroethanolic extract of the stem bark of Virola elongata (Benth.) Warb. in in vitro and in vivo models.

Ethnopharmacological Relevance: Virola elongata (Benth.) Warb. (Myrsticaceae), referred to as "mucuíba" in Mato Grosso, is a native tree species that can be found in the Amazon Rainforest regions of South America and the Tropical Forests of Central America. The macerated extracts from the stem bark of this tree have been traditionally used to address various health issues, including gastric ulcers, infections, inflammations, and other ailments. In scientific literature, V. elongata has demonstrated pharmacological properties such as antiulcer, gastroprotective, antiproliferative, antimitotic, and psychoactive effects. Nevertheless, it is important to note that the safety profile of V. elongata has not been thoroughly established.

Aim Of The Study: To evaluate the toxicity of the hydroethanolic extract of the stem bark of Virola elongata (HEVe) in experimental models in vivo and in vitro.

Materials And Methods: HEVe was obtained by macerating the stem bark powder in 70% hydroethanolic solution (1:10 w/v). The cytotoxicity of HEVe (3.125-200 μg/mL) was evaluated by Alamar blue assay in Chinese hamster ovary epithelial cells (CHO-k1) and human gastric adenocarcinoma (AGS). Genotoxicity assessment of HEVe (10, 30, or 100 μg/mL) was performed in CHO-k1 cells by the micronucleus test. The acute toxicity of HEVe was assessed by single-dose oral administration (2000 mg/kg) in mice of both sexes. The subacute toxicity of HEVe was assessed by oral administration of 300, 600, and 1200 mg/kg of the extract over 30 days in rats. Clinical observations of toxicological parameters were noted and pooled every 6 days. After the treatment period, blood was collected for hematological and biochemical analyses, and some organs were removed for macroscopic and histopathological analyses.

Results: HEVe did not show cytotoxicity in CHO-K1 and AGS cells (IC > 200 μg/mL) and did not cause DNA damage in CHO-k1 cells. Oral administration of HEVe in a single dose of 2000 mg/kg did not result in the death of the mice, with a reduction in body weight variation (33.03%, p < 0.05) and an increase in the relative weight of the stomach (12 0.82%, p < 0.05) in male mice, and increased relative weight of the spleen (25.00%, p < 0.01) in female mice. In the assessment of subacute toxicity, HEVe did not result in the death of the animals over the 30 days. A reduction (p < 0.05) in water consumption of 36.65% and 34.12% was observed in the groups treated with 300 and 600 mg/kg, respectively, of HEVe on D6., and the urine excretion of animals treated with 600 mg/kg of HEVe showed an increase (p < 0.05) throughout the experiment, with a maximum value of 46.72% on D12. The blood counts showed that the dose of 300 mg/kg reduced (p < 0.05) the absolute number of lymphocytes, while the doses of 300, 600, or 1200 mg/kg of HEVe reduced the red blood cell count in whole blood by 24.84% (p < 0.01), 16.72% (p < 0.05), and 22.14% (p < 0.01), and the absolute number of monocytes (p < 0.05) in 59.77%, 65.51%, and 79.81%, respectively. As for the biochemical parameters, the glucose level found increased by 22.41% (p < 0.05) only at the highest dose, while creatinine was reduced by 44.71% (p < 0.05) at the dose of 300 mg/kg of HEVe. In animals treated with the three doses tested, plasma levels of AST and alkaline phosphatase showed a reduction (p < 0.05) with the vehicle group. However, the hematological and biochemical changes observed are within the physiological limits for this animal species. No macroscopic and histopathological changes were observed in the organs of the animals treated with the three doses of HEVe within 30 days.

Conclusion: The results showed that HEVe did not show cytotoxicity or genotoxicity in vitro. HEVe proved to be safe in rodents in both acute and subacute toxicity tests. In rats, the no-observed-adverse-effect level (NOAEL) dose was greater than 1200 mg/kg p. o. in rats.