Preclinical acute toxicological evaluation of the methanolic stem bark extract of Parahancornia amapa (Apocynaceae)

Parahancornia amapa is an endemic plant species of Amapá in the Amazon region. This study aimed to evaluate the acute toxicity of methanol extract of the bark of P. amapa. Different concentrations of the extract were added to the brine shrimps (Artemia salina) and 50% lethality concentration (LC₅₀) was assessed. The results of the brine-shrimp assay indicated that the extract was found to be non-toxic. Acute toxicity was studied in Wistar rats (males and females) after single dose (2000 mg kg^-1) by oral gavage. Food and water intake, body weight, general behavioral changes and mortality of animals were noted. Blood samples were collected for haematological and serum biochemical parameters measurements. Subsequently, they were euthanized and their organs (heart, kidneys, liver and lungs) subjected to macroscopic and histopathological analysis. There was no mortality or any sign of behavioral change or toxicity observed after oral administration of the extract. Nevertheless, it was observed a significant increase (p<0.05) on water intake of female rats treated with the extract of P. amapa (127.64 mL) when compared to control group (101.93 mL). A significant increase (p<0.05) in platelet count was also observed in both male (288.00x10³ mm³⁾ and female (220.83x10³ mm³⁾ rats that received the extract when compared to their respective control groups (128.33x10³ mm³; 109.50x10³ mm³⁾. Histopathological changes were not related to the treatment with extract in any of the analyzed organs. These results suggest that P. amapa extract has a non-toxic effect.

Keywords:
Amapazeiro; Phytotherapy; Bioprospecting