Abstract
The hot aqueous extract of the aerial part (leaves, flowers, fruits and tender branches) of Guaiacum officinale Linn (Zygophyllaceae) was evaluated for antifertility effects. In over 50 trials, the extract caused abortion in mice and rats. The extract caused abortion in the second and third trimesters only. The abortion ED 50 in pregnant mice was 320.50 ± 20.00 mg/kg, while the LD 50 was 1280.13 ± 9.03 mg/kg. At a dose of 480.75 mg/kg, the extract significantly reduced the litter size in mice when given during the first trimester (day 5) of pregnancy. The extract did not produce contraction of either the primed or gravid uteri derived from these animals. Similarly, the extract did not cause contraction of the guineapig ileum. However, it potentiated the contractions caused by acetylcholine. These findings tend to support the utility of the hot water extract of Guaiacum officinale in folk medicine for antifertility purposes.