1. Osbeckia octandra is a plant used in traditional medicine to treat
jaundice and other liver disorders. In this study, the effects of Osbe
ckia leaf extract on paracetamol-induced liver injury were investigate
d both in vivo in mice and in rat hepatocytes in vitro. 2. Oral admini
stration of Osbeckin extract (330 mg/kg) at the same time as paracetam
ol (450 mg/kg) to mice, resulted in a significant protection (p < 0.05
) against liver damage, as assessed by improvements in the blood Normo
test (39.1 +/- 1.9 versus 46.3 +/- 2.0s), total liver glutathione (730
+/- 39 versus 574 +/- 27 mu g/250 mg liver), plasma aspartate aminotr
ansferase level (916 +/- 225 versus 1965 +/- 291 iu/l), and liver hist
opathology at 24 h after paracetamol administration. 3. In experiments
to assess the direct effects of Osbeckia extract, significant protect
ion was also found in freshly isolated rat hepatocytes against damage
induced by 185 mu M 2,6-dimethyl N-acetyl p-quinoneimine (2,6-diMeNAPQ
I, an analogue of NAPQI, the toxic metabolite of paracetamol) in vitro
. When Osbeckia extract (500 mu g/ml) was added to the incubation medi
um at the same time as 2,6-diMeNAPQI significant changes in cell viabi
lity (78.4 +/- 3.3 versus 47.2 +/- 5.8% of control, p < 0.001), cell r
educed glutathione (GSH) level (350 +/- 3.1 versus 23.8 +/- 1.5%, P =
0.009), and reduced release of lactate dehydrogenase (129.9 +/- 6.6 ve
rsus 224.6 +/- 12.1%, P < 0.001) were demonstrated after 1 h incubatio
n as compared with 2,6-diMeNAPQI alone. 4. Significant protection was
still obtained against 2,6-diMeNAPQI in vitro when addition of Osbecki
a extract was delayed by 20 min. These results indicate that Osbeckia
extract can protect against paracetamol-induced liver injury.