Plaunotol, an acyclic diterpenoid with highly effective antigastric ulcer properties, has been commercially isolated from leaves of
Croton stellatopilosus Ohba. This Thai medicinal plant was traditionally used in the form of crude extracts, suggesting that it is
possible to administer these plaunotol-containing extracts without toxicity. To confirm its safety, the oral toxicity of a partially
purified plaunotol extract (PPE) was evaluated in vivo.The PPE was simply prepared by 95% ethanol reflux extraction followed by
hexane partition. The obtained extract was analyzed and found to contain 43% w/w of plaunotol and another compound, likely a
fatty acid-plaunotol conjugate that is considered a major impurity. Oral administration of PPE to ICR mice and Wistar rats was
conducted to evaluate acute and chronic toxicity of the plaunotol extract, respectively.The acute toxicity study demonstrated that
PPE was practically nontoxic based on its high median lethal dose value (LD50
= 10.25 g/kg). The chronic toxicity studies also
showed the absence of mortality and clinical symptoms in all rats treated with 11–1,100mg/kg/day of PPE during a 6-month period.
Histopathological and hematological analyses revealed that altered liver and kidney function and increased blood platelet number,
but only at the high doses (550–1,100mg/kg/day). These results suggest that PPE is potentially safe for further development as a
therapeutic agent in humans.