Acute and chronic oral toxicity of a partially purified plaunotol extract from Croton stellatopilosus Ohba

Abstract

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 11-1,100 mg/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 (550-1,100 mg/kg/day). These results suggest that PPE is potentially safe for further development as a therapeutic agent in humans.

Figure 1

Densitometric TLC for separation of PPE constituents in PPE and quantitative analysis of plaunotol. (a) TLC chromatogram of PPE showing two major peaks of plaunotol and a main impurity. (b) Comparison of the UV absorption spectra obtained from the wavelength scanning at the spots of standard plaunotol, PPE plaunotol, and the PPE impurity shown in (a).

Figure 2

GC-MS chromatogram of PPE (a) and the mass spectra (b) of the two major peaks of plaunotol and the impurity identified based on the total ion chromatograms (TIC) of plaunotol and the major impurity in PPE.

Figure 3

Growth curves of the male and female rats receiving PPE for 6 months.

Figure 4

Food consumptions for male and female rats receiving PPE for 6 months.