HPTLC fingerprinting and safety profile of Warburgia ugandensis Sprague (Fam. Canellaceae)

Abstract

Despite the extensive breakthrough of conventional medicine, herbal medicine use is on the increase worldwide. The continued lack of quality control measures such as proper identification, and safety evaluation data constitute major challenges affecting herbal medicine acceptance in the era of evidence-based medicine. This study sought to develop an HPTLC fingerprint profile for W. ugandensis leaf and stembark extracts and further investigate the acute and subacute toxicity to provide identification and safety information on the medicinal plant for purposes of drug development and regulation. Methods: This was an experimental study. The leaf and stembark of W. ugandensis were collected from Mabira forest in Central Uganda, and extracted by maceration using acetone, ethyl acetate, hexane and methanol for HPTLC analysis; and 70% ethanol and distilled water for safety assessments. A mobile phase system of hexane: acetone (70: 30) for the leaf extracts, and ethyl acetate: acetone: hexane (10:5:3) for the bark extracts was used for HPTLC analysis. OECD Tests 432 and 407 were followed for assessment of acute and sub-acute toxicity respectively of the aqueous leaf, aqueous stembark, 70% ethanolic leaf and 70% ethanolic stembark extracts. Results: The acetone extract of the leaf showed the highest number of bands in both white light and derivatized modes of visualization with 9 and 12 bands respectively corresponding to an RF range of 0.06 to 0.90. On the other hand, the acetyl acetate extract of the stembark produced the highest number of bands in the derivatized chromatogram with 7 corresponding to an RF range of 0.04-0.87. No mortalities were observed in the acute toxicity studies of the extracts of W. ugandensis with the LD50 estimated as 5000mg/Kg. There was no loss of weight in study animals in both the acute and subacute studies. The W. ugandensis extracts appeared to increase AST levels nearly two-fold compared to control group in the subacute study but neither raised creatinine nor urea levels compared to control group. A delayed enhancement of RBC count was reported in animals that received W. ugandensis extracts. Conclusion: This study demonstrated that a simple HPTLC method using vanillin as a staining agent can be used to develop fingerprints for W. ugandensis leaf and stem bark Extracts. The study further showed the safety of W.ugandensis leaf and stem bark, aqueous and 70% ethanolic extracts in acute use. However, there should be caution in the development of herbal therapies that involve repeated dosing exceeding two weeks due to possibility liver toxicity.