Toxicity studies on dermal application of plant extract of Plumbago zeylanica used in Ethiopian traditional medicine

Plant-based therapeutic preparations are cyclically returning to complement dermatologic therapy, however, data on the toxicity profile of such plants are lacking. In the present study, Plumbago zeylanica, a medicinal plant commonly used in Ethiopia for skin diseases was subjected to a systematic dermatotoxicity study. To this effect, the dermatotoxicity of 80% methanol extract of the root part of Plumbago zeylanica was investigated in animals following standard procedures for irritation, sensitization, acute toxicity and repeated toxicity tests. Extraction of plant material with 80% methanol resulted in 9.45% of crude extract of Plumbago zeylanica. The skin irritation test on rabbits showed Plumbago zeylanica extract to be a moderate irritant, with a primary irritation index of 2.00. Sensitization test on mice by the Mouse Ear Swelling Test method revealed the extract to be non-sensitizer in a dose range of 4-10mg/ml and the percent responder was zero. Acute dermal toxicity test on rats did not produce any overt signs of toxicity, except that there was a weight gain difference between the test and control groups of female rats. This was not, however, supported by other parameters, like the absolute and relative organ weights. Repeated dose toxicity test was associated with increased relative testis weight (P<0.05) as well as higher values for Blood urea nitrogen and K+ (P<0.05) in both sexes with the highest dose (1000 mg/kg) group, although histopathological analyses failed to lend support to these observations. Taken together, the dermatotoxicity test results from this study suggest that Plumbago zeylanica toxic effects might be limited to effects like moderate irritation.