Studies On The Pharmacological Potential And Toxicological Evaluation Of The Crude Extracts Of Asparagus Africanus And Caesalpinia Volkensii

Abstract

This study was undertaken to investigate whether crude extracts from medicinal plants were able to alter parametres of non-specific immune functions in viva. The plants used in the study were Caesalpinia volkensii and Asparagus africanus. Dried plant materials were extracted with water and ethanol. Water and ethanol extracts of plant materials were screened for biological activity by the Artemia salina and Aedes aegypti larvae bioassays. In all cases, ethanol extracts showed higher toxic activity than water extracts in the two bioassays. The ethanol extracts of A. african us roots was' most toxic in the A. salina bioassay with LCso of 61ppm in 48 hours, while the least toxic was the water extract of C volkensii with an LC50 of 676ppm in 48 hours. The extracts were also tested for their hemolytic activity by spectrophotometric method. Again in all cases, the ethanol extracts still showed higher hemolytic activity than the water extract. The ethanol extracts of A. africanus roots had a higher hemolytic activity with an LC50 of 1098ppm in 30 minutes, while the water extract of C. va/kensii leaves had the lowest hemolytic activity with an LC50 of 32246ppm in 30 minutes. To test the extracts for their ability to act as immunomodulators, the capacity of the extracts to enhance the clearance of intravenously injected colloidal carbon was tested in rabbits. The extracts were found to significantly enhance the clearance rate (ANOVA, F5, 25 (1) = 154.6, P<0.0001). The capacity to elevate white blood cell counts in mice was also tested. It was found that the extracts, given as single doses, significantly elevated the total white blood cell counts three days after administration (ANOVA F2, 10 (1) = 33.9, P <0.0001). When the same treated mice were intraperitaneally injected with colloidal carbon and left for nine days, the level of white blood cell count was found to have gone down back to normal levels. The decrease was also found to be statistically significant (ANOVA F2, 10 (1) = 33.9, P<0.0001). On dissection, colloidal carbon was found to have been sequestered in areas near the liver and most of it near the spleen unlike in the controls where it was evenly distributed within the viscera. In a second experiment, there wasn't a significant increase in the total white blood cell count 3 days after the mice h:;c first been injected with colloidal carbon nor was the count significantly elevated 9 days later after treatment of the same animals with single doses of extracts (ANOVA F2, 10 (1) = 1.596, P = 0.1730. Dissections revealed that colloidal carbon was sequestered in the same areas within the viscera as in the first experiment in animals treated with extracts, while the colloidal carbon was evenly distributed in the viscera of control animals. Toxicological assessment of the extracts indicated that they were safe at the doses administered. There was no mortality with animals treated with the extracts nor was there any pathological changes in the liver when histological sections were observed under the compound microscope. The result of this study has demonstrated that the extracts of C. volkensii and A. africanus are able to alter certain parameters of non-specific immune functions in vivo. Furthermore it has been demonstrated that the extracts were safe at the doses given.