In vitro antimicrobial, cytotoxicity, and anti-proliferative properties of selected medicinal plant extracts used in management of aids-related opportunistic infections in the Lake Victoria basin of Kenya

Abstract

ABSTRACT The current management of HIV and its related opportunistic infections involves use of highly active antiretroviral therapy (HAART), however this regimen is characterized by challenges such as toxicity, emergence of drug resistance, mutations, and cost implications because the supply of HAART is donor driven. The quest for alternative medicine has been in progress and crude extracts made from plants obtained from different ecological zones have been explored for their antimicrobial activities, cytotoxicity, and anti-proliferative properties. The chemotherapeutic components of plant preparations in Lake Victoria Basin (LVB) of Kenya has not been fully determined. This study determined the potential antimicrobial properties, cytotoxicity, and anti-proliferative effects of Piptadeniastrum africanum (bark), Chaemacrista nigricans (leaves), Kigelia africana (fruit), and Centella asiatica (leaves) extracts used in the management of HIV and AIDS opportunistic infections in LVB. These plants were identified through ethno botanical surveys in Luo-Suba in the LVB. In an in vitro experimental laboratory study design, cultures of Staphylococcus aureus, Escherichia coli, and Candida albicans, were used to investigate the antimicrobial properties of the plant extracts using the susceptibility tests. Mammalian leukemia cell lines (CCRF-CEM) were also cultured and nourished with complete RPMI 1640 media for five days. Aliquots of 1x103 of the cell lines were seeded in 96-well plate and subjected to varying concentrations of the plant extracts to investigate the cytotoxicity and antiproliferative activity on plant extracts on the cells. The cytotoxicity level was determined microscopically for the presence of morphological changes and chemically using 3-(4, 5-Dimethylthiaazol-2-yl)-2, 5-Diphenyltetrazolium Bromide (MTT) assay. Cell viability and MTT assays were used to determine the antiproliferative effects of the plant extracts. Pearson correlation and chi-square test were used to determine the relationship between the plant extract concentrations and the resistance level expressed by the test microorganisms in the antimicrobial susceptibility tests. Nonlinear regression analysis was used to compare the cytotoxicity level of the plant extracts through determination of IC50 values. The plant concentrations ≥500mg/mL had antibacterial effect on S. aureus (df=3, p=0.019,), E. coli (df=3, p=<0.017) and C. albicans (df=3, p=<0.017). However, K. africana caused toxicity to CCRF-CEM leukemia cells at a concentration of 1096mg/mL. The plant extracts showed antiproliferative effect on CCRF-CEM cells within 72 hours treatment period. The overall findings show that high concentrations of the plant extracts are required in management of HIV and AIDS-related opportunistic infections caused by bacteria and fungi. However, the high concentrations of the plant extracts are not likely to cause toxicity to the cells. Therefore, this study provides crucial information toward clinical application of the traditional uses of these selected plants in the management of HIV and AIDS-related infections.