Abstract:
Tuberculosis, caused by Mycobacterium tuberculosis, is a worldwide disease affecting millions of people. The rise of resistant strains, coupled with toxicity of current chemotherapy, requires effective alternatives against mycobacterial infections. Some plants from the Menispermaceae family have been used to treat tuberculosis and cough related symptoms. In this study, acetone, methanol:water (4:1), dichloromethane:methanol (1:1) and hot water extracts of different plant parts of Cissampelos owariensis, Cissampelos mucronata and Tinospora fragosa were tested against M. aurum, M. bovis, M. fortuitum, M. smegmatis and M. tuberculosis using a two-fold serial microdilution assay. Cytotoxicity of the active extracts was determined against Vero and HepG2 cells. The hepatoprotective effect of the active extracts was evaluated using rifampicin and acetaminophen as toxic drugs against HepG2 cells. The hot water leaf extracts were most active with promising minimum inhibitory concentration (MIC) values of 20 and 40 µg/mL against M. smegmatis and M. fortuitum respectively. The acetone extracts of C. owariensis, C. mucronata and T. fragosa had the lowest MIC values (0.03 – 1.67 mg/mL). The root extract of C. owariensis was not toxic to Vero cells while the leaf extract was more toxic. The acetone extract of C. mucronata leaves was toxic to Vero cells but the other extracts had low toxicity. The active leaf and root extracts had protective effects on rifampicin-induced toxicity on HepG2 cells. The root extract also had a protective effect on acetaminophen-induced toxicity on HepG2 cells but the leaf extract had no protective effect. The hot water extracts of C. owariensis, C. mucronata and T. fragosa had a more protective effect on the toxin-induced cells than the acetone extracts. These results support further investigation on the bioactive compounds in these plant extracts.
