Antimicrobial and anthelmintic potential of root and leaf extracts of Gazania krebsiana Less. subsp. serrulata (DC.) Roessler: An in vitro assessment

IntroductionPhytotherapy has found relevance in the management and treatment of diseases in South Africa, particularly among the rural dwellers. In the present study, root and leaf extracts of Gazania krebsiana were investigated for antimicrobial and anthelmintic activities.MethodsG. krebsiana's antimicrobial activity was evaluated against human pathogenic bacteria and fungi using agar well dilution method, while its anthelmintic activity was tested against gastrointestinal nematodes of sheep using egg hatchability and larvae mortality assays.ResultsThe extracts elicited varied degrees of antimicrobial activity with the ethanol extract showing the lowest minimum inhibitory concentrations (MICs) of 0.16-0.63 mg/mL. The activity of the water extract appeared to be the least with MICs ranging from 10 to 20 mg/mL on most of the isolates. At 10 mg/mL, both the ethanol and acetone root extracts of G. krebsiana caused 100% egg hatch inhibition, and competed well with Tramisol®. Similarly, except for ethanol extract, other leaf extracts displayed commendable and concentration-dependent anthelmintic activity of nearly 100% (90.70-93.70%) inhibitions and a corresponding 100% parasite mortality after 72 h exposure period at 10 mg/mL dose.ConclusionThe observed effects could be adduced to the presence of active principles as revealed by the phytochemical analysis of the extracts. There is a need for in vivo studies to complement the present findings, the data so far presented have validated and lent scientific support to the applications of G. krebsiana as a vermifuge and antimicrobial agent by the Basotho people of the eastern Free State of South Africa.