(Baker f.) R. Fern. & A. Fern. Root Extract Inhibits the Production of Extracellular Proteases by .

Treatment of infections caused by has become a challenge due to the emergency of resistant strains. root extracts have been used in traditional medicine to treat throat and chest pains in Zimbabwe. The objective of the study was to determine the effects of root bark extracts on the production of extracellular proteases by . The root barks were collected, dried, and crushed into powder. To obtain different phytoconstituents, plant extractions were performed. Extractions were carried out using two solvent mixtures: ethanol : water (50 : 50 v/v) and dichloromethane : methanol (50 : 50 v/v). Serial exhaustive extractions were also performed using methanol, ethanol, dichloromethane, acetone, ethyl acetate, hexane, and water. The broth microdilution assays were used to assess the antibacterial effects of the root bark extracts against . Ciprofloxacin was used as a positive control. Qualitative screening for extracellular protease production by on BCG-skim milk agar plates using the most potent extract was carried out. The proteolytic zones were measured and expressed as the ratio of the diameter of the colony to the total diameter of the colony plus the zone of hydrolysis ( values). The ethyl acetate extract was found to be the most potent inhibitor of the growth of with 99% inhibition and a minimum inhibitory concentration (MIC) of 100 g/mL. Inhibition of extracellular protease production was directly proportional to the concentration of the extract. At 100 g/mL, the ethyl acetate extract had a value of 0.84, indicative of mild proteolytic activity. A value of 0.94 was observed at a concentration of 200 g/mL and signified weak proteolytic activity. In conclusion, the extract inhibited the production of extracellular proteases in . Further work on the isolation and purification of bioactive compounds responsible for inhibiting the production of extracellular proteases is of importance in the discovery of agents with antivirulent effects on .