Isolating and characterizing the active ingredient in medicinal plants is the beginning step for many new drugs. Isosteviol is a purified component of a plant commonly used in the treatment of a wide variety of conditions including leprosy, bronchitis, and rheumatism. Al Dhabi et al. Discovered that isosteviol has a wide variety of bioactivities and is a promising lead for many new antimicrobials. 

Read more here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4460244/