Abstract: There is currently a high demand for new therapeutic antibiotics with new mechanisms of action. Disclosed are two small molecules, tryglysin A and B, with novel chemical structures and potent antibiotic activity against a narrow spectrum of bacteria. This narrow spectrum of activity indicates the tryglysins could be working through a novel antibiotic mechanism of action. Due to this narrow spectrum, the tryglysins could be used as highly targeted therapeutics to treat or prevent disease without disturbing other important, “beneficial” bacteria within the human microbiome, which is a great improvement over virtually all other clinically used antibiotics that are broad-spectrum. The tryglysins are potent against several streptococcal pathogens, including Streptococcus pneumonia, the leading cause of pneumonia, and Streptococcus mutans, the primary causative agent of tooth decay and gum disease.