Researchers created a new peptide called C16LL-37 that homes in on the cavity‑causing bacteria Streptococcus mutans. In lab tests it kills the bacteria at relatively low concentrations, leaves human red blood cells unharmed, and stays active under different temperatures, pH levels, and salt amounts. It looks promising for future anti‑cavity products, but it’s still an early‑stage lab finding, not something you can buy or safely use yet.

This study aimed to evaluate the biological characteristics of a human specifically targeted antimi- crobial peptide C16LL-37 against Streptococcus mutans (S. mutans). In this study, an antimicrobial peptide LL-37, a peptide derived from CSP(C16) (S. mutans competence stimulating peptide), and recombinant peptide C16LL-37 were synthesized by Fmoc-chemistry-based strategy. The selectivity and antibacterial activity of C16LL-37 were identified by the colony counting method on microbial culture plates. After treatment of C16LL-37 at 32 µmol · L⁻¹, the morphological changes in S. mutans were observed by using scanning electron microscopy (SEM). In addition, enzyme-linked immunosorbent assay was used to evaluate the hemolytic activity and antibacterial activity of C16LL-37 under different conditions. 1) The minimum inhibitory concentration of C16LL-37 was 16 µmol · L⁻¹, and the minimum bactericidal concentration was 64 μmol ·L⁻¹. 2) The survival rate of S. mutans was 3.46% after C16LL-37 treatment at 64 µmo-L⁻¹ for 30 min, whereas it was 0% at 64 µmol · L⁻¹ for 60 min. The survival rates of four other kinds of bacteria were more than 60% at any time (P < 0.05). 3) The morphological change in S. mutans was observed after C16LL-37 treatment at 32 µmol · L⁻¹ by using SEM. S. mutans presented an irregular shape, rough surface, and evident splitting. 4) The hemolysis rate of C16LL-37 (≤ 64 µmol · L⁻¹) was less than 0.33%. 5) This study showed no significant in- fluence on the antibacterial activity of C16LL-37 under different conditions, such as temperature, pH, salinity, and trypsin at low concentration (P > 0.05). C16LL-37 exhibited obvious specificity for S. mutans, strong antibacterial activity, low toxicity, and high stability. Thus, C16LL-37 has good potential in caries research and clinical application.