Berberine molecule. Computer model of a molecule of the plant alkaloid berberine. Atoms are represented as spheres and are colour-coded: carbon (green), hydrogen (white), oxygen (red) and nitrogen (blue). Berberine is used in herbal medicine as an antipyretic and an antibacterial and antifungal agent. It has also been found to increase the sensitivity of muscle and liver tissue to insulin, and so could be used to treat type 2 diabetes.