(+) -Menthol (Standard) is the analytical standard of (+) -Menthol. This product is intended for research and analytical applications. (+) -Menthol (D-Menthol) is one of the optical isomers of Menthol. (+) -Menthol can reduce the electrically evoked contractions of rat phrenic hemidiaphragm in vitro. Local anaesthetic activity. (+) -Menthol inhibits fungal growth and sporulation. (+) -Menthol can also inhibit the growth of Microcystis aeruginosa cells[1][2][3][4].