Leptosperin

Leptosperin (originally but no longer "leptosin") is a bioactive component of Mānuka honey. It is the gentiobiose glycoside of syringic acid methyl ester. It is named for the genus Leptospermum, the shrubs from which bees harvest nectar to make this type of honey. This bioactive component is the source of antibacterial property of Manuka honey or other Leptospermum species derived honey.

Leptosperin content can be used as a marker for the quality of the honey.