Mellein is an isochromane produced mainly by fungi, but also plants, insects and bacteria. The structure of mellein as (-)-3,4-dihydro-8-hydroxy-3-methyl isocoumarin was confirmed in 1955. The biological activity and biosynthesis of melleins were reviewed by Evidente and colleagues, University of Università di Napoli Federico II, Italy in 2019. Mellein has a broad bioprofile, including phytotoxic, antifungal, antibacterial, antiviral, herbicidal, algicidal, larvicidal and cytotoxic activities.