Mellein is a dihydroisocoumarin, a phenolic compound produced by the mold species Aspergillus ochraceus.[1]
4-Hydroxymellein is also produced by Aspergillus ochraceus.[1]
6-Hydroxymellein, together with S-adenosyl methionine, is a substrate of the enzyme 6-hydroxymellein O-methyltransferase to form 6-methoxymellein and S-adenosylhomocysteine in Apiaceae.[2] 6-Methoxymellein is one of the compounds responsible for bitterness in carrots.