In the 1H NMR-guided fractionation of extracts from the edible mushroom Lactarius deliciosus, two new azulene-type sesquiterpenoids, 7-isopropenyl-4-methyl-azulene-1-carboxylic acid (1) and 15-hydroxy-3,6-dihydrolactarazulene (2), together with seven known compounds were characterized. Their structures were determined on basis of spectroscopic evidence, as well as by comparing with literature data. Amongst the known metabolites, the 13C NMR assignment of 15-hydroxy-6,7-dihydrolactarazulene (3) is reported here for the first time. Moreover, 7-acetyl-4-methylazulene-1-carbaldehyde (5) displayed a moderate antibacterial activity against Staphylococcus aureus. *Digital image of L. deliciosus. Retrieved March 17, 2017 from https://upload.wikimedia.org/wikipedia/commons/e/e3/Lactarius_deliciosus_1_(1).jpg .
Keywords: Antibacterial activity; Azulene sesquiterpenoids; Fungal pigments; Lactarius deliciosus.