Laricifomes officinalis, also known as agarikon, eburiko, or the quinine conk, is a wood-decay fungus that causes brown heart rot on conifers native to Eurasia, North America, and Morocco. This fungus is the only member of the genus Laricifomes. The fruiting bodies grow in large conks on the trunks of trees.

1. officinalis was used by the Ancient Greeks to treat consumption (tuberculosis) according to the writings of Pedanius Dioscorides in 65 AD, and by some indigenous people to treat smallpox. Later on, the conks were collected extensively for production of medicinal quinine, hence the name "quinine conk", which they were thought to contain because of the bitter taste of the powdered conk, however they do not contain quinine, nor do they possess anti-malarial properties.

Mycologist Paul Stamets has performed numerous investigations of the biological activities of Agarikon; its extracts have demonstrated antiviral activity against a range of viruses in vitro. This activity has been specifically observed against pox family viruses, HSV-1 and HSV-2, Influenza A, Influenza B, and Mycobacterium tuberculosis in vitro.

Other researchers have identified novel chlorinated coumarins in the organism which demonstrated notably low minimum inhibitory concentrations against the Mycobacterium tuberculosis complex.