Omphalotaceae

A family of gilled wood-rotting fungi that is worth knowing precisely because it holds two organisms at opposite ends of usefulness. On one branch sits shiitake — the second most cultivated mushroom on earth and the source of a licensed oncology adjuvant. On another sits Omphalotus, the jack-o’-lantern: bioluminescent, strikingly orange, and genuinely poisonous.

The pairing is a standing argument against reasoning about mushrooms by family. Omphalotus is also the classic chanterelle mimic, and its green glow in darkness is the field character that gives the family its common name.

Shiitake carries more evidence than almost any other medicinal fungus. Lentinan, its purified β-1,3-glucan, is an injectable adjuvant used alongside chemotherapy in Japan for gastric cancer — a regulatory approval, not a supplement claim, and one that says nothing about eating the mushroom. Eritadenine, a purine alkaloid essentially unique to shiitake, lowers cholesterol by interfering with methionine metabolism; the effect is real in animals and modest in people.

Omphalotus contributes to medicine from the other direction. Its toxin illudin S was too poisonous to use, but a semisynthetic derivative, irofulven, was developed as an anticancer agent — one of the cleaner examples of a mushroom poison becoming a drug lead.

Lentinan and related β-glucans, eritadenine, ergothioneine and ergosterol characterise the shiitake side; the family is one of the richest natural sources of ergothioneine. The Omphalotus side runs on illudins — sesquiterpene toxins — and on the luciferin chemistry behind fungal bioluminescence. Lenthionine, a cyclic sulfur compound, gives shiitake its distinctive aroma and carries mild antiplatelet activity.