Rhodocollybia maculata

The cap is up to 9 centimetres (3+1⁄2 in) wide and cream-colored with red-brown spots.^[3] The edge remains inrolled for an extended period of time. The whitish gills are crowded, becoming spotted in age. The similarly colored stipe is up to 10 cm long,^[3] tough, hollow, and tapered downwards.^[4] The spore print is whitish to yellowish.^[3]

A variety known as scorzonerea is characterized by yellowish color of its gills, and sometimes the stipe.^[4]

It is widespread in North America.^[3] It often appears in decomposing conifer duff.^[4]

Though non-toxic,^[5] this species is considered inedible due to its toughness and unpalatability;^[6] it is typically bitter.^[7]

In 2016, Gupta et al. reported that collybolide exhibited high-potency, selective kappa-opioid receptor (KOR) agonism.^[8] Due to its attractive bioactivity and chemical similarity to salvinorin A, collybolide garnered attention in the synthetic chemistry and pharmacology fields as a potential scaffold for developing next-generation analgesics, antipruritics, and antidepressants.^[9][10][11]

In 2022, Shevick et al. completed the first enantioselective total synthesis of collybolide and profiled the activity of synthetic collybolide at the KOR. Despite previous findings by Gupta et al., these assays showed that neither enantiomer of collybolide had KOR activity.^[12] The synthetic sample was identical to natural collybolide isolated from R. maculata. Assays of crude R. maculata extracts by other groups additionally showed no KOR activity.^{[12][Note 1]} These assays of synthetic and natural samples contradict the findings of Gupta et al., and suggest that collybolide and the other constituents of R. maculata have no activity at KOR.