Pertusaria amara

Picrolicbenic Acid. 6-Hydroxy-2 -methoxy-2,4 dioxo-4,6 -dlpentylspi rofben zofuran-3 2H),T -[2,5jcyclo-hexadieneJ-5-carboxylic acid picrolichenin. C H O, md wt 442.49. C 67.85%, H 6.83%, O 25.31%. Bitter acidic principle of crustose lichen, Pertusaria amara (Ach.) Nyl., Pertusariaceae. Isoln Alms, Ann. Pharm. 1, 61 (1832). 

C25HJ0O7, Mr 442.51, prisms, mp. 184-I87°C (decomp.) with an extremely bitter taste. P. a. belongs to the small group of depsones it occurs in some lichens of the genus Pertusaria (e. g., Pertusaria amara, on the bark of old deciduous trees). In the past it was used successfully in doses of 0.5-1 g for the treatment of intermittent fever. 

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