Urea

Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C₅H₄N₄O₃.

Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species. It was first isolated by German scientist W. Knop in 1844[1] and first synthesized between 1933-1937 by Curd and Robertson.At normal conditions, usnic acid is a bitter, yellow, solid substance. It is known to occur in nature in both the d- and l-forms as well as a racemic mixture.