ウスニン酸

解説ウスニン酸，Usnea，Alectoria，Ramalina，Cetraria，Parmelia，Lecanora属など，地衣類にもっとも広汎に存在する抗菌性物質．生合成的には，2分子の2-アセチル-4-メチルフロログルシノールが酸化的に縮合して生成したと考えられる．天然には(＋)-体と(－)-体のほか，ラセミ体が存在する．黄色の柱状結晶．融点203～204 ℃．[α]D ＋492°(クロロホルム)．塩化鉄(Ⅲ)で赤褐色を呈する．

使用Usnic acid is a major metabolite from a number of lichen and fungal species and is perhaps one of the longest known microbial metabolites, first isolated in 1844. Usnic acid exhibits a broad range of biological activity, indeed it is easier to list the bioassays in which it does not exhibit activity. More often than not, potency is low and of limited value. Usnic acid is an important metabolite for dereplication in discovery research programs.

純化方法This very weak acid is the natural form which is recrystallised from Me2CO, MeOH or *C6H6. At 25o it is soluble in H2O (<0.01%), Me2CO (0.77%), EtOAc (0.88%), MeOCH2CH2OH (0.22%) and furfural (7.32%). [Curd & Robertson J Chem Soc 894 1937, Barton & Brunn J Chem Soc 603 1953, resolution: Dean et al. J Chem Soc 1250 1953, synthesis: Barton et al. J Chem Soc 538 1956, Beilstein 18/5 V 586.]