Nocardia acidophilus, mycomycin

Allenes are compounds with adjacent carbon-carbon double bonds. Many allenes are chiral, even though they don t contain chirality centers. Mycomycin, for example, a naturally occurring antibiotic isolated from the bacterium Nocardia acidophilus, is chiral and has = -130. Explain why mycomycin is chiral. Making a molecular model should be helpful. 

Mycomycin is a naturally occurring antibiotic produced by the fungus Nocardia acidophilus. The molecular formula of the substance is Ci3Hi0O2, and its systematic name is 3,5,7,8-tridecatetraene-10,12-diynoic acid. Draw the structure of mycomycin. 

Many isolated acetylenic compounds have pronounced antifungal activity (and often antibacterial activity), but their inherent instability limits their usefulness for this purpose. One example is the antibiotic mycomycin (12) isolated from a basidiomycete, Nocardia acidophilus (Weiss and Edwards, 1980). 

Mycomycin, which was isolated by Celmer and Solomons from the culture fluid of the actinomycete, Nocardia acidophilus, was shown to contain a polyacetylenic structure and also an optically active allene unit (XLII). Van t Hoff had predicted that the aUene unit should show optical activity, but mycomycin provided the first example of its existence in nature. Nemotin (XLIII) and nemotinic acid (XLIV), which are formed by Poria corticola and Poria tenuis, are also allenes. A related compound, odyssic acid (XLV), is produced by the same fungi. 

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