Helvolic acid from Aspergillus fumigatus

Protostane and their 29-nor-derivatives denoted as fusidanes are fimgal metabolites. Cephalosporium caerulens, for instance, produces (-l-)-protosta-17(20)-( -24-diene-3p-ol. Fusidanes sueh as helvolic acid from the Helvola mutant of the mold Aspergillus fumigatus and related structures are widely used as antibacterials. Fusi-dic acid isolated from the fermentation broth of Fusidium coccineum and related tribes is an example. Its sodium salt has immunosuppressive and antibacterial properties, and is applied in ointments against multiresistant staphylococci during the therapy of wound infections... 

Helvolic acid (5.145) was the first of the steroidal fusidane antibiotics to be isolated. It was obtained from Aspergillus fumigatus var helvola in 1943 by Chain and Florey. Cephalosporin Pi (5.146) was deseribed by Abraham as a metabolite of the same Brotzu strain of Cephalosporium acremonium as that... 

Helvolic acid (164) originally isolated from Aspergillus fumigatus has also been identified in Gliocladium species where it cooccurs with the 1, 2-dihydro analogue [59]. Helvolic acid shares the unusual tetracyclic triterpene skeleton of the fusidanes with fusidic acid and the cephalosporin Pi and all show antibacterial activity [230, 231]. 

---