Gregatin B
Gregatin B is a metabolite of the fungi Cephalosporium gregatum and Aspergillus panamensis with the molecular formula C14H18O4 Gregatin B is a weak antibiotic. Gregatin B was discovered in 1982 and has been the subject of total synthesis. References

Further reading 

 
 
 

Gregatin B
Antibiotics
Cyclopentenes
Methyl esters