 In the 1970s the Japanese microbiologist Akira Endo first discovered natural products with a powerful inhibitory effect on HMGR in a fermentation broth of "Penicillium citrinum", during his search for antimicrobial agents.The first product was named compactin (ML236B or mevastatin).Animal trials showed very good inhibitory effect as in clinical trials, however in a long term toxicity study in dogs it resulted in toxic effects at higher doses and as a result was believed to be too toxic to be given to humans.