Neoaureothin is an unusual chain-extended analogue of aureothin. Neoaureothin was first reported as a co-metabolite of neoantimycin in Streptomyces orinoci. Neoaureothin has anti-HIV and antifungal activity. Recent investigations have identified two photo-isomers of neoaureothin, SNF4435C and SNF4435D, as potent immunosuppressive agents.