Demalonyl derivatives of guanidylfungin A and copiamycin: Their synthesis and antifungal activity.

Guanidylfungin A was chemically modified by alkylation, reduction and/or demalonylation. Demalonylmethylguanidylfungin A became soluble in water and showed approximately eight-fold higher activity against fungi and Gram-positive bacteria than guanidylfungin A along with strongly fungicidal effect. Similarly, copiamycin was converted to demalonylmethylcopiamycin, which also showed higher antifungal activity than copiamycin itself.