In Vitro Antifungal Activity of Sanguinarine and Chelerythrine Derivatives against Phytopathogenic Fungi

In order to understand the antifungal activity of some derivatives of sanguinarine (S) and chelerythrine (C) and their structure-activity relationships, sixteen derivatives of S and C were prepared and evaluated for in vitro antifungal activity against seven phytopathogenic fungi by the mycelial growth rate method. The results showed that S, C and their 6-alkoxy dihydro derivatives S-1-S-4, C-1-C-4 and 6-cyanodihydro derivatives S-5, C-5 showed significant antifungal activity at 100 mu g/mL against all the tested fungi. For most tested fungi, the median effective concentrations of S, S-1, C and C-1 were in a range of 14-50 mu g/mL. The structure-activity relationship showed that the C=N+ moiety was the determinant for the antifungal activity of S and C. S-1-S-5 and C-1-C-5 could be considered as the precursors of S and C, respectively. Thus, the present results strongly suggested that S and C or their derivatives S-1-S-5 and C-1-C-5 should be considered as good lead compounds or model molecules to develop new anti-phytopathogenic fungal agents.