HPLC profiling with at-line microdilution assay for the early identification of anti-fungal compounds in plants from French Polynesia

Introduction: The search for anti-fungal compounds has maintained a scientific interest notably due to existing difficulties in the treatment of mycoses and their increasing occurrence in hospitals.

Objective: Development of a simple method to rapidly identify anti-fungal compounds in crude plant extracts based on a HPLC microfractionation approach combined with an at-line anti-Candida assay.

Methods: The scale of the semi-preparative HPLC microfractionation was adapted to fit the sensitivity of the Candida albicans anti-fungal in a 96-well microdilution assay. This format is also compatible for MS and NMR dereplication of the active compounds.

Results: Based on the screening of 12 crude extracts of plants from French Polynesia, three plants, which displayed various levels of anti-fungal activities, were selected to assess the efficiency of the HPLC anti-fungal profiling and the scale necessary for microfractionation. The same anti-Candida assay was performed on the HPLC microfractions collected using a generic profiling method. Analysis of active microfractions by MS and NMR issued from the most active extract enabled an efficient dereplication of the compounds responsible for the anti-fungal activity.

Conclusion: A generic HPLC anti-fungal profiling method was developed which revealed that only 50 mg of crude extract were sufficient for a rapid identification of compound(s) responsible for the anti-Candida activity. This approach was illustrated by the study of Alphitonia zizyphoides, a plant traditionally used to treat dermatomycoses.