A rapid at-line LC-QTOF-MS/MS based targeting and guided isolation approach uncovers 2-methoxy-1,4-naphthoquinone from Impatiens balsamina Linn. as an anti-Malassezia agent

Abstract

Background

Impatiens balsamina Linn. is an annual plant traditionally used to treat several cutaneous fungal infections, including conditions often associated with Malassezia spp. However, its anti-Malassezia activity, biomarkers, and underlying mechanisms remain insufficiently defined. This study establishes a rapid at-line LC-ESI-QTOF-MS/MS screening platform coupled with a colorimetric antifungal assay to identify anti-Malassezia biomarkers and assess their modes of action.

Methods

An at-line LC-ESI-QTOF-MS/MS platform was used to screen I. balsamina extracts and identify bioactive constituents. The most active extract was subjected to preparative HPLC for isolation of biomarkers. The resazurin-based microdilution antifungal assays were performed against M. furfur. The mechanisms of action of the identified compounds were investigated by lipase assay and biofilm formation assay.

Results

The ethyl acetate extract exhibited the most potent antifungal activity. The LC-ESI-QTOF-MS/MS and bioactive chromatograms pinpointed 2-methoxy-1,4-naphthoquinone (2MN) as the only active compound. Purified 2MN showed MIC values of 6.510 ± 1.906 µg/mL and MFC values of 8.854 ± 4.543 µg/mL. The compound reduced extracellular lipase activity and effectively inhibited biofilm formation of M. furfur.

Conclusions

The at-line LC-ESI-QTOF-MS/MS platform successfully guided and reduced the time and sample scale for purification of the anti-Malassezia compound. 2MN from I. balsamina exerts a significant antifungal effect and reduces fungal biofilm. Our rapid targeting approach and findings here encourage the discovery of antifungal phytochemicals as a candidate for anti-Malassezia therapy.