Identification of antifungal quinolizidines using GC/MS-based metabolomics

Genisteae plants synthesize quinolizidines as a defense strategy against herbivores and pathogens [1], so their production may depend by a particular biotic pressure. The variation of these alkaloids can be exploited to detect promptly bioactives in extracts through integration of chemical and biological activity datasets using supervised statistics. Thus, several accessions of Genisteae plants (from different locations in Bogotá plateu) were investigated through a comprehensive targeted GC/MS-based metabolomics approach in order to explore the quinolizidine variation between sample set and its implication on antifungal activity against Fusarium oxysporum. Quinolizidine-enriched extracts were obtained from leaves of Genisteae plants (n>66) by means of ultrasound-assisted acid-base extraction. Resulting extracts were separately tested against F. oxysporum, through amended-medium method in 12-well plates at 0.1-500 μg/mL, and mycelial growth inhibition was then recorded. Chemical differences in extracts were examined by partial-least squares (PLS) discriminant analysis using MS features data (retrieved from GC/MS profiles using MZmine 2.37). Single-Y PLS was also used to integrate the chemical and biological datasets. Extracts showed antifungal capacity at different levels (2>IC₅₀(µg/mL)>55). PLS-DA indicated several differences between samples and clustered according characteristic chemical constituents and/or activity. Single-Y PLS analysis evidenced three aphylline-like compounds to be related to antifungal activity (AUC>0.9), which were confirmed by independent antifungal in-vitro assays using the isolated quinolizidines (IC₅₀ >3 µg/mL). This chemical and antifungal activity integration led to the rapid detection of bioactive quinolizidines in extracts improving the efficiency during antifungals discovery against F. oxysporum. Product derived from Project IMP-CIAS-2924 financed by UMNG - Validity 2019.

• References

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