Evaluation of the phytotoxic and antifungal activity of C17-sesquiterpenoids as potential biopesticides

Authors: CÁRDENAS, DAVID - University Of Cadiz; Bajsa-Hirschel, Joanna; Cantrell, Charles; RIAL, CARLOS - University Of Cadiz; VARELA, ROSA - University Of Cadiz; MOLINILLO, JOSÉ M. - University Of Cadiz; MACÍAS, FRANCISCO - University Of Cadiz

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2022
Publication Date: 6/16/2022
Citation: Cárdenas, D.M., Bajsa Hirschel, J.N., Cantrell, C.L., Rial, C., Varela, R.M., Molinillo, J.G., Macías, F.A. 2022. Evaluation of the phytotoxic and antifungal activity of C17-sesquiterpenoids as potential biopesticides. Pest Management Science. https://doi.org/10.1002/ps.7042.
DOI: https://doi.org/10.1002/ps.7042

Interpretive Summary: Natural products are a promising source for the development of new pesticides with alternative mechanisms of action. Sesquiterpene lactones (SLs) are one of the largest family of natural products and a broad range of bioactivities have already been reported. SLs are mainly isolated from the aerial parts of the family of the Compositae although they can also be found in other plant families, such as Umbelliferae, Lauraceae, and Magnoliaceae. Recent isolation studies have led to the discovery of a novel family of sesquiterpene lactones commonly named C17-sesquiterpenoids. In this study, we evaluated the phytotoxic and antifungal activity of a novel family of natural C17-sesquiterpenoids and examined the relationship between chemical structure and activity. Many tested compounds exhibited a strong, phytotoxic activity. Lappalone and pertyolide B were the most potent molecules from the tested group. Regarding the antifungal activity, pertyolide B presented significant activity against Colletotrichum fragareae and Fusarium oxysporum.

Technical Abstract: BACKGROUND: Natural products are a promising source for the development of new pesticides with alternative mechanisms of action. In this study, we evaluated the phytotoxic and antifungal activity of a novel family of natural C17-sesquiterpenoids and performed a structure-activity relationship (SAR) study on the presence of the a-methylene-'-butyrolactone system and its importance to their biological activity. RESULTS: Many tested compounds exhibited a strong, phytotoxic activity. Lappalone and pertyolide B were the most potent molecules from the tested group. Lappalone displayed a strong inhibition profile against selected weed species, reaching outstanding IC50 values against Echinochloa crus-galli L. shoot (IC50: 5.0 µM) and the germination ratio of Amaranthus viridis L. (IC50: 5.7 µM), as well as, a good stimulation of the germination of Phelipanche ramosa L. Pertyolide B demonstrated excellent inhibition against Amaranthus viridis L. (IC50: 56.7, 70.3 and 24.0 µM against the root and shoot growth and germination ratio, respectively) and outstanding IC50 values against Allium cepa L. (representative of the Liliaceae family, IC50: 25.3 and 64.4 µM against root and shoot). Regarding the antifungal activity, pertyolide B presented significant activity against Colletotrichum fragareae and Fusarium oxysporum with a minimum inhibitory concentration of 6.6 µg/µL. CONCLUSION: The bioassays revealed that frequently the presence of the a-methylene butyrolactone system is not essential for the bioactivities of sesquiterpene lactones and suggests that C17-sesquiterpenoids may function through a different mechanism of action not related to the widely assumed Michael addition.