Pogostemon cablin Constituents: A Promising Source of Natural Fungicides and Herbicides

Antifungal screening identified Pogostemon cablin essential oil (EO) as a potent fungicide against Colletotrichum fragariae, prompting bioassay-directed fractionation. This process identified patchoulol and pogostone as antifungal constituents. Pogostone exhibited strong activity with IC₅₀ values of 8.5 ± 0.5, 2.34 ± 0.13, 7.74 ± 0.23, and 6.34 ± 0.85 μg mL^–1 against C. fragariae, C. gloeosporioides, C. acutatum, and Botrytis cinerea, respectively, at 48 h. Due to its structural similarities to β-triketone herbicides, its phytotoxicity was assessed. It exhibited herbicidal activity against Lemna paucicostata (IC₅₀ = 0.9 μM) comparable to atrazine (IC₅₀ = 1.1 ± 0.23 μM), and Amaranthus palmeri in postemergence trials, showing similar efficacy to glyphosate. Despite its herbicidal effect, photosystem II disruption is unlikely, suggesting a novel mechanism. Molecular modeling also supported the idea that it may act through a distinct mode from known HPPD inhibitors. These results indicate pogostone’s potential as a dual-function agrochemical with both antifungal and herbicidal properties.