Journal of Pesticide Science
Online ISSN : 1349-0923
Print ISSN : 1348-589X
ISSN-L : 0385-1559
Regular Articles
Identification of two phthalide derivatives and an oxindole compound isolated from the edible mushroom Pleurotus ostreatus and their inhibitory activities against plant pathogenic microorganisms
Enrico M. CabutajeKotomi UenoKumiko Osaki-OkaKazutaka KidoThomas Edison E. dela CruzAtsushi Ishihara
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2023 Volume 48 Issue 4 Pages 156-167


The excessive use of chemical pesticides in agricultural fields for controlling plant pathogenic microorganisms harms human health, the environment, and other beneficial microorganisms in the soil and plants. To address this challenge, it is essential to isolate and discover bioactive compounds from biological resources that could inhibit plant pathogenic microorganisms. In this study, the culture filtrate of the edible mushroom Pleurotus ostreatus was subjected to bioassay-guided isolation, and two phthalide derivatives—4,6-dimethoxyphthalide (1) and 5,7-dimethoxyphthalide (2)—were identified, along with an oxindole compound—3-hydroxy-3-methyloxindole (3). The inhibitory activities of the three compounds were evaluated against four fungal and five bacterial pathogens. Remarkably, 1 and 2 exhibited the lowest IC50 values against the conidial germination and germ tube elongation of the rice blast fungus Pyricularia oryzae. However, their effectiveness against bacterial pathogens was relatively low. The (S) and (R)-enantiomers of 3-hydroxy-3-methyloxindole showed different activities against plant fungal pathogens and bacterial plant pathogens.

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© Pesticide Science Society of Japan 2023. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License (

This article is licensed under a Creative Commons [Attribution-NonCommercial-NoDerivatives 4.0 International] license.
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