Chemical constituents and antimicrobial activity of a Ganoderma lucidum (Curtis.) P. Karst. aqueous ammonia extract

• Autor(a) principal: Sánchez-Hernández, Eva
• Data de Publicação: 2023
• Outros Autores: Teixeira, Ana, Pereira, Catarina, Cruz, Adriana, Martín-Gil, Jesús, Oliveira, Rui Pedro Soares de, Martín-Ramos, Pablo
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/1822/85719
• topic: Antifungal activity; Anti-oomycete activity; Chitosan oligomers (COS); Dehesa ecosystem; Gas chromatography-mass spectrometry (GC-MS); Mushroom extracts; Natural products; Phytopathogens; Quercus ilex; Reishi

Mushroom extracts have shown potential as a source of new antimicrobial agents. This study investigates the chemical profile of an aqueous ammonia extract obtained from the carpophores of <i>Ganoderma lucidum</i>, which grows on <i>Quercus ilex</i> trees, and explores its valorization as a biorational. The major chemical constituents of the extract, identified through gas chromatography–mass spectrometry, include acetamide, oleic acid, 1,2,3,4-butanetetrol, monomethyl azelate, undecane, and palmitic acid. The anti-oomycete and antifungal activity of <i>G. lucidum</i> extract was evaluated against <i>Phytophthora cinnamomi</i>, the primary threat to <i>Quercus</i> spp. in the <i>dehesa</i> biome, as well as three Botryosphaeriaceae fungi. In vitro tests revealed minimum inhibitory concentration (MIC) values of 187.5 μg·mL⁻¹ against <i>P. cinnamomi</i> and 187.5–1000 μg·mL⁻¹ against the fungi. Furthermore, conjugation of the <i>G. lucidum</i> extract with chitosan oligomers (COS) synergistically enhanced its antimicrobial activity, resulting in MIC values of 78.12 and 375–500 μg·mL⁻¹ against <i>P. cinnamomi</i> and the fungi, respectively. These MIC values are among the highest reported to date for natural products against these phytopathogens. Subsequent ex situ testing of the COS-<i>G. lucidum</i> conjugate complex on artificially inoculated <i>Q. ilex</i> excised stems resulted in high protection against <i>P. cinnamomi</i> at a dose of 782 µg·mL⁻¹. These findings support the potential utilization of this resource from the <i>dehesa</i> ecosystem to protect the holm oak, aligning with sustainable and circular economy approaches.