Antifungal Activity of Plant Waste Extracts against Phytopathogenic Fungi: Allium sativum Peels Extract as a Promising Product Targeting the Fungal Plasma Membrane and Cell Wall

Abstract

The harmful effect of synthetic fungicides on the environment and the development of resistance by fungi raises concerns about their security and future efficacy. In this work, we investigated plant by-products with the antifungal activity that could be safe alternatives to conventional fungicides. The in vitro antifungal potential of plant by-product extracts showed that garlic peel extract (GPE) was the most effective against several phytopathogenic fungi. Accordingly, in ex situ assays with apples, GPE significantly reduced the lesion size caused by subepidermal inoculation with Colletotrichum acutatum spores. In addition, Saccharomyces cerevisiae mutant strains affected in ergosterol synthesis showed higher resistance to GPE than the parental strain, indicating that the extract might target an intermediate of this pathway. Moreover, GPE affects the cell wall, given that bck1 and mkk1/mkk2 mutants were less able to cope with the stress because of the impairment of the remodeling mechanisms. Regarding the apoptosis-deficient mutant yca1, sensitivity was similar to that of the parental strain, suggesting that the extract does not induce apoptosis. A diverse group of sulfur compounds was identified by gas chromatography–mass spectrometry (GC/MS). Our findings contribute to the elucidation of the antifungal mechanism of GPE and highlight its potential as an alternative biofungicide in agriculture.

Antibacterial Activity of Ginkgo biloba Extracts against Clavibacter michiganensis subsp. michiganensis, Pseudomonas spp., and Xanthomonas vesicatoria

“…The presence of catechol should be attributed to the rupture of catechin (a constituent identified by Lin et al [6] in the G. biloba leaves aqueous methanol extract) (Figure 2). Catechol had previously been identified in the extracts of Taxus baccata L. [31], Allium sativum L. [32], Sambucus nigra L. [33], and Quercus ilex L. [34], with concentrations ranging from 1.6 to 6.4% (compared to 3.3−7.9% in the extracts reported herein). Catechol oxidizes to melanoid pigments that are derivatives of benzoquinone, which is reported to have antimicrobial properties, slowing the decay of damaged fruits and other parts of plants.…”

Chemical Constituents and Antimicrobial Activity of a Ganoderma lucidum (Curtis.) P. Karst. Aqueous Ammonia Extract

“…Oleic acid, or 9-octadecenoic acid, has been identified in damask rose oil [ 24 ], Chenopodium album L. root methanolic extract [ 25 ], Allium sativum Regel L. [ 26 ], Sesuvium portulacastrum L. [ 27 ], Armeria maritima (Mill.) Willd.…”

Novel Perspectives on Food-Based Natural Antimicrobials: A Review of Recent Findings Published since 2020

“…Phytopathogenic fungi play a significant role in plant diseases [ 72 ]. The use of plant-based food waste extracts or powders with antifungal properties as natural biofungicides is being investigated for their potential in disease management [ 73 , 74 , 75 ]. Endophytic microbes have been reported, including the species of Trichoderma sp., Aspergillus sp., Fusarium sp., Mucor sp., Aeromonas sp., Corynebacterium sp., Enterobacter sp., Sphingomonas sp., and Penicillium sp., and Bacillus sp.…”

“…This suggests the potential application of the extract as a biofungicide for controlling the disease [ 74 ]. Teixeira et al [ 75 ] demonstrated the antifungal potential of garlic ( Allium sativum ) peel extract, showcasing its effectiveness against a range of phytopathogenic fungi. Notably, ex situ experiments conducted with apples revealed that the application of garlic peel extract led to a significant reduction in lesion size caused by Colletotrichum acutatum spores.…”

“…Further investigations in this study have shed light on the antifungal mechanism of action, indicating that the extract targets the fungal plasma membrane and cell wall. These insights underscore the promising role of garlic peel extract as a viable alternative biofungicide in agricultural contexts [ 75 ].…”