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Article

The Effect of 3′,4′-Methylenedioxychalcone Derivatives on Mycelial Growth and Conidial Germination of Monilinia fructicola: An In Silico and In Vitro Study

1
Laboratorio de Productos Naturales y Síntesis Orgánica (LPNSO), Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Avda. Leopoldo Carvallo 270, Playa Ancha, Valparaíso 2340000, Chile
2
Laboratorio de Pruebas Biológicas, Departamento de Química, Universidad Técnica Federico Santa María, Av. España N1680, Valparaíso 2340000, Chile
3
Center of Interdisciplinary Biomedical and Engineering Research for Health (MEDING), Escuela de Obstetricia y Puericultura, Facultad de Medicina, Universidad de Valparaíso, Angamos 655, Reñaca 2520000, Chile
4
Instituto de Microbiología Clínica, Facultad de Medicina, Universidad Austral de Chile, Los Laureles s/n, Isla Teja, Valdivia 5090000, Chile
5
Centro de Investigación Austral Biotech, Facultad de Ciencias, Universidad Santo Tomás, Avda. Ejército 146, Santiago 8320000, Chile
*
Author to whom correspondence should be addressed.
Agriculture 2025, 15(9), 983; https://doi.org/10.3390/agriculture15090983
Submission received: 28 March 2025 / Revised: 25 April 2025 / Accepted: 29 April 2025 / Published: 1 May 2025
(This article belongs to the Section Crop Protection, Diseases, Pests and Weeds)

Abstract

:
Monilinia fructicola causes brown rot on a wide variety of stone fruits, causing several losses in the field and during storage of fruits. Due to the diverse biological activity of chalcones and their derivatives, they have emerged as a promising alternative for controlling phytopathogenic fungi. The aim of this study was to synthesize 3′,4′-methylenedioxychalcone derivatives and evaluate their in vitro inhibitory effect on mycelial growth and the conidial germination of M. fructicola. Additionally, a molecular docking study and the prediction of lipophilicity were carried out to investigate their chemical behavior. The results showed that compound F exhibited the most potent antifungal activity, with EC50 and MIC values of 20.61 µg/mL and <10 µg/mL for mycelial growth and conidial germination, respectively, presenting an adequate lipophilicity (Log p values = 2.79), which would allow proper diffusion through the fungal cell membrane. The in silico study revealed a great number of interactions between compound F and the different active sites of the succinate dehydrogenase enzyme, suggesting a favorable interaction with a binding energy score value of −6.9 kcal/mol, similar to CBE, the native ligand of this enzyme. These types of compounds could provide preventive protection in various stone and other crops.

1. Introduction

The agricultural industry constantly faces challenges due to crop diseases caused by phytopathogenic fungi, which reduce harvest yields and lead to economic losses [1]. One example is fruit rots caused by Monilinia fructicola (G. Winter) Honey, a necrotrophic fungus that affects a wide variety of stone fruit hosts, especially of the Prunus genus, such as peaches (Prunus persica), apricots (P. armeniaca), plums (P. domestica), cherries (P. avium), and sour cherries (P. cerasus), causing brown rot of these fruits [2]. In orchards, the overwinter conidia find the right climatic conditions to germinate and infect blossoms and immature fruits during the early spring (humidity above 80% and temperatures above 15–16 °C favor it) [3]. New conidia are generated from infected tissues, which can eventually be dispersed by wind or raindrops, leading to secondary infections [4]. The vegetative mycelium develops mainly in the subepidermal layers, forming a set of hyphae that form the stromata. It degrades the mesocarp tissues that soften and, progressively, lose their hyphal content to completely destroy the fruit [5].
M. fructicola is responsible for the loss of approximately 10% of the world’s post-harvest productivity, estimated at 1.7 billion dollars, which, in addition to causing rot, causes blossom wilt and fruit mummification [6]. This devastating disease was once effectively controlled by the application of benzimidazoles. However, sensitivity to this treatment has been reduced due to resistance developed by M. fructicola that is associated with binding site mutations in β2-tubulin proteins, which are involved in the mechanism of action of these fungicides [7]. As a result of this resistance, higher doses of pesticides are being required, increasing the frequency of pesticide applications and causing environmental problems due to their excess. The challenges associated with the restriction of the spectrum of available antifungals for phytosanitary health affect a wide variety of commercial crops and trigger the search for new control alternatives [8].
Different authors have proposed the use of chalcones (or 1,3-diphenylprop-2-en-1-ones) as excellent candidates for the control of phytopathogens [9,10,11]; these molecules are α,β-unsaturated ketones of two aromatic rings, A and B, linked by a three-carbon aliphatic carbonyl system and can be found in a wide variety of plants, where they act as bioprecursors of flavonoids and isoflavonoids, among others, as well as bioactive heterocyclic compounds [12]. The interest in the study of chalcones arises from their potent biological activity, including antioxidant, anticancer, anti-inflammatory, antiviral, antibacterial, and antifungal, among many others [13]. Previous research using structure–activity relationship (SAR) studies has shown that the antifungal activity against phytopathogenic fungi of a series of synthetic and natural chalcones is related to the presence of methoxy and hydroxyl groups in their molecular structure [14,15,16].
Chalcones and their derivatives can be obtained from natural sources, but their chemical synthesis has been preferred due to its logistical advantages. They are conventionally synthesized from aldehydes and acetophenones by Claisen–Schmidt condensation under basic conditions or using acids, and applying green methodologies to obtain them, such as microwave-assisted synthesis, ultrasound irradiation, or solvent-free grinding techniques [17].
Therefore, considering the potential antifungal activity of natural and synthetic chalcone derivatives, which varies based on the substituents and substitution patterns in each ring, there is no background information on the activity of 3′,4′-methylenedioxychalcone derivatives against M. fructicola. We propose the synthesis of seven chalcone derivatives via the Claisen–Schmidt condensation of 3′,4′-(methylenedioxy)acetophenone with a series of aldehydes. The aim of this study was to evaluate the ability of 3′,4′-methylenedioxychalcone derivatives to inhibit the mycelial growth and conidial germination of M. fructicola. Additionally, a molecular docking study was conducted to investigate the binding affinity between 3′,4′-methylenedioxychalcone derivatives and the enzyme succinate dehydrogenase (SDH), and in silico prediction of lipophilicity values was performed.

2. Materials and Methods

2.1. Chemical

All chemicals were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA) and AK Scientific, Inc. (Union City, CA, USA) and were used without purification. Thin layer chromatography (TLC) was performed on TLC precoated silica gel 60 F254 glass-backed plates (Merck KGaA, Darmstadt, Germany).

2.2. Synthesis of 3′,4′-Methylenedioxychalcone Derivatives

Chalcones tested in this study were obtained through the synthesis of 3′4′-(methylenedioxy)acetophenone (98% purity, Sigma-Aldrich) and a series of aromatic aldehydes by Claisen–Schmidt condensation, following protocols that have been described previously [18]. A mixture of 3′4′-(methylenedioxy)acetophenone, aromatic aldehyde, and LiOH∙H2O was prepared in methanol in a 1:1:1 mole ratio. The mixture was subjected to an ultrasound bath (Elmasonic S 10 H, Elma Schmidbauer GmbH, Sigen, Germany) at 30 °C with a frequency of 25 KHz for 3 h. The end of the reaction was verified by TLC.
Then, the reaction mixture was neutralized and extracted using ethyl acetate (EtOAc). The recovered organic layer was dried with Na2SO4 anhydrous, filtered, and concentrated under vacuum using a rotary vapor. Compounds were separated and purified by column chromatography using a hexane/EtOAc mixture with increasing polarity (20.0:0.0→16.0:4.0 v/v). All the compounds were characterized and confirmed by 1H and 13C NMR to be identical with those published in the literature [19,20,21,22]. The spectroscopy data detail is described in the Supplementary Material (Figure S1 and Table S1).

2.3. Antifungal Activity

2.3.1. Fungal Growing Conditions

The fungal isolates used in this study were kindly provided by the Mycology Unit of the Servicio Agrícola y Ganadero (SAG), Chile. The isolate was recovered from infected nectarines from commercial orchards in the province of Maipo, Metropolitan Region, Chile, and identified to species level with a PCR assay developed by the molecular biology laboratory belonging to SAG. Potato dextrose agar (PDA; DIFCO™) was used as medium for the cultures of the M. fructicola isolate, and they were incubated at 23 °C for 9 days. Spore suspensions were obtained from cultures of 6 days’ growth in 90 mm Petri dishes by the methodology described elsewhere [23]. The desired concentrations were obtained by serial dilution in sterile distilled water.

2.3.2. Effect of the Compounds on the Mycelial Growth of M. fructicola

The antifungal capacity of the samples was determined by measuring the radius of mycelial growth. The compounds were dissolved in ethanol/water and added to PDA plates at concentrations of 10, 25, 50, 150, and 250 µg/mL. For each treatment, a 4 mm disc of mycelium was inoculated in the center of a plate and incubated for 5 days at 23 °C in complete darkness. The percentage inhibition (%I) was calculated by the standard method [24] using the following Formula (1):
%I = [(dc − d0) − (ds − d0)]/(dc − d0) × 100
where d0: diameter of the fungus cut, dc: diameter of the blank control fungus, and ds: diameter of the compound-treated fungus.
PDA containing 1% ethanol was used as a negative control. The commercial fungicides Mystic® 520 SC (Pyrimethanil 400 g/L, Trifloxystrobin 120g/L) (Lot: PAIS004727; Bayer, Santiago, Chile) and BC-1000® (grapefruit seed and pulp extract (Citrus x paridisi), 50% w/v (500 g/L)) were used as positive controls and were measured under the same conditions as the compounds. Results were expressed as the mean effective concentration (EC50), i.e., the concentration at which mycelial inhibition was reduced by 50%, which was obtained using Origin Pro V.8 software (OriginLab Corporation, Northampton, MA, USA) by regression of percent growth inhibition values versus concentrations of each compound. All the measurements were obtained from two independent experiments, and each one was performed in triplicate. Significant differences were determined using a one-way analysis of variance, followed by a pairwise comparison of means (LSD test; p < 0.05).

2.3.3. Effect of the Compounds on Conidial Germination of M. fructicola

The inhibition of conidial germination by the compounds was determined following the methodology described by Pereira et al. with modifications [25]. Spore suspensions were prepared from 6-day-old M. fructicola colonies grown on PDA at 23 °C. A 40 µL aliquot of a spore suspension at a concentration of 1 × 105 conidia/mL was spread on the plates with culture medium contained in the treatments at different concentrations (10, 25, 50, 50, 150, and 250 µg/mL) and then incubated at 23 °C for 16 h in the dark. Sterile distilled water was used as a negative control. Conidia were considered germinated when they developed germ tubes at least twice their width. The percentage of inhibition of conidial germination (ICG%) was calculated using the following Formula (2):
ICG% = [(CC − CT)/CC] × 100
where CC: total conidia germinated in the control and CT: total conidia germinated in the treatment.
The minimum inhibitory concentration (MIC) of conidia was estimated using the percentage of germinated conidia by randomly examining 100 conidia in the center of each plate by microscopy (40× magnification; Leica DM500, Leica Microsystems, Wetzlar, Germany). All the measurements were obtained from three independent experiments; each was carried out in triplicate.

2.4. In Silico Analysis

2.4.1. Molecular Docking

Three-dimensional models of the ligands were constructed using Avogadro 1.2.0n software. The ligands’ geometries were optimized and their energies minimized using the MMFF94 force field. Images were generated using the free version of Discovery Studio Visualize software (v17.2.0.16349 2016). The crystallized structure of succinate dehydrogenase (SDH; PDB ID: 2FBW, 2.06 Å resolution) [26] was sourced from the Protein Data Bank (http://www.rcsb.org/ (accessed on 5 March 2025)). Molecular docking of succinate dehydrogenase and chalcone ligands was carried out with the AutoDock4 package using the Lamarckian genetic algorithm [27] and assuming rigid ligands in the macromolecule and full flexibility for the inhibitors. The search parameters included 50 runs with a maximum of 25,000,000 evaluations per ligand. An RMSD threshold of <0.5 Å was used for clustering. The ligand crystallized in the enzyme 2-methyl-N-phenyl-5,6-dihydro-1,4-oxathiine-3-carboxamide (CBE) served as a reference for the docking studies. The grid coordinates were 20.46 Å (X), 60.98 Å (Y), and 20.31 Å (Z), while the grid square sizes were 40 grid points to X, Y, and Z. The result was analyzed by ranked cluster and binding energy ΔG, where the lowest energy and most populated cluster was selected as the best protein–ligand complex for further analysis. Co-crystallized ligand was docked again under the same conditions to check the docking accuracy, and an RMSD of 2.49 Å was obtained.

2.4.2. Prediction of Lipophilicity

All experiments were performed at physiological pH. Prediction of the lipophilicity of selected compounds was compiled using Swiss ADME software online platform (http://www.swissadme.ch/index.php (accessed on 10 March 2025)) and expressed as the partition coefficient Log p.

3. Results and Discussion

3.1. Synthesis of 3,4-Methylenedioxychalcone Derivatives

Seven chalcones were obtained from the base-catalyzed condensation of 3′,4′-(methylenedioxy) acetophenone and different aromatic aldehydes (IVII) using ultrasound methodology and are shown in Scheme 1.
The reactions were carried out in the presence of a strong base. Considering this medium, it is suggested that it is the base that initiates the nucleophilic attack on the methyl group of acetophenone, and then the acetophenonate ion that is produced attacks the carbon of the aldehyde group; this is the slowest step of the reaction [28]. The use of ultrasonic irradiation to assist reactions has been preferred because it allows the acceleration of the process, achieving improvements in yields. In fact, it has been shown that the US-assisted synthesis of chalcones can be about 200 times faster and produces fewer undesired products, like products of the Cannizzaro reaction [29]. As can be seen in Scheme 1, the reaction yields were found to be in the range of 60.0% to 91.1%. Previously, other authors reported lower yields for compound G, close to 47%, presumably due to the use of other synthesis methods [30], but in this case, the ultrasound-assisted synthesis allowed us to obtain a yield of 91.1%.

3.2. Inhibitory Effect of 3,4-Methylenedioxychalcone Derivatives on Mycelial Growth and Conidial Germination Inhibition of M. fructicola

It is relevant to determine the effect of the molecules synthesized as possible fungicides on the different organs of the pathogenic fungus (spores and mycelium), to apply the product at the right moment of the biological cycle of the phytopathogen, and to determine its range of action; in this way, an integrated management of the disease in the field can be carried out.
The antifungal activity of the samples was determined by mycelial growth assay, and their mean effective concentration (EC50) is expressed in Table 1. Compounds A, B, C, and F showed an inhibitory effect on the mycelium growth of M. fructicola. The inhibitory effect was moderate for compounds A and B, with EC50 values of 72.09 and 72.65 µg/mL, respectively. Compound F showed promising antifungal activity, achieving an EC50 value of 20.61 µg/mL, but this was less potent than the commercial standards. Specifically, its EC50 value was approximately 2.46 and 1.95 times higher than that of the synthetic fungicide Mystic ® 520 SC and the organic fungicide BC-1000® (based on grapefruit extracts), respectively. Although these four molecules (A, B, C, and F) were active against M. fructicola, the capacity to inhibit mycelial growth did not overcome that of the positive controls.
Furthermore, the ability of the compounds to inhibit M. fructicola spore germination is also presented in Table 1. Here, the moderate activity on the inhibition of mycelial growth observed for compound B correlates with a moderate inhibition of conidial germination, both showing MIC values of 150 µg/mL. Although the mycelial growth inhibition is comparable, compound A outperforms compound B due to its marked inhibitory activity on conidial germination, even at the lowest concentration tested of <10 µg/mL, making it a promising candidate for fungal control in the field.
Similarly, the stronger inhibitory effect of compound F on mycelium development was consistent with a conidial inhibition value of <10 µg/mL, indicating high effectiveness of this molecule. In contrast, compounds D and G did not exhibit activity against M. fructicola mycelium but showed a greater potential to inhibit conidia at low concentrations. In general, the synthesized compounds have the capacity to inhibit conidial germination at low concentrations. The inhibitory effect on conidia germination of compounds A, C, D, and F was similar to the effect of the commercial organic (BC-1000®) and synthetic fungicide Mystic 520®.
This stronger inhibitory effect on conidial germination compared to the effect on mycelial growth is similar to that reported by Shin et al. [31], where the commercial fungicide Mancozeb exhibited greater efficacy in preventing the germination of Cylindrocarpon destructans conidia compared to its moderate effect on controlling the mycelial growth of the same fungus. It is possible that the antifungal activity of compounds A, C, D, and G is more closely related to alterations in conidial cells rather than a direct impact on fungal metabolism and mycelial development [32].
It has been reported that natural molecules can produce severe damage to the conidial cells of phytopathogenic fungi, preventing fungal colonization [33,34]. For instance, the use of volatile organic compounds of the marine bacterium Staphylococcus saprophyticus strain L-38 [33], as well as benzothiazole compounds, induces morphological changes on conidia such as surface malformation, leading to suppression of the germination process [34].
In the case of M. fructicola, an inhibitory effect on conidial germination has been described for phenolic compounds, highlighting the antifungal activity of ferulic acid [35,36]. Although the mechanism of action of phenolic compounds is not completely elucidated, it has been suggested that their appropriate lipophilicity and their chemical structure, particularly the presence of hydroxyl groups, are associated with their antifungal action.
In chalcone derivatives, the presence of hydroxyl groups in dihydrocarvone hybrids increases the antifungal action against M. fructicola by enhancing the binding affinity between the compound with hydroxyl substitution and the SDH enzyme [37]. On the other hand, the antifungal activity of hybrid dihydrochromane–chalcones against M. fructicola also depends on the dipole moment, the electronic density in C1, and the carbonyl carbon [10]. Moreover, Camargos et al. [38] reported that methoxyl substitution on different chalcones maximizes their antifungal activity against the filamentous fungus Alternaria alternata, which, like Monilinia, is responsible for the rot of a wide variety of plants. In fact, among the 137 chalcones analyzed in the mentioned study, those containing 3,4-methylenedioxy motifs in the A ring were active even when they did not have substituents in the B ring. The synthetized 3,4-methylenedioxychalcone derivatives with better antifungal activity in terms of the inhibition of conidia germination (C, D, and F) share the presence of methoxyl groups on the B ring of the chalcone at the C-3 and C-4 positions, coinciding with other studies that indicate the methoxyl substitutions as a key for the bioactivity of chalcones [14,39,40]. Compound A also showed MIC values of <10 µg/mL. However, there are no substitutions in the B ring, suggesting that the 3,4-methylenedioxy substituent in the A ring could be enough to be active against Monilinia conidia. In the case of compound F, the better antifungal activity, both mycelium growth inhibition and conidia inhibition, could be explained by the fact that the compound retains the 3,4-methylenedioxy motifs in the A ring while in the B ring, it contains the methoxy and hydroxyl substituents in meta- and para- positions, respectively, enhancing its antifungal activity. This suggests that introducing methoxy and hydroxyl groups at m- and p- positions improves the antifungal properties of compound F. This finding aligns with the study of Gupta et al. [41], where the same positions on the aromatic ring of chalcone derivatives containing methoxy groups increase the lipophilicity of the compounds, leading to the enhanced inhibition of the dermatophyte strain of Microsporum gypseum.
Hence, compounds A, C, D, and F exhibited strong antifungal activity to inhibit conidia germination at low concentration, and they could be considered as effective alternatives for the preventive control of M. fructicola. Conidia represent the primary inoculum source for brown rot infection in the field and during the postharvest stage. These conidia are disseminated by wind, rain, biological vectors, and human activities [4]. Once conidia land on the fruit surface, the infection process begins with their germination, leading to the formation of a germ tube or an appressorium to penetrate the fruit cuticle. The pathogen then remains in a quiescent state, awaiting favorable conditions for colonization and going unnoticed during the visual external examination of fruits [42]. Moreover, temperature and relative humidity conditions used in packinghouses can keep conidia viable for longer periods [43], increasing the risk of secondary infections that can occur throughout the spread of conidia from infected fruits to healthy ones [44]. Therefore, a preventive strategy that enables the inhibition of conidial germination is essential for reducing potential infections before the fungus colonizes host tissues, making its control more challenging.
Finally, compound F exhibited the most complete antifungal activity, as indicated by the lowest EC50 and MIC values to inhibit mycelial growth and conidial germination, respectively. Thus, this molecule could potentially reduce disease development on infected fruits and prevent postharvest infections without the negative consequences of synthetic fungicides. The efficacy of a fungicide will depend on whether it is able to reach the entire surface of the plant and act on the spores at the early stage of infection so that it cannot continue its biological cycle and spread to other parts of the plant or other crops.

3.3. Molecular Docking and Lipophilicity

The enzyme succinate dehydrogenase (SDH), also known as mitochondrial complex II, is an enzyme associated with the inner mitochondrial membrane that participates in important cellular processes such as the Krebs cycle and the electron transport chain. Succinate dehydrogenase (SDH) is an ideal target for fungicides, as it inhibits fungal respiration by blocking electron transfer from succinic acid to panquinone in the respiratory chain [45,46,47,48]. In a molecular docking analysis, possible interactions between 3′,4′-methylenedioxychalcone-derived and SDH were evaluated using the crystal structure PDB 2FBW. 2-methyl-n-phenyl-5,6-dihydro-1,4-oxathien-3-carboxamide as the reference ligand. Compounds that demonstrated activity against M. fructicola by inhibiting mycelium development and conidial germination were selected to evaluate the activity on SDH.
The docking results shown in Table 2 suggest that compound C has the highest binding energy (−5.52 Kcal/mol), while compound F achieved the lowest binding energy score with a value of −6.9 kcal/mol, indicating that this compound would form a stable and energetically favorable complex comparable to the complex formed by CBE, the co-crystallized ligand of the protein.
The activity of the compounds on SDH is related to the type of molecular interactions formed between the ligand and the amino acid residues of the protein. One of the most important interactions corresponds to hydrogen bonds; a higher number of hydrogen bonds of this type would apparently be related to higher activity [49]. Compound F, the most active of the series, formed three hydrogen bonds with residues Gly214 (3.07 Å), Asp232 (2.04 Å), and Hse56 (2.62 Å), in addition to three carbon–hydrogen bonds with residues Tyr176 (2.70 Å), Val47 (2.59 Å), and Lys49 (2.44 Å), as can be seen in Figure 1. Aslan and Beydemir [50] demonstrated that phenolic compounds such as 4-hydroxybenzoic, 3,5-dihydroxybenzoic, 3,4-dihydroxybenzoic, p-coumaric, ferulic salicylic, ellagic, caffeic, and gallic acids exert effects on SDH enzymatic activity. Compound F shows a strong structural similarity to ferulic acid, as both share a p-phenolic group attached to the α,β-unsaturated system and have the presence of a methoxyl group adjacent to the phenol. It has been described that ferulic acid shows a high inhibitory impact on SDH [51]. Additionally, ferulic acid has antifungal activity against mycelial growth and the conidia germination of M. fructicola [35,36].
Molecular docking results show that compound A formed three hydrogen bonds with residues Ala178 (1.81 Å), Thr48 (2.42 Å), and Ala26 (1.92 Å); and compound B formed one hydrogen bond with residue Ala26 (2.31 Å) and two carbon hydrogen bonds with residues Glu397 (3.04 Å) and Thr213 (2.07 Å). Finally, compound C formed two hydrogen bonds with residues Ala178 (1.09 Å) and Ala26 (1.93 Å).
The biological activity of compounds also depends on their interaction with the cell membrane of microorganisms. Physicochemical properties, specifically lipophilicity, play a key role in the diffusion of compounds through the cytoplasmic membrane [52]. In general, relatively hydrophobic compounds are able to diffuse more quickly across the cell membrane, while non-hydrophobic molecules can diffuse exclusively through specific pores, and highly hydrophobic molecules tend to establish strong interactions with the phospholipid bilayer [53]. Hence, a balance between lipophilicity and hydrophilicity is required for a molecule to be able to exert a biological action. All compounds presented adequate lipophilicity values (Log p between 1 and 5), indicating that these compounds can cross the cell membrane and achieve the desired antifungal action.

4. Conclusions

Synthesized compounds derived from 3′,4′-Methylenedioxychalcone exhibit strong antifungal activity against M. fructicola, especially in inhibiting conidial germination. Compound F is particularly effective, and its activity is likely due to methoxy and hydroxyl substitutions on the B ring. Molecular docking showed that compound F was the most active on SDH, with hydrogen bonds in the union sites allowing for better antifungal action. This derivative shows promise for managing crop diseases by preventing fungal infections, but further studies are needed to ensure its non-toxicity and practical application.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agriculture15090983/s1, Figure S1: Base structure of 3′,4′-methylenedioxychalcone derivatives A–G; Table S1: 1H- and 13C-NMR spectroscopic data of compounds AG (400 and 100 MHz, CDCl3).

Author Contributions

Conceptualization, A.M., V.S. and C.F.; methodology, A.M. and K.D.; formal analysis, E.M.; investigation, C.F., G.V., P.G. and N.C.; resources, A.M., I.M. and K.D; writing—original draft preparation, C.F., V.S. and E.M.; writing—review and editing, K.D., M.M.-L. and F.V.; supervision, A.M.; funding acquisition, A.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the University of Playa Ancha, Plan de Fortalecimiento de Universidades Estatales UPA 21992 of the Chilean Ministry of Education.

Institutional Review Board Statement

Not applicable.

Data Availability Statement

All data are available for the scientific community.

Acknowledgments

The authors would like to thank Programa de Apoyo para el pago de Procesamiento de Artículos 2025, Dirección General de Investigación, Universidad de Playa Ancha, Chile and FONDECYT grant number 1230311.

Conflicts of Interest

The authors declare no conflicts of interest.

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Scheme 1. Synthesized chalcones and their respective yields. a. LiOH∙H2O, ethanol, US, 40 °C. I. benzaldehyde; II. m-methoxybenzaldehyde; III. p-methoxybenzaldehyde; IV. 3,4-dimethoxybenzaldehyde; V. p-dimethylaminobenzaldehyde; VI. vanillin; VII. piperonal.
Scheme 1. Synthesized chalcones and their respective yields. a. LiOH∙H2O, ethanol, US, 40 °C. I. benzaldehyde; II. m-methoxybenzaldehyde; III. p-methoxybenzaldehyde; IV. 3,4-dimethoxybenzaldehyde; V. p-dimethylaminobenzaldehyde; VI. vanillin; VII. piperonal.
Agriculture 15 00983 sch001
Figure 1. Three-dimensional predicted binding mode of compounds A, B, C, and F into the allosteric site of enzyme SDH (PDB: 2FBW).
Figure 1. Three-dimensional predicted binding mode of compounds A, B, C, and F into the allosteric site of enzyme SDH (PDB: 2FBW).
Agriculture 15 00983 g001
Table 1. EC50 and MIC values of chalcones (AG) on the inhibition of mycelial growth and conidial germination of M. fructicola.
Table 1. EC50 and MIC values of chalcones (AG) on the inhibition of mycelial growth and conidial germination of M. fructicola.
CompoundsEC50 (µg/mL) MIC (µg/mL)
A72.09 ± 0.80 c<10 a
B72.65 ± 0.30 c150 c
C206.24 ± 0.01 d<10 a
D>250 e<10 a
E>250 e>250 d
F20.61 ± 0.18 b<10 a
G>250 e25 b
Mystic 520®8.38 ± 2.44 a<10 a
BC-1000®10.55 ±1.74 a<10 a
Values expressed as the mean values ± standard deviation of two independent experiments, each performed in triplicate. MIC is the lowest concentration of a compound that inhibits the germination of the conidia. Different letters in the same column indicate significant differences; (p ≤ 0.05).
Table 2. Binding energies and lipophilicity obtained from molecular docking studies on SDH.
Table 2. Binding energies and lipophilicity obtained from molecular docking studies on SDH.
CompoundBinding Energy
(Kcal/mol)
Lipophilicity Log p
A−6.053.17
B−6.133.14
C−5.523.15
F−6.902.79
CBE−7.22.12
CBE: 2-methyl-n-phenyl-5,6-dihydro-1,4-oxathiine-3-carboxamide ligand crystallized in SDH (2FBW).
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Ferreira, C.; Silva, V.; Muñoz, E.; Valle, G.; Martínez-Lobos, M.; Valdés, F.; Díaz, K.; Montenegro, I.; Godoy, P.; Caro, N.; et al. The Effect of 3′,4′-Methylenedioxychalcone Derivatives on Mycelial Growth and Conidial Germination of Monilinia fructicola: An In Silico and In Vitro Study. Agriculture 2025, 15, 983. https://doi.org/10.3390/agriculture15090983

AMA Style

Ferreira C, Silva V, Muñoz E, Valle G, Martínez-Lobos M, Valdés F, Díaz K, Montenegro I, Godoy P, Caro N, et al. The Effect of 3′,4′-Methylenedioxychalcone Derivatives on Mycelial Growth and Conidial Germination of Monilinia fructicola: An In Silico and In Vitro Study. Agriculture. 2025; 15(9):983. https://doi.org/10.3390/agriculture15090983

Chicago/Turabian Style

Ferreira, Catalina, Valentina Silva, Evelyn Muñoz, Gissella Valle, Manuel Martínez-Lobos, Francisca Valdés, Katy Díaz, Iván Montenegro, Patricio Godoy, Nelson Caro, and et al. 2025. "The Effect of 3′,4′-Methylenedioxychalcone Derivatives on Mycelial Growth and Conidial Germination of Monilinia fructicola: An In Silico and In Vitro Study" Agriculture 15, no. 9: 983. https://doi.org/10.3390/agriculture15090983

APA Style

Ferreira, C., Silva, V., Muñoz, E., Valle, G., Martínez-Lobos, M., Valdés, F., Díaz, K., Montenegro, I., Godoy, P., Caro, N., & Madrid, A. (2025). The Effect of 3′,4′-Methylenedioxychalcone Derivatives on Mycelial Growth and Conidial Germination of Monilinia fructicola: An In Silico and In Vitro Study. Agriculture, 15(9), 983. https://doi.org/10.3390/agriculture15090983

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