NRMJ_9_4_273-288

Introduction

Plant pathogenic microorganisms, encompassing bacterial and fungal diseases, represent a substantial risk to agricultural production and global food security (Aamer et al., 2024). Bacterial and fungal pathogens, including Pectobacterium carotovorum, Pectobacterium atrosepticum, Ralstonia solanacearum, Streptomyces scabiei, Fusarium oxysporum, Botrytis cinerea, and Rhizoctonia solani, are implicated in numerous plant diseases that impact crop quality and yield (Erbs and Newman, 2024; Ali et al., 2025). The increasing resistance of such pathogens to conventional antimicrobial agents necessitates the development of alternative control strategies. The emergence of antimicrobial resistance has become a global health concern, prompting researchers to explore alternative sources of antimicrobial agents (Cotugno et al., 2025). Plant-derived compounds have garnered significant attention due to their diverse bioactive constituents and potential therapeutic applications (Pereira et al., 2025). Medicinal plants have been utilized for centuries in traditional medicine systems worldwide, serving as a valuable reservoir of novel antimicrobial compounds with diverse mechanisms of action (Bhattacharjee and Sharma, 2025).

Recent studies demonstrated the efficacy of plant-derived antimicrobial agents against various plant pathogens (Košćak et al., 2025; Pérez-Flores et al., 2025). The significant antibacterial activity of the phenolic-rich plant extracts against the phytopathogenic bacteria, such as R. solanacearum has been reported, highlighting their potential as eco-friendly alternatives to the synthetic bactericides (Yihune and Yemata, 2019). Similarly, the antifungal properties of the plant extracts against phytopathogenic fungi emphasize their applications in sustainable agriculture and forestry (Nguyen et al., 2024). The growing body of evidence supporting the antimicrobial efficacy of plant extracts underscores their potential as natural alternatives to conventional antimicrobial agents in agricultural and pharmaceutical applications (Chaachouay and Zidane, 2024). Despite the promising antimicrobial properties of various plant extracts, comprehensive studies investigating the relationship between their phytochemical composition and biological activities remain limited (Kumar et al., 2023; Murugan et al., 2025). Understanding this relationship is essential for developing standardized plant-based antimicrobial formulations with consistent efficacy and safety profiles. Moreover, identifying specific bioactive compounds responsible for the observed antimicrobial activities could facilitate the development of novel antimicrobial agents with enhanced potency and selectivity.

Plant secondary metabolites, particularly phenolic compounds, have been extensively studied for their antimicrobial potencies (Benalach et al., 2025). These compounds exhibit diverse mechanisms of action against microbial pathogens, including disruption of cell membranes, leading to increased permeability and subsequent cell death, inhibition of microbial enzymes, and suppression of virulence factors (Arzani et al., 2025; De Rossi et al., 2025). A recent study highlighted the significant correlation between the phenolic content of plant extracts and their antimicrobial efficacy against various pathogenic microorganisms (Pérez-Flores et al., 2025). Identifying and characterizing the bioactive compounds in the plant extracts are crucial for understanding their antimicrobial mechanisms and potential applications. Advanced analytical techniques such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) have revolutionized the field of natural product studies, enabling the precise identification and quantification of bioactive constituents in the complex plant matrices (Debnath et al., 2025). HPLC analysis is particularly effective for separating and quantifying phenolic compounds, while GC-MS provides valuable information about the volatile and semi-volatile components of plant extracts.

The genus Erica (family Ericaceae) comprises approximately 860 species distributed across Europe, the Mediterranean region, and South Africa (Dias et al., 2015). Various Erica species have demonstrated significant biological activities, including antimicrobial, antioxidant, and anti-inflammatory properties (Guendouze-Bouchefa et al., 2015). Erica verticillata, a species native to the Cape Floristic region of South Africa, has been traditionally used for treating various ailments, including respiratory infections and urinary tract disorders (Ojewole, 2008). Despite its ethnomedicinal significance, comprehensive scientific investigations into the antimicrobial potential and phytochemical composition of E. verticillata remain limited. The objectives of this study were to evaluate the antibacterial and antifungal activities of E. verticillata methanolic extract against selected plant pathogenic microorganisms, and correlate these activities with the phytochemical composition of the extract. This study employs a multifaceted approach, combining in vitro antimicrobial assays with advanced analytical techniques (i.e., HPLC and GC-MS) to provide comprehensive insights into the antimicrobial potential and chemical profile of E. verticillata extract. The findings of this study could contribute to the development of natural antimicrobial agents for sustainable plant disease management and potentially address the growing challenge of antimicrobial resistance in agricultural settings.

Materials and Methods

Source of bacterial and fungal strains

This study utilized various bacterial and fungal strains to evaluate the antimicrobial activity of a methanolic extract obtained from leaves of E. verticillata. The bacterial strains comprised P. carotovorum (GenBank accession number OQ878656), P. atrosepticum (GenBank accession number MG706146), R. solanacearum (GenBank accession number OQ878653), and S. scabiei (GenBank accession number OR437480). These strains were previously isolated from potato plants exhibiting characteristic symptoms of bacterial infections. The fungal strains, including F. oxysporum (GenBank accession number OQ820156) sourced from infected potato tubers, B. cinerea (GenBank accession number MN398400) obtained from infected strawberry fruits, and R. solani (GenBank accession number OQ880457) isolated from infected bean plants.

Preparation of a plant extract

Healthy plant samples of E. verticillata were collected from Jebel Akhdar in Libya. Plants devoid of visible morphological diseases were selected. The plant materials were transported to the laboratory, where they were washed with tap water to remove debris and contaminants. The washed plant materials were dried at room temperature (25±2 °C) in the shade for 10 d until fully desiccated, a method recommended for preserving biologically active phenolic compounds (Dai and Mumper, 2010). Dried samples were ground using a mill to obtain particles of 0.5 mm, and 50 g of the powder were extracted with 500 mL of 80 % methanol in a rotary shaker at 100 rpm for 12 h at room temperature. This method is deemed adequate for extraction of phenolic compounds from plant materials, as evidenced by prior studies conducted by Azwanida (2015), Altemimi et al. (2017). The supernatant; free of plant debris, was obtained via filtration using Whatman No. 1 filter paper, and finally the methanol was evaporated at 25-30 °C in a rotary evaporator Re-52A (Wincom, Jiangsu, China).

In-vitro antibacterial assay

The agar disc diffusion method was used to evaluate the antibacterial potential of the methanolic plant extract (Bashir et al., 2024). Briefly, a single colony of the purified bacterial strain was inoculated into 100 mL of the nutrient broth (NB) medium and incubated overnight at 27 °C. At the end of the incubation period, bacterial growth concentrations were adjusted to 108 CFU/ mL using NB medium. Afterward, 100 μL were transferred and spread on the surface of Glycerol Nutrient Agar (GNA) using a sterile glass spreader. Different extract concentrations were prepared in 10 % DMSO to final concentrations of 300, 500, 700, and 1000 μg/ mL in 100 mL of NB medium. The negative control group of the experiment was adjusted using 10 % DMSO in NB medium without the extract. Aliquots of 15 μL of each extract concentration were added to 5 mm diameter filter paper discs, and then left to dry at 4 °C for 24 h. The plant extract-loaded filter paper discs were placed individually on surface of the seeded plates and incubated at 27 °C for 24 h. The positive control groups were adjusted using amoxicillin as a standard antibiotic with a concentration of 25 μg/ disc. After incubation, the antibacterial activities were quantified by measuring the inhibition zone diameter (mm) using a calibrated ruler in triplicate against the control groups.

The inhibition percentages (%) were calculated based on the obtained inhibition zone diameters using the following formula:

(Valgas et al., 2007).

In-vitro antifungal assay

The antifungal effects of the plant extract against some plant pathogenic fungi were evaluated using the radial growth assay on poisoned food procedures, as previously described by Khalil et al. (2024). Briefly, different extract concentrations were added to the potato dextrose agar (PDA) plates to obtain final concentrations of 1000, 2000, 3000, 4000, and 5000 µg/mL. A 5 mm disc of 5-day-old fungal culture was placed at the midpoint of each treated plate. The concentration of each extract was evaluated against the negative control (DMSO-PDA) and the positive control (Copper hydroxide) at a concentration of 1.5 g/ L. All plates were incubated for 7 d at 25 °C. After incubation, the antifungal activities were detected by determining the fungal mycelial growth inhibition percentage, which was calculated according to the following equation:

Mycelial growth inhibition (%) = [(A0 - At)/A0] × 100

Where A0 is the average diameter in gth untreated plates (control), and At is the average diameter of fungal growth in the treated plates (Bashir et al., 2024).

High-performance liquid chromatography analysis

Polyphenolic compounds were identified in the methanol extract using high-performance liquid chromatography (HPLC) (Agilent 1260 Infinity HPLC Series, Santa Clara, CA, USA), which was outfitted with a quaternary pump. The conditions for HPLC were established as follows: A Zorbax Eclipse Plus C18 column (100 mm × 4.6 mm) from Agilent Technologies (Santa Clara, CA, USA), was utilized for separation at 30 °C. The separation process was carried out with a 20 μL injection volume, employing a ternary linear elution gradient of water with 0.2 % H3PO4 (HPLC grade v/v), methanol, and acetonitrile. The detected peaks were analyzed with a VWD detector calibrated to 284 nm, utilizing a range of phenolic compound standards, including gallic acid, catechol, p-hydroxybenzoic acid, caffeine, vanillic acid, caffeic acid, syringic acid, vanillin, p-coumaric acid, ferulic acid, ellagic acid, benzoic acid, o-coumaric acid, salicylic acid, and cinnamic acid. Analysis using HPLC is regarded as a highly accurate and trustfull technique for identifying and examining the polyphenolic compounds in the extract, as supported by several prior studies (Naczk and Shahidi, 2004; Abdelkhalek et al., 2024).

Gas chromatography-mass spectrometry analysis

Gas chromatography-mass spectrometry (GC-MS) analysis is a reliable technique for identifying volatile and semi-volatile organic compounds in plant extracts. The potential bioactive ingredients in the extract were determined using an (Agilent Technologies, Santa Clara, Ca, USA),, which included an Agilent mass spectrometric detector featuring a direct capillary interface and a fused silica capillary column (HP-5MS), with specifications of 30 m × 0.32 mm × 0.25 μm film thickness. The column temperature was initially set at 50 °C with a ramp rate of 5 °C/min and then increased to 230 °C. The temperature was maintained at 290 °C for 2 min. before being increased to the final temperature of 300 °C. The sample injection process and program conditions were executed according to a previously published protocol (Youssef et al., 2021). The bioactive components of the extract were identified through a search of mass spectral libraries (NIST and Wiley) and by comparing the mass spectra and retention times with information available in the Wiley and NIST mass spectral library databases.

Statistical analysis

A one-way analysis of variance (ANOVA) was performed using the CoStat program (version 6.45) from the Cohort program to analyze the data statistically. The Tukey honest significant difference (HSD) test was used to evaluate differences and determine the statistical significance of the procedure at a significance level of p ≤ 0.05. An average value (mean ± standard deviation [SD]) together with its standard deviation was displayed for the data. The letters arranged in descending order demonstrated the link and indicated statistical significance (where; a > b > c). The comparable letters indicated no significant alteration.

Results

Antibacterial activity of Erica verticillata extract

Figure 1 illustrates the antibacterial potency of the methanolic extract of E. verticillata. The data indicated different sensitivity levels among the tested bacterial strains in response to the extract treatments. P. atrosepticum and S. scabiei exhibited the highest sensitivity, even at reduced treatment concentrations (300 µg/ mL), recording inhibition percentages of 33.33 % and 62.48 %, respectively.. The results indicate that these bacterial strains exhibited a notable vulnerability to the bioactive compounds present in the extract. R. solanacearum and P. carotovorum showed moderate sensitivity, with inhibition percentages of 60.51 % and 28.36 %, respectively, when treated with 700 µg/ mL of the extract. This evidence suggests that larger amounts of the extract were necessary to suppress the growth of these bacterial strains effectively. Whereas, R. solanacearum and S. scabiei bacterial strains demonstrated a notable sensitivity to the plant extract treatments at a concentration of 1000 µg/ mL, resulting in inhibition percentages of 63.19 % and 75.05 %, respectively. This discovery highlights the potential of E. verticillata extract as a viable antimicrobial option for combating multi-drug resistant bacteria. The statistical analysis revealed no significant differences in in the inhibition percentages across all the tested concentrations of the plant extract against the bacterial strains (p < 0.05). This finding shows that the antibacterial impact of the methanolic extract reaches an inhibitory limit at a specific concentration; however, adding more concentration does not significantly enhances its ability to inhibit the bacteria.

Antifungal activity of Erica verticillata extract

The antifungal properties of methanolic extract from E. verticillata were evaluated against three significant plant pathogenic fungi: F. oxysporum, B. cinerea, and R. solani. The findings are depicted in Figure 2. The extract had substantial inhibitory effects against all the tested fungal strains, particularly demonstrating notable action against B. cinerea. At 5000 µg/ mL, the extract displayed an impressive fungal growth inhibition rate of 78.2 % against B. cinerea, notably surpassing the positive control (copper hydroxide 1.5 g/L), which exhibited only 58.7 % inhibition. Statistical analysis revealed no significant differences (p < 0.05) in the efficacy of the extract against B. cinerea when administered at concentrations of 3000, 4000, and 5000 µg/ mL. These findings suggest that a lower concentration (3000 µg/mL) effectively achieved maximum inhibitory potential against this fungal pathogen, presenting a cost-effective alternative for potential applications. The extract demonstrated significant activity (p < 0.05) against R. solani at a concentration of 5000 µg/mL, with an inhibition percentage of 70.4 %.

The obtained results revealed a performance level of the extract comparable to that of the copper hydroxide treatment (67.1 %) and displayed a significant improvement over the untreated control. The obtained data suggest that the extract may be a natural substitute for chemical fungicides in managing R. solani infections. Similarly, notable suppression of F. oxysporum growth was recorded after applying plant extract concentrations of 2000, 3000, 4000, and 5000 µg/ mL, yielding inhibition percentages of 52.2 %, 66.9 %, 69.1 %, and 70.7 %, respectively. The values observed were significantly greater than the inhibition obtained through copper hydroxide treatment (34.2 %) at p < 0.05, highlighting the enhanced antifungal properties of the E. verticillata extract compared to the traditional fungicides.

High-performance liquid chromatography (HPLC) analysis for the detection of phenolic and flavonoid compounds

The chemical composition of E. verticillata methanolic extract was analyzed using HPLC to identify and quantify the phenolic and flavonoid compounds present. Figure 3 and Table 1 display the HPLC chromatograms and the obtained quantitative results. The HPLC analysis indicated that gallic acid

(2620.3 µg/ g), caffeic acid (606.5 µg/ g), and syringic acid (580.9 µg/ g) were the predominant phenolic compounds in the methanolic plant extract. The potent antioxidant and antimicrobial characteristics of these phenolic acids may substantially enhance the antibacterial and antifungal effects observed in the extract. Naringenin (198.4 µg/ g) and quercetin (169.4 µg/ g) were identified as the most abundant flavonoid compounds in the extract. Flavonoids exhibit a range of biological activities such as antimicrobial effects, and their inclusion in the extract likely enhances its overall bioactivity. Additionally, other phenolic and flavonoid compounds were identified at lower concentrations, including catechin (143.5 µg/ g), coumaric acid (63.8 µg/ g), kaempferol (54.9 µg/ g), and hesperetin (43.4 µg/ g). The presence of these bioactive compounds together may lead to synergistic antimicrobial effects, improving the overall effectiveness of the extract against the phytopathogenic microorganisms.

Gas chromatography-mass spectrometry (GC-MS) analysis of the extract’s secondary metabolites

Figure 4 and Table 2 summarize the results obtained from the GC-MS analysis. The collected data validated the existence of seven primary compounds, each was characterized by a distinct chemical structure and retention time. Hexadecanoic acid emerged as the predominant compound (26.4 %), observed at a retention time of 26.36 min. This fatty acid exhibits antimicrobial properties and may significantly contribute to the bioactivities observed in the extract. Phorbol was identified as the second most prevalent compound (16.4 %). Phorbol and its derivatives exhibit a range of biological activities, including antimicrobial effects, which may enhance the efficacy of the tested extract against the phytopathogens.

Table 1: Analysis of phenolic and flavonoid compounds of methanolic extract of E. verticillata using high-performance liquid chromatography (HPLC).

Compounds	Area	Concentration (µg/ g)
Gallic acid	430.61	2620.3
Caffeic acid	110.45	606.5
Syringic acid	123.61	580.9
Ferulic acid	61.53	265.3
Ellagic acid	15.97	202.6
Naringenin	27.29	198.4
Vanillin	60.89	177.8
Cinnamic acid	139.25	174.1
Quercetin	18.72	169.4
Catechin	8.64	143.5
Daidzein	33.41	136.8
Coumaric acid	29.97	63.8
Methyl gallate	16.97	63.3
Kaempferol	11.84	54.9
Hesperetin	12.07	43.4
Chlorogenic acid	Not detected	Not detected
Pyro catechol	Not detected	Not detected
Rutin	Not detected	Not detected
Apigenin	Not detected	Not detected

Additional compounds were identified at moderate concentrations, comprising α-sitosterol, octadecenoic acid, tibolone, stigmasterol, and methyl phaseate. Figure 4 illustrates the relative area percentages of these compounds, offering a visual representation of their proportions in the extract. Other compounds, such as columbin and loperamide, were detected at lower concentrations. The variety of secondary metabolites in the E. verticillata extract suggests a complex phytochemical profile, contributing to its extensive antimicrobial effectiveness observed against several bacterial and fungal phytopathogens. The synergistic effect of these compounds probably enhances the extract’s efficacy as a natural antimicrobial agent.

Discussion

Plant pathogens, including bacteria and fungi, are known to cause significant qualitative and quantitative harm to the crop production (Al-Askar et al., 2025). Using plant extracts as alternative antimicrobial medicines has recently attracted considerable attention due to their efficacy, efficiency, and diminished side effects. The current study investigated the antimicrobial properties and chemical composition of the methanolic extract of E. verticillata concerning various phytopathogenic bacteria and fungi. The results indicated notable antibacterial and antifungal properties, as well as a range of bioactive compounds contributing to these observed effects. The results of the antibacterial assay suggested that the extract exhibited differing inhibitory effects against the examined phytopathogenic bacterial strains. The differential sensitivity levels observed among the bacterial strains indicate the specificity of the modes of action of the extract’s bioactive compounds. This observed specificity may be attributed to variations in the cell wall composition and membrane permeability of the tested bacteria, affecting their susceptibility to the antimicrobial agents (Nazzaro et al., 2013). A rrecent study demonstrated that plant extracts can serve as alternatives or adjuncts to conventional antibiotics, as their various compounds possess antimicrobial properties that may help combat antimicrobial resistance, a primary global health concern (Hernández-Bolaños et al., 2025).

The antibacterial assay showed that P. atrosepticum and S. scabiei exhibited high sensitivity to the extract, even at a lowe concentration (300 µg/ mL), which holds considerable importance. P. atrosepticum is responsible for blackleg disease in potatoes, resulting in significant economic losses in global potato production (Czajkowski et al., 2015). Similarly, S. scabiei is responsible for common scab disease in potato and other root crops, leading to diminished marketability and yield (Zhang et al., 2024). The pronounced sensitivity of these pathogens to E. verticillata extract indicates promising avenues for developing natural bactericides to manage these economically significant plant diseases. The observation that certain bacterial strains, specifically R. solanacearum and S. scabiei, which exhibit resistance to conventional antibiotics, demonstrated notable sensitivity to the plant extract at elevated concentrations (1000 µg/ mL) is particularly intriguing. This finding is consistent with recent studies that emphasized the potential of plant-derived compounds in addressing antibiotic-resistant bacteria (Angelini, 2024). The rise of antimicrobial resistance poses a growing challenge to human health and agriculture, making it particularly crucial to develop alternative antimicrobial agents (Salam et al., 2023; Ferraz, 2024). Our findings indicated that E. verticillata extract may represent a significant source of innovative antimicrobial compounds for tackling this issue. The absence of notable variations in inhibition zone diameters across the various extract concentrations suggests a saturation effect, implying that increasing the concentration beyond a specific limit does not improve the antibacterial activity (Al-Askar et al., 2025; Gaber et al., 2025).

In this study, the methanol extract exhibited significant antifungal efficacy against B. cinerea. This finding holds particular importance as B. cinerea is a necrotrophic fungal pathogen affecting many hosts, leading to gray mold disease in more than 200 plant species and causing considerable pre- and post-harvest losses (Hamdy et al., 2024). The significant antifungal activity demonstrated against R. solani and F. oxysporum highlights the extensive range of the antifungal activities of the extract. R. solani is a soil-borne pathogen responsible for various diseases, including damping-off, root rot, and stem canker, which affects many crops (Abo-Zaid et al., 2024). F. oxysporum is a complex of pathogenic strain responsible for vascular wilt diseases affecting various economically significant plants (Shehzadi et al., 2025). Successful suppression of these pathogens by E. verticillata extract indicates promising possibilities for creating natural fungicides with comprehensive disease management approaches (Salem et al., 2025). The exceptional antifungal efficacy of the plant extracts compared to copper hydroxide, is especially significant (Lamichhane et al., 2018). Copper-based fungicides have been extensively utilized in agriculture for many years; however, worries about their environmental persistence, soil accumulation, and adverse effects on non-target organisms have led to the exploration of alternative solutions (Lamichhane et al., 2018). The findings of this study suggest that E. verticillata extract may serve as an eco-friendly alternative to traditional copper-based fungicides, thereby promoting more sustainable agricultural practices. The mechanisms by which the extract exhibits antifungal properties may include the disruption of ergosterol; a crucial component of fungal cell membranes, or the inhibition of essential enzymes involved in the biosynthesis of fungal cell walls (Eliaš, Tóth Hervay, and Gbelská, 2024; Song et al., 2025).. The evidence suggests that numerous compounds derived from plants exhibit antifungal effects through similar mechanisms (Song et al., 2025; Xie et al., 2025). This finding is consistent with a recent study that showed methanolic extracts from various plant sources frequently exhibited potent antifungal effects by disrupting fungal cell wall synthesis or altering cellular metabolism, thereby inhibiting growth and development (Xie et al., 2025). To elucidate these effects, the phytochemical composition of the extract was analyzed.

High-performance liquid chromatography (HPLC) analysis revealed the presence of various phenolic and flavonoid compounds in the extract. The most abundant phenolic compounds identified were gallic acid (2620.3 µg/ g), caffeic acid (606.5 µg/g), and syringic acid (580.9 µg/ g). Additionally, naringenin (198.4 µg/ g) and quercetin (169.4 µg/ g) were noted as the predominant flavonoids. These results provide valuable insights into the potential bioactive compounds that contribute to the extract’s antimicrobial activity. Gallic acid has been documented to exhibit potent antimicrobial properties against various bacterial and fungal pathogens (Flores-Maldonado et al., 2024). The mechanism of action involved disrupting the cell membrane, inhibiting vital enzymes, and chelating metal ions essential for microbial growth (Nasaj et al., 2024; Khwaza and Aderibigbe, 2025). The elevated levels of gallic acid in the extract probably play a crucial role in enhancing its antimicrobial effectiveness. Caffeic acid and syringic acid have shown antimicrobial properties in earlier studies (Ecevit et al., 2022; Beulah et al., 2025). Caffeic acid exhibits the ability to inhibit bacterial growth by disrupting cell membrane integrity and inhibiting essential cellular processes (Beulah et al., 2025). Syringic acid exhibits antimicrobial properties through comparable mechanisms and has been shown to enhance the efficacy of the standard antibiotics when used in conjunction (Ecevit et al., 2022). Naringenin and quercetin are flavonoids that exhibit well-documented antimicrobial properties (Shamsudin et al., 2022; Veiko et al., 2023; Hasnat et al., 2024). Naringenin can inhibit the growth of bacteria and fungi by disrupting cell membrane function and inhibiting essential enzymes (Liu et al., 2025). Quercetin exhibits antimicrobial activities through various mechanisms, including inhibition of DNA gyrase, disruption of cell membrane integrity, and interference with energy metabolism (Liang et al., 2021). The presence of these flavonoids in the extract probably plays a significant role in its wide-ranging antimicrobial activity. A recent study on E. manipuliflora suggest that the genus Erica is rich in vanillic acid, fumaric acid, catechin hydrate, quercetin, and phloridzin dihydrate, all contributing to its antimicrobial potential (Yüksel et al., 2021). This study revealed that E. manipuliflora extract exhibited effectiveness against several pathogenic microorganisms, such as Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium, reinforcing the antimicrobial potential of the Erica genus.

The GC-MS analysis identified about 15 primary compounds in the extract, with hexadecanoic acid and phorbol being the most prevalent metabolites. This study also detected α-sitosterol, octadecenoic acid, tibolone, stigmasterol acid, and methyl phaseate as less prevalent metabolites. Hexadecanoic acid, also known as palmitic acid, is a saturated fatty acid recognized for its antimicrobial potential (Ganesan et al., 2024). The mechanism of action involved disrupting the cell membrane, resulting in increased permeability and ultimately leading to cell death (Nasaj et al., 2024; El-Bilawy et al., 2025; Khwaza and Aderibigbe, 2025). Numerous studies detailed the direct beneficial effects of fatty acids, such as linoleic acid, palmitic acid, and their derivatives in managing phytopathogens (Zheng et al., 2005; Liu et al., 2008; Sumayo et al., 2014; López-Arellanes et al., 2025). Phorbol and its derivatives exhibit a range of biological activities, notably antimicrobial effects (Goel et al., 2007). The high concentrations of these compounds in the extract may play a significant role in its antimicrobial efficacy. The variety of bioactive compounds found in the E. verticillata extract suggests that its antimicrobial activity is likely attributed to the combined effects of several compounds rather than relying on a single active principle (Guimarães and Venâncio, 2022; Vaou et al., 2022; Gadouche et al., 2023; Jabal et al., 2025). This synergism may enhance overall efficacy and reduces the likelihood of resistance development, making plant extracts crucial in sustainable disease management strategies (Ayaz et al., 2019). Before synthetic pesticides were introduced, the botanical pesticides were widely used in subsistence and commercial agriculture for a long time. The active components in botanical pesticides are naturally occurring substances extracted from plants using organic solvents and/or combined with essential pesticide adjuvants (Ngegba et al., 2022). The effectiveness and efficacy of synthetic pesticides in managing crop diseases led to a gradual decline in the use of plant-based pesticide products. However, concerns about the environmental and health risks of the synthetic pesticides to humans have since emerged.(Chowdhury et al., 2024; Shekhar et al., 2024).

Finally, the findings of this study have important implications for sustainable plant disease management. The current antimicrobial efficacy of E. verticillata extracts against significant phytopathogens, and their enhanced performance relative to traditional antimicrobial agents in certain instances, highlights their potential as natural alternatives to the synthetic pesticides. Identifying specific bioactive compounds in the E. verticillata extract establishes a basis for subsequent studies on isolating and characterizing these compounds for potential commercial development as biopesticides. Moreover, comprehending the chemical composition of the extract may enhance the standardization and quality control of the botanical formulations, thereby addressing a significant challenge in the commercialization of plant-derived antimicrobial products.

Conclusions and Recommendations

This study demonstrated that methanolic extract of Erica verticillata leaves possess broad-spectrum antimicrobial activity against economically significant phytopathogens, including antibiotic-resistant bacterial strains (e.g., Ralstonia solanacearum) and fungi (Botrytis cinerea, Fusarium oxysporum). Notably, the extract outperformed the conventional copper hydroxide fungicides in inhibiting B. cinerea, recotrding 78.2 % vs. 58.7 %, respectively at 5000 µg/mL, highlighting its potential as a sustainable alternative to the synthetic agrochemicals. Phytochemical profiling revealed high concentrations of multiple bioactive compounds, including gallic acid (2620.3 µg/ g), hexadecanoic acid (26.4 %), and phorbol (16.4 %), which likely drive these amntimicrobial impacts through synergistic mechanisms, mainly membrane disruption and enzyme inhibition. Based on the strong antimicrobial efficacy demonstrated, it is recommended that E. verticillata methanolic extract be further explored and developed as a natural biopesticide for integrated plant disease management. Its superior activity against key phytopathogens, especially Botrytis cinerea, positions it as a sustainable alternative to conventional agrochemicals.

Acknowledgement

The authors express their sincere thanks to the City of Scientific Research and Technological Applications (SRTA-City) and the Faculty of Agriculture (Saba Basha), Alexandria University, Egypt, for providing the necessary research facilities.x

Novelty Statement

This study examined the bioactive potential of Erica verticillata methanol extract focusing on its phytochemical profile, and assessing its antibacterial and antifungal properties against various phytopathogenic microorganisms. The study provided a comprehensive evaluation of the bioactive compounds present in E. verticillata extract, highlighting their unique antimicrobial efficacy against phytopathogenic organisms for the first time. Moreover, it highlights the biocontrol prospects of the detected bioactive compounds and lays the groundwork for future applications as a natural source of antimicrobial agents for the sustainable management of plant diseases.

Author’s Contribution

Abdallah Khalil, Karrar A. Hamzah, and Shimaa Bashir: Methodology, Investigations, and Writing the original draft. Said Behiry and Ahmed Abdelkhalek: Supervision, Statistical study design and analysis, Molecular data analysis, Revision and editing of the manuscript. All authors approved the final version of the manuscript.

Funding source

No funds, grants, or other support were received during the preparation of this study.

Ethical approval

None-applicable.

Conflict of interests

The authors have declared no conflicts of interest.

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