Introduction

Rising global population is increasing the demand for cereals, prompting the expansion and intensification of large-scale cereal production. However, this agricultural intensification has led to a surge in cereal pest populations, contributing to approximately one-third of global cereal losses1. Callosobruchus maculatus is identified as a significant pest that poses a serious threat to stored grains. It is found globally and is particularly damaging to crops such as chickpeas, green beans, black beans, kidney beans, and cowpeas, especially in tropical and subtropical regions2. Damage caused by seed weevils, including weight loss and reduced nutritional quality, can lead to substantial economic and health-related impacts3. In Africa, losses due to this pest can lead to food shortages and malnutrition4. The widespread use of synthetic pesticides has contributed to the development of pesticide resistance among numerous insect populations, driving the search for natural alternatives that pose fewer risks to both the environment and human health5. Essential oils demonstrate potential as an eco-friendly solution for managing stored grain pests. Notably, they exhibit higher efficacy even at lower concentrations, minimizing the risk of environmental harm6,7.

The rise of microbial pathogen resistance poses a significant threat to global health, as microorganisms are increasingly developing resistance mechanisms against antibiotics, antimicrobials, and even newly developed drugs8,9. According to a simulation model, microbial resistance is projected to cause more than ten million deaths each year by 205010. The primary driver behind microbial pathogen resistance is the improper utilization of antibiotics and synthetic antimicrobials. Scientists are exploring novel compounds sourced from various outlets, such as medicinal plants, in the pursuit of infection treatments11,12. In recent years, there has been a renewed interest in using medicinal plants, rooted in tradition, to treat and cure ailments13. This increase in popularity is mainly attributable to the growing demand for these herbs, especially in emerging markets, where they are more affordable than conventional medicines14,15.

In Africa, traditional medicine is used by more than 80% of the population. The continent is rich in plant diversity, with a significant number of species being harnessed for their medicinal properties. Globally, there are approximately 300,000 plant species, of which over 200,000 are found in the African tropics and are valued for their health benefits16,17.

Morocco is home to a substantial portion of its population that depends on medicinal plants for self-care and treatment18. Morocco’s unique geographical location, diverse geological formations, varied topography, and favorable climate make it a vital center of plant biodiversity in North Africa19. Due to its diverse and varied environment, it exhibits exceptional plant diversity, with approximately 4,800 species20, distributed among 981 genera and 155 families21. Among these, roughly 800 are indigenous22, and 1,600 taxa are classified as scarce23. Moreover, approximately 600 species are employed in herbal medicine24. Moroccan flora contributes to over half of the endemic species found in North African nations25.

German chamomile (Matricaria recutita, syn. Matricaria chamomilla) is an annual herb belonging to the Asteraceae family26. It is originally from Europe, Western Asia, North and East Africa27, now widely distributed worldwide28. This plant is among the most widely used medicinal herbs globally, traditionally employed in the treatment of various conditions, including digestive disorders29, sleep and hepatic disorders30, also used against pain and infections31,32, colds (Güzel, Mehmet and Miski 2015). M. chamomilla (L.) contains a variety of bioactive compounds, such as flavonoids, tannins, and coumarins, which contribute to its therapeutic properties. These constituents are responsible for its medicinal effects33. Studies have shown that German chamomile exhibits anti-inflammatory effects34, antioxidant35, antifungal36, antimicrobial37, antispasmodic, sedative, and analgesic properties, among others36. As a medicinal plant, German chamomile can be consumed in various forms, such as herbal tea, infusions, or extracts26, Chamomile essential oil is widely utilized across various industries, such as pharmaceuticals, cosmetics, agri-food, and more, due to its versatile properties and benefits28. To our knowledge, no prior studies have explored the molecular characterization and biological activities of the essential oil derived from the flowers of Matricaria chamomilla (L.) collected in the Taounate region of Northern Morocco. Although M. chamomilla has been extensively studied, essential oil composition is highly sensitive to regional climatic, edaphic, and ecological factors. Our study presents, for the first time, the chemical profile and biological activities of M. chamomilla essential oil from this bioclimatic zone, contributing novel chemotaxonomic and pharmacological data. In addition to conventional GC-MS analysis and in vitro evaluations, we employed molecular docking to characterize the oil’s active compounds against microbial and insecticidal targets an approach scarcely applied to this regional chemotype. This integrative strategy allowed us to explore antioxidant, antibacterial (including efficacy against antibiotic-resistant strains), antifungal, and insecticidal potentials. The demonstrated insecticidal activity against Callosobruchus maculatus is particularly noteworthy, as such applications remain underexplored for Moroccan chamomile oils, positioning our findings within the growing interest in biopesticides. In light of these aspects, we believe our study offers novel regional insight, original molecular interpretation, and a broad biological assessment that enhances the current understanding of this medicinal species.

Materials and methods

Plant material and extraction of essential oil

M. chamomilla (L.) flowers were harvested on the morning of April 1, 2022, during the peak flowering season, in the Tahar Souk region, located approximately 50 km from the town of Taounate, Morocco (geographical coordinates: 35°1’22” N, 4°8’27” W, altitude: 592 m). The region experiences a Mediterranean climate, with maximum temperatures soaring up to 40 °C. The collected plant material was identified by botanist Amina Bari, a Professor in the Biology Department of the Faculty of Sciences (FSDM), Fez-Morocco, and was assigned the specimen reference number 05–21-TT0015. The flowers of Matricaria chamomilla were air-dried in the laboratory under controlled conditions, protected from light and humidity, at room temperature.

The essential oil was extracted from 100 g of fresh plant material using 1 L of distilled water by hydrodistillation for 2 h in a Clevenger-type apparatus. These conditions were selected based on preliminary trials and literature data, optimizing for oil yield and chemical stability. Following extraction, the EO-MC was dehydrated using anhydrous sodium sulfate, filtered to remove impurities, and stored in sealed flasks at 4 °C for subsequent use14,38.

All experimental research and field studies on Matricaria chamomilla (L.) complied with institutional, national, and international guidelines and legislation. The plant material was collected with appropriate authorization, and its identification was verified by a qualified botanist. No endangered or protected species were involved in this study.

Extraction and PCR of genomic DNA and sequencing

The protocol described by Jawhari et al. (2023) was used for DNA extraction from randomly selected fresh M. chamomilla flowers of the same age39. The Rbcl (Ribulose-1,5-Bisphosphate Carboxylase) region was amplified by PCR with the universal primers rbcL a-f (5’-ATGTCACCACAAACAGAGACTAAAGC3’) and rbcL a-r (5’-GTAAAATCAAGTCCACCGCG3’)40. Amplification conditions were as follows: 35 cycles at 95 °C for 4 min, 94 °C for 30 s, 55 °C for 1 min, 72 °C for 1 min. PCR results were visualized by 1.5% agarose gel electrophoresis. Sequences were aligned and processed using ChromasPro sequence analysis software (version 2.1.10.1). They were then analyzed using Blast search to identify sequences homologous to each other in the GenBank databases. They were then deposited in the previous database. A phylogenetic tree was created from the sequences obtained. The M. chamomilla (L.) isolate was used to form a main group using MEGA 5.0 software. The sequence of Artemisia giraldii (OK128342) was selected as outgroup. The maximum likelihood (ML) approach was employed to compute phylogenetic connections. To evaluate the support for each branch in the resulting tree, 1000 bootstrap replications were conducted.

Oil identification by GC-MS

Gas chromatography-mass spectrometry (GC-MS) analysis was utilized to determine the chemical composition of the essential oil (EO). Two capillary columns were employed: an HP-5MS column (30 m × 0.25 mm i.d., 0.25 μm film thickness) with a non-polar stationary phase, and a DB-HeavyWAX column (30 m × 0.25 mm i.d., 0.25 μm film thickness) with a polar stationary phase. The oven temperature program was as follows: initial temperature 50 °C (held for 2 min), ramped to 150 °C at 3 °C/min, then to 250 °C at 10 °C/min, and held for 10 min. Helium was used as the carrier gas at a constant flow rate of 1.0 mL/min. The injection volume was 1 µL in split mode with a split ratio of 1:20. Injector and detector temperatures were set at 250 °C. Mass spectrometry was carried out in electron impact (EI) mode at 70 eV, with a scan range of m/z 40–450. Identification of compounds was achieved by comparing the mass spectra and calculated retention indices with those in the NIST-MS Search Version 2.0 library and literature data41,42.

Antioxidant activity in vitro

The DPPH assay was conducted following the procedure suggested by El Moussaoui et al.38. A 0.004% DPPH solution was prepared, and 100 µl of M. chamomilla (L.) essential oil extract, diluted to various concentrations in methanol, was mixed with 750 µl of the DPPH solution. The same procedure was applied to butylated hydroxytoluene (BHT), a synthetic antioxidant, also diluted to different concentrations in methanol. After incubating for 30 min at room temperature, absorbance at 517 nm was measured using a UV-Vis spectrophotometer (JENWAY 85617). The percentage inhibition of DPPH (PI%) was computed using the following equation:

$$\:\mathbf{P}\mathbf{I}\left(\mathbf{\%}\right)\:=\:100\times\:(\mathbf{A}0\:-\:\mathbf{A}/\mathbf{A}0)\:\:$$

PI stands for the percentage of inhibition. A0 indicates the absorbance of the negative control (DPPH without the sample), while A represents the absorbance of the sample with DPPH.

The antibacterial activity of EO-MC

The antibacterial effects of EOMC were evaluated against four bacterial strains: Proteus mirabilis ATCC29906, Escherichia coli K12, Klebsiella pneumoniae CIP A22, and Staphylococcus aureus ATCC6633. These strains were obtained from the CHU Hassan II in Fez. The zone of inhibition was determined using the disk diffusion technique. Bacterial strains were introduced onto Petri dishes filled with Mueller-Hinton agar at a concentration of 106 to 108 CFU/mL (0.5 McFarland). Following this, 6 mm-diameter filter paper discs were soaked with 10 µL of EOMC, and a positive control was conducted using streptomycin antibiotic (25 µg/disc). The plates were incubated for 24 h at 37 °C. After incubation, the diameter of growth inhibition zones was assessed. The results, expressed in millimeters, were used to evaluate the antibacterial activity of EOMC14,43,44.

Antifungal activity

The study aimed to evaluate the antifungal activity of OE-MC against four fungal species: Candida albicans ATCC, Aspergillus flavus, Fusarium oxysporum MTCC9913, and Aspergillus niger MTCC282. To perform the test, fungi were inoculated onto Petri dishes containing malt agar extract medium. Then, 6 mm Whatman paper discs were soaked with 20µL of OE-MC. The plates were incubated for 7 days at 30 °C for A. niger, A. flavus and F. oxysporum, while C. albicans was incubated at 37 °C for 24–48 h. Positive controls were included using the antibiotic Fluconazole (15 mg/mL). After the incubation, the inhibition diameter (in mm) was measured for C. albicans, while growth in mm was assessed for both the negative and positive tests. This data was then used to calculate the percentage of inhibition for strains of filamentous fungi using the following formula45:

$$\:\varvec{\%}\:\varvec{I}\varvec{n}\varvec{h}\varvec{i}\varvec{b}\varvec{i}\varvec{t}\varvec{i}\varvec{o}\varvec{n}=\frac{\mathbf{N}\mathbf{e}\mathbf{g}\mathbf{a}\mathbf{t}\mathbf{i}\mathbf{v}\mathbf{e}\:\mathbf{t}\mathbf{e}\mathbf{s}\mathbf{t}-\mathbf{P}\mathbf{o}\mathbf{s}\mathbf{i}\mathbf{t}\mathbf{i}\mathbf{v}\mathbf{e}\:\mathbf{t}\mathbf{e}\mathbf{s}\mathbf{t}}{\mathbf{N}\mathbf{e}\mathbf{g}\mathbf{a}\mathbf{t}\mathbf{i}\mathbf{v}\mathbf{e}\:\mathbf{t}\mathbf{e}\mathbf{s}\mathbf{t}}\times\:100$$

Measurement of minimum inhibitory concentration

The MICs of OE-MC against the four fungal and four bacterial strains were determined using the micro-dilution method, following the protocol described by Sarker et al.46. Briefly, a sterile 96-well microplate was employed. For bacterial and fungal strains, 50 µl of Mueller-Hinton (M-H) medium and malt extract (ME), respectively, were added to each well. EO-MC was diluted at a ratio of 1/10 (v/v) in 10% DMSO, and 100 µl of this solution was dispensed into the first column of the microplate. Subsequently, microbial strains (30 µl) were added following a 1:2 dilution series up to column 11. Plates were placed in incubators at 37 °C–30 °C for 24 h, 48 h or 7 days, respectively for bacteria, C. albicans and filamentous fungi. Following the incubation period, 20 µl of a 0.2% solution of 2,3,5-triphenyl-tetrazolium-chloride was added to each well to facilitate the visualization of microbial growth47. The MIC was defined as the minimum concentration that did not lead to red coloration, and the outcomes were expressed in mg/ml.

Insecticidal action against C. maculatus

Fumigation test

The fumigation experiment evaluated the efficacy of essential oil vapors against C. maculatus using sealed 1 L containers. Whatman No. 1 paper squares (3 × 3 cm) were saturated with varying concentrations of essential oil (4–20 µl/L of air) and attached to the inner surface of the container lids to prevent direct contact with the insects. Ten pairs of C. maculatus, aged 0–48 h, were introduced into each container. The experiment included repeated treatments and an untreated control group. Mortality rates were recorded daily for five days under controlled environmental conditions (temperature 27 ± 1 °C, relative humidity 70 ± 5%, and a 14:10 light/dark photoperiod). The process continued until complete mortality of bruchid insects was observed in all treated groups48.

Total adult mortality was calculated using Abbott’s formula49:

$$\:\mathbf{P}\mathbf{v}=\frac{\varvec{P}\varvec{a}-\varvec{P}\varvec{i}}{100-\varvec{P}\varvec{i}}\:\:\times\:100$$

Where: Pc: percentage mortality, Pi: mortality observed in the negative control and Pa: mortality observed in the test.

Repellent effect of EO-MR

The repellency of EO-MC against adults C. maculatus was evaluated using the preferential zone methodology on filter paper, following the method described by50. Half-discs of Whatman No1 paper (8 cm) were treated with different doses of EO-MC (4–20 µl/0.5 ml acetone) or with pure acetone as a control. After allowing the treated halves to dry, they were reassembled into full discs, and five pairs of adult insects were placed at the center. Repellency was assessed 30 min later based on the distribution of the insects, using the formula by McDonald et al.50:

$$\:\mathbf{P}\mathbf{R}\:\left(\mathbf{\%}\right)=\frac{\mathbf{N}\:-\:\mathbf{N}\mathbf{T}}{\mathbf{N}\:+\:\mathbf{N}\mathbf{T}}\:\:\times\:100$$

Repellency percentage (RP) is determined by comparing the number of C. maculatus adults found on the acetone-treated (control) side (N) to those on the essential oil-treated side (NT).

Molecular Docking

The study explored the effects of OE-MC on insecticidal, antioxidant, and antimicrobial activities through molecular docking techniques.

Preparation of the ligand

We retrieved all GC/MS-identified molecules of EOMC from the PubChem database in SDF format. Subsequently, Schrödinger’s Maestro 11.5 software was used to prepare the molecular structures. The OPLS3 force field was applied, and the LigPrep tool was employed to generate 32 stereoisomers for each ligand, considering ionization states at pH 7.0 ± 2.051.

Protein Preparation

Proteins targeting NADPH oxidase (2CDU.pdb)52, β-ketoacyl synthase from E. coli K12 (PDB ID: 1FJ4), nucleoside diphosphate kinase from Staphylococcus aureus (PDB ID: 3Q8U), β−1,4 endoglucanase from A. niger (PDB ID: 5I77), sterol 14-alpha demethylase (CYP51) from C. albicans (PDB ID: 5FSA)53, and the crystal structure of an insecticide-resistant acetylcholinesterase (PDB ID: 6ARY) were obtained from the RCSB protein database (pdb)54. These proteins were then prepared according to the standard protocol by removing water molecules and all corresponding co-crystallized ligands while adding Gasteiger fillers.

The prepared proteins were docked to the main compound of the plant under study using Autodock software. Finally, all the interactions produced were visualized using Discovery Studio software55.

Statistical analysis

Mean standard deviation values were acquired using GraphPad Prism 8.0.1. Statistical analysis was conducted employing ANOVA, followed by Tukey’s test. Significance was determined by a p-value of less than 0.05.

Results and discussion

Molecular identification of M. chamomilla (L.)

PCR amplification of the rbcL gene yielded products approximately 600 bp in size. Sample A (M. chamomilla (L.)) demonstrated strong amplification of the rbcL primer. BLAST analysis, conducted using the NCBI GenBank, revealed that sequence A exhibited 99.29% identity with M. chamomilla var. recutita. The sequence was subsequently deposited in the GenBank database under the accession number OR838665 and identified as M. chamomilla var. recutita.

Using the Neighbor-Joining (NJ) method for phylogenetic analysis, the rbcL gene was shown to be a reliable tool for species identification and classification. Genetic similarities among species were utilized to construct phylogenetic trees, facilitating a deeper understanding of evolutionary relationships56. In this study, the analyzed plant sample clustered within a single clade of M. chamomilla (Fig. 1), indicating a very close genetic relationship.

Fig. 1
figure 1

Phylogenetic analysis of Matricaria chamomilla OR838665 samples.

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Volatile profile of essential oil

The yield of MCEO, obtained by Clevenger, was approximately 0.45 ± 0.26% (w/w), with the identification of 26 chemical compounds in the EO-MC representing 99.96% of the overall EO (Fig. 2; Table 1). Analysis via GC/MS indicated that sesquiterpenes comprised the predominant chemical class in EO-MC, accounting for 56.57%, followed by monoterpenes at 30.15%. The main components were germacrene (19.46%), followed by alpha-curcumene (19.00%) and caprylic acid (15.81%). It’s worth mentioning that the yield rate achieved in this research is inferior to that reported in earlier studies by Neelav et al., and Mahdavi et al., who documented rates of 1.27% and 0.65%, respectively57,58. However, it exceeds the rate reported by Hajjaj et al., who documented a rate of 0.4%59. The findings align with previous studies, indicating that the EO-MC from Romania is predominantly comprised of sesquiterpenes (91.65%), with oxyde de bisabolol A (70.2%) being the most abundant component60. Similarly, Neelav et al. (2023) demonstrated that M. chamomilla in India has a predominance of sesquiterpenes, representing 92.75% of the identified compounds58. Research carried out in Brazil by Demarque et al. (2012) revealed that OE-MC was composed by 18 elements, of which alpha-bisabolol oxide B (26.08%), beta-farnesene (16.35%) and bisabolol oxide A (14.7%) are the main constituents61. In contrast, Fadel et al. (2020) discovered 16 compounds, constituting 96.0% of the essential oil. The principal constituents found were alpha-Bisabolol oxide A (45.5%), alpha-bisabolol oxide B (14.7%), cis-beta-farnesene (5.7%), alpha- bisabolone oxide A (12.9%) and cis-beta-farnesene (5.7%)62. Further research by Stanojevic et al. (2016) revealed the presence of 52 different compounds in OE-MC, with (E)-β-farnesene (29.8%) being the main constituent, followed by α-farnesene (9.3%) and alpha-bisa- bolol oxide A (7%)63. The content and chemical composition of plant essences can fluctuate due to a variety of environmental factors. These include the specific part of the plant used, the plant’s stage of development, its maturity, the time of harvest and even the plant’s genetic heritage53.

Fig. 2
figure 2

GC-MS chromatogram of Matricaria chamomilla (L.) EO.

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Table 1 Phytochemical composition of M. chamomilla identified by GC/MS.
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Scavenging of the free radical DPPH•

The DPPH assay is a widely used method for evaluating the antioxidant activity of substances in laboratory settings. The test is based on the transfer of hydrogen (H) atoms or electrons (E) from antioxidant compounds to DPPH radicals dissolved in a solution. This interaction causes the DPPH radicals to change color from purple to yellow, signifying the formation of a stable diamagnetic molecule as a result of their reaction with reducing substances64. The alteration in color is quantified spectrophotometrically at a wavelength of 517 nm65. This method is highly effective and useful for assessing antioxidant activity. Lower IC50 values indicate a higher antioxidant capacity of the sample66,67. The antioxidant capacity of EO-MC was assessed using the DPPH test. The results obtained are summarized in Table 2. EO-MC demonstrated PDPH inhibition with an IC50 value of approximately 456.57 µg/mL. For BHT, a standard antioxidant, the IC50 value was 17.83 µg/mL (Fig. 3).

Table 2 Antibacterial activity (mm) and MIC in (µg/mL) of EO-MC against the bacterial strains tested.
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A literature review highlighted several studies on the antioxidant activity of EO-MC. One study conducted in Bosnia-Herzegovina revealed that essential oils derived from this species exhibit an IC50 concentration of 2.07 mg/mL63. Another study, conducted in northern Iran, reported an IC50 concentration of 5.63 mg/mL for EO-MC, further supporting its antioxidant properties68. These findings align with those reported by Chouia et al. (2018) and Qasem et al. (2022), who documented IC50 values of 416.57 µg/mL and 533.89 ± 15.05 µg/mL, respectively, further corroborating the antioxidant potential of EO-MC69,70. Conversely, these values are lower than those reported by Mahdavi et al. (2019) and Zeynep Demirci et al. (2018), who recorded IC50 values of 793.89 ± 15.45 µg/mL and 2.20 mg/mL, respectively. This variability may reflect differences in experimental conditions, plant origin, or extraction methods57,71. Furthermore, our results surpass those published by Sarma et al.. (2023) and Abdoul-latif et al. (2011), who recorded IC50 values of 21.95 and 4.18 µg/mL, respectively58,72.

Fig. 3
figure 3

DPPH test for antioxidant activity of essential oil and BHT (µg/mL).

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Antibacterial activity of EO-MC

The EO-MC compound showed considerable anti-bacterial activity versus all four types of bacteria tested, in particular Gram-negative bacteria such as Proteus mirabilis ATCC29906, Escherichia coli K12 and Klebsiella pneumoniae CIP A22 and Gram-positive bacteria such as Staphylococcus aureus A5TCC6633. The results of the disk diffusion method (Table 2) indicate that EO-MC blocked the growth of all examined species. Among the bacterial strains tested, the largest diameter of inhibition was found for E. coli (21.5 ± 0.5 mm), followed by P. mirabilis (15.5 ± 1.03 mm) and K. pneumoniae (12.5 ± 1.5 mm). The smallest inhibition diameter was found for S. aureus (11.667 ± 0.577 mm). These findings suggest that all the bacteria tested showed sensitivity to EO-MC. MIC results for EO-MC indicate that the lowest value was observed for S. aureus (2.5 ± 0.02 µg/mL), while the highest value was observed for E. coli (20.0 µg/mL). Essential oils of M. recutita, collected in Algeria, showed significant efficacy versus K. pneumoniae, E. coli and P. aeruginosa bacteria, with zones of inhibition varying from 10.67 mm to 18.33 mm69. In a Moroccan study by El-Assri et al. (2021), essential oil derived from M. recutita (L.) was shown to have considerable antibacterial efficacy versus B. subtilis, with a 15.2 mm diameter of inhibition and a MIC of 6.25 µL/mL, followed by S. aureus (14.13 mm) and an MIC of 8.33 µL/mL, then E. coli (13.28 mm) and an MIC of 8.33 µL/mL, and finally P. aeruginosa (13.07 mm) and an MIC of 8.33 µL/mL14. In Iran, Kazemi et al. (2015) demonstrated that EO-MC possessed significant anti-bacterial activity versus S. aureus, B. subtilis and P. aeruginosa, with zones of inhibition reaching up to 32 mm73. Conversely, oil extracted from M. recutita from the Horn of Africa (Djibouti) showed very encouraging antibacterial effects against eleven bacterial strains, with inhibition diameters of between 14 mm and 30 mm, while MICs vary from 1 to 4 µg/mL72. In addition, Soković et al. (2010) demonstrated that the MIC of M. recutita essential oil was 7 µg/mL (B. subtilis), 8 µg/mL (S. aureus) and 10 µg/mL (E. coli and P. aeruginosa)74. Other publications have shown that EO-MC was capable of destroying S.aureus, followed by E. coli and Salmonella enterica, with diameter of inhibition of 40, 31 and 25 mm, resp75. Mahdavi et al. (2019) demonstrated that M. recutita essential oil was effective against P. aeruginosa ATCC27853 (108.77%), Enterococcus faecalis ATCC 14,506 (106.7%), E. coli ATCC (99.66%) and K. pneumoniae ATCC 13,883 (75.04%)57. Numerous previous studies have shown that positive Gram bacteria are more susceptible than negative Gram bacteria73,76. However, this study is contrary to the previous one, as Gram-negative bacteria, such as E. coli, were found to be more sensitive to EO-MC.

Antifungal activity of EO-MC

The percentages of inhibition and MIC values of EO-MC versus the 4 fungal strains tested are shown in Table 3. The findings show that EO-MC exerts significant antifungal activity, with higher percentages of inhibition against A. niger (31.19%) than against A. flavus (17%). MIC values for EO-MC varied between 0.02 ± 0.0 to 0.04 ± 0.0 µg/ml. The results of this investigation align with previous scientific research demonstrating the antifungal efficacy of OE-MC versus various fungal strains. Al-snafi (2016), Göger et al. (2018), Roby et al. (2012), and Tolouee et al. (2010) have all documented similar findings in their respective studies34,36,77,78. The results obtained concerning the antifungal activity of EOMCs are consistent with results published in 2012 in Egypt by Roby et al. (2012)78, who showed antifungal activity of EOMCs against C. albicans ATCC10231 a 14 mm inhibition diameter and a MIC of 10 µg/mL, while the inhibition diameter of A. flavus ATCC 16,875 was 18 mm and the MIC 12.5 µg/mL. Abdoul-latif et al. (2011) conducted a study in Djibouti, which demonstrated notable antifungal effects versus C. albicans ATCC10231, with a 20 mm zone of inhibition and a MIC of 1 µg/mL. In addition, they observed activity against A. niger, with an inhibition zone of 17 mm and a MIC of 2 µg/Ml72. In parallel, results obtained in another study revealed significant antifungal efficacy, notably against A. flavus AFl375, A. niger FC24771, F. culmorum CBS 128,537 with percentage inhibition of 10.66–52.33%, 89.66–100%, 91-86.66.66.66%, respectively79. Moreover, Prabodh Satyal et al. (2015) indicated that the MIC of EOMC against C. albicans ATCC10231 was 313 µg/mL, and for A. niger ATCC 16,888, it was 625 µg/mL80.

Table 3 Antifungal activity (% inhibition) and MIC (mg/mL) of EO-MC against fungal strains tested.
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Insecticide activity test

Fumigation test

The results of the study, illustrated in Fig. 4 and Table 4, show a direct correlation between the applied dose, the duration of exposure, and the mortality of adult C. maculatus. Statistical testing revealed a significant correlation between C. maculatus adult mortality and the dose applied, as well as the duration of exposure (F = 271.73; df = 4, 40; P < 0.0001; F = 129.76; df = 3, 40; P < 0.0001). After a 72-hour exposure period, EO-MC showed increased toxicity at higher concentrations of 20 and 16 µL/L of air. In fact, EO-MC caused 100% absolute mortality in insects at concentrations of 16 µL/L and above after 72 h’ exposure (Table 3). The median lethal concentration (LC50) of EO-MC was 20.64 and 1.86 µL/L of air after 24 and 72 h, respectively. These findings suggest that EO-MC compounds are relatively more toxic to C. maculatus adults. The findings of this study align closely with those reported by Tandorost et al. (2012), El-Khyat et al. (2017), and Arannilewa et al. (2006), demonstrating a positive relationship between mortality rates and the duration and dosage of exposure81,82,83. Similarly, the results are consistent with previous research conducted by Abouellata et al. (2016), indicating that MC essential oil exhibits strong insecticidal activity against C. maculatus adults, with a lethal concentration (LC50 = 2.058 mg/L) observed after 24 h of fumigation84. Moreover, OE-MC displayed potent insecticidal effects against E. cautella adults at concentrations of 62.5, 125, and 250 mg/L of air over a 72-hour exposure period. Additionally, Mousavi et al. (2020) found that chamomile essential oil was more efficacious against this pest compared to other essential oils85. Furthermore, several studies have highlighted the effectiveness of essential oils rich in sesquiterpenes and monoterpenes against insect pests due to their potent volatile nature53,86,87.

Fig. 4
figure 4

Percentage mortality of C. maculatus adults as a function of concentration and duration of exposure to EO-MC. Means (± SD, n = 3) marked with a star indicate a significant difference according to two-way ANOVA and Tukey’s multiple interval tests at p < 0.05.

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Table 4 LC50 and χ2 of EO-MC against C. maculatus adults.
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Repellency test

For generations, aromatic plants have served as highly efficient natural insect repellents in traditional herbal medicine88. Several studies have evaluated the repellent properties of chamomile species against agricultural pests (Mousavi and Maroof 2020). This study assessed the repellent potential of OE-MC versus C. maculatus insects using the surface preference technique on filter paper. The results presented in Fig. 5 indicate that the repellent effect of OE-MC correlates with dosage. Specifically, at the smallest concentration examined (4 µL/cm2), a repellent effect of 30 ± 1.54% was observed. In contrast, at the highest concentration (20 µL/cm2), a repellent effect of 55 ± 19.14% was observed against C. maculatus adults. Based on a concentration of 12 µL/cm2, OE-MC was found to have an average repellency of 55%, using the calculation method of McDonald et al. (1970)50. The findings of this study accord with those of Allali et al. (2022), who also observed an average repellent activity (50.83%) of OE-MC against C. maculatus adults at a concentration of 20 µL/cm²89. Similarly, El-Khyat et al. (2017) showed that EO-MC presented moderate repellent activity (49.33 ± 1.33%) at the concentration of 62.5 mg/L of air against E. cautella83. These data indicate that EO-MC could be used as a natural repellent against harmful agricultural insects. Essential oils comprise intricate blends of volatile organic compounds, encompassing monoterpenoids and sesquiterpenes. These constituents exhibit insecticidal attributes, particularly by perturbing the hormonal equilibrium of insects90,91.

Fig. 5
figure 5

Repellent index of MC-EO against C. maculatus. Means (± SD, n = 3) marked with a star indicate a significant difference according to two-way ANOVA and Tukey’s multiple interval tests at p < 0.05.

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Molecular docking

During the assessment of antioxidant activity, three molecules namely butanoate, bisabolone oxide, and piperitenone oxide were found to be the most potent ones targeting the NAD(P)H oxidase active site. Butanoate was found to have the highest value of −5.313 kcal/mol, followed by bisabolone oxide with a value of −5.301 kcal/mol and piperitenone oxide with a value of −4.997 kcal/mol (Table 5). Moreover, butanoate showed interactions with two residues, TYR 159 and ILE 160, in the NAD(P)H oxidase active site, forming two H-bonds (Figs. 6A and 7A).

Table 5 Docking results of ligand in the active sites.
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Inhibition of acetylcholinesterase (AChE) is a common mechanism of action for many insecticides. Acetylcholinesterase is an enzyme that degrades the neurotransmitter acetylcholine in the nervous system. In insects, acetylcholine plays a crucial role in transmitting nerve impulses at synapses. Inhibiting acetylcholinesterase leads to an accumulation of acetylcholine, disrupting normal nerve function, and ultimately causing the insect’s death92,93. In our in silico study, bisabolone oxide, Globulol and Prenyl cyclopentanone exhibited the greatest inhibitory impact on acetylcholinesterase, Glide Gscore values for these compounds were − 6.988, −6.916 and − 6.626 kcal/mol respectively (Table 5). In addition, bisabolone oxide established a unique H-bond with residue TYR 282 in the acetylcholinesterase active site, as illustrated in Figs. 6B and 7B.

Docking scores represent the binding free energy between the ligand and the target protein. The more negative the value, the stronger the binding affinity. In general, values around − 6 kcal/mol indicate a moderate interaction, values ≤ − 7 kcal/mol reflect a strong and stable interaction, while values ≤ − 9 kcal/mol indicate a very high binding affinity.

In addition, the antibacterial effectiveness of a substance was tested against Escherichia coli K12 and Staphylococcus aureus ATCC6633 bacteria. The results showed that EO-MC had glide Gscores of −7.098, −6.545, and − 6.510 kcal/mol against E. coli β-ketoacyl-[acyl carrier protein] synthase, while butanoate, bisabolone oxide, and p-menthane were most effective against S. aureus nucleoside diphosphate kinase, with glide Gscores of −7.903, −5.252, and − 4.490 kcal/mol, respectively (Table 5). Furthermore, Figs. 6C and 7C show that piperitenone oxide formed two H-bonds with residues THR 300 and THR 302 in the active site of E. coli beta-ketoacyl-[acyl carrier protein] synthase. Meanwhile, Butanoate formed a single hydrogen bond with residue HIE 52 and a salt bridge with residue MG 159 in the active site of S. aureus nucleoside diphosphate kinase, as shown in Figs. 6D and 7D. In the evaluation of antifungal activity against C. albicans and A. niger, certain molecules were identified as active in the active site of sterol 14-alpha demethylase (CYP51) of the pathogenic yeast C. albicans. Spathulenol, globulol, and beta-himachalene were found to be active with glide Gscores of −7.015, −6.909, and − 6.854 kcal/mol, respectively (Table 5). In the active site of a beta-1,4-endoglucanase from A niger, researchers identified phenyl-tert-butanol, spathulenol, and piperitenone oxide as the most effective molecules. These molecules had glide gscore values of −5.060, −4.860, and − 4.629 kcal/mol, respectively. Moreover, among these three, phenyl-tert-butanol established a single hydrogen bond with residue TYR 227 in the same active site (Table 5; Figs. 6F and 7F).

Fig. 6
figure 6

The following is a list of ligands and their interactions with various active sites, as viewed in 2D: (A and D): Butanoate interacts with the active sites of NADPH oxidase and Staphylococcus aureus nucleoside diphosphate kinase. (B): Bisabolone oxide interacts with the active site of acetylcholinesterase. (C): Piperitenone oxide interacts with the active site of beta-ketoacyl-[acyl carrier protein] synthase from E. coli. (E): Spathulenol interacts with the energetic site of a beta-1,4-endoglucanase from A. niger. (F): Phenyl-tert-butanol interacts with the active site of sterol 14 alpha demethylase (CYP51) from a pathogenic yeast C. albicans.

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Fig. 7
figure 7

Three-dimensional viewer of ligand interactions in the active sites using Maestro 11.5, Schrödinger Suite 2018. A and D: interactions of butanoate with the active sites of NADPH oxidase and nucleoside diphosphate kinase from S. aureus. B: interactions of bisabolone oxide with the active site of acetylcholinesterase. C: Interactions of peritenon oxide with the active site of Escherichia coli beta-ketoacyl-[acyl carrier protein] synthase. E: Interactions of spathulenol with the energetic site of a beta-1,4-endoglucanase from A. niger. F: Interactions between phenyl-tert-butanol and the active site of sterol 14-alpha demethylase (CYP51) from the pathogenic yeast C. albicans.

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Conclusion

This study provides new insights into the chemical composition, molecular characterisation, biological properties, and molecular interactions of chamomile (Matricaria chamomilla L.) essential oil cultivated in the Taounate region of Morocco. Molecular characterisation of the plants, based on DNA sequencing, confirmed a 99.22% identity with M. chamomilla var. recutita. The GC-MS analysis revealed a unique chemical profile dominated by germacrene, α-curcumene, and capric acid, which differs from previously reported compositions for chamomile oils from other geographical origins. This highlights the influence of local environmental factors on the phytochemical variability of this species.

In addition to confirming the well-known antioxidant and antimicrobial properties of chamomile essential oil, our results demonstrate, for the first time, its strong insecticidal activity against Callosobruchus maculatus, a major storage pest of legumes, as well as significant activity against antibiotic-resistant bacterial strains. The combined in vitro and in silico approach allowed us to predict potential molecular targets involved in these biological effects, thereby providing mechanistic insights rarely explored in previous works on chamomile essential oils.

Overall, this research contributes to the literature by expanding the pharmacological and pesticidal potential of M. chamomilla EO from a Moroccan population that has not been previously studied in depth. These findings support its potential applications in pharmaceutical, food preservation, and eco-friendly pest control sectors, while paving the way for future studies on its formulation, safety evaluation, and mechanism of action.