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Article

Phytotoxicity Evaluation of Leaf Extracts and Isolation of Phytotoxic Compounds from Trewia nudiflora Linn. for Natural Weed Control

by
Mst. Rokeya Khatun
1,2,3,*,
Shunya Tojo
4,
Toshiaki Teruya
5 and
Hisashi Kato-Noguchi
1,2
1
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Miki 761-0795, Kagawa, Japan
2
The United Graduate School of Agricultural Sciences, Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566, Ehime, Japan
3
Department of Entomology, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
4
Graduate School of Engineering and Science, University of the Ryukyus, 1 Senbaru, Nishihara 903-0213, Okinawa, Japan
5
Faculty of Education, University of the Ryukyus, 1 Senbaru, Nishihara 903-0213, Okinawa, Japan
*
Author to whom correspondence should be addressed.
Processes 2025, 13(11), 3691; https://doi.org/10.3390/pr13113691 (registering DOI)
Submission received: 6 October 2025 / Revised: 9 November 2025 / Accepted: 12 November 2025 / Published: 15 November 2025
(This article belongs to the Special Issue Extraction, Separation, and Purification of Bioactive Compounds)
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Abstract

This research focuses on examining the phytotoxic effect of leaf extracts of T. nudiflora on the growth of one dicot, Lepidium sativum L. (cress), and one monocot, Lolium multiflorum Lam. (Italian ryegrass), plant. Significant shoot and root growth suppression occurred in both plants treated with different concentrations of T. nudiflora leaf extracts (p ≤ 0.05). An increase in T. nudiflora leaf extracts was associated with a progressive decline in the root and shoot development of both plants. The half maximum inhibitory doses (I50 values) for cress and Italian ryegrass root growth were 0.00037 and 0.00071 g dry weight (DW), while concentrations of 0.00129 and 0.006 g DW equivalent T. nudiflora leaf extract in mL–1 were needed for a similar reduction in shoot growth. According to these values, root development exhibited a greater sensitivity than shoot development to the applied extract, and dicot plants were more susceptible to T. nudiflora extracts than monocot plants. Chromatographic fractionation of the extracts led to the successful isolation of two phenolic acids; protocatechuic acid and gallic acid. Bioassays of T. nudiflora leaf extract-derived two phenolic acids against treated plants demonstrated significant toxic action that correlated with the concentrations of the compounds, which varied between the two plants. These results suggest that these two phenolic acids are key contributors to the phytotoxic activity observed in extracts from T. nudiflora leaves and might contribute to the development of sustainable agricultural practices, including the design of allelopathy-based weed management strategies.

1. Introduction

The global population is expected to reach 9.7 billion in the next three decades, posing a challenge for the agricultural sector to meet the increasing food demand with limited land availability [1,2]. To tackle this issue, agricultural intensification has been employed. Weeds, unwanted plants that grow alongside crops, compete for vital growth resources, leading to reduced crop yields, poor-quality produce, and higher production costs [3,4]. Herbicides have been widely used to suppress weeds due to their effectiveness, ease of use, and affordability. However, their extensive use has resulted in detrimental environmental effects such as soil and water pollution and health risks for humans and animals [5]. Beneficial organisms and biodiversity also suffer from herbicide use [6]. In addition, the excessive utilization of herbicides has led to the emergence of herbicide-resistant weeds, thereby exacerbating the issue [7]. Hence, it is imperative to prioritize the advancement of safer and more sustainable alternatives to herbicides. Reducing the use of synthetic herbicides for weed control and increasing the use of bioherbicides produced from plant sources are vital to safeguarding our ecosystem from the damaging effects of herbicides. The utilization of phytotoxic compounds derived from plants has become increasingly favored as an effective biological alternative to conventional approaches for managing weeds.
Research into the phytotoxic potential of different plant species provides valuable insights into complex allelopathic interactions (plants or microorganisms exert direct or indirect influences—beneficial or harmful—on surrounding biological communities, known as allelopathy) [8,9]. Allelopathy offers opportunities for developing sustainable weed control practices and natural resource management strategies through plant-derived phytotoxic compounds [10,11,12]. Phytotoxic compounds derived from diversified plant extracts have the potential to enhance crop productivity while concurrently suppressing weed growth. These additives may be incorporated into agricultural systems by applying them as mulch, integrating them through intercropping, establishing them as cover crops, or administering them directly to the soil as drenches [13,14]. Therefore, it is essential to screen and evaluate plant species exhibiting phytotoxicity and its compounds to substitute conventional herbicides with environmentally sustainable alternatives.
Trewia nudiflora Linn. is a medium-sized Euphorbiaceae tree native to Southeast Asia. T. nudiflora is found in various types of forests, including moist deciduous forests, evergreen forests, and mixed forests (Figure 1) [15]. It tends to thrive in areas with well-drained soils and moderate amounts of rainfall. However, this plant has a long history of use in traditional medicine in various parts of Asia. Some of the medicinal uses of T. nudiflora include curing pain, gout, headaches, toothaches, and menstrual cramps [16,17,18]. Leaves, particularly those obtained through water and ethanol extraction, have been documented to exhibit antioxidant, anti-ulcerogenic, cerebroprotective properties, among others, with no observed phytotoxic effects documented thus far [19,20,21,22]. Therefore, the present study was designed to investigate the herbicidal efficacy of aqueous methanolic leaf extracts of T. nudiflora, as well as to isolate and characterize the responsible phytotoxic compounds for this activity.

2. Materials and Methods

2.1. Plant Species Collection

Leaf sampling of T. nudiflora was conducted in Sirajganj, Bangladesh (24°36′28″ N, 89°37′54″ E), from March to June, 2020. Following collection, the leaves were washed and air-dried in the shade, and then ground into a powdered form to facilitate the extraction procedure. For growth experiments, two plant species were selected: Lepidium sativum L. (cress), representing dicots, and Lolium multiflorum Lam. (Italian ryegrass), representing monocots. These species were chosen because they have previously been recognized as responsive to phytotoxic plant extracts and compounds [23].

2.2. Methods of T. nudiflora Leaf Extraction

T. nudiflora leaf powder (100 g) underwent an extraction process using aqueous methanol (30:70) for 48 h. The mixture was then filtered using No. 2 filter paper (Toyo Roshi Kaisha Ltd., Tokyo, Japan). A second round of extraction was performed using methanol for 24 h, followed by filtration. The yielded crude extract was the amalgamation of filtrates that evaporated at 40 °C. This extract was solubilized in MeOH to create seven different treatment concentrations (0.0001, 0.0003, 0.001, 0.003, 0.01, 0.03, and 0.1 g DW equivalent T. nudiflora extract in mL−1). The prepared aliquots were applied to a 28 mm Petri plates and dried in a flow chamber. Each of them contained ten sprouts of Italian ryegrass, which had been sprouted at 25 °C for 48 h, and ten alfalfa seeds. These seeds were hydrated with 600 µL of a solution containing Tween 20 (0.05% v/v), and there was a control group treated with 0.05% Tween 20 only. The Petri plates were placed under controlled growth conditions (25 °C in the dark) for 48 h. Following this growth period, the lengths of both the root and shoot of the tested plants were measured to assess the growth-retarding effects of T. nudiflora in comparison to the control group.

2.3. Different Purification Steps for the Isolation of Phytotoxic Compounds

The air-dried leaf powder of T. nudiflora (2900 g) was extracted twice following the methods described in the previous section to obtain enough crude. The crude was mixed with water, and the pH of the aqueous residue was balanced to 7.0 for partitioning. EtOAc (ethyl acetate) was used for partitioning, and the process was repeated 6 times with the same volume of the solvent. The efficacy of different purification steps was determined using a cress growth bioassay. The EtOAc fraction showed greater cress growth inhibition, and this fraction was eluted into 9 different fractions by a column containing 60 g of silica gel (70–230 mesh, Nacalai Tesque, Kyoto, Japan). EtOAc in n-hexane (F1–F9) with 20–80%, 100% (v/v; 150 mL in each fraction), and 200% MeOH was used to make the eluents of 9 fractions. The eluents of fractions F5 (60%) and F6 (70%) had the most inhibitory activity, and these two fractions were individually separated into 5 fractions (F1–F5) by a column containing 100 g of Sephadex LH-20 (GE Healthcare, Uppsala, Sweden). The eluents consisted of 20, 40, 60, and 80% of hydro-MeOH (v/v; 150 mL in each fraction) and 100% of MeOH (150 mL two times). The eluent of fraction F3 (60%) from both F5 and F6 silica fractions inhibited cress growth the most and was fractionated by the C18 cartridge (1.2 × 6.5 cm; YMC Co., Ltd., Kyoto, Japan) into 7 fractions (F1–F7) eluted with 20–60, 80% of aqueous-MeOH (v/v; 15 mL in each fraction), and 200% of MeOH (30 mL). The eluent of active fraction F1 (20%) from both F3 Sephadex fractions was finally purified by reverse-phase HPLC (500 × 10 mm I.D., S-5 µm, 12 nm; YMC Co., Ltd., Kyoto, Japan) with 15 and 25% (v/v) of hydro-MeOH, respectively, at a flow rate of 1.5 mL min−1 (wavelength 220 nm at 40 °C), and the active peak was detected at retention times of 38–50 and 150–155 min, respectively. Final purification of the peak was carried out using a 3 and 5 µm size column (4.6 I. D. × 250 mm; Inertsil ODS-3; GL Sciences Inc., Tokyo, Japan) with 8 and 10% (v/v) of aqueous-MeOH, respectively, at a flow rate of 0.5- and 0.8 mL min−1, and the active peak was found at the retention times of 13–38 and 30–70 min, respectively.

2.4. Compound Efficacy Evaluation Through Growth Bioassay

To conduct a bioassay, solutions with concentrations of 0.3, 1, 3, 10, and 30 mM of the two compounds were prepared by solubilizing each in 4000 µL of MeOH. These solutions were added to the filter paper in the Petri plate and placed in a flow chamber to dry. Each Petri plate was seeded with 10 sprouts of Italian ryegrass and ten cress seeds, along with a control. Each Petri plate was hydrated with 600 µL of 0.05% Tween 20 and then transferred to a growth chamber. Following a 48 h period, the growth of the treated plants was measured and compared to the control to determine the percentage of growth inhibition associated with each concentration of the compounds.

2.5. Analysis

Statistical analysis was performed on the phytotoxic bioassay data of T. nudiflora extract and its identified compounds on test plants roots and shoots. This analysis utilized a one-way ANOVA followed by Tukey’s post hoc test (p = 0.05). The data were presented as a percentage difference from the control group and were processed using SPSS software (16.0 version). The GraphPad Prism 6.0 software [24] was used to calculate the half-maximum inhibitory concentration (I50 values represent the concentrations necessary to inhibit 50% of the growth of the tested species) [25]) for each compound, and the LSD test was employed to determine statistical differences between the values, as the differences between individual values are minimal. The extract bioassay was repeated two times with a total of 3 replications each (n = 60), while the compound bioassay was performed once with 3 biological replicates (n = 30).

3. Results

3.1. Phytotoxicity of T. nudiflora Extracts on Cress and Italian Ryegrass

Aqueous-MeOH extracts of T. nudiflora leaf significantly inhibited the root and shoot growth of Italian ryegrass and cress with 0.0003 g DW equivalent T. nudiflora leaf extract in mL–1 (Figure 2 and Figure 3). More than 50% of root and shoot growth was reduced by 0.001 and 0.01 g DW equivalent T. nudiflora leaf extract in mL–1. At the concentration of 0.003 g DW, the root growth of cress and Italian ryegrass was inhibited by ≥70%, and shoot growth was reduced by 60.39 and 22.78%, respectively. Cress root growth was limited to >85% with 0.01 g DW equivalent T. nudiflora leaf extract in mL–1, whereas Italian ryegrass root and shoot were reduced by 82 and 70% with the same doses, respectively. Italian ryegrass growth (root and shoot) was inhibited by >90%, and cress growth was completely stopped at a concentration of 0.03 g DW equivalent T. nudiflora leaf extract in mL–1. Both plants’ growth completely ceased at the dose of 0.1 g DW equivalent T. nudiflora leaf extract in mL–1. The half-maximum inhibitory concentrations (I50 values) for cress and Italian ryegrass root growth were 0.00037 and 0.00071 g DW, while concentrations of 0.00129 and 0.006 g DW equivalent T. nudiflora leaf extract in mL–1 were required for a similar shoot growth reduction (Table 1). According to these values, the extracts exerted a stronger inhibitory effect on root compared to shoot growth, and dicot species exhibited greater vulnerability than monocot species.

3.2. Identification of the T. nudiflora-Derived Isolated Compounds

The chemical structure of the compounds was identified by HRESIMS, and all NMR spectroscopic data was recorded with an optical rotation of 500 MHz, identifying them as colorless powder. Compound 1 was found to be C7H6O4. The 1H NMR spectrum of the compound as measured in CD3OD showed the presence of three aromatic proton signals at δH 7.43 (1H, d, J = 1.6), 7.42 (1H, dd, J = 8.1) and 6.79 (1H, d, J = 8.1). The 1H NMR spectrum of the compound was confirmed as protocatechuic acid, aligning with this documented data [26] (Figure 4a).
Compound 2 was identified as having the chemical formula C7H6O5. The 1H NMR spectrum of the compound showed the presence of two aromatic proton signals at δH 7.05 (2H, s) and confirmed as gallic acid, agreeing with this data [27] (Figure 4b).

3.3. The Phytotoxicity of Protocatechuic and Gallic Acid Against Test Plants

The effects of protocatechuic and gallic acids on plant growth were evaluated by examining their phytotoxicity toward cress and Italian ryegrass (Figure 5 and Figure 6). Significant cress root growth inhibition was noted at concentrations of 0.3 mM of protocatechuic acid and 3 mM of gallic acid, respectively, while shoot growth inhibition was observed with 3 mM of both compounds (p ≤ 0.05). At a dosage of 10 mM, protocatechuic acid decreased cress root and shoot by 83.5 and 49.2%, respectively, but gallic acid inhibited them by 76.4 and 67.8%, respectively. At the highest concentration (30 mM), protocatechuic acid completely inhibited cress growth; in contrast, gallic acid inhibited root and shoot growth by 92.1 and 83.6%, respectively. In the case of Italian ryegrass, significant growth inhibition was observed at 3 mM of protocatechuic acid, whereas gallic acid significantly arrested Italian ryegrass root and shoot growth at a concentration of 1 mM. With a dosage of 10 mM, protocatechuic acid restrained Italian ryegrass root and shoot by 90.5 and 50.1%, while gallic acid inhibited it by 73.5 and 63.7%, respectively. At the highest concentration (30 mM), protocatechuic acid completely stopped Italian ryegrass root growth, and shoot growth was reduced to 84.5% of the control. Gallic acid inhibited root and shoot growth by 96 and 85.2%, respectively, with the same concentration. The 50% growth reduction of the two plants was achieved with 2.07–4.50 mM of gallic acid and 1.50–10.18 mM of protocatechuic acid. These results suggest that the plants were more responsive to gallic acid than to protocatechuic acid (Table 2) (Figure 7).

4. Discussion

Aqueous-MeOH extracts of T. nudiflora leaf exhibited significant phytotoxicity towards the development of Italian ryegrass and cress at concentrations of 0.0003 g DW equivalent extract mL–1, except Italian ryegrass shoot (Figure 3). It was clear that the half-maximum inhibitory doses of the root were the lowest compared to the shoots of both treated dicot and monocot plants. The level of phytotoxicity resulting from the extracts correlates with its concentration, and the impact varies across plant species. The growth inhibition of both tested species was similarly observed to be dose-dependent when exposed to leaf extracts derived from Acacia pennata and Stephania japonica [28,29]. Hence, the demonstrated dose-dependent phytotoxicity of T. nudiflora aqueous-MeOH leaf extracts on the experimented plants highlights its strong allelopathy. This prompted the isolation of the extracts through chromatography, resulting in the identification of two phenolic acids: protocatechuic and gallic acids. These compounds could likely account for the observed phytotoxicity of T. nudiflora on the test plants.
Evaluation of protocatechuic acid and gallic acid via bioassays conducted on Italian ryegrass and cress demonstrated notable phytotoxic effects that were contingent upon dosage levels (Figure 5 and Figure 6). Several investigations have revealed that the presence of these phenolic acids in mango cultivars has been linked to a constraining impact on the growth of various weed and crop plants, with the degree of this phenomenon dependent on their respective concentrations [30,31,32]. Moreover, protocatechuic and gallic acids demonstrated notable antiviral, anticancer, antibacterial, antidiabetic, antioxidant, and anti-inflammatory properties [33,34,35,36,37]. Previous studies on extracts of T. nudiflora leaves identified various compounds with phytotoxic properties, including phenolics [38,39]. Growth restrictions mediated by phenolic acids have been reported by different researchers and are well established for exerting inhibitory impacts on seed germination, root elongation, photosynthesis, and nutrient uptake. For instance, Xuan and Pardo-Muras [40,41] recorded the inhibitory effects of phenolic acids from various plants on weed growth through growth bioassays. In our investigation, we observed a consistent pattern where higher levels of protocatechuic and gallic acids corresponded to a gradual reduction in the growth of cress and Italian ryegrass. This result aligns with the findings of [42], who found that protocatechuic and gallic acids derived from goat weed effectively restricted the growth of M. vaginalis and barnyard grass. The presence of phenolics prompts increased permeability of cell membranes, resulting in leakage of cellular contents and an increase in lipid peroxidation. Consequently, this hampers the growth of plant tissues, interferes with nutrient uptake, and disrupts normal development. A study [43] demonstrated that elevated doses of gallic acid had effects on the inner cell structure of algae, alleviating membrane lipid peroxidation and damaging cell structure. In contrast, protocatechuic acid had a notable suppressive impact on the rate of net photosynthesis and the conductance of stomata in Rhododendron delavayi seedlings [44]. Moreover, hydroxyl benzoic acid and polyphenols have been documented to counteract the functional effects of plant hormones such as gibberellin and IAA, resulting in the inhibition of regular physiological processes in plants [45].
According to Figure 7, the susceptibility of two plants to protocatechuic acid and gallic acid varies, with root growth being more affected than shoot growth. The level of sensitivity is influenced by the concentration of the individual compounds. Our research is consistent with that of [46], where phenolic acids demonstrated similar root growth retardation in Poa annua and Buchloe dactyloides. The heightened vulnerability of root growth could be due to the direct contact of the newly emerged root cells with the compounds, as roots primarily ensure structural stability and acquire essential nutrients, whereas shoot systems perform photosynthetic activity and coordinate the allocation of produced resources throughout the plant. Phenolic acids in allelopathic interactions seem to increase the permeability of root tips, leading to increased oxidative stress, which hampers plant growth, as suggested by Bubna [47]. Other studies, such as [48,49], have also proposed that increased root tip permeability contributes to reduced root growth. On another note, the structural differences in protocatechuic acid and gallic acid play a significant role in their varying toxic effects on the test plants, as pointed out by Dayan [50]. One research [51] demonstrated different phytotoxic effects of phenolic acids on monocot and dicot weeds. Variations in the arrangement and position of functional hydroxyl and methoxy groups in these phenolic acids could potentially explain the differences in their bioactivity, as reported in several studies [52,53]. The distinct responses to allelopathic compounds are also influenced by the unique biochemical and physiological roles specific to each plant species, as indicated in the results of [54,55]. Similar findings were reported in the studies conducted by Khatun et al. (2023) [38] and identified two polyphenols in T. nudiflora extracts, while this study is the first to identify protocatechuic acid and gallic acid as phytotoxic compounds in these extracts. Utilizing water extracts from sorghum resulted in a 40% reduction in barnyard grass biomass and an 18% increase in rice yield, as demonstrated in [56]. Thus, our experimental results suggest similar implications for T. nudiflora extracts and the identified protocatechuic acid and gallic acid in weed management. This could involve directly incorporating these extracts into agricultural practices or developing bioherbicides from these compounds to promote sustainable weed control.

5. Conclusions

The aqueous-MeOH extracts of T. nudiflora exhibited significant phytotoxic action on two weed species, cress and Italian ryegrass. Through chromatographic purification, two phenolic acids—protocatechuic acid and gallic acid—were successfully isolated from the extract. Subsequent bioassays conducted on the tested weeds confirmed that both compounds exerted concentration-dependent phytotoxicity, although the extent of their activity varied between the weed species. These findings imply that the herbicidal efficacy of T. nudiflora is strongly associated with the presence of these phenolic compounds. Collectively, the T. nudiflora crude extract and the isolated phytotoxic phenolics represent promising, environmentally benign alternatives to synthetic herbicides. Further investigations, particularly those evaluating their effectiveness under field conditions and unraveling the underlying mode of action, might offer valuable insights for sustainable weed suppression. Advancing this research could reduce reliance on conventional chemical herbicides and foster more eco-friendly weed management strategies in agricultural systems.

Author Contributions

Conceptualization, M.R.K. and H.K.-N.; methodology, M.R.K., S.T., T.T., and H.K.-N.; software, M.R.K.; validation, S.T., T.T., and H.K.-N.; formal analysis, M.R.K.; investigation, M.R.K.; data curation, H.K.-N.; writing (original draft preparation), M.R.K.; writing (review and editing), H.K.-N.; visualization, M.R.K.; supervision, H.K.-N. All authors have read and agreed to the published version of the manuscript.

Funding

The Japanese government provided funding for this research through a Ministry of Education, Culture, Sports, Science and Technology (MEXT) scholarship (Grant Number MEXT-203626).

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Acknowledgments

We thank the United Graduate School of Agricultural Sciences (UGAS), Ehime University, Japan, for correcting the English of this manuscript.

Conflicts of Interest

The authors declare no conflicts of interest.

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Processes 13 03691 g001
Figure 1. Leaf (A) and trunk (B) of T. nudiflora tree.
Figure 1. Leaf (A) and trunk (B) of T. nudiflora tree.
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Figure 2. Effects of seven different hydro-methanolic extracts concentrations of T. nudiflora leaves on the growth (root and shoot) of cress and Italian ryegrass.
Figure 2. Effects of seven different hydro-methanolic extracts concentrations of T. nudiflora leaves on the growth (root and shoot) of cress and Italian ryegrass.
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Figure 3. Effects of seven different hydro-methanolic extracts concentrations of T. nudiflora leaves on the growth (root and shoot) of cress and Italian ryegrass. Values are means ± SEs of three replications (n = 60), and the bars represent the mean SE. Significance in differences between treatment and control groups was indicated by distinct alphabetical lettering, determined using Tukey’s HSD test (p ≤ 0.05).
Figure 3. Effects of seven different hydro-methanolic extracts concentrations of T. nudiflora leaves on the growth (root and shoot) of cress and Italian ryegrass. Values are means ± SEs of three replications (n = 60), and the bars represent the mean SE. Significance in differences between treatment and control groups was indicated by distinct alphabetical lettering, determined using Tukey’s HSD test (p ≤ 0.05).
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Figure 4. The molecular structure of identified protocatechuic acid (a) and gallic acid (b).
Figure 4. The molecular structure of identified protocatechuic acid (a) and gallic acid (b).
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Figure 5. Effects of protocatechuic acid and gallic acid treatment on cress growth (root and shoot). Values are means ± SEs of three replications (n = 30), and the bars represent the mean SE. Significance in differences between treatment and control groups depicted by distinct alphabetical lettering (Tukey’s HSD at p ≤ 0.05).
Figure 5. Effects of protocatechuic acid and gallic acid treatment on cress growth (root and shoot). Values are means ± SEs of three replications (n = 30), and the bars represent the mean SE. Significance in differences between treatment and control groups depicted by distinct alphabetical lettering (Tukey’s HSD at p ≤ 0.05).
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Figure 6. Effects of protocatechuic acid and gallic acid treatment on Italian ryegrass growth (root and shoot). Values are means ± SEs of three replications (n = 30), and the bars represent the mean SE. Significance in differences between treatment and control groups depicted by distinct alphabetical lettering (Tukey’s HSD at p ≤ 0.05).
Figure 6. Effects of protocatechuic acid and gallic acid treatment on Italian ryegrass growth (root and shoot). Values are means ± SEs of three replications (n = 30), and the bars represent the mean SE. Significance in differences between treatment and control groups depicted by distinct alphabetical lettering (Tukey’s HSD at p ≤ 0.05).
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Figure 7. The half-maximum inhibitory concentrations of protocatechuic acid and gallic acid for cress and Italian ryegrass growth (root and shoot).
Figure 7. The half-maximum inhibitory concentrations of protocatechuic acid and gallic acid for cress and Italian ryegrass growth (root and shoot).
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Table 1. The half-maximum inhibitory concentrations (I50 values) for cress and Italian ryegrass root and shoot growth.
Table 1. The half-maximum inhibitory concentrations (I50 values) for cress and Italian ryegrass root and shoot growth.
Test Plant SpeciesI50 Value
(g DW Equivalent T. nudiflora Leaf Extract in mL−1)
Dicots
Monocots		 rootshoot
Cress0.00037 b 0.00129 b
Italian ryegrass0.00071 b0.00600 a
Distinct letters within each treatment group denote significant differences (p < 0.05; LSD test).
Table 2. I50 values of protocatechuic and gallic acids identified from the methanolic extracts of T. nudiflora for cress and Italian ryegrass growth (shoot and root) inhibition.
Table 2. I50 values of protocatechuic and gallic acids identified from the methanolic extracts of T. nudiflora for cress and Italian ryegrass growth (shoot and root) inhibition.
Test PlantsI50 Value
(mM)
Cress Protocatechuic acidGallic acid
Shoot10.18 a4.50 d
Root1.50 h3.77 e
Italian ryegrassShoot9.92 b2.07 g
Root4.90 c3.27 f
Distinct letters within each treatment group denote significant differences (p < 0.05; LSD test).
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MDPI and ACS Style

Khatun, M.R.; Tojo, S.; Teruya, T.; Kato-Noguchi, H. Phytotoxicity Evaluation of Leaf Extracts and Isolation of Phytotoxic Compounds from Trewia nudiflora Linn. for Natural Weed Control. Processes 2025, 13, 3691. https://doi.org/10.3390/pr13113691

AMA Style

Khatun MR, Tojo S, Teruya T, Kato-Noguchi H. Phytotoxicity Evaluation of Leaf Extracts and Isolation of Phytotoxic Compounds from Trewia nudiflora Linn. for Natural Weed Control. Processes. 2025; 13(11):3691. https://doi.org/10.3390/pr13113691

Chicago/Turabian Style

Khatun, Mst. Rokeya, Shunya Tojo, Toshiaki Teruya, and Hisashi Kato-Noguchi. 2025. "Phytotoxicity Evaluation of Leaf Extracts and Isolation of Phytotoxic Compounds from Trewia nudiflora Linn. for Natural Weed Control" Processes 13, no. 11: 3691. https://doi.org/10.3390/pr13113691

APA Style

Khatun, M. R., Tojo, S., Teruya, T., & Kato-Noguchi, H. (2025). Phytotoxicity Evaluation of Leaf Extracts and Isolation of Phytotoxic Compounds from Trewia nudiflora Linn. for Natural Weed Control. Processes, 13(11), 3691. https://doi.org/10.3390/pr13113691

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