Somala, Naphat

Preferred name

Somala, Naphat

Alternative Name

Somala, N.

Main Affiliation

School of Agricultural Technology

naphat.so@kmitl.ac.th

Now showing 1 - 10 of 15

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Characterization of Diaporthe fungal extract composition and phytotoxicity on the aquatic noxious weed Eichhornia crassipes: inhibitory effects on photosynthetic machinery and membrane integrity
(2025-01-01)
Somala, Naphat
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Manichart, Nutcha
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Thongbang, Muanfan
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Wichittrakarn, Pattharin
;
Laosinwattana, Chamroon
Fungal extract-based natural herbicides are a promising avenue for the development of sustainable weed management. The study investigates the herbicidal activity of fungal extracts against the prominent aquatic invasive weed Eichhornia crassipes (water hyacinth). The ethanol crude fraction derived from Diaporthe sp. strain EC010 demonstrated the highest phytotoxicity. Chemical characterization using gas chromatography-mass spectrometry revealed 2(3H)-furanone, dihydro-4-hydroxy- (22.81%), linoelaidic acid (6.87%), and hordenine (6.62%) as major constituents. Phytotoxicity was evaluated by wrapping bioassay under greenhouse conditions. Observable foliar damage, such as necrosis, chlorosis, and depigmentation, occurred within 1 day after treatment (DAT). The rapid onset of visible damage within 1 DAT and the detailed analysis of tissue damage are particularly noteworthy. Lesion progression reflected the phytotoxicity of the extract, increasing to 77.33% visible phytotoxicity at 14 DAT for the highest concentration (8.0% w/v). Microscopic analysis revealed disintegration and complete deformation of epidermal and parenchymal tissues, and treated plants featured extensive aerenchyma spaces. Furthermore, the Diaporthe sp. extract decreased chlorophyll a, b, and carotenoid concentrations while increasing electrolyte leakage and malondialdehyde, indicative of weed deterioration. The current work offers valuable insights for sustainable and eco-friendly strategies in the management of water hyacinth populations in a lentic ecosystem. The findings suggest that Diaporthe sp. extract could serve as a natural herbicide, offering an environmentally friendly alternative to synthetic chemicals in managing water hyacinth.
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Oxidative damage in Echinochloa crus−galli seeds exposed to Diaporthe sp. (Diaporthales, Ascomycota) fungal extract during germination
(2024-01-01)
Somala, Naphat
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Manichart, Nutcha
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Laosinwattana, Chamroon
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Wichittrakarn, Pattharin
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Yoneyama, Kaori
This study investigates the inhibitory effects of Diaporthe sp. isolate EC010 extract on barnyardgrass (Echinochloa crus-galli) seed germination and growth. Application of sequential extraction techniques to Diaporthe sp. mycelium resulted in partial separation of the phytotoxic compounds. The ethyl acetate (EtOAc) fraction most greatly reduced seed germination (81.01%), root length (89.18%), and shoot length (84.74%) compared to the control. Chemical characterization using gas chromatography-mass spectrometry revealed major constituents of linoleic acid, butyl ester (9.69%), hexadecanoic acid (7.99%), and 14-pentadecenoic acid (7.86%). With regard to physiological and biochemical indexes, treated seeds exhibited lower imbibition, significantly decreased α-amylase (EC 3.2.1.1) activity (p<0.05), and increased accumulation of malondialdehyde (85.52%) and hydrogen peroxide (141.10%). Moreover, activity of the antioxidant enzymes superoxide dismutase (EC 1.15.1.1) and guaiacol peroxidase (EC 1.11.1.7) was upregulated (67.24 and 61.62%, respectively), while catalase (EC 1.11.1.6) activity was downregulated (-33.75%). The inference is that an imbalance in ROS levels combined with reduced antioxidant potential drives the gradual accumulation of oxidative damage in seed cells and consequent loss of seed viability. All told, these results confirm the Diaporthe extract to induce oxidative stress and inhibit antioxidant enzymes. This study clearly demonstrates the oxidative damage associated with Diaporthe allelochemicals.
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Ultrasonic emulsification of Cananga odorata nanoemulsion formulation for enhancement of herbicidal potential
(2025-12-01)
Laosinwattana, Chamroon
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Somala, Naphat
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Dimak, Jantra
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Teerarak, Montinee
;
Chotsaeng, Nawasit
A nanoemulsion was fabricated from Cananga odorata essential oil (EO) and stabilized by incorporation of Tween 80 using ultrasonication. The major constituents of the EO were benzyl benzoate, linalool, and phenylmethyl ester. Differing sonication amplitude (20–60%) and time (2–10 min) were assessed for effects on nanoemulsion droplet size and polydispersity index (PI). The smallest droplet size of 43.98 nm (PI 0.222) was obtained using 40% amplitude for 8 min; this nanoemulsion was evaluated for its droplet characteristics and pre-emergence herbicidal activities on Amaranthus tricolor. FT-IR confirmed ultrasonic emulsification to not affect the EO components. Regarding stability, storage at 4 °C was determined appropriate, with droplet size changing slightly after five weeks. Assays of herbicidal potential showed the coarse emulsion and nanoemulsion to both reduce A. tricolor germination and growth, with the nanoemulsion being more effective at a given concentration and the difference in effectivity correlating to droplet size. Remarkably, treatment with 250 ppm nanoemulsion and coarse emulsion respectively resulted in 100% and 63.75% germination inhibition. Both emulsions decreased seed imbibition and alpha-amylase activity. The highest relative electrolyte leakage was achieved in seed treated with the nanoemulsion. Therefore, this ultrasonic-based nanoemulsion may have utility as bioherbicide alternative.
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High-Energy Emulsified Clove Essential Oil Nanoemulsion as a Natural Herbicidal Product: Germination Suppression and Seed Structure Alteration in Echinochloa crus-galli
(2026-03-01)
Sikhao, Potjana
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Somala, Naphat
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Manichart, Nutcha
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Dimak, Jantra
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Poonpaiboonpipat, Thanatsan
Clove (Syzygium aromaticum (L.) Merr. & L.M. Perry) essential oil (EO)-based nanoemulsions may have a promising future in eco-friendly herbicide development. Clove EO was found to have a high eugenol content of 87.27%. Organic-solvent-free nanoemulsions using clove EO as a bioactive ingredient were fabricated using ultrasonication and microfluidization emulsification methods. Fourier-transform infrared spectroscopy confirmed that both emulsification methods did not affect the EO components. The droplet size of optimized nanoemulsions was determined using dynamic light scattering. The smallest size of 66.9 nm was obtained by microfluidization at 20,000 psi and eight passes. Additionally, the smallest droplet size for a sonicated nanoemulsion was 103.9 nm, obtained by ultrasonication at 20% for 6 min. Transmission electron microscopy confirmed the droplet sizes of both optimized nanoemulsions. In a storage test, both optimized nanoemulsions were stored at 4 °C for at least four weeks. Finally, both nanoemulsions were evaluated on pre-emergence herbicidal activities against Echinochloa crus-galli. The results showed that both nanoemulsions inhibited E. crus-galli germination and seedling growth, and additionally, inhibited seed imbibition and α-amylase activity. Micro-morphological and ultrastructural analysis was observed using a scanning electron microscope and an energy dispersive X-ray spectrometer (SEM-EDS). SEM-EDS micrographs of the treated seeds showed that the seed structure was damaged, especially the endosperm, leading to the inhibition of seed germination.
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Citronella essential oil-based nanoemulsion as a post-emergence natural herbicide
(2023-12-01)
Somala, Naphat
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Laosinwattana, Chamroon
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Chotsaeng, Nawasit
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Teerarak, Montinee
A natural herbicide nanoemulsion was fabricated from citronella (Cymbopogon nardus L.) essential oil (CEO) and a nonionic surfactant Tween 60 mixed with Span 60 at hydrophilic-lipophilic balance 14 using a microfluidization method. The main constituents of CEO were citronellol (35.244%), geraniol (21.906%), and citronellal (13.632%). CEO nanoemulsion droplet size and polydispersity index (PI) were evaluated by dynamic light scattering (DLS). The smallest droplet size (33.2 nm, PI 0.135) was obtained from a microfluidizer at 20,000 psi, 7 cycles. Nanoemulsion droplet in transmission electron microscopy correlated with DLS confirmed CEO to successfully produce nanoemulsion. The herbicidal activity of the nanoemulsion as a foliar spray was evaluated against Echinochloa cruss-galli and Amaranthus tricolor as representative narrow- and broadleaf weed plants, both of which presented visual toxicity symptoms. The modes of action of the nanoemulsion were then determined in terms of membrane integrity (relative electrolyte leakage; REL), malondialdehyde (MDA), and photosynthetic pigment contents. The results showed increase in REL and MDA which indicated the destruction of the treated plants; additionally, chlorophylls and carotenoid contents were decreased. Consequently, CEO nanoemulsion may have the possibility to act as a natural herbicide resource, and natural herbicides from citronella nanoemulsions could be good alternatives for use in sustainable agriculture.
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Chemical Analysis and Bioactivities of Gaultheria procumbens L. Essential Oil: Herbicidal, Antioxidant and Antibacterial Activities
(2023-03-02)
Jintanasirinurak, Sumonrat
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Manichart, Nutcha
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Somala, Naphat
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Laosinwattana, Chamroon
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Teerarak, Montinee
The chemical composition of wintergreen (Gaultheria procumbens L.) essential oil (WEO) was identified by gas chromatography-mass spectrometry (GC-MS) and evaluated for its biological activities. Methyl salicylate (100%) was the main compound in the wintergreen essential oil. The herbicidal efficacy of the WEO was confirmed by germination inhibition, radical and shoot length reduction, and phytotoxicity assessment with Echinochloa crus–galli and Amaranthus tricolor seedlings. The WEO significantly reduced the germination and seedling growth of both weeds. It showed highly significant inhibition of seed germination (93.37%) and seedling growth of A. tricolor at the highest dose (6 µL/petri dish) assayed. The WEO was formulated as an emulsifiable concentrate (EC-EO) for post-emergence application, and was applied at a range of concentrations from 10 to 80 mL/L. Both treated plant leaves appeared wilted and slightly discolored within 1 day of application (DAA). The visible weed control efficacy was most remarkable at 80 mL/L treatment, which was a level that ultimately killed the seedlings of both species at 3 DAA, suggesting promising herbicidal potential for the WEO. The WEO showed weak scavenging activity with a high IC<inf>50</inf> value (IC<inf>50</inf> >2×104 and >5×104 ppm) for DPPH scavenging and metal chelating assays, respectively. The WEO showed moderate antibacterial activity, and its zones of inhibition against bacterial test strains were 7.90±0.8 mm and 23.9±0.9 mm for Escherichia coli TISTR 780 and Staphylococcus aureus TISTR 1466, respectively. Therefore, the results suggest the possibility of using WEO as an active ingredient to produce natural herbicides.
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Herbicidal Activity of the Invasive Weed Malachra capitata L.: Growth Stage Dependence, Bioassay-Guided Fractionation, and Physiological Effects on Seed Germination
(2026-03-01)
Wichittrakarn, Pattharin
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Sathuwijarn, Sirichai
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Manichart, Nutcha
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Yoneyama, Kaori
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Sikhao, Potjana
The invasive weed Malachra capitata is unsuitable for human or animal consumption but has recently attracted attention for potential alternative uses. In this study, the allelopathic potential of M. capitata for weed control was investigated, as were its allelopathic effects on selected crops. The influence of plant developmental stage on its phytotoxic activity was also assessed. In addition, the physiological effects of the extract on seed germination were investigated. Aqueous leaf extracts were obtained across a range of growth stages and evaluated using seed germination and seedling growth bioassays, followed by bioassay-guided fractionation and GC-MS analysis. Leaves extracts collected at 35 days after planting exhibited the strongest inhibitory activity. Dicot plant species (Phaseolus lathyroides, Cucumis sativus, Brassica oleracea, and B. chinensis) were more susceptible to M. capitata extracts than grassy species (Echinochloa crus-galli, Zea mays, and Oryza sativa), indicating selective phytotoxicity. In pot experiments, application of leaf residues as surface mulch at rates of 100, 200, and 400 g/m2 significantly reduced P. lathyroides emergence by 11.25%, 35.00%, and 71.25%, respectively. Bioassay-guided fractionation indicated the ethyl acetate-soluble acidic fraction to contain the active allelochemicals. This inhibition was associated with reduced water uptake and suppression of α-amylase activity during seed germination. The most abundant GC-MS detectable components of the acidic fraction were octadecane (12.45%), eicosane (9.74%), and hexadecane (9.60%). Overall, these findings highlight the allelopathic potential of M. capitata, providing a foundation for further applied research and supporting its valorization for sustainable weed management.
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Design, Synthesis, and Herbicidal Activity of Novel Dihydrochalcones Derived from Flavokawains and Their Analogs
(2026-05-01)
Poprom, Suriyaphong
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Meesin, Jatuporn
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Chotpatiwetchkul, Warot
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Waratchareeyakul, Watcharee
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Chotsaeng, Nawasit
Weeds are a major cause of crop production losses worldwide, and environmentally friendly chemical control based on natural or semisynthetic compounds has attracted increasing attention. In this study, flavokawains, a class of natural chalcones, and their analogues were converted into dihydrochalcones (1–27) via Pd-catalyzed hydrogenation. The herbicidal activities of these compounds were evaluated against Chinese amaranth (Amaranthus tricolor) and barnyard grass (Echinochloa crus-galli). Several compounds significantly inhibited seed germination and seedling growth in both species. Herbicidal activity was strongly influenced by the type and position of aromatic substituents, with electron-withdrawing groups and meta substitution providing higher activity. The meta-chloro derivative (15) exhibited the highest activity, markedly inhibiting seed germination as well as shoot and root growth. Further investigation of its mode of action revealed that this compound interfered with seed imbibition, inhibited α-amylase activity, and affected membrane integrity and malondialdehyde (MDA) levels in A. tricolor in a concentration-dependent manner. These findings provide valuable insights for the development of natural product-derived herbicides.
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Formulation process, physical stability and herbicidal activities of Cymbopogon nardus essential oil-based nanoemulsion
(2022-12-01)
Somala, Naphat
;
Laosinwattana, Chamroon
;
Teerarak, Montinee
Essential oil-based bioherbicides are a promising avenue for the development of eco-friendly pesticides. This study formulated nanoemulsions containing citronella (Cymbopogon nardus) essential oil (CEO) as an herbicidal product using a high-pressure homogenization method with hydrophilic-lipophilic balance (HLB) values ranging 9–14.9 for the surfactant mixture (Tween 60 and Span 60). The CEO was high in monoterpene compounds (36.333% geraniol, 17.881% trans-citral, 15.276% cis-citral, 8.991% citronellal, and 4.991% β-citronellol). The nanoemulsion at HLB 14 was selected as optimal due to having the smallest particle size (79 nm, PI 0.286), confirmed by transmission electron microscopy. After 28 days of storage, particle size in the selected formulation changed to 58 and 140 nm under 4 °C and 25 °C, respectively. Germination and seedling growth assays with Echinochloa crus-galli showed that the nanoemulsion exerted a significant dose-dependent inhibitory effect at all tested HLBs (9–14.9) and concentrations (100–800 µL/L). The inhibitory effect was greatest at HLB 14. Treatment of E. cruss-galli seed with the HLB 14 nanoemulsion significantly reduced seed imbibition and α-amylase activity. Our findings support that CEO nanoemulsions have a phytotoxic effect and hence herbicidal properties for controlling E. cruss-galli. Accordingly, this nanoemulsion may have potential as a bioherbicide resource.
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Formulation and evaluation of nanoemulsions from Jasminum officinale essential oil for controlling postharvest browning and maintaining quality in jasmine (Jasminum sambac) flowers
(2025-01-01)
Yeamsuriyotai, Kittiya
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Pradabkun, Natthamon
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Manichart, Nutcha
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Yonsawad, Nipaporn
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Khamchatra, Na Monrug
The jasmine (Jasminum sambac (L.) Aiton) flower has delicate petals, resulting in rapid browning after harvest. The aim of this study was to search for an innovative postharvest treatment for delaying browning of jasmine petals using plant essential oils. J. officinale L. f. var. grandiflorum (L.) essential oil was found to reduce peroxidase activity in jasmine flower by 44.21% in the in vitro condition. The antioxidant activities and chemical composition of J. officinale essential oil were subsequently characterized. The essential oil exhibited the ability to scavenge 2,2-diphenyl-1-picrylhydrazil (DPPH) radicals with a 50% inhibition (EC<inf>50</inf>) value of 6.72 ± 0.89 mg/mL, a chelating effect with EC<inf>50</inf> value of 7.42 ± 1.59 mg/mL, and reducing power with EC<inf>0.5</inf> value of 14.89 ± 0.73 mg/mL. GC-MS analysis detected 29 compounds in the oil, with benzyl alcohol (20.68%) and benzyl acetate (19.87%) predominating. As plant essential oils have restricted water solubility, an oil-in-water emulsion was formulated using a spontaneous emulsification method. The resulting J. officinale essential oil naonoemulsion (JEN) had an oil droplet size of 70.2 ± 0.39 nm and a narrow polydispersity index. In vivo testing confirmed the inhibitory effects of JEN on jasmine flower browning and relevant enzyme activities. Jasmine flowers were soaked in various concentrations of JEN for 5 min, packed in polyethylene plastic bags, and stored in a refrigerator at 10 ± 3°C with relative humidity 66 ± 5%. Flowers treated with 1 and 2 mg/mL JEN showed effective delay of petal browning and maintained good quality with minimum flower opening index, high freshness score, and high color retention index. JEN treatment also reduced phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD) activities, indicating postponement of the browning process. In addition, scanning electron microscopy micrographs of treated flower epidermis cells revealed delayed cell wall collapse, indicating retention of intact cells. Taken together, these results support JEN as a potential preventative of enzymatic browning and hence petal browning in jasmine flower.

Somala, Naphat

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