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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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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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Synthesis of pyrimidines from flavokavains and their 2′-hydroxychalcone analogues
(2026-01-01)
Songpao, Laksakarn
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Poprom, Suriyaphong
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Chotsaeng, Nawasit
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Meesin, Jatuporn
Pyrimidines are an important class of heterocycles with diverse biological activities; however, their synthesis from certain substrates remains challenging. In this work, flavokavains and their derivatives were converted into pyrimidines, although initial reactions under basic conditions gave low yields due to a competing intramolecular isomerization to flavanones. Systematic investigation identified solvent as a key factor, with 1,4-dioxane effectively suppressing flavanone formation and enabling the synthesis of a broad range of pyrimidines in moderate to high yields. Both guanidine and benzamidine served as effective nucleophiles, and the reaction was readily scalable to the gram scale. This protocol provides a practical and efficient route to ortho-hydroxyphenyl-substituted pyrimidines, which may serve as useful scaffolds for medicinal chemistry.
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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
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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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Allyl Syringate
(2025-09-01)
Thimpa, Naruedech
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Poprom, Suriyaphong
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Songpao, Laksakarn
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Chotsaeng, Nawasit
Syringic acid (1) is a naturally occurring compound with diverse biological activities. Structural modification of syringic acid often enhances its utility; however, the spectroscopic data for several derivatives remain unreported, and the procedures to obtain them can be synthetically challenging. In this study, we report the allylation of syringic acid (1) to afford a novel derivative, allyl syringate (1c). The structure of this compound was confirmed by IR, NMR, and MS spectroscopy and compared with those of closely related derivatives (1a and 1b). These findings provide a useful foundation for further studies on the allylation of syringic acid and related phenolic acid derivatives.
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DBU-Mediated Reaction of 3-Chlorooxindole and 9-Xanthyl Fluorene for Synthesis of 3-Arylidene Oxindole
(2025-04-01)
Purahong, Nitchakan
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Teerawatananond, Thapong
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Chotsaeng, Nawasit
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Janthakit, Pattarapapa
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Nalaoh, Phattananawee
This work reports a new route for the synthesis of 3-(9H-fluoren-9-ylidene)indolin-2-one derivatives via the reaction of 3-chlorooxindoles and O-ethyl S-(9H-fluoren-9-yl) carbonodithioates mediated by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The reactions readily proceeded at room temperature, enable a collection of 3-alkenyl oxindoles to be prepared within a short reaction time (15 minutes). The 3-alkenyl oxindoles can be easily converted to 3-fluorenyl oxindoles by NaBH<inf>4</inf> reduction.
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Electrochemically driven reductive cyclization of o-nitroanilines: synthesis of 1,2-fused benzimidazoles and benzo[d]imidazoles
(2025-03-31)
Saetan, Jutamart
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Purahong, Nitchakan
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La-Ongthong, Kannika
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Hassa, Nattawoot
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Chotsaeng, Nawasit
The electrochemical synthesis of 1,2-fused benzimidazoles and benzo[d]imidazoles from o-nitroanilines in an undivided cell under constant current conditions was developed. The electrosynthesis proceeded through a tandem process involving nitro reduction/C(sp<sup>3</sup>)-H amination/condensation. The method can accommodate a broad range of o-nitroanilines and results in the desired products in yields of up to 99%. A plausible reaction mechanism was proposed on the basis of controlled experiments and cyclic voltammetry (CV) analysis. The benefits of the developed method include one-pot synthesis, open-air conditions, gram-scale synthesis and no requirement for a strong reductant.
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Synthesis and Cytotoxicity Evaluation of Novel C-3 Aminocarbamate Pregnenolone Derivatives
(2025-03-06)
Charoenying, Patchanee
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Chotsaeng, Nawasit
Cancer is one of the leading causes of death worldwide. There are many ongoing studies in the search for new treatments or drugs to combat cancer. Similarly, in this research, twelve 3-aminocarbamate pregnenolones (2a–2l) were designed, synthesized, and evaluated for their cytotoxicity against five cancer cell lines: Human hepatocellular carcinoma (HepG2), Human colon adenocarcinoma (HT-29), Human oral cavity carcinoma (KB), Human breast adenocarcinoma (MCF-7), Murine leukemia (P388), and one normal cell line, African green monkey kidney fibroblast (Vero), using the MTT assay. Notably, 3-aminobenzylcarbamate pregnenolone (2b), 3-diaminoheptylcarbamate pregnenolone (2f), and 3-diaminopropanolcarbamate derivative (2i) were the most potent against these cancer cell lines. Specifically, for P388 cell lines, these compounds were more potent than the positive control drug, vinblastine sulfate salt. Results from the SAR study demonstrated that the length of the alkyl chain of diaminocarbamate derivatives was crucial for their anticancer properties. These findings will be useful in the future research and development of anticancer drugs.
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Bioassay-Guided Extraction and Isolation of Natural Herbicides from Dried Zanthoxylum limonella Alston Fruits
(2025-01-01)
Chotpatiwetchkul, Warot
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Charoenying, Patchanee
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Teerarak, Montinee
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Meesin, Jatuporn
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Jongkon, Nathjanan
Weeds are problematic plant species around the world. Various strategies exist for controlling weeds, but chemical treatment remains the preferred method, particularly when using natural substances. In this research, a crude aqueous-methanol extract from dried Zanthoxylum limonella fruits was acid-base partitioned into four fractions: neutral extract (NE), acid extract (AE), basic extract (BE), and aqueous extract (AQ). These fractions were further separated into seventeen subfractions: NEF1 to NEF7, AEF1 to AEF5, and BEF1 to BEF5, which were then tested for herbicidal activity against the growth of Chinese amaranth (Amaranthus tricolor) and barnyard grass (Echinochloa crus-galli). Active subfractions were isolated via column chromatography and identified using spectroscopic methods, yielding seven active compounds: xanthoxyline (1), tambulin (2), atanine (3), prudomestin (4), skimmianine (5), p-methoxybenzoic acid (6), and methyl caffeate (7). Compounds 2–7 had not been previously reported in Z. limonella. Xanthoxyline (1) was identified as the most potent botanical herbicide, fully inhibiting seed germination of Chinese amaranth and barnyard grass. This compound also decreased seed imbibition and α-amylase activity in both species. Molecular docking studies on the α-amylase enzyme (PDB ID: 1BG9) revealed that the aromatic, hydroxy, and carbonyl groups of xanthoxyline (1) interact with the enzyme's active sites.
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Antioxidant and Antibacterial Activities of Jasminum officinale L. f. var. grandiflorum (L.) Kob. Leaf Extracts
(2024-05-01)
Charoenying, Patchanee
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Laosinwattana, Chamroon
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Chotsaeng, Nawasit
The investigation of phytochemicals and their effects on plants is currently receiving significant attention due to the well-known fact that plants contain secondary metabolites that have high levels of usefulness in various applications. These applications include food additives, biopesticides, and pharmaceuticals. In a recent study, we thoroughly examined the total phenolic content (TPC), and the antioxidant, and antibacterial properties of Jasminum officinale L.f. var. grandiflorum (L.) Kob. (also known as Spanish jasmine) leaf extracts, providing valuable insights into its potential benefits. Our study performed a crude methanol (ME) extraction of Spanish jasmine leaves with acid-base solvent partitioning, resulting in an acidic fraction (AE), a neutral fraction (NE), and an aqueous fraction (AQ). The Folin-Ciocalteu method was used to determine the TPC of the extracts. The AE fraction displayed the highest TPC (79.8±0.61 mgGAE/g dry weight), followed by the NE and AQ fractions. The extracts were further evaluated for their antioxidant activity using the DPPH assay. The AE fraction had the highest antioxidant activity with an EC<inf>50</inf> value of 4.6±0.40 µg/mL. The main active compound, oleuropein, was isolated and determined using spectral data. The isolated compound displayed excellent antioxidant activity with an EC<inf>50</inf> value of 13.0±0.06 µg/mL. Moreover, the antibacterial activity of the Spanish jasmine leaf extracts was calculated using the disc diffusion method based on the minimum inhibitory concentration. The AE fraction exhibited activity against the Gram-negative bacteria, Vibrio parahaemolyticus, with a MIC value of 0.78 µg/mL. The AE fraction also displayed the highest degree of activity against Staphylococcus strains, including drug-resistant strains (MRSA and VRSA), with a MIC range of 0.39-12.5 µg/mL. It is important to highlight that the AE fraction demonstrated the highest level of activity against all VRSA strains tested despite their resistance to vancomycin and oxacillin. These findings strongly indicate that Spanish jasmine leaves possess potent natural antioxidant and antibacterial properties, positioning them as a highly promising plant source.

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