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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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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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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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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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Synthesis and Anti-Plant Pathogenic Fungal Activity of Flavokawain-Derived Flavones and Related Flavones Against Rhizoctonia solani
(2024-01-03)
Onnom, Panuwat
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Chotpatiwetchkul, Warot
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Meesin, Jatuporn
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Thapanapongworakul, Pilunthana
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Kittiwongwattana, Chokchai
Flavones are organic compounds in the flavonoid family that have a diverse range of biological functions. In this research, many flavones with various substituents were designed and synthesized from flavokawains A, B, and C, and their chalcone derivatives via an iodinecatalyzed oxidative cyclization process. All synthetic flavones were investigated for antifungal activities against Rhizoctonia solani, a plant pathogenic fungus. At 400 µg, most of the substances did not inhibit the tested species and R. solani growth was inhibited by only obromoflavone (40) by 74.88±0.91%. This indicated that the detrimental effect of flavones depends on the type and position of substituent, with the ortho bromo group showing the most promise. The molecular docking study on the succinate dehydrogenase (SDH) enzyme revealed that the bromophenyl moiety (ring B) is a key molecular substructure of the flavone fungicide. The findings of this study will be used to develop novel plant pathogenic fungicides.
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DBU-Mediated Dimerization: Facile Access to 9,9′-Bifluorenylidenes and Isoindigos
(2023-11-14)
Purahong, Nitchakan
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Hongthong, Sakchai
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Chotsaeng, Nawasit
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Kuhakarn, Chutima
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Meesin, Jatuporn
The present work describes the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-promoted self-dimerization of 9-chlorofluorenes and 3-chlorooxindoles for the preparation of the corresponding 9,9 -bifluorenylidene and isoindigo derivatives in moderate to good yields of 29 97%. The reactions proceed readily in a short reaction time under mild and metal-free conditions. Scale-up syntheses (5.0 mmol) of selected 9,9 -bifluorenylidene derivatives proceed in decent yields, highlighting the synthetic utility of the reported protocol.
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Sulfonylated Indeno[1,2-c]quinoline Derivatives as Potent EGFR Tyrosine Kinase Inhibitors
(2023-06-06)
Hengphasatporn, Kowit
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Aiebchun, Thitinan
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Mahalapbutr, Panupong
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Auepattanapong, Atima
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Khaikate, Onnicha
The epidermal growth factor receptor (EGFR) has been considered a potential target for lung cancer therapy due to its essential role in regulating the survival and proliferation of cancer cells. Although erlotinib, a potent EGFR tyrosine kinase (EGFR-TK) inhibitor, has been used as the first-line drug for lung cancer treatment, acquired drug resistance caused by the T790M secondary mutation of EGFR-TK inevitably develops after a median response duration of 9-13 months. Thus, the search for promising compounds to effectively target EGFR-TK has become an imperative necessity. In this study, the kinase inhibitory activities of a series of sulfonylated indeno[1,2-c]quinolines (SIQs) against EGFR-TK were experimentally and theoretically investigated. Among the 23 SIQ derivatives studied, eight compounds showed enhanced EGFR-TK inhibitory activity (IC<inf>50</inf> values of ca. 0.6-10.2 nM) compared to the known drug erlotinib (IC<inf>50</inf> of ∼20 nM). In a cell-based assay in human cancer cell lines with EGFR overexpression (A549 and A431 cells), the eight selected SIQs all showed more significant cytotoxicity against A431 than A549 cells, consistent with the higher EGFR expression in A431 cells. Molecular docking and FMO-RIMP2/PCM calculations revealed that SIQ17 occupies the ATP-binding site of EGFR-TK, where its sulfonyl group is mainly stabilized by C797, L718, and E762 residues. Triplicate 500 ns molecular dynamics (MD) simulations also confirmed the binding strength of SIQ17 in complex with EGFR. Overall, the potent SIQ compounds obtained in this work could be further optimized for developing novel anticancer drug candidates targeting EGFR-TK.
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Dimerization of 3-Chlorooxindoles Mediated by Potassium Ethylxanthate: Synthesis of Isoindigos
(2022-08-17)
Meesin, Jatuporn
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Chotsaeng, Nawasit
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Kuhakarn, Chutima
A novel dimerization of 3-chlorooxindoles promoted by potassium ethylxanthate to access isoindigo derivatives is described. The reactions proceeded readily at room temperature in short reaction times. A mechanistic study revealed that the 3-chlorooxindole is initially converted into O-ethyl S-(2-oxo-2,3-dihydro-1H-indol-3-yl) dithiocarbonate, which subsequently undergoes dimerization with elimination of arbon disulfide. In almost all cases, analytically pure isoindigos were isolated in moderate to good yields without a requirement for chromatographic purification.
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Synthesis of indolo- and benzothieno[3,2-c]quinolines via POCl3 mediated tandem cyclization of o-alkynylisocyanobenzenes derived from o-alkynyl-N-phenylformamides
(2022-08-01)
Uppalabat, Thikhamporn
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Tapdara, Anyawan
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Khaikate, Onnicha
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Worakul, Thanapat
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Surawatanawong, Panida
A synthesis of indolo[3,2-c]quinolines and benzothieno[3,2-c]quinolines has been developed employing o-alkynyl-N-phenylformamide derivatives as the substrates. The reaction proceeded via a tandem process involving POCl<inf>3</inf>-assisted intramolecular cyclization of the firstly formed o-alkynylisocyanobenzenes, leading to the desired products in moderate to high yields. Furthermore, the reaction is efficient on a gram-scale and the products were structurally modified by amination, Suzuzki-Miyaura reaction and Heck cross-coupling. Photophysical properties of several selected indolo[3,2-c]quinolines were studied by UV-Visible and fluorescence spectroscopy and rationalized using time-dependent DFT calculations.

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